Pour citer cet article : Le Loir M, Cochener B. Résultats à long terme de l’implantation phaque de chambre postérieurepour la correction des amétropies fortes. J Fr Ophtalmol (2012), doi:10.1016/j.jfo.2011.06.006
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ARTICLE ORIGINAL
Résultats à long terme de l’implantation phaque dechambre postérieure pour la correction desamétropies fortes
Long-term results of posterior chamber phakic intraocular lens implantationfor correction of high ametropia
M. Le Loir ∗, B. Cochener
Service d’ophtalmologie, hôpital Morvan, CHU de Brest, 5, avenue Foch, 29609 Brest cedex,France
Recu le 6 janvier 2011 ; accepté le 23 juin 2011
MOTS CLÉSImplantationphaque ;ICL ;Suivi à long terme
RésuméObjectif. — Évaluer l’efficacité, la stabilité et la sécurité de l’implantation phaque de chambrepostérieure à l’aide de l’implant Visian ICL STAAR dans le traitement des amétropies fortes avecun recul moyen de cinq ans (de 3,5 à dix ans).Patients et méthodes. — Nous avons réalisé une étude rétrospective monocentrique portantsur 90 yeux de 53 patients amétropes forts (45 myopes, dix hypermétropes, 35 présentant unastigmatisme combiné) opérés par un seul chirurgien, en utilisant principalement le modèle ICLV4 (87 yeux). Nous avons évalué en pré- et postopératoire les principaux critères d’efficacitéréfractive, la densité cellulaire endothéliale, l’opacification cristallinienne et les dimensionsdes différents compartiments intraoculaires.Résultats. — L’acuité visuelle sans correction moyenne atteint 0,77 au 12e mois postopératoire ;17 des 90 yeux ont bénéficié d’un traitement photoablatif complémentaire pour astigmatismerésiduel. Quarante-huit pour cent des yeux implantés ont gagné au moins une ligne de meilleureacuité visuelle corrigée. Après l’implantation, la diminution de la densité cellulaire endothélialeest restée stable à 0,69 %/an, et 91 % des yeux n’ont pas présenté d’opacification cristallinienne.Les distances moyennes endothélium/ICL et ICL/cristallin ont respectivement été mesurées à2,41 mm et 0,52 mm. Enfin, le niveau de satisfaction des patients atteints 96 % au 36e moispostopératoire.
Pour citer cet article : Le Loir M, Cochener B. Résultats à long terme de l’implantation phaque de chambre postérieurepour la correction des amétropies fortes. J Fr Ophtalmol (2012), doi:10.1016/j.jfo.2011.06.006
L’implantation phaque représente l’option chirurgicaleréfractive de choix pour la correction des amétropies fortes(myopie supérieure à neuf dioptries, hypermétropie et astig-matisme supérieurs à quatre dioptries). Elle reste unealternative en cas d’intolérance aux lentilles de contactou de contre-indication au LASIK (cornée fine ou oblate,opacités cornéennes, enophtalmie. . .). Au-delà des limitesde la photoablation, elle respecte la cornée (et sa prola-ticité), autorise une meilleure qualité de vision, offre uneréversibilité réfractive et anatomique, et enfin permet unéventuel traitement photoablatif complémentaire (Bioptic).Cette technique est le plus souvent réalisée de facon bila-térale chez des patients âgés de 20 à 40 ans.
Les contre-indications actuelles sont les suivantes : uneinfection chronique des annexes oculaires, un antécédent dechirurgie oculaire, de pathologie inflammatoire cornéenneet intraoculaire, de pseudoexfoliation ou de dispersion pig-mentaire, une insuffisance endothéliale (< 2000 cell/mm2),une hypertonie oculaire ou un glaucome, une opacificationcristallinienne même débutante, un antécédent de décolle-ment rétinien ou de pathologie maculaire (à exclure par OCTet/ou angiographie fluorescéinique), tout patient porteurd’une pathologie générale telle que le diabète sucré, unemaladie auto-immune ou une pathologie systémique sévèreou soumis à un traitement immunosuppresseur. De plus,comme dans toute chirurgie réfractive, en cas d’amblyopieminime et modérée, il faut prévenir le patient des limitesde récupération. De même tout astigmatisme supérieur à1,5 dioptries ne constitue pas une contre-indication abso-lue mais il faudra évoquer la possibilité de choix parmi la
chirurgie incisionnelle, l’implantation intraoculaire toriqueet la photoablation secondaire. Enfin, la grossesse est unecontre-indication transitoire [1—3].
L’implantation phaque de chambre antérieure est deve-nue impopulaire en raison de complications tardivesobtenues avec les implants à appui angulaire et à un moindredegré avec les implants à fixation irienne [4—8]. La plusredoutée est l’œdème cornéen par perte cellulaire endo-théliale, lié au contact mécanique des anses en appui surl’endothélium, aux microtraumatismes mettant en contactendothélium et implant au sein d’une chambre antérieuretrop étroite, ou à une mauvaise biotolérance du matériaude l’implant. Citons également l’ovalisation pupillaire et lacataracte précoce. Ces complications ont conduit au retraitdu marché de la quasi-totalité des implants phaques dechambre antérieure à appuis angulaires (à l’exception del’Acrysof phaque [Alcon®]) et à la nécessité d’un suivi rigou-reux à long terme [9,10].
L’implantation phaque de chambre postérieure peut êtreréalisée grâce à deux modèles d’implants. Le plus uti-lisé, l’ICL (Implantable Collamer Lens, distribué par StaarSurgical®) est constitué d’un matériel flexible et hydrophile,le Collamer, dont l’indice de réfraction est de 1,45. Sa lar-geur est de 7,0 mm et la détermination de sa longueur (quivarie de 11,5 à 13 mm) repose en partie sur la distance« blanc à blanc » de limbe à limbe horizontal, approxima-tion du diamètre du sulcus ciliaire. L’optique, plan-concave,présente un diamètre compris entre 4,5 et 5,5 mm selon lapuissance dioptrique de l’implant. Cet implant se positionneen chambre postérieure, ses haptiques étant positionnéesdans le sulcus ciliaire (Fig. 1—3). Le PRL (Phakic Refrac-tive Lens, distribué par Zeiss®) fait de silicone, souple et
Pour citer cet article : Le Loir M, Cochener B. Résultats à long terme de l’implantation phaque de chambre postérieurepour la correction des amétropies fortes. J Fr Ophtalmol (2012), doi:10.1016/j.jfo.2011.06.006
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Implantation phaque de chambre postérieure pour correction des amétropies fortes 3
Figure 1. Implant ICL sphérique (STAAR Surgical) souple, consti-tué de Collamer, de largeur 7 mm et de longueur comprise entre11,5 et 13 mm, avec une optique plan-concave de 4,5 à 5,5 mm dediamètre selon la puissance. Les haptiques sont au contact du sulcusciliaire.
élastique, repose théoriquement sur les fibres zonulaires etse positionne librement en chambre postérieure.
L’implantation précristallinienne est à ce jour restéede diffusion timide en France du fait de sa réputationd’inducteur de cataracte précoce de type sous-capsulaireantérieur, notamment pour les premières générations d’ICL.Mais la validation par la Food and Drug Administrationd’implants ICL V4 (quatrième génération) au dessin optimiséet le recul des implants de chambre antérieure expliquentsa diffusion exponentielle dans le monde [11—13].
Figure 2. Implant ICL torique (STAAR Surgical) positionné enchambre postérieure ; les repères axiaux (flèches) diamétralementopposés, et visualisables en mydriase extrême, sont alignés avecl’axe de l’astigmatisme préopératoire.
Figure 3. Implant ICL en position précristallinienne (flèche)lors d’un examen biomicroscopique en mydriase thérapeutique.L’implant apparaît à distance de l’endothélium cornéen, et à dis-tance de la cristalloïde antérieure (vault).
Depuis 1998, de nombreuses études ont démontrél’efficacité et la prédictibilité réfractive de l’implantationphaque de chambre postérieure [13—20] avec des résul-tats comparables à ceux obtenus avec les implants phaquesde chambre antérieure [21—25]. En revanche, la durée desuivi souvent inférieure à trois années [13—20], ne permet-tait pas de valider la sécurité de la technique vis-à-vis decomplications à long terme : opacification cristallinienne,perte cellulaire endothéliale, syndrome de dispersion pig-mentaire, glaucome pigmentaire et blocage pupillaire.Récemment, Kamiya et al. [26] ont conclu à l’efficacitéréfractive et la sécurité de l’implantation ICL avec un reculprolongé à 4 ans pour la correction des myopies comprisesentre −4 et −15 dioptries. Pesando et al. [27] ont effec-tué une étude avec dix ans de suivi mais uniquement surdes patients hypermétropes. Notre travail est original à plu-sieurs titres. Avec un recul moyen proche de cinq ans, iltraite de l’implantation ICL pour corriger non seulementles myopies, mais aussi les hypermétropies et astigmatismesmodérés à sévères, en s’affranchissant du biais « opérateur-dépendant ».
Notre étude réalisée à l’aide de l’ICL V4 proposed’évaluer l’efficacité réfractive et abérrométrique maiségalement les sécurités anatomiques (endothéliale, cris-tallinienne, angulaire irido-cornéenne) et pressionnelleintraoculaire grâce à un suivi régulier et prolongé à dix ans.
Patients et méthodes
Nous avons réalisé une étude monocentrique rétrospec-tive sur la période août 1998—novembre 2008, incluant90 yeux de 53 patients forts amétropes (myopie compriseentre − 6 et − 23 D, hypermétropie comprise entre + 4,5 et+ 10 D ou porteurs d’un astigmatisme combiné compris entre1,75 à 3,25 D), âgés de 18 à 44 ans, intolérants aux len-tilles de contact et ne présentant pas de contre-indicationà l’implantation phaque. Tous les patients ont été opé-rés par le même chirurgien, à l’aide de l’implant phaquede chambre postérieure ICL STAAR® (3 V3 et 87 V4). La
Pour citer cet article : Le Loir M, Cochener B. Résultats à long terme de l’implantation phaque de chambre postérieurepour la correction des amétropies fortes. J Fr Ophtalmol (2012), doi:10.1016/j.jfo.2011.06.006
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réfraction cible est l’emmétropie. Le calcul du diamètre del’implant est basé sur la distance « blanc à blanc » mesuréeau biomicroscope et la puissance est déterminée à l’aide ducalculateur fourni par STAAR Surgical®. Ont été implantés55 ICL sphériques de puissance moyenne − 14,9 D pour lesmyopes et + 7,5 D pour les hypermétropes et 35 ICL toriques(en cas d’astigmatisme préopératoire supérieur à 1 D).
