Posterior staphyloma is often a feature of pathologicalmyopia. The complex optics in high refractive error andthe difficulties in viewing the fundus in myopic eyes canlead to a mistaken diagnosis of retinal detachment ortumour on routine examination. This can cause anxiety topatients. We report two such cases. Curtin (1977)suggested a classification for posterior staphyloma and wehave used it in the description of our cases.
Case 1
A 45-year-old female was referred urgently by heroptometrist with suspicion of bilateral retinal detachmentsto the emergency eye clinic at Doncaster Royal Infirmary.She had been for a routine check-up and wasasymptomatic. There was a history of high myopia and inthe past she had had right-eye squint surgery. The vision
had been poor in both eyes since childhood.Her best corrected visual acuity was 6/24 in the right eyeand 6/36 in the left eye. The refraction was–31.00DS/–1.50DC axis 10 in the right eye and–31.00DS/–2.00DC axis 180 in the left eye. Anteriorsegments of both eyes were unremarkable except for deepanterior chambers. Examination showed myopicdegeneration in both eyes. Posterior staphyloma Curtintype VIII was seen in both eyes (Curtin 1977; Figure 1).There was an area of ectasia centred around the discextending 4 disc diameters nasal to the optic nerve andtemporally to within 1 disc diameter of the macula withsingle step along the nasal wall of the staphyloma. Neitherretinal detachment nor retinal tears could be seen in eithereye. The axial lengths were: right eye 35.79mm, left eye35.55mm. Ultrasound B-scan confirmed the staphylomaand retinal detachment was ruled out (Figure 2). Thepatient was reassured and discharged back to the optician.
Case 2
A 72-year-old woman was referred urgently to theemergency eye clinic at Bradford Royal Infirmary by theoptometrist who had noticed an elevated area in the rightfundus and suspected choroidal melanoma. Once again itwas a ‘routine’ eye check-up and the patient wasasymptomatic. There was a history of bilateral myopia andthe right eye was amblyopic.
On examination the patient’s best corrected visual acuitywas 6/60 in the right eye and 6/6 in the left eye. Therefraction was –7.00DS/–2.00DC axis 135 in the right eyeand –1.75DS in the left eye. Anterior segments of both eyeswere unremarkable. Examination showed myopic fundaldegeneration in both eyes but posterior staphyloma only inthe right eye. It was of Curtin type V with an area of ectasiaaround the disc, extending 1 disc diameter above the disc
to about 5 disc diameters inferiorly (Curtin 1977). Nostaphyloma was found in the other eye. Ultrasound B-scanof the right eye showed only staphyloma but no tumour(Figure 3). The axial lengths of the right and left eye were29.3mm and 22.48mm respectively. The patient wasreassured and discharged.
Discussion
The word ‘myopia’ is derived from the ancient Greek myops , half-closing the eyes, a reference to the stenopaeiceffect achieved by so doing. It is a refractive condition thatresults when the image of a distant object is focused infront of the retina by the relaxed eye. Myopia can beclassified into simple myopia and pathological myopia.Simple myopia is the most common eye disorderworldwide. Pathological myopia, also called progressivemyopia, involves structural alterations to the globe, whichmay threaten sight and ocular health.
Pathological myopia is due to the development of structural defects in the posterior segment of the eye. Itcomprises 2% of all myopias. It is thought to result from a
Posterior Staphyloma: Can it be RetinalDetachment or Tumour?Nonavinakere P Manjunatha 1 MD MRCOphth (Lon), Shrivatsa P Desai 1 MS FRCS,
Aravind Reddy 2 MS FRCS and Siddharth Goel 1 MRCOphth (Lon) FRCS (Edn) FRCS (Gls)
1Doncaster and Bassetlaw NHS Foundation Trust, UK 2Bradford Teaching Hospitals NHS Foundation Trust, UK Accepted for publication 23 January 2006
Address for correspondence: Mr NP Manjunatha, Ophthalmology Department, Doncaster Royal Infirmary, Armthorpe Road, Doncaster, SouthYorkshire, DN2 5LT, UK.