Le même protocole opératoire a été respecté pourtous les patients. Sous anesthésie générale, pupille pré-parée en mydriase, l’incision principale est réalisée à12 heures, d’une longueur de 3,2 mm et tunnellisée sur2 mm. Le produit viscoélastique est injecté en regard ducentre pupillaire afin de réaliser un matelas protecteurde la cristalloïde antérieure. L’introduction de l’implantdans la chambre antérieure se fait à l’aide d’un injec-teur, puis les haptiques sont prudemment positionnées enarrière de l’iris au moyen d’un micromanipulateur. Uneinjection intracamérulaire d’acéthylcholine (Miochol®) per-met l’obtention d’un myosis. Une iridectomie périphériquelinéaire perforante est réalisée avant lavage du viscoélas-tique. En fin d’intervention, l’étanchéité de l’incision estassurée par suture de monofilament nylon 10.0 (ôtée àJ5 postopératoire). Les implantations bilatérales sont réa-lisées à une semaine d’intervalle.
Pour chaque patient, les signes fonctionnels suivants(douleurs oculaires, halos colorés, dédoublement, éblouis-sement, confort en vision mésopique et photopique) ontété relevés et côtés de l’absence totale de gêne (0) à lagêne invalidante (3+) à l’aide d’un questionnaire de qualitéde vision. L’examen clinique complet s’est plus particu-lièrement porté sur l’acuité visuelle sans correction, lameilleure acuité visuelle corrigée, les réfractions manifesteet cycloplégique (mesurée au plan lunettes avec respectd’une distance vertex de 12 mm), et sur l’examen biomi-croscopique sans et avec dilatation pupillaire étudiant laforme pupillaire, la dispersion pigmentaire, la profondeurde chambre antérieure, la transparence cristallinienne (àl’aide de la Lens Opacification Classification Scale III), letonus oculaire et le fond d’œil. La densité et la morpholo-gie cellulaires endothéliales cornéennes centrales ont été
analysées par microscopie spéculaire non contact (moyennede trois mesures) à l’aide du NonCon Robo CA (Konan®). Latopographie cornéenne, la pachymétrie centrale, la valeurde l’angle irido-cornéen, la profondeur de chambre anté-rieure et le diamètre pupillaire ont été précisés par lePentacam (Oculus®). La distance endothélium cornéen/ICL,la distance ICL/cristallin, la valeur de l’angle irido-cornéenet la profondeur de chambre antérieure ont été rappor-tées par l’OCT de segment antérieur (Visante OCT, Zeiss®).L’épaisseur fovéolaire a été appréciée par l’OCT de segmentpostérieur (Stratus OCT, Zeiss®), et enfin la qualité de visiona été objectivée (RMS total, RMS high order aberration,Blurry effect total, Blurry effect high order aberration) paraberrométrie wavefront (Wavescan, Visx®).
L’ensemble de ces paramètres sont relevés en préopé-ratoire, puis au 1er mois postopératoire (M1), à M3, M6,M12 puis annuellement.
En présence d’une erreur réfractive résiduelle signifi-cative (supérieure ou égale à 1 D) entre le quatrième etle 12e mois postopératoire, un traitement complémentairepar photokératectomie réfractive (PKR) au laser excimerétait alors proposé au patient. L’analyse statistique a étéréalisée grâce au logiciel Numbers de Mac OS X. Les compa-raisons de moyennes ont nécessité le t-test de Student, lescomparaisons de pourcentages le test du Chi2. Le seuil designificativité retenu était p < 0,05.
Résultats
Efficacité et prédictibilité réfractives
En préopératoire, les réfractions manifestes en équivalentsphérique (RMSE) moyennes sont respectivement de + 8,03(± 1,60) D et de − 12,06 (± 4,77) D pour les popula-tions hypermétrope et myope. L’âge moyen le jour del’intervention est de 29,3 ans. La durée de suivi moyennes’étend à 4,7 années.
Au troisième mois postopératoire, l’acuité visuelle sanscorrection (AVSC) moyenne atteint 0,70 (± 0,22) ; elle est
Figure 4. Acuités visuelles sans correction obtenues du premier au 60e mois post-implantation (Visian ICL V4 ; STAAR Surgical).
Pour citer cet article : Le Loir M, Cochener B. Résultats à long terme de l’implantation phaque de chambre postérieurepour la correction des amétropies fortes. J Fr Ophtalmol (2012), doi:10.1016/j.jfo.2011.06.006
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Implantation phaque de chambre postérieure pour correction des amétropies fortes 5
Figure 5. Pourcentage d’yeux avec ± 0,5 et ± 1,0 dioptrie (D) de la réfraction manifeste cible (en équivalent sphérique) du premier au60e mois post-implantation ICL.
supérieure à 0,5 et 1 pour respectivement 85 % et 56 %des yeux opérés (Fig. 4). La RMSE moyenne est alors de0,53 ± 0,51 D. L’erreur réfractive résiduelle par rapport àl’emmétropie est de ± 1 D et de ± 0,5 D pour 78 % et 61 % desyeux opérés (Fig. 5).
Au 12e mois postopératoire, alors que 17 des 90 yeuxont bénéficié d’un traitement PKR complémentaire, l’AVSCmoyenne atteint 0,77 ± 0,21 ; elle est supérieure à 0,5 et1 pour respectivement 93 % et 63 % des yeux opérés. La RMSEmoyenne est de − 0,29 ± 0,32 D. L’erreur réfractive rési-duelle par rapport à la réfraction cible devient de ± 1 Det de ± 0,5D pour 89 % et 68 % des yeux opérés. Précisonsque la valeur absolue moyenne de la correction PKR étaitde 1,11 ± 0,38 pour l’amétropie sphérique résiduelle et de1,56 ± 0,51 pour l’amétropie torique résiduelle. Au 60e moispostopératoire, l’AVSC moyenne est de 0,75 ± 0,28.
Du 12e au 60e mois postopératoire, la variation moyennedes RMSE est de 0,18 (± 0,37) D.
La meilleure acuité visuelle corrigée (MAVC) moyenneest passée de 0,64 ± 0,23 en préopératoire à 0,8 ± 0,21 au60e mois postopératoire. Au 48e mois postopératoire, 3 % desyeux opérés ont perdu deux lignes ou plus de MAVC, alors que48 % ont gagné au moins une ligne de MAVC (Fig. 6).
Sécurité endothéliale
La densité cellulaire endothéliale centrale préopératoiremoyenne était de 2587 ± 364 cellules/mm2. La perte cellu-laire a atteint 3,7 % la première année suivant la chirurgie,puis 0,69 %/an en moyenne jusqu’au 60e mois postopératoire(Fig. 7). Aucun patient n’a présenté de perte cellulaire endo-théliale significative.
La distance moyenne entre l’endothélium central cor-néen et la face antérieure de l’ICL a été mesurée à2,41 ± 0,35 mm au troisième mois postopératoire, stable
Figure 6. Évolution de meilleure acuité visuelle corrigée (en ligne de Snellen) rapportée au pourcentage des yeux implantés avec l’implantVisian ICL (STAAR Surgical) au 48e mois postopératoire.
Pour citer cet article : Le Loir M, Cochener B. Résultats à long terme de l’implantation phaque de chambre postérieurepour la correction des amétropies fortes. J Fr Ophtalmol (2012), doi:10.1016/j.jfo.2011.06.006
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Figure 7. Évolution de la densité cellulaire cornéenne endothé-liale centrale (en cellules/mm2) avant et jusqu’à 60 mois aprèsimplantation ICL (STAAR Surgical).
tout au long du suivi (p = 0,15 au 48e mois postopératoire),en condition standard ou cycloplégique (p > 0,09) (Fig. 8).
Sécurité cristallinienne
Quatre vingt-onze pour cent des yeux opérés n’ontpas présenté d’opacification cristallinienne. Trois yeuxont présenté une cataracte sous-capsulaire antérieure
Figure 8. Évolution de la distance séparant les centres de la facepostérieure de l’endothélium cornéen et de la face antérieure del’ICL jusqu’au’ 60e mois après implantation ICL (STAAR Surgical).
cliniquement significative, dont deux d’un patient implantébilatéralement à 43 ans par des ICL V4 (cataractes survenuesentre les sixième et 12e mois postopératoires), et un seuld’un patient implanté unilatéralement à 45 ans par un ICL V3(cataracte survenue au 48e mois postopératoire). Les deuxpatients présentaient des myopies fortes (RMSE > −12,5 D).
Figure 9. Rapports intraoculaires (visante OCT, Zeiss®) sur l’axe 0—180◦ en condition standard. La distance séparant les centres del’endothélium et de la face antérieure de l’ICL est de 2,33 mm. La distance séparant les centres de la face postérieure de l’ICL et de lacristalloïde antérieure est de 0,67 mm. Le diamètre pupillaire est de 3,79 mm. La profondeur de chambre antérieure est mesurée à 3,28 mm.
Figure 10. Rapports intraoculaires (OCT visante) sur l’axe 0—180◦ en mydriase thérapeutique. La distance séparant les centres del’endothélium et de la face antérieure de l’ICL est de 2,39 mm. La distance séparant les centres de la face postérieure de l’ICL et dela cristalloïde antérieure est de 0,69 mm. Le diamètre pupillaire est de 6,94 mm. La profondeur de chambre antérieure est mesurée à3,39 mm.
Pour citer cet article : Le Loir M, Cochener B. Résultats à long terme de l’implantation phaque de chambre postérieurepour la correction des amétropies fortes. J Fr Ophtalmol (2012), doi:10.1016/j.jfo.2011.06.006
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Figure 11. Évolution de la distance séparant les centres de la facepostérieure de l’ICL et de la cristalloïde antérieure (vault) jusqu’au72e mois post-implantation ICL (STAAR Surgical).
Les trois yeux ont bénéficié d’une bilensectomie (explan-tation, phacoémulsification et implantation en chambrepostérieure) avec un gain d’une ligne de MAVC par rapportà la situation pré-implantation phaque.
La distance moyenne séparant le cristallin de la face pos-térieure de l’ICL (appelée « vault ») en leur centre, a étémesurée à 0,52 ± 0,20 mm. Le « vault » ne varie significa-tivement ni avec le temps (p = 0,13), ni avec la dilatationpupillaire (p = 0,22) (Fig. 9—11).
Sécurité irienne et camérulaire antérieure
L’étude de la tolérance irienne rapporte quatre cas dedéformation pupillaire minime, deux cas d’hyporéactivitépupillaire et huit cas de dispersion pigmentaire (dépôtde pigment sur la cristalloïde antérieure). Le diamètrepupillaire réel préopératoire (5,73 ± 0,46 mm) n’est passignificativement modifié du premier au 48e mois suivantl’implantation (p = 0,19).
La profondeur de chambre antérieure mesurée à l’aide del’OCT de segment antérieur et du Pentacam, décroît légère-ment (de 3,26 ± 0,24 mm en préopératoire à 3,17 ± 0,15 mmde facon stable jusqu’au 60e mois postopératoire) mais defacon non significative (p = 0,14). Ajoutons que dans notreétude, la dilatation pupillaire n’a pas d’influence sur la pro-fondeur de chambre antérieure (p = 0,22).
L’angle irido-cornéen subit une diminution d’environ32 % après implantation (de 37 ± 6,7◦ à 25,2 ± 6,2◦) quireste stable au terme du suivi. Notons qu’après dilatation,l’angle irido-cornéen s’accroit significativement (p < 0,05)d’environ 25 %. (Fig. 9 et 10).