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combination of genetic and environmental factors(Grossniklaus & Green 1992). Pathological myopes maypresent with decreased visual acuity, strabismus, open-angle glaucoma, premature lenticular opacification, andincreased axial length. Features of myopic degenerationinclude one or more of the following: vitreous syneresis,tilted discs, posterior staphyloma, myopic crescent, patchychoroidal atrophy within the posterior pole, breaks inBruch’s membrane with accompanying choroidal atrophyknown as lacquer cracks, subretinal neovascularmembrane, Fuchs spots and retinal breaks or detachments.
A staphyloma is a protrusion of the outer coat of the eyewith incarceration of uveal tissue. It is derived from theGreek word which means ‘a bunch of grapes’. It can beclassified anatomically into corneal, ciliary, intercalary,equatorial and posterior staphyloma (Duke-Elder 1965). A discussion on the first four is out of the scope of this article.
A histopathological study (Grossniklaus & Green 1992)reported posterior staphyloma in 35.4% of pathologicalmyopia eyes. The prevalence increases to 71.4% if axiallength is 33.5–36.6mm (Curtin & Karlin 1970). There is atendency for posterior staphyloma to expand and deepenwith age (Curtin 1977). The posterior staphyloma isbelieved to result from slowly progressive chorioretinalstretching, mechanical tearing and atrophy (Albert & Jakobiec 1994). Sclera has also been shown to be abnormal
in eyes with pathological myopia. There is thinning of scleral collagen bundles and decreased number of collagenstriations (Curtin & Teng 1958).
In 1977 Curtin proposed a classification and described 10types of posterior staphyloma. These were classifiedaccording to the fundus area in which the ectasia waslocated. The types of staphyloma differed not only in thearea of fundus involvement, but also in their size, shapeand depth, the abruptness of their margins and theassociated changes in the appearance of the optic nerveand retinal vessels. The first five varieties were calledprimary posterior staphylomas and the remaining fivetypes compound staphylomas.
In type I the area of ectasia is between 2 and 5 discdiameters nasal to the optic nerve and extendingtemporally to macula or several disc diameters beyond it.Type VIII is distinguished by the presence of tiers or stepsacross the wall of a primary type I staphyloma. These stepsor terraces may be single or multiple and are almostinvariably found along the nasal wall of the staphyloma. Atthese abrupt edges the retinal vessels sharply bend anddisappear in the ‘shadow’. The deeper the staphyloma, thesharper or more abrupt are the margins (Curtin 1977). Theectatic areas appear relatively pale in comparison to theuninvolved areas of the fundus. All of the above features
can give the impression of a retinal detachment, as in ourcase no. 1.
In type V primary staphyloma the ectatic area is inferior tothe optic nerve (Curtin 1977). The posterior staphyloma isdeepest at the disc and at the inferior edge the retina mightlook elevated, which mimics an elevated lesion or tumour,as happened in case no. 2.
Myopes can have an increased risk of developing retinaldetachment and the prevalence in pathological myopia is11.4% (Curtin & Teng 1958). The retinal tear might bepresent at or originate from an area of posteriorstaphyloma and might lead to retinal detachment. Butmost of these patients are symptomatic (Phillips & Dobbie1963).
We have illustrated two different problems encountered inoptometric practice worth taking note of. In symptomaticmyopic patients retinal detachment should always be keptin mind while examining the fundus. Elevated retinallesion even in an asymptomatic eye should be carefullyexamined to make a correct diagnosis and, if need be,referred to ophthalmologists for confirmation or exclusionof the initial diagnosis. The difficulties of visualisation of the fundus in patients with high refractive errors and thepresence of staphyloma in pathological myopia can lead to
presumptive diagnosis of retinal detachment or tumour, asillustrated by our two cases. A thorough assessment,including biomicroscopic fundus examination andbiometry, can avoid needless anxiety and stress to patients.
Acknowledgement
We are grateful to Ms Laura Ferguson for photography.
References
Albert DM, Jakobiec FA (1994) Principles and Practice of Ophthalmology. Philadelphia: WB Saunders
Curtin BJ (1977) The posterior staphyloma of pathologic myopia.Trans Am Ophthalmol Soc 75 , 67–84
Curtin BJ, Teng CL (1958) Scleral changes on pathological myopia.Trans Am Acad Ophthalmol Otolaryngol 62 , 777–90
Curtin BJ, Karlin DB (1970) Axial length measurements and funduschanges of the myopic eye. Part 1. The posterior fundus. T rans AmOphthamol Soc 68 , 312–34
Duke-Elder S (1965) Systems of Ophthalmology , vol. 8 (part 2), pp998–9. London: Henry Kimpton
Grossniklaus HE, Green WR (1992) Pathologic findings in pathologicmyopia. Retina 12 , 127–33
Phillips CI, Dobbie JG (1963) Posterior staphyloma and retinaldetachment. Am J Ophthalmol 55 , 332–5
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NP Manjunatha, SP Desai, A Reddy & S Goel
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Posterior Staphyloma: Can it be Retinal Detachment or Tumour?
Figure 2 Ultrasound B-scan pictures showing posterior staphyloma in case no. 1. Left, ultrasound B-scan picture of right eye. Right, ultrasound B-scan picture of left eye.
Figure 1 Fundus pictures showing posterior staphyloma in case no. 1. Left, Fundus picture of right eye. Right, fundus picture of left eye.
Figure 3 Ultrasound picture of right eye showing posterior staphyloma with inferior elevated area in case no. 2.
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Comment Manjunatha et al. present two cases of posteriorstaphyloma associated with pathological myopia presentinginitially to the optometrist. Both cases were referredurgently and the diagnosis of posterior staphyloma wasconfirmed by B-scan ultrasound biometry.
The authors describe the pathology of posteriorstaphyloma, describing it as an ectasia – a thinning – of scleral tissue. From the figures, it can be seen that thestaphylomatous area is atrophic. This is due to the loss of the choriocapillaris and subsequent atrophy of the retinalpigment epithelium and photoreceptors. Staphyloma canalso be complicated by breaks in Bruch’s membrane thatheal to form ‘lacquer cracks’, and, in some instances,subretinal neovascularisation and disciform scarring.
Atrophy of photoreceptors of course leads to visual fielddefects. However, visual field defects are also associatedwith local detachments and with tumours. Visual fieldtesting is also difficult in pathologically myopic eyesbecause of the reduced visual acuity and the constrictioncaused by high-minus corrections, so visual field testing isunlikely to help differentiate posterior staphylomas fromtumours or retinal detachments. The authors suggest thatdetachments are usually symptomatic, which is a fair point,
although not a universal rule, especially in an eye that maybe amblyopic and suppressed. It is also worth pointing outthat the authors were confident of their diagnosis only afterperforming B-scan ultrasound scans. Unfortunately,ultrasound scanners are not in the typical optometrist’sarmamentarium and so prompt or urgent referral seemsappropriate in these cases. The authors themselvesconcede that an ultrasound scan is indicated, even if thereferral does have the unfortunate side-effect of causing‘needless anxiety and stress’. However, if the optometristincludes posterior staphyloma in the differential diagnosisand tells the patient that this is a possibility (which shouldnow be the case given this timely article!), fears canperhaps be allayed.
It is unclear from the report whether the optometrists usedeither fundus biomicroscopy (with eg a Volk lens) orheadband indirect fundoscopy. The authors argue thatstereoscopic fundus examination would have helped inthese cases. I agree with this view, although again, one of the cases exhibited a convex fundal elevation rather than aconcave depression. It would be difficult to rule out atumour with confidence and maybe a detachment in suchcases, so once more, prompt referral seems the appropriatecourse of action, at least for the case with a staphylomatouselevation. It is perhaps worth mentioning here thatoptometrists should bear in mind the useful sign of anteriorvitreous tobacco dust as an indicator of a retinal tear(though not an exudative detachment).