Sécurité pressionnelle
La pression intraoculaire mesurée au tonomètre à applana-tion ne semble pas influencée par l’implantation et ce, àlong terme (13,6 ± 2,1 mmHg au 60e mois postopératoire).Nous avons rapporté trois cas d’hypertonie oculaire post-opératoire transitoires, résolus sous traitement médical et
probablement liés à la rémanence de solution viscoélastiqueau niveau du trabéculum.
Qualité de vision
Enfin, la qualité de vision subjective relevée au 48e moispostopératoire souligne que seuls trois patients se plaignentd’éblouissement, deux patients présentent des halos noc-turnes, et deux autres patients décrivent un inconfort visuel.Au sixième mois postopératoire, à la question : « Referiez-vous la chirurgie ? » 96 % des patients répondent « oui ». Laqualité de vision objectivée par l’aberrométrie, retrouveun taux d’aberrations d’ordre élevé notablement bas (RMShoa moyen égal à 0,25 [± 0,12]) pour un RMS total moyenégal à 0,89 ± 0,32 et un Blurry effect hoa moyen égal à0,21 ± 0,13 pour un Blurry effect total moyen égal à 0,63(± 0,28) au 36e mois postopératoire, mais l’échantillon étu-dié (28 yeux) est insuffisant pour être représentatif.
Discussion
Les résultats de notre étude sont en faveur de l’efficacitéréfractive, de la prédictibilité, de la stabilité et de la sécu-rité à long terme de l’implantation ICL pour la correctiondes amétropies modérées à fortes. Depuis 1998, de nom-breuses études ont démontré l’efficacité et la prédictibilitéréfractive de l’implantation phaque de chambre postérieure[13—20] mais la durée de suivi inférieure à trois années,ne permettait pas de valider la sécurité de la technique àlong terme. Récemment, Kamiya et al. [26] ont conclu àl’efficacité réfractive et la sécurité de l’implantation ICLavec un recul prolongé à 4 ans pour la correction des myo-pies comprises entre − 4 et − 15 dioptries. Notre étude estoriginale à plusieurs titres. Avec un recul moyen prochede cinq ans, elle traite de l’implantation ICL pour corrigernon seulement les myopies, mais aussi les hypermétropieset astigmatismes modérés à sévères, en s’affranchissant dubiais « opérateur-dépendant ».
En comparaison aux techniques de photoablation cor-néenne, Sanders et Vukich ont démontré que l’implantationICL était supérieure au LASIK standard en termes d’efficacitéet de sécurité pour la correction des myopies modérées àsévères ainsi que pour la correction des myopies faibles[28—30]. La photoablation cornéenne, qui augmente avecl’importance de l’amétropie à corriger est à l’origined’aberrations d’ordre élevé (HOA), majorée en procédureLASIK standard par rapport à la procédure LASIK guidéepar aberromètre [31,32]. En attendant les résultats d’uneétude randomisée comparant les deux techniques pour lacorrection des amétropies faibles à modérées, Igarashi adémontré que l’implantation ICL induisait significativementmoins d’HOA et une meilleure sensibilité au contraste quele LASIK guidé par aberrométrie pour la correction des myo-pies supérieures à − 6 dioptries [33] ; d’après Kamiya [34],l’implantation ICL torique est supérieure au LASIK guidé paraberrométrie en termes de sécurité, efficacité, prédictibi-lité et stabilité pour la correction des forts astigmatismesmyopiques. L’implantation ICL induirait significativementmoins d’HOA du fait de la préservation du profil prolate de lacornée [35], et une meilleure magnification rétinienne que
Pour citer cet article : Le Loir M, Cochener B. Résultats à long terme de l’implantation phaque de chambre postérieurepour la correction des amétropies fortes. J Fr Ophtalmol (2012), doi:10.1016/j.jfo.2011.06.006
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8 M. Le Loir, B. Cochener
Figure 12. Cataracte sous-capsulaire antérieure diffuse au neu-vième mois post-implantation ICL (STAAR Surgical) nécessitant unebilensectomie.
les techniques photoablatives, permettant une augmenta-tion de la meilleure acuité visuelle corrigée [36].
La perte cellulaire endothéliale centrale atteint à cinqans 6,4 % du capital préopératoire, soit 3,78 % la premièreannée principalement expliquée par l’incision cornéenneperopératoire, puis 0,69 % par an en moyenne jusqu’auterme du suivi, ce qui correspond à la perte physiologiqueannuelle admise (0,6 %). La diminution de la densité cellu-laire endothéliale varie selon les études : de 3,7 % à quatreans pour Kamiya [26], de 6,5 % à deux ans pour Jiménez-Alfaro [16] ou de 8,4 à 9,7 % à trois ans selon l’étude FDA[13]. Cette relative inocuité endothéliale s’explique par labiocompatibilité de l’ICL et par le respect d’une distance desécurité moyenne de 2,41 (± 0,23) mm entre l’endothéliumcentral et la face antérieure de l’ICL. Pitault [37] a mesurépar biomicroscopie ultrasonore (UBM) cette même dis-tance de sécurité moyenne de 2398 (± 203) �m sur 17 casd’implantation ICL. La PKR adjuvante pratiquée sur 17 yeuxn’a pas majoré la perte cellulaire endothéliale (− 6,2 %)confirmant les résultats de Patel [38]. Signalons que le seulimplant phaque de chambre antérieure à appuis angulairesencore disponible, l’implant Acrysof phaque (Alcon®) nesemble pas induire de majoration de la perte cellulaireendothéliale à un an [21].
Nous avons rapporté cinq cas d’opacification capsulaireantérieure (5,5 %) et trois cataractes cliniquement significa-tives (3,3 %) induits par l’implantation ICL (Fig. 12). Les troiscas de cataracte ont concerné des patients de plus de 43 ans,présentant des myopies fortes, et obtenu avec l’implant ICLV3 pour un cas (Fig. 9 et 10). Les études de Gonvers [39],Lackner [12] et Sanders [11] identifient l’âge supérieur à45 ans, les myopies fortes, le traumatisme peropératoire, etun design et une taille d’implant inadéquats comme des fac-teurs de risque d’opacification capsulaire précoce. Kamiya[26] a rapporté une incidence de 1,8 % de cataracte clini-quement significative à quatre ans avec l’ICL V4 ; Sanders[13] a rapporté une incidence de cataracte sous-capsulaireantérieure avec les modèles d’ICL V3 et V4 respectivementde 12,6 % et 2,9 %, probablement en raison du « vault » sup-plémentaire de 0,13 à 0,21 mm du modèle V4 par rapportau V3. Dans notre étude, le « vault » moyen était de 0,52
(± 0,24) mm, peu différent de la mesure UBM de Pitault [37](402 ± 194 �m), et ne variant significativement ni avec letemps ni avec la dilatation pupillaire. D’après Kamiya [40] le« vault » diminue sensiblement avec le temps du fait du jeupupillaire, de l’épaississement cristallinien lié à l’âge et dela position figée des haptiques de l’ICL ; dans la même étude,le « vault » n’influence pas l’efficacité réfractive suggérantqu’un positionnement strict de l’implant entre la face pos-térieure de l’iris et le sulcus ciliaire conduit à une meilleureprédictibilité réfractive.
Le diamètre pupillaire joue un rôle fondamental dansles résultats réfractifs. L’étroitesse du rapport iris/ICL est àl’origine de rares complications telles que le blocage pupil-laire, le syndrome de dispersion pigmentaire, l’uvéite. . .
Keuch et Bleckmann [41] ont rapporté que les cycles decontraction/dilatation pupillaire, le diamètre pupillaire etl’amplitude de contraction pupillaire diminuaient aprèsl’implantation suggérant une interférence mécanique del’ICL avec la contraction pupillaire. Mais une étude plusrécente de Kamiya [42] portant sur 30 yeux, a démontréque les diamètres pupillaire d’entrée et pupillaire réeldiminuaient sensiblement le premier jour postopératoireavant de retrouver leur valeur préopératoire à la premièresemaine postopératoire, et ce de facon stable jusqu’au12e mois postopératoire, en faveur d’une irritation méca-nique peropératoire et d’une réaction inflammatoire uvéalepostopératoire immédiate. Notre étude n’a pas relevé demodification significative du diamètre pupillaire du premierau 48e mois postopératoire. Les rares cas de déformationpupillaire, d’hyporéactivité pupillaire ou de dispersion pig-mentaire à long terme soulignent l’inocuité mécanique etinflammatoire de l’implantation ICL.
Le rétrécissement significatif de l’angle irido-cornéend’environ 40 % selon Chung [43] (32 % dans notre étude) eststable au-delà du premier mois post-implantation ICL, et nes’accompagne pas d’augmentation de la pression intraocu-laire ni de la pigmentation trabéculaire. Un suivi rigoureuxle premier mois postopératoire est cependant requis dansce contexte.
Selon l’étude américaine FDA [44], l’implantation ICLtorique a fait preuve de son efficacité et de sa prédictibilitéréfractives pour la correction des astigmatismes myopiquesmodérés à forts. Schallhorn et al. [45] ont rapporté lasupériorité de l’implantation ICL torique sur la PRK entermes de sécurité, efficacité, reproductibilité et stabilitéréfractives.
En conclusion, l’implantation ICL est le traitement dechoix pour la correction des amétropies modérées à fortesen garantissant d’excellents résultats réfractifs et unesécurité stable dans le temps. La quête d’une efficacitéet d’une sécurité absolues de l’implantation phaque enchambre postérieure requiert deux conditions : d’une part,le suivi rapproché et prolongé des patients implantés,d’autre part, l’accès au 3D sans extrapolation du sulcuspostérieur — exclusivement accessible par l’échographie 3Dhaute fréquence — dans un double objectif : la prétentionde l’ajustage sur mesure de la taille de l’implant avecsimulation préopératoire et l’aide au suivi postopératoire.L’implantation ICL deviendrait alors une alternative à laphotoablation cornéenne pour la correction des amétropiesfaibles (sous réserve d’un niveau de sécurité et de prédicti-bilité acquis).
Pour citer cet article : Le Loir M, Cochener B. Résultats à long terme de l’implantation phaque de chambre postérieurepour la correction des amétropies fortes. J Fr Ophtalmol (2012), doi:10.1016/j.jfo.2011.06.006
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Déclaration d’intérêts
Les auteurs déclarent ne pas avoir de conflits d’intérêts enrelation avec cet article.
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The improvements in excimer laser technologymade hyperopic excimer refractive surgery a valuableoption for hyperopia correction. However, despite thegood visual and refractive outcomes of excimer laserphotorefractive keratectomy (PRK) and laser in situKeratomileusis (LASIK) treatments, they are moreeffective and stable for the correction of low degrees ofhyperopia than high hyperopia1-7. Refractive regres-sion8,9 and significant increase in ocular and cornealaberrations10,11 have been reported.
The Implantable Collamer Lens (Visian ICL;STAAR Surgical, Nidau, Switzerland) is a foldable pha-kic intraocular lens (pIOL) designed to be placed in theposterior chamber behind the iris with the haptic zoneresting on the ciliary sulcus and has demonstrated to besafe and effective among various clinical settings12-16,including hyperopia correction17-20. Currently, toric
181
ARTICLE
Phakic Collamer Lens (ICL) Implantation Followed byExcimer Laser Treatment (Bioptics) to Correct Hyperopia
with Astigmatism
José F. Alfonso1,2, Carlos Lisa1, Begoña Baamonde1,2, Paulo Fernandes3, Jorge Jorge3, Robert Montés Micó4
PURPOSE: To evaluate the efficacy and safety results of excimer corneal surgery followingposterior chamber phakic Implantable Collamer Lens (Bioptics) to treat hyperopia withastigmatism.
SETTING: Fernández-Vega Ophthalmological Institute, Oviedo, Spain.
METHODS: This cohort study included 62 eyes who underwent ICH V3 implantationfollowed by photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) totreat residual refractive errors (mainly astigmatism). Mean follow-up was 9.3±4.7 monthsafter laser ablation (range 1 to 29 months).
RESULTS: Preoperatively the average manifest refractive sphere (MRSE) was 5.73±1.79diopters (D) (range 1.50 to 11.00) and manifest refractive cylinder (MRCYL) was–2.07±1.03 D (range –4.00 to 0.00). Following ICH implantation, the mean sphericalequivalent (SE) was –0.07±0.09 D (range –2.88 to 0.75 D); after laser treatment the meanMRSE was –0.01±0.08 D (range –0.5 to 0.25) and MRCYL was –0.19±0.36 D (range–1.50 to 0.00). The mean UDVA was at least 20/25 in almost 70% of laser-treated eyes;over 90% of the eyes achieved UDVA of 20/32 or better. No eye lost ≥2 lines of preoper-ative CDVA and a loss of 2 lines of UDVA after laser treatment compared to the CDVAafter ICH implantation was noted in 4 (6.5%) eyes. After bioptics all eyes were within±1.00 D and 60 eyes (96.8%) within ±0.50 D of SE.
CONCLUSION: Bioptics procedure combining posterior chamber phakic IOL implanta-tion and corneal refractive surgery showed to be a safe procedure to treat hyperopia associ-ated with astigmatism.
J Emmetropia 2011; 2: 181-187
Submitted: 11/30/2011Accepted: 12/21/2011
1 Fernández-Vega Ophthalmological Institute, Oviedo, Spain.2 Surgery Department, School of Medicine, Universidad de Oviedo,
Spain.3 Clinical & Experimental Optometry Research Lab; Center of
Physics, School of Sciences. Universidade do Minho. Braga. Portugal.4 Optics Department, Faculty of Physics, Universidad de Valencia,
Spain.
Acknowledgements and Disclosure: The authors have no propri-etary interest in any of the materials mentioned in this article. Thisarticle was supported in part by a Ministerio de Ciencia eInnovación Research Grant to Robert Montés-Micó (#SAF2009-13342#) and a grant from de Fundação para a Ciência e Tecnologiato Paulo Fernandes (#FCT-SFRH-BD-34303-2007#).
Address: José F. Alfonso MD, PhD, Instituto OftalmológicoFernández-Vega, Avda. Dres. Fernández-Vega 114, 33012 (Oviedo),Spain. E-mail: [email protected]
ICL implants to correct hyperopia with astigmatism arestill not available, and therefore, the pIOL could onlycorrect the spherical component of the refractive errorand as a result coexisting astigmatic error had to betreated by either keratorefractive procedure. Combinedphakic IOL implantation and corneal refractive surgerywas initially described by Zaldivar et al21 who termedthe use of LASIK after pIOL implantation bioptics totreat extreme myopia and myopia combined with astig-matism. However, to our knowledge there are noreports on bioptics to treat residual refractive error afterhyperopic ICL. With the present study we assessed theefficacy and safety results on bioptics with ICL implan-tation to treat hyperopia with astigmatism.
PATIENTS AND METHODS
The study population comprised 62 eyes of 35patients who underwent PRK or LASIK for the correc-tion of residual refractive errors after implantation of aCollamer pIOL for hyperopia correction (ICL) at theFernández-Vega Ophthalmological Institute (Oviedo,Spain) between February 2005 and April 2009. At thetime of the surgery, all patients were fully informed ofthe details and possible risks of the surgical procedures.Written informed consent was obtained from allpatients before surgery in accordance with theDeclaration of Helsinki and an institutional reviewboard approved the study.
The inclusion criteria for ICL implantation were cor-rected distance visual acuity (CDVA) of 20/50 or better,stable refraction and clear central cornea. The exclusioncriteria included age <22 years, anterior chamber depth<2.8 mm, endothelial cell density (ECD)<2000 cell/mm2, cataract, history of glaucoma or retinaldetachment, macular degeneration or retinopathy,neuro-ophthalmic diseases and history of ocular inflam-mation. Before the ICL implantation, patients had acomplete ophthalmologic examination, including mani-fest and cycloplegic refraction, keratometry, cornealtopography and pachymetry using the Orbscan II(Bausch & Lomb, Rochester, NY), ECD (SP 3000P;Topcon Europe Medical, Netherlands), slit-lamp exami-nation, Goldmann aplanation tonometry and binocularindirect ophthalmoscopy through dilated pupils.
ICL size and power calculation
All eyes were implanted with a model ICHV3(STAAR Surgical, Nidau, Switzerland). The ICL sizewas individually determined based on the horizontalwhite-to-white distance and anterior chamber depth(ACD) measured with Orbscan II (Bausch & Lomb.Rochester, NY) following the manufacturer’s recom-mendations. Power calculation for the ICL was per-formed using the software ICL power table provided by
the manufacturer using a modified vertex formula. TheICL surgical procedure was the same as the one previ-ously reported by the authors22,23.
Laser surgery
LASIK or PRK were performed at least 3 monthsafter ICL surgery and every eye showed a stable refrac-tion and corneal topographic pattern for at least 3months before performing LASIK or PRK, both sur-geries were carried out by the same surgeon (JFA).
LASIK was performed in 50 eyes and PRK in 12eyes depending on the corneal thickness and ablationdepth of each patient.
In the case of myopic astigmatism, ablation was per-formed in the steepest meridian (negative cylinder abla-tion). In the case of mixed astigmatism, half of the abla-tion was performed in the steep meridian (negative cylin-der ablation) and half in the flat meridian (positive cylin-der ablation), the so-called cross-cylinder technique.
All surgical procedures were uneventful and with-out post-surgical complications within the follow-uptime presented in this study.
Postoperative Assessment
Both after pIOL surgery and after LASIK/PRK allthe patients fulfilled the follow-up protocol in which theexamination visits were carried out at Day 1, Week 1,and Month 1, and then every 3 months as necessary.Data obtained in each postoperative follow-up visitincluded uncorrected distance visual acuity (UDVA),CDVA, slit-lamp examination, refraction, ECD, fundusexamination, intra-ocular pressure (IOP) and centralseparation between the lens anterior surface and the pos-terior surface of the ICL (Vault). For averaging, visualacuities were converted to logMAR values; then, themeans and standard deviations were back calculated toSnellen acuity. Sphero-cylindrical refractive results wereconverted into vectors expressed by three dioptric pow-ers: M, J0, and J45; with M being equal to the sphericalequivalent (SE) of the given refractive error, and J0 andJ45 the two Jackson crossed cylinders equivalent to theconventional cylinder. Manifest refractions in conven-tional script notation (S [sphere], C [cylinder], · [axis])were converted to power vector coordinates and overallblurring strength using the formulas described byThibos and Horner24: M = S+C/2; J0 = (–C/2)*cos (2α);J45 = (–C/2)* sin (2α) and B = (M2 + J0
2+ J452)1/2.
Data analysis was performed using SPSS forWindows version 16.01 (SPSS Inc. Chicago. IL).Normality of data was checked by Kolmogorov-Smirnov test and analyzed using the Wilcoxon ranksum test, or analysis of variance with multiple compar-isons correction where appropriate, to explore statisti-cal differences for refractive and visual acuity scores
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among different follow-up visits. Bivariate correlationsbetween attempted versus achieved refraction were ana-lyzed using a non-parametric (Spearman’s coefficient)correlation analysis. Differences were considered to bestatistically significant when the p value was <0.05.
RESULTS
The mean age of the 35 patients, 19 women(54.3%) and 16 men (45.7%), was 27.6 years ± 4.3(SD) (range 20 to 40 years). The mean intervalbetween ICL surgery and LASIK /PRK was 4.9± 3.9months (range 3 to 19 months). Fifty-one eyes hadresidual myopia or myopic astigmatism, 11 eyes hadmixed astigmatism after ICL surgery. Mean follow-upafter laser treatment was 9.7±7.4 months (range 3 to27 months). Table 1 shows the preoperative patientdemographics and ICL characteristics.
Refractive outcomes
The overall change in manifest refraction is shownin Figure 1. Prior to ICL implantation, the mean man-
ifest refractive sphere was 5.73±1.79 D (range 1.50 to11.00 D) and the mean manifest refractive cylinder was–2.07±1.03 (range –4.00 to 0.00 D). At the latest fol-low-up visit following laser treatment the mean mani-fest refractive sphere was –0.01±0.08 (range –0.50 to0.25 D) and manifest refractive cylinder was–0.19±0.36 (range –1.50 to 0.00 D). The distributionof the refractive components after vector conversionbefore and after the different laser treatments is shownin table 2. No statistically significant differences existedin the M, J0 or J45 components among patients under-going either laser procedure. The power vector magni-tude was reduced either after ICL surgery or after differ-ent laser treatments and the mean value in all compo-nents of refraction after laser surgery were neither clini-cally nor statistically significant between the differentlaser procedures (P>0.05, Kruskal-Wallis test for all vec-tor components of refraction). Figure 2 shows the astig-matic components of the power vector as represented bythe 2-dimensional vector plot (J0, J45). The dispersion
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Table 1. Descriptive statistics for demographic data ofpatients and characteristics of implanted HyperopicImplantable Collamer Lens
Table 2. Mean values and standard deviation (SD) of components of vectorial decomposition of refraction before and at differentfollow-up times after surgery
SD: Standard deviation.* Independent-Samples Kruskall-Wallis Test.
Figure 1. Time course of the Manifest refractive sphere (MRSE)and cylinder (MRCYL) in diopters (D) after laser surgery.
of preoperative data and its concentration around theorigin (0,0 coordinates) is apparent at the last follow-upvisit after Laser treatment. Sixty eyes (96.8%) werewithin ±0.50 D for the M component and all eyes werewithin ±1.00 D of the desired refraction (r2=0.99 forattempted vs. achieved correlation analysis), while forastigmatic components, 56 (90.3%) and 60 (96.8%)eyes were within ±0.50 D and 61 (98.4%) and 62
(100%) were within ±1.00 D, for J0 (r2=0.95) and J45(r2=0.98), respectively, as shown in Figure 3.
Visual Outcomes
The change in uncorrected (UCVA) and corrected(CDVA) distance visual acuity (decimal notation) issummarized in Figure 4. Mean preoperative UDVAwas 0.39±0.22 Snellen lines and it was 20/200 or bet-ter in all 62 eyes. Following phakic IOL implantationit significantly improved in all but 1 eye (P<0.01,Wilcoxon Test); the mean UDVA was 0.67±0.28 with91% eyes achieving at least 20/63 or better (Figure 5).Following excimer laser treatment the UDVAimproved in all eyes. It was at least 20/40 in 58(93.5%) eyes and 20/25 or better in 43 (69.4%) eyes(P<0.01, Wilcoxon Test). Preoperative mean CDVAwas 0.84±0.21 and it was equal to or better than 20/40in 58 eyes (93.5%) and equal to or better than 20/20
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Figure 2. Scatter plot of the astigmatic vectors (J0 and J45) beforeand after Bioptics treatment. The more central location of postop-erative data represents the reduction of preoperative astigmatism.
Figure 3. Plots of achieved against attempted correction (pre-dictability) as spherical equivalent (M) and the astigmatic compo-nents (J0 and J45) in diopters (D) at the last follow-up visit afterbioptics treatment. Coefficients of determination (r2) are 0.99, 0.95and 0.98 for M, J0 and J45, respectively.
Figure 4. Changes in mean decimal visual acuity over the entirefollow-up period after ICL implantation and laser surgery.
Figure 5. Preoperative cumulative UDVA Snellen acuity versus post-operative UDVA after pIOL implantation and after Laser surgery.
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in 25 eyes (40.3%) (Figure 6). Following phakic IOLimplantation the mean CDVA was 0.81±0.20 Snellenacuity and it was equal to or better than 20/40 in 59(95.2%) eyes and 20/20 or better in 20 (32.3%) ofeyes. After laser treatment the mean CDVA was0.84±0.18 (p=0.632, Wilcoxon Test) and it was at least20/25 in 45 (72.6%) eyes and 20/20 or better in 21(33.9%) eyes. Changes in CDVA (safety) over the fol-low-up and the changes of CDVA after IOL implanta-tion when compared with UDVA after laser treatmentare shown in Figure 7. After phakic IOL implantation1 (1.6%) eye had lost more than 2 lines of CDVA, 6eyes (9.7%) had lost 2 lines, 17 eyes (27.4%) had lost1 line and 38 eyes (61.3%) had no change or improvedCDVA from preoperatively. After laser treatment, noeyes lost more than 2 lines of preoperative CDVA, 5(8.1%) eyes lost 2 lines and 10 eyes (16.1%) lost 1 linewhile 47 (75.8%) eyes maintained or gained lines ofvisual acuity. Both the safety index (ratio of postopera-tive CDVA to the preoperative CDVA) and the effica-cy index (ratio of postoperative UDVA to the preoper-ative CDVA) significantly improved after laser treat-ment (P>0.05, Wilcoxon Test for both indexes); theywere 1.04±0.21 and 0.99±0.20, respectively.
Despite the improvement in UDVA after lasertreatment, when compared with CDVA after ICLimplantation a loss of >2 lines of visual acuity wasnoted in 1 (1.6%) eye. Furthermore, a gain of 1 linewas noted in 13 (21%) eyes and a gain of 2 lines wasobserved in 5 (8.1%) laser treated eyes.
Adverse Events
There were no intraoperative complications. NoICL required explantation or repositioning, and noICL was decentered. There were no cases of pupillaryblock or anterior subcapsular cataract. No eye had
chronic increased postoperative intraocular pressure(IOP); 1 eye had a mild, transient increase in IOP upto 25 mmHg that did not require treatment. We didnot observe dislocation or decentration of the ICL andno dehiscence of the ICL incision due to laser treat-ment was observed either.
DISCUSSION
In this prospective study with 62 eyes, high levels ofsafety, efficacy and predictability were achieved for thecombined use of a posterior chamber phakic IOL andLASIK or PRK (bioptics) in eyes with hyperopia andastigmatism. After laser treatment, all eyes were within±1.00 D of the predicted correction and nearly 97%were within ±0.50 D. Hyperopia and astigmatism wasreduced from a mean +5.73 ± 1.79 D and –2.07±1.03 Dto –0.01 ± 0.08 D and –0.19±0.36 D, respectively, andastigmatic components (J0, J45) showed values over 95%within ±1.00 D in all eyes (Figure 3 middle and bot-tom). Moreover, we have observed good visual outcomesin relation to the safety index (over 1.00) and the effica-cy index (about 1.00) with about 75% of eyes maintain-ing or gaining several lines of CDVA.
In 1999, Zaldivar et al21 presented the results of com-bining ICL implantation and LASIK in 67 myopic eyeswith SE of at least –18.00 D or with high levels of astig-matism. Fifty-seven eyes (85%) were within ±1.00 D ofemmetropia and 45 (67%) within ±0.50 D; fifty-one(76%) eyes gained 2 or more lines of CDVA and no eyeslost 2 or more lines of CDVA at last examination.Sánchez-Galeana et al25 report a series of 37 eyes of 31patients who had PRK or LASIK for a residual refractiveerror after ICL implantation. Three months after LASIKor PRK, the mean SE was within ±1.00 D in 97.2% ofeyes and within ±0.50 D in 83.7%. Arne et al26 report aseries of 32 eyes of 28 patients, (preoperative SE was
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Figure 6. Preoperative cumulative CDVA Snellen acuity versus post-operative CDVA after pIOL implantation and after Laser surgery.
Figure 7. Changes in CDVA (safety) over the entire follow-upperiod and changes between UDVA after laser surgery when com-pared with CDVA after ICL implantation.
–18.70±5.67 D; range –7.75 to –29.00 D) and afterbioptics the postoperative SE was within ±1.00 D in91.3% of eyes in the LASIK group and 97.6% of eyes inthe PRK group. UDVA improved in all eyes but a loss of1 line of the CDVA after ICL implantation occurred in22.2% of PRK-treated eyes and in 13.6% of LASIK-treated eyes. These results, similar to those obtained inthe present study, indicate that the combination of theVisian ICL and LASIK/PRK can be also successfullyused in eyes with high hyperopia and astigmatism.
The safety and efficacy of ICL implantation to cor-rect hyperopia was well established in several publishedstudies. Davidorf et al in 199819 described the implanta-tion of the Visian ICL lens in 24 hyperopic eyes with amean SE of +6.51 ± 2.08 D (range, +3.75 to +10.50 D).After a mean follow-up of 8.4 months, the postoperativeSE was –0.39±1.29 D (range, +1.25 to –3.88 D), with79% (19 eyes) within ±1.00 D and 58% (14 eyes) with-in ±0.50 D of emmetropia. One eye lost 2 or more linesof CDVA due to a progressive neovascular glaucoma,which was precipitated by an episode of postoperativepupillary block, while a gain of two or more lines ofCDVA was seen in 2 eyes (8%) and postoperativeUDVA was 20/20 or better in 2 eyes (8%) and 20/40 orbetter in 15 eyes (63%). In the U.S. Food and DrugAdministration’s (U.S. FDA) trials, a Phase I study wasinitially published in 199917 including 10 hyperopiceyes with a SE range of +2.50 to +10.875 D. Six monthspostoperatively, the SE was +0.20±0.61 D (range, –0.50to +1.50 D). Eight out of 10 eyes (80%) were within±0.50 D of emmetropia, 9 eyes (90%) were within±1.00 D. There were no complications reported, with alleyes seeing 20/40 or better UDVA. In 2002, as part ofthe U.S FDA Phase III clinical trial, Bloomenstein et al20
reported on 20 eyes, (preoperative SE of +5.55 D), andpostoperatively, the mean SE was +0.06, with more than80% of the eyes having an uncorrected visual acuity of20/40 or better. Recently Pesando et al18 reported theresults of a 10-year follow-up study on 59 eyes of 34patients with hyperopia who had implantation of anICL. Preoperatively, the mean SE was +5.78± 2.54 D(range +2.50 to +11.75 D). At 10 years, the mean SEwas +0.0±0.54 D; it was within ±0.50 D in 81% of eyes,within ±1.00 D in 96%, and within ±1.50 D in 100%and 86.5% had a change in SE refraction within±0.50 D during follow-up. The CDVA was reduced by1 Snellen line in 8.3% of eyes and the UCVA was 20/20or better in 49.8% of eyes, 20/40 or better in 87.6%,and 20/70 in 100%. In the present study, we obtainedsimilar results following ICL implantation; a significantreduction in the manifest refractive sphere, nearlyemmetropia and a reduction of about 0.57 D in astig-matism that may be explained by the change in cornealastigmatism surgically induced after ICL implantation27.
In the present study we observed that after ICLimplantation, 17 (27.4%) eyes lost at least 1 line of
CDVA; 6 (9.7%) lost 2 lines and 1 (1.6%) eye lost morethan 2 lines (Figure 6). However, this effect has been par-tially corrected after LASIK or PRK and it returned tothe preoperative levels after laser enhancement (Figure6); at the end of the bioptics procedure, 5 (8.1%) eyeslost 2 lines of CDVA but no eye lost 2 or more lines. Theloss of CDVA after ICL implantation observed in thisstudy could be explained by the decrease in the size ofthe retinal image that is produced in eyes with highhyperopia corrected by pIOLs28. In addition, a corneawith high astigmatism causes greater distortion of theretinal image than a cornea with low astigmatism. WhenLASIK or PRK is performed for the correction of astig-matism, it is common to observe an increase in CDVAafter surgery29. Thus, a reduction in the amount of astig-matism through corneal refractive procedures such asthat obtained in this study could have improved visualacuity, reducing the retinal image distortion.
Studies of hyperopic PRK and hyperopic LASIKsurgery showed similar outcomes in terms of residualametropia (<1.00 D), and predictability (about 50%within ±0.50 D; about 70% within ±1.00 D)1,5,6,9.Sources of variability between them may include differ-ences in the ablation zone parameters and the ablationprofile between the lasers; differences in the nomo-grams used may account for the variation in the report-ed results. A similar behavior regarding predictabilityand regression of refractive effect is also observed, withacceptable efficacy for corrections up to +4.00 D, butlimited predictability for higher dioptric corrections,and a modest hyperopic regression of about 0.50 Dduring follow-up4,9. In the present study we observedbetter results of predictability with the biopticsapproach when compared with similar studies usinghyperopic PRK or LASIK. This may be explained bythe fact that to calculate the power of the phakic IOLto be implanted, we considered only the spherical partof the refraction with the cylinder in negative sign, asastigmatism was corrected by laser in a second step.Doing this, after phakic IOL implantation, most eyesin this study presented myopic or mixed astigmatismthat was corrected by myopic LASIK/PRK, which issuperior to hyperopic LASIK/PRK in efficacy and pre-dictability as well as having a perfect centration that isalso even more critical in hyperopic LASIK30,31.
Increased intraocular pressure, pupillary block, andcataract formation, have been the most documentedsafety concerns related to ICL implantation32.Allegedly, the risk is higher in hyperopic eyes than inmyopic eyes because of the more crowed anterior seg-ments. However, the incidence rate seems to be lowerin hyperopic ICLs18,32. In the present study, there wereno cases of chronic elevated postoperative IOP orcataract development. Furthermore, LASIK and PRKdid not cause dislocation or decentration of the ICLand there was no dehiscence of the ICL incision.
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The goal of refractive surgery is to achieveemmetropia trough any corrective procedure and there-fore the existence of toric IOLs became a need33.However, while hyperopic toric ICLs are not available,bioptics using the hyperopic ICL followed by LASIK orPRK offers a safe and effective method for correctingmoderate to high hyperopia with or without astigmatism.Bioptics reduced preoperative spherical and astigmaticerrors with high predictability and safety. However, moretime and investigation are needed to draw conclusionsabout the mechanisms of cataract formation and refrac-tive regression in ICL implanted hyperopic eyes.
REFERENCES
1. Spadea L, Sabetti L, D’Alessandri L, Balestrazzi E.Photorefractive keratectomy and LASIK for the correction ofhyperopia: 2-year follow-up. J Refract Surg 2006; 22: 131-6.
2. Zadok D, Raifkup F, Landau D, Frucht-Pery J. Long-termevaluation of hyperopic laser in situ keratomileusis. J CataractRefract Surg 2003; 29: 2181-8.
3. Alio J, Galal A, Ayala MJ, Artola A. Hyperopic LASIK withEsiris/Schwind technology. J Refract Surg 2006; 22: 772-81.
4. Varley GA, Huang D, Rapuano CJ, et al. LASIK for hyper-opia, hyperopic astigmatism, and mixed astigmatism: a reportby the American Academy of Ophthalmology.Ophthalmology 2004; 111: 1604-17.
5. Jaycock PD, O’Brart DP, Rajan MS, Marshall J. 5-year follow-up of LASIK for hyperopia. Ophthalmology 2005; 112: 191-9.
6. O’Brart DP, Patsoura E, Jaycock P, et al. Excimer laser pho-torefractive keratectomy for hyperopia: 7.5-year follow-up. JCataract Refract Surg 2005; 31: 1104-13.
7. Clara Arbelaez Ma, Vidal C, Arba Mosquera S. Six-monthclinical outcomes after hyperopic correction with theSCHWIND AMARIS Total-Tech laser. Journal of Optometry2010; 03: 198-205.
8. Cobo-Soriano R, Llovet F, Gonzalez-Lopez F, et al. Factorsthat influence outcomes of hyperopic laser in situ keratomileu-sis. J Cataract Refract Surg 2002; 28: 1530-8.
9. Desai RU, Jain A, Manche EE. Long-term follow-up of hyper-opic laser in situ keratomileusis correction using the Star S2excimer laser. J Cataract Refract Surg 2008; 34: 232-7.
10. Nagy ZZ, Palagyi-Deak I, Kovacs A, et al. First results withwavefront-guided photorefractive keratectomy for hyperopia. JRefract Surg 2002; 18: S620-S623.
11. Alio JL, Pinero DP, Espinosa MJ, Corral MJ. Corneal aberra-tions and objective visual quality after hyperopic laser in situkeratomileusis using the Esiris excimer laser. J Cataract RefractSurg 2008; 34: 398-406.
12. Alfonso JF, Baamonde B, Fernandez-Vega L, et al. Posteriorchamber collagen copolymer phakic intraocular lenses to cor-rect myopia: Five-year follow-up. J Cataract Refract Surg2011; 37: 873-80.
13. Alfonso JF, Baamonde B, Madrid-Costa D, et al. Collagencopolymer toric posterior chamber phakic intraocular lenses tocorrect high myopic astigmatism. J Cataract Refract Surg2010; 36: 1349-57.
21. Zaldivar R, Davidorf JM, Oscherow S, et al. Combined pos-terior chamber phakic intraocular lens and laser in situ ker-atomileusis: bioptics for extreme myopia. J Refract Surg 1999;15: 299-308.
22. Alfonso JF, Lisa C, Palacios A, et al. Objective vs subjectivevault measurement after myopic implantable collamer lensimplantation. Am J Ophthalmol 2009; 147: 978-83.
23. Alfonso JF, Lisa C, Abdelhamid A, et al. Three-year follow-upof subjective vault following myopic implantable collamer lensimplantation. Graefes Arch Clin Exp Ophthalmol 2010; 248:1827-35.
24. Thibos LN, Horner D. Power vector analysis of the optical out-come of refractive surgery. J Cataract Refract Surg 2001; 27: 80-5.
25. Sanchez-Galeana CA, Smith RJ, Rodriguez X, et al. Laser insitu keratomileusis and photorefractive keratectomy for resid-ual refractive error after phakic intraocular lens implantation.J Refract Surg 2001; 17: 299-304.
26. Arne JL, Lesueur LC, Hulin HH. Photorefractive keratectomyor laser in situ keratomileusis for residual refractive error afterphakic intraocular lens implantation. J Cataract Refract Surg2003; 29: 1167-73.
28. Alio JL, Mulet ME, Shalaby AM. Artisan phakic iris clawintraocular lens for high primary and secondary hyperopia. JRefract Surg 2002; 18: 697-707.
29. Munoz G, Alio JL, Montes-Mico R, et al. Artisan iris-clawphakic intraocular lens followed by laser in situ keratomileusisfor high hyperopia. J Cataract Refract Surg 2005; 31: 308-17.
30. Davidorf JM, Zaldivar R, Oscherow S. Results and complica-tions of laser in situ keratomileusis by experienced surgeons. JRefract Surg 1998; 14: 114-22.
Toric collagen copolymer phakic intraocularlens to correct myopic astigmatism
in eyes with pellucid marginal degenerationGerardo D. Camoriano, MD, Muhammad Aman-Ullah, MD, Mona K. Purba, OD,
Julia Sun, BSc, Howard V. Gimbel, MD, MPH
PURPOSE: To evaluate the clinical outcomes of implantation of the Implantable Collamer Lenscollagen copolymer toric phakic intraocular lens (pIOL) to correct myopic astigmatism in eyeswith mild pellucid marginal degeneration (PMD).
SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada.
DESIGN: Retrospective chart review.
METHODS: All consecutive cases with PMD that had implantation of the toric pIOL from January 1,2003, to May 30, 2011, were retrospectively reviewed for postoperative outcomes. Perioperativevariables of interest included uncorrected (UDVA) and corrected (CDVA) distance visual acuities,manifest refraction, and corneal topography.
RESULTS: The study comprised 10 eyes of 5 patients. The mean age was 37.4 yearsG 2.6 (SEM).The mean CDVA was 0G 0.03 logMAR (20/20) preoperatively and �0.04G 0.03 logMAR (20/18)postoperatively. The mean postoperative UDVA was C0.14 G 0.05 logMAR (20/28). The meanspherical equivalent (SE) was �6.71 G 0.9 diopters (D) preoperatively and �0.58 G 0.1 D atthe last follow-up. All eyes had improved CDVA after surgery. One patient reported severe glareand halos in 1 eye postoperatively, requiring removal and replacement of the toric pIOL becauseof a hyperopic refractive surprise. The new toric pIOL was subsequently repositioned becauseof high residual astigmatism related to changes in corneal topography postoperatively anda small shift in the position of the toric pIOL. The final manifest refraction for this eye wasplano �1.00 � 160.
CONCLUSIONS: Implantation of the collagen copolymer toric pIOL was a safe, effective surgicalprocedure for the correction of myopic astigmatism in eyes with mild PMD.
Financial Disclosure: No author has a financial or proprietary interest in any material or methodmentioned.
At present, several options for the visual rehabilitationof patients with pellucid marginal degeneration(PMD) are available. Usually, a graded approach totreatment is taken, starting with the least invasivemeans of vision correction the patient can tolerate.Spectacles and soft toric contact lenses may workinitially; however, as the condition progresses, theymay fail to provide the patient with adequate vision.Rigid gas-permeable (RGP) contact lenses are anotheroption; however, some patients experience discomfortwearing them.1 In addition, because of the peripheralthinning of the cornea, patients with PMD are notori-ously difficult to fit with contact lenses.2 When optical
devices fail to comfortably or adequately correctvision, PMD patients may benefit from surgicalapproaches. These have included implantation ofintrastromal corneal ring segments,3,4 crescenticwedge resection,5 crescentic lamellar keratoplasty,6
central penetrating keratoplasty (PKP),7 oversizedcentral PKP,8 and inferiorly decentered PKP.7,9 Morerecently, corneal collagen crosslinking (CXL) withriboflavin and ultraviolet light has shown promise instabilizing the pathology of PMD and improvingkeratometric astigmatism.10,11
Co.) has been used to safely and reliably correctmoderate to high myopia and astigmatism.12–16 Giventhat the progression of corneal thinning and ectasia inPMD, like keratoconus, tends to stabilize in the third orfourth decade of life,17 toric pIOL implantationmay beanother option for the surgical correction of myopicastigmatism in this setting. Studies18–20 are beginningto show the safety and efficacy of this treatmentmodality in keratoconus. To our knowledge, there isonly 1 case report of a patient with PMD who derivedbenefit from toric pIOL implantation.21 This retrospec-tive case series evaluated patients with myopicastigmatism secondary to PMDwho had implantationof the toric pIOL.
PATIENTS AND METHODS
All consecutive cases with PMD that had implantation ofthe toric pIOL by the same surgeon (H.V.G.) from January1, 2002, to May 30, 2011, were retrospectively reviewed forpostoperative outcomes. Most patients initially presentedfor consultation regarding corneal refractive surgery dueto contact lens intolerance. Eligibility for toric pIOL implan-tation was determined on an individual basis. Stability inthe manifest refraction (within G0.50 diopter [D]) in theyear before surgery was required. Exclusion criteria in-cluded previous ocular surgery, trauma, amblyopia, ante-rior segment pathology other than PMD, posteriorsegment pathology other than myopia, and anterior cham-ber depth (ACD) less than 2.70 mm. Informed consentwas obtained after detailed discussion of all relevant risks,benefits, and alternatives of the procedure. In particular,patients were informed about the paucity of literatureregarding the use of the toric pIOL in patients with PMD.After surgery, patients were invited to complete a shortsurvey detailing the quality of their distance and nightvision; the presence of glare, halos, image ghosting, ordouble vision; other symptoms; and overall satisfactionwith the procedure.
Preoperative Evaluation
All eyes had a comprehensive preoperative ophthalmicexamination that included corrected distance visual acuity(CDVA), manifest refraction by autorefraction (Canon,RK-F1), keratometry, ACD, corneal topography by OPDScan II (ARK 10000, Nidek Co. Ltd.) andOrbscan IIz (Bausch& Lomb), and axial length by partial coherence interferome-try (IOLMaster, version 5, Carl ZeissMeditec AG). Diagnosis
of PMD was based on these data, analysis of corneal topog-raphy indices by the Corneal Navigator feature of the OPDScan II, and clinical judgment. All patients had a high indexof suspicion (above 90%) for PMD as indicated by theCorneal Navigator. Figure 1 shows the corneal topographyof 1 patient.
Surgical Technique
All eyes had implantation of an Implantable CollamerLens toric pIOL, which is currently approved in Canadafor the correction of myopia between �4.00 D and�20.00 D and astigmatism between 1.00 D and 4.00 D. Beforesurgery, all patients had 2 neodymium:YAG peripheraliridotomies in each eye to prevent pupillary block glaucoma.The horizontal meridian was marked preoperatively at theslitlamp to account for posture-related ocular cyclotorsion.Topical anesthesia of bupivacaine (Marcaine 0.75%) wasadministered, and the eye was prepared and draped in thestandard sterile fashion. Two limbal paracenteses werecreated at 6 o’clock and 12 o’clock. Intracameralpreservative-free lidocaine 1.00% was injected, and theanterior chamber was filled with hydroxypropyl methylcel-lulose (Ocucoat). A temporal clear corneal incision wascreated with a 2.75 mm diamond keratome blade (AlconLaboratories, Inc.).
Next, the toric pIOL was implanted in the eye using anMSI-TR injector (Staar Surgical Co.) and allowed to unfold.The haptics were gently maneuvered into the ciliary sulcususing 2 Pallikaris manipulators (Duckworth & Kent Ltd.)in a hand-over-hand technique. The toric pIOL was gentlyrotated into the orientation specified by the manufacturerto correct the astigmatism. The 11 o’clock peripheral iridoto-my was entered and stretched with a Pallikaris manipulatorto confirm patency. After the ophthalmic viscosurgicaldevice was irrigated from the anterior chamber, care wastaken to ensure that the orientation of the toric pIOL hadnot shifted.
Stromal hydration was performed to achieve woundintegrity, and a small bolus of intracameral vancomycin(1 mg in 0.1 mL of sterile balanced salt solution) was admin-istered through 1 of the paracenteses. At the end of thesurgery, a drop of apraclonidine 0.5% (Iopidine) and 2 dropsof ofloxacin (Ocuflox) were given. The same surgical proto-col was followed in the fellow eye on the same day or 1 or2 days later.
Postoperative Evaluation
All eyes were examined postoperatively at 1 day, 1 week,and 1, 3, and 6 months. The examinations included UDVA,CDVA, manifest refraction, intraocular pressure, and pIOLvaulting. Outcome measures were recorded at the last post-operative visit and included UDVA, CDVA, manifest refrac-tion, and corneal topography performed using the samedevices as preoperatively.
Statistical Analysis
The mean and standard error of the mean (SEM) werecalculated for the following variables: age, preoperativeCDVA (expressed as the logMAR), postoperative CDVA,preoperative spherical equivalent (SE), postoperative SE,and postoperative UDVA. Histograms showing the percent-age of patients achieving a particular level of UDVA, change
Submitted: June 6, 2011.Final revision submitted: August 12, 2011.Accepted: August 14, 2011.
From Gimbel Eye Centre (Camoriano, Aman-Ullah, Purba, Sun,Gimbel) and the University of Calgary (Camoriano, Gimbel),Calgary, Alberta, Canada; Loma Linda University (Gimbel), LomaLinda, California, USA.
Corresponding author: Howard V. Gimbel, MD, MPH, Gimbel EyeCentre, 450, 4935 - 40 Avenue Northwest, Calgary, Alberta T3A2N1, Canada. E-mail: [email protected].
in CDVA, and deviation from emmetropia were createdusing Excel 2002 software (Microsoft Corp.).
RESULTS
This study evaluated 10 eyes of 5 patients with mildPMD. The mean age of the 3 men (60%) and 2 women(40%) was 37.4 G 2.6 years. Table 1 shows the preop-erative and postoperative patient data.
The mean CDVA was 0.00 G 0.03 logMAR (20/20)preoperatively and �0.04 G 0.03 logMAR (20/18)postoperatively. The mean postoperative UDVA wasC0.14 G 0.05 logMAR (20/28). The postoperativeUDVA was 20/20 or better in 4 eyes (40%) and20/40 or better in all eyes (Figure 2). The postoperativeCDVA improved by 2 Snellen lines in 1 eye (10%),improved by 1 line in 4 eyes (40%), remained the
same in 4 eyes (40%), and decreased by 1 line in1 eye (10%) (Figure 3).
The mean SE in all 10 eyes at the last postoperativevisit was�0.58G 0.1 D. The SEwaswithinG0.50 D ofplano in 7 eyes (70%), within G1.00 D of plano in 9eyes (90%), and within G1.50 D of emmetropia in alleyes (Figure 4). Figure 5 is a comparison of the preop-erative and postoperative astigmatism.
No cataract formation or complications resultingfrom inappropriate toric pIOL vault occurred.
All 5 patients completed the postoperative survey.Of these, 4 patients reported improvement to distanceand night vision and were satisfied overall with theoutcomes of the surgery. The remaining patient wasnot satisfied because of severe glare, halos, and ghost-ing in 1 eye. These symptoms occurred in the eye withthe less advancedPMD.Thepatient had apreoperativerefraction of �5.75 �2.50 � 95 in the affected eye, andthe plan was for a residual refractive error of �0.08 Dafter surgery. Instead, the patient had a refractivesurprise of C1.75 �1.50 � 40, which remained stableafter 6 months. She then had removal and replacementof the toric pIOL because rotation of the pIOL wouldnot have changed the hyperopic SE. The postoperativerefractionwith thenewtoricpIOLwasC1.25�2.75� 38despite the orientation of the toric pIOLbeing 2degreescounterclockwise, within G7 degrees of the manufac-turer’s recommended orientation of 5 degrees clock-wise. Upon repeat testing, it was determined that themean keratometry (measured by the same instrument)had steepened by 0.44 D and the steep corneal axis hadrotated 12 degrees clockwise compared with preoper-atively. After vector analysis of the postoperative re-fraction, the toric pIOL was rotated 26 degreesclockwise, after which the manifest refraction wasplano �0.50 � 7 and the UDVA was 20/15�1; thepatient remains satisfied with her vision.
Figure 1. Corneal topography of a patient with PMD.
Table 1. Preoperative and postoperative patient data.
Preoperative Postoperative
Pt Age (Y) Eye Sex Refraction CDVA Refraction UDVA CDVA FU (Mo)
1 48 R M �0.75 �3.50 � 96 20/20 0.00 �0.50 � 22 20/20 20/15 231 48 L M C0.75 �6.75 � 89 20/25 C0.50 �2.00 � 81 20/30 20/15 232 38 R F �5.75 �2.50 � 95 20/15 0.00 �0.50 � 7 20/15 20/15 242 38 L F �1.00 �5.50 � 95 20/20 �0.25 �1.00 � 95 20/40 20/20 243 39 R F �6.50 �4.50 � 76 20/25 �1.00 �0.75 � 14 20/40 20/20 333 39 L F �3.50 �4.75 � 98 20/20 0.00 �1.00 � 147 20/30 20/20 334 24 R M �6.50 �4.00 � 77 20/20 0.00 �0.75 � 150 20/20 20/15 704 24 L M �6.75 �3.75 � 96 20/15 0.00 �0.75 � 25 20/20 20/15 705 38 R M �7.25 �4.25 � 64 20/20 �0.75 sphere 20/40 20/20 265 38 L M �7.75 �4.75 � 121 20/25 0.00 �1.00 � 107 20/40 20/30 26
CDVA Z corrected distance visual acuity; FU Z follow-up; Pt Z patient; UDVA Z uncorrected distance visual acuity
258 TORIC PIOL FOR MYOPIC ASTIGMATISM IN PMD
J CATARACT REFRACT SURG - VOL 38, FEBRUARY 2012
DISCUSSION
The management of refractive errors in cases of mod-erate or advanced PMD is challenging. The highlyirregular against-the-rule astigmatism of PMD isusually not amenable to spectacle correction withspherocylindrical lenses.17 Although RGP contactlenses are another alternative, theymust often be over-sized to overcome the peripheral corneal thinning andsteepening, leading to decreased comfort.1,2 Intrastro-mal corneal ring segments have been used with somesuccess in PMD cases; however, most studies foundmarginal improvement in UDVA, especially in caseswith high preoperative cylinder.22 Although thismodality of vision correction has been better evaluatedin keratoconus patients, the long-term effects of thistechnology in PMD are less understood.4,22 Crescenticwedge resection or lamellar keratoplasty may helpflatten the steep axis; however, significant astigmatismusually remains after the procedure.5,6 Residualastigmatism also poses a problem for corneal
transplantation, which is compounded by the issuesof graft rejection and suture management.7,9 Anotherrecently advocated strategy for the treatment ofPMD is corneal CXL. This technique has been success-fully used to decrease keratometric astigmatism, stabi-lize corneal ectasia, and improve vision in keratoconusand PMD patients. However, as with the other previ-ously described surgical techniques, patients withmoderate to advanced PMD still need RGP contactlenses after the procedure.10,11,23 Hence, it would bebeneficial for PMD patients who cannot tolerate con-tact lenses to have access to a technology that most ac-curately and reliably corrects myopic astigmatism,allowing the best possible uncorrected visual acuity.
Toric Implantable Collamer Lens pIOLs have beenvalidated in many studies as safe and effective forthe correction of moderate to high myopic astigma-tism.12–16 Randomized prospective comparisonsbetween toric pIOL implantation and excimer laservision correction24,25 show better safety, predictability,
Figure 2. Postoperative UDVA. Figure 3. Change in CDVA.
Figure 4. Postoperative deviation from emmetropia. Figure 5.Comparison ofmean preoperative and postoperative astig-matism (SE Z spherical equivalent).
259TORIC PIOL FOR MYOPIC ASTIGMATISM IN PMD
J CATARACT REFRACT SURG - VOL 38, FEBRUARY 2012
and stability profiles with pIOLs. Based on these stud-ies, surgeons are now using toric pIOLs to successfullytreat myopic astigmatism in keratoconus andkeratoconus-suspect eyes.18–20 In the largest case seriesof keratoconic eyes with the toric pIOL (25 eyes),18 themean postoperative SE refraction was 0.32 G 0.6 D at1 year, with 84% of cases being within G0.50 D ofemmetropia. The mean postoperative UDVA andCDVAwere 0.17G 0.6 (20/30) and 0.12G 0.1 logMAR(20/25), respectively. The results are similar in our caseseries, in which we found toric pIOL implantation tobe efficacious and safe for the correction of myopicastigmatism in eyes with PMD.
In our postoperative survey, 1 patient was dissatis-fied with the quality of vision in the eye with the lessadvanced PMD. This patient had removal and replace-ment of the toric pIOL due to a hyperopic refractivesurprise. This was followed by repositioning of thenew toric pIOL due to high residual astigmatism(a combination of a postoperative change in thecorneal topography and slight shift in the position ofthe toric pIOL postoperatively). This case underscoresthe challenges involved in high-cylinder corrections.These include corneal irregularity with higher-orderastigmatism; cases in which the vertex of the toricpIOL does match the vertex of the corneal cylinder;facial asymmetry, which presents challenges in mea-suring and marking the meridians with a consistentfacial orientation; and slight rotation of the toricpIOL from its original position, all of which mayplay important roles in the final refractive outcome.
A concern about toric pIOL implantation in patientswith PMD is the progression of ectasia and astigma-tism after the procedure. In PMD, this usually happensin the third and fourth decades of life.17 Hence, carefulpatient selection is important to ensure stability of thecorneal topography before surgery. However, in casesof contact lens intolerance, toric pIOL implantationmay be justified in patients with active PMD. In thissetting, this procedure debulks the astigmatism toa level at which spectacles may provide acceptablevision. Moreover, although not ideal, the reversibilityof the procedure allows the removal and replacementof the pIOL at a later time, as in the case of our dissat-isfied patient with a hyperopic refractive surprise.
Implantation of a posterior chamber phakic intraoc-ular lens for the surgical correction of myopia has beenproved to be a safe procedure with regard to visual andrefractive results1-9. Recent multicenter clinical studiesof the United States Food and Drug Administration(FDA) for the STAAR myopic Implantable CollamerLens (ICL, STAAR Surgical, Monrovia, CA) demon-strated the safety and effectiveness of this lens in thetreatment of moderate to high myopia2,3,5,6,9. In addi-tion, recent published outcomes from the clinical FDAtoric ICL clinical trial10 and other studies11-15 showedalso good efficacy and predictability for this lens.
Considering the increasing number of implants forthis phakic intraocular lens, the question arises whetherthis lens will affect the results of axial length measure-ment. We need to consider that the speed of soundthrough the various materials of phakic lenses, in gener-al, is widely different and is different from the averagevelocity used to measure the eye. Then, differencesbetween axial length estimation may happen if this meas-urement is done before or after ICL implantation. It isobvious that an accurate biometry is necessary to calcu-late the power of any intraocular lens for cataract surgery,and becomes highly relevant when a phakic intraocularlens is implanted in the cataractous eye. Then, the pur-pose of this study is to analyze if there is any change inthe axial length measurement before and after a myopicor toric ICL implantation using optical biometry.
PATIENTS AND METHODS
All patients included in this non-randomized,prospective study underwent a myopic or a toric ICLimplantation at the Instituto de Microcirugía Ocular,Barcelona or at the Fernández-Vega OphthalmologicalInstitute, Oviedo (Spain) between November 2009 and
9
ARTICLE
Axial length measurement in eyes implanted with phakicposterior chamber intraocular lenses
Daniel Elies, MD1; José Alfonso, MD; José Güell1,2,3, MD; Oscar Gris, MD1
ABSTRACT: Purpose: To determine where eye length measurements obtained with anoptical biometer before and after Implantable Collamer Lens (ICL) implantation wouldshow any change.
METHODS: We have analyzed a prospective study a sample of 32 eyes of 19 consecutivepatients implanted with an ICL (Staar Surgical, CA). Spherical equivalent refractionranged from –5.50 to –21 diopters (D) (mean –13.73±4.48 D). Axial length was measuredusing the IOL Master® (Carl Zeiss, Jena, Germany) non-contact optical biometer beforeand after ICL implantation.
RESULTS: Mean axial length value was 27.28±2.05 mm (ranging from 24.43 to33.36 mm) and 27.31±1.98 mm (ranging from 24.56 to 32.76 mm), before and after thesurgery, respectively. Mean axial length difference between both values was –0.03±0.12(ranging from –0.17 to 0.10 mm). The paired t-test revealed no statistically significant dif-ferences in axial length between before and after ICL implantation (P=0.1653). Both meas-urements correlated in a highly positive manner (R = 0.99, P < 0.0001).
CONCLUSION: This study shows that axial length measurement before ICL implanta-tion is comparable to measurements carried out after surgery. Optical biometry achievesvalid and reliable axial length measurements in eyes implanted with ICL.
KEYWORDS: Axial length, ICL, optical biometry.
J Emmetropia 2011; 2: 9-11
Submitted: 11/23/2010Accepted: 12/22/2010
1 Especialista en Catarata y Cirugía Refractiva. Instituto deMicrocirugia Ocular (IMO), Barcelona, Spain.
2 Associate professor of Ophthalmology at Universitat Autonomade Barcelona, Barcelona, Spain
3 Director of the Cornea and Refractive Surgery Unit, InstitutoMicrocirugia Ocular, Barcelona, Spain.
July 2010. Surgery was performed by two surgeons(DEA and JFA) after a written informed consent wasobtained. The eyes included in this study had primarymyopia and astigmatism with no previous surgery andno abnormal findings diagnosed in the preoperativeophthalmologic examination. All patients were inap-propriate for other methods of refractive correction dueto one of the following exclusion criteria: insufficientcorneal thickness for excimer ablation orabnormal/irregular corneas. Patients with endothelialcell counts less than 2200 cells/mm2, anterior chamberdepth (ACD) from the endothelium less than 2.8 mm,abnormal iris or other eye diseases were excluded.
Patients were enrolled with baseline errors between–5.50 to –21.00 D of myopia (sphere) and 3.00 or5.00 D of astigmatism (cylinder). All patients present-ed a stable refraction for 12 months before studyenrollment with a best-spectacle corrected visual acuity(BCVA) of at least 20/25 in the study eye. All patientsenrolled in the study were between 22 and 44 years old.
The Staar ICL is a Collamer (collagen-copolymer),biocompatible, UV-absorbing, foldable lens with arefractive index 1.45 at 35°C. This lens is designed tocorrect myopia between –3 to –23 D and astigmatism(if toric) between +1 to +6 D with powers in half-diopter increments. The lens has an optical diameterfrom 4.65 to 5.5 mm and available lengths from 11.5to 13.0 mm. To determine the appropriate size of thelens, the white-to-white distance was evaluated with anOrbscan II (Bausch&Lomb, Rochester, NY) and theACD distance using both an Orbscan II and an anteri-or segment OCT (Visante, CarL Zeiss-Meditec, Gena,Germany). The appropriate lens power was determinedwith a proprietary software program (ICL calculating
software, STAAR Surgical, Monrovia, CA), with a tar-get refraction of emmetropia in all cases. The ICMV4and TICMV4 models were implanted in these eyes.
All patients underwent pre- and postoperative axiallength measurement using the IOL Master non-con-tact optical biometer (Carl Zeiss, Jena, Germany). TheIOL Master® optical biometer uses partial coherenceinterferometry with a 780 mm laser diode infraredlight to measure axial length. The measurement processusing this system is fast and the non-contact characterof the method reduces the risk of infection and avoidscorneal compression hence improving axial lengthaccuracy. Partial coherence interferometry has beenshown to have the same accuracy as immersion biome-try16-19. The measurement of the axial length was donepreoperative and at one month after the surgery.
Data analysis was performed using SPSS forWindows version 16.0 (SPSS Inc., Chicago, IL).Normality was checked by the Shapiro-Wilk test, andthe t-test was performed to compare pre- and post-sur-gery outcomes. Differences were considered to be sta-tistically significant when the P value was <0.05 (i.e., atthe 5% level).
RESULTS
Thirty-two eyes of 19 consecutive patients (10males and 9 females) implanted with the ICL wereincluded in this study. Spherical equivalent refractionranged from –5.50 to –21 D (mean –13.73±4.48 D).The mean preoperative BCVA was 0.90±0.07 (Snellendecimal visual acuity, ranging from 0.80 to 1.0), themean spherical ICL power was –13.53±4.37 D (rang-ing from –5.50 to –21.00 D) and the mean cylinderwas –4.17±1.04 D (ranging from 0 to + 5.00 D). Meanimplanted ICL size was 12.41±0.34 mm (ranging from12.00 to 13.00 mm).
Mean axial length value was 27.28±2.05 mm (rang-ing from 24.43 to 33.36 mm) and 27.31±1.98 mm(ranging from 24.56 to 32.76 mm), before and afterthe surgery, respectively. Mean axial length differencebetween both values was –0.03±0.12 (ranging from–0.17 to 0.10 mm). The paired t-test revealed no sta-tistically significant differences in axial length betweenbefore and after ICL implantation (P = 0.1653). Figure1 shows the axial length values measured both beforeand after ICL implantation. Continuous line repre-sents the best linear fit showing a high correlationbetween values (R = 0.99, P < 0.0001).
DISCUSSION
The results found in the present study point outthat ICL implantation does not affect axial lengthmeasurement. We have obtained a mean reduction inthe axial length value of 0.03±0.12 mm after ICL
AXIAL LENGTH MEASUREMENT IN EYES WITH pIOL10
JOURNAL OF EMMETROPIA - VOL 2, JANUARY-MARCH
Figure 1. Axial length measurement before and after ICL implan-tation using the IOL Master optical biometer. Continuous line rep-resents the best linear fit (y = 0.96x + 0.99, R = 0.99, P < 0.0001).
implantation, but being no statistically significant(P = 0.1653). Measurements of axial length before andafter the surgery highly correlate as is shown in figure 1.Our results, obtained in a sample of 32 eyes, showedthat there were no differences in axial length measure-ment before and after ICL implantation.
Unfortunately, there are no previous studies analyz-ing the theoretical effect on axial length measurementusing partial coherence interferometry of phakicintraocular lenses. However, it is interesting to discussa previous work carried out by Hoffer20 analyzing thiseffect with ultrasound biometry. As we have introducedthe speed of sound through the various materials ofphakic intraocular lenses is variable and changes withthe material (collamer, PMMA, silicone or acrylic) andthe power (thickness) of the lens. Ultrasound velocityfor collamer material is 1740 m/s and the correctionvalue in axial length using ultrasound biometry after acollamer ICL implantation is very small, with about11% of the lens thickness added to the axial lengthmeasured. Optical biometry may be affected in a simi-lar way. Then, the expected effect on axial length meas-urement is low in eyes with myopic lenses with verythin centers (0.1-0.2 mm). Similarly it would happenfor toric lenses. Although hyperopic lenses have athicker center (0.3-1.0 mm), the expected change foraxial length up to ICL powers of +20 D would beabout 0.1 mm giving an effective error in intraocularlens power calculation about a quarter of diopter.Then, the effect on axial length of hyperopic ICL isalso minimal being not a concern for a surgeon in aclinical practice. Clinical research studies on eyesimplanted with hyperopic ICLs should be performedin order to prove this statement.
In summary, the present study has confirmed thatthere is not a significant change on the axial lengthmeasurement after myopic or toric ICL implantationusing partial coherence interferometry (IOL Master®
optical biometer). Axial length measurements show ahigh correlation before and after ICL implantation,showing that optical biometry is a valid and reliabletechnique for axial length measurement in eyesimplanted with ICLs. This application is practical tomeasure axial length in eyes implanted with ICLs need-ing cataract surgery.
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