One issue that I would like to bring to optometrists’attention is the appearance of the optic discs in thesehighly myopic eyes. Both eyes show tilted discs andperipapillary myopic degeneration, which makes themextremely difficult to assess, especially from the point of view of glaucoma. Given the difficulties associated withvisual field testing discussed above, high myopes can bedifficult to manage in this situation. Serial stereoscopicoptic disc photography would be the ideal, but I would urgepractitioners to have a good look using fundusbiomicroscopy and at least to draw a diagram of the disc,paying particular attention to where the disc stops and the
myopic degeneration starts, as well as the contour of anycupping.
This is an interesting article and the authors are to becongratulated for reminding practising optometrists of thisentity. I hope you enjoyed reading it as much as I did.
Dr Russell J. Watkins
Specialist Registrar in Histopathology Leeds General Infirmary
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Posterior Staphyloma: Can it be Retinal Detachment or Tumour?
1. Which of the following is a posterior staphyloma oftenmistakenly diagnosed as?
(a) optic atrophy(b) retinal detachment(c) advanced glaucomatous optic nerve head damage(d) all of the above
2. Which of the following tests is routinely employed in ahospital eye department to confirm or exclude adiagnosis of posterior staphyloma?
(a) direct ophthalmoscopy(b) gonioscopy(c) ultrasound b-scan(d) pachymetry
3. Which of the following statements is true regardingpathological myopia?
(a) it comprises 2% of all myopias(b) it can present with early cataracts(c) choroidal atrophy is common(d) all of the above
4. How is type VIII staphyloma distinguished from type I?(a) the presence of an associated retinal break(b) the ectatic area is inferior to the optic nerve(c) the presence of tiers or steps along the wall of the
staphyloma(d) an axial length of >29.3mm as measured by ultrasound
b-scan
5. Which of the following statements is true regardingretinal detachments in pathological myopes?
(a) a tear can originate from an area of posteriorstaphyloma
(b) there is no increased risk of retinal detachment inpathological myopes
(c) most of these patients are asymptomatic(d) the prevalence is <10%
6. What proportion of pathological myopic eyes werereported to have staphylomas in a histopathologicalstudy?
(a) <20%(b) between 20% and 30%(c) between 30% and 40%(d) >40%
Multiple Choice QuestionsThis paper is reference C-3114. One credit is available. Please use the inserted answer sheet. Copies can be obtained from Optometry inPractice Administration, PO Box 6, Skelmersdale, Lancashire WN8 9FW. There is only one correct answer for each question.
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The rules governing the use and supply of medicines in theUK are laid down in the Medicines Act (1968).Optometrists have traditionally been granted exemptionsfrom the general rules laid down in the Act to allow themto use certain prescription-only medicines (POMs) in thecourse of their professional practice and in particularcircumstances to supply POMs to their patients. The list of drugs to which exemptions apply has changed little in theyears since the establishment of the Medicines Act;however, in 2005 significant changes to medicineslegislation occurred. These changes included:
• an update to the list of POMs available to all registeredoptometrists.
• a relaxation of the rules governing the supply of pharmacy (P) and general sales list (GSL) medicines byoptometrists
• the establishment of a list of further POMs that can be
used and supplied by optometrists who have completedextended training
In parallel with these changes, a further development aroseout of a wider National Health Service (NHS) policyinitiative to extend the authority to prescribe to non-medical healthcare professionals. The rationaleunderpinning this policy was described in the NHS Plan(2000) and included: (1) improving patient access tomedicines; (2) breaking down traditional demarcationsbetween clinical roles; and (3) making better use of theknowledge and clinical skills of non-medical healthcareprofessionals. Two distinct categories of prescriber havebeen defined in legislation:
1. independent prescribers, who are responsible forassessing the patient, making a diagnosis and drawingup a clinical management plan
2. supplementary prescribers, who have the authority toprescribe within the parameters of an agreedmanagement plan for patients whose condition has beendiagnosed by an independent prescriber
Nurses and pharmacists were the first healthcareprofessionals to train as supplementary prescribers and in2005 this opportunity was extended to other professionalgroups, including optometrists.
This article will summarise these changes to medicineslegislation and discuss their implications for the care thatoptometrists can provide to their patients.
Update to the List of POMs Available to AllRegistered Optometrists
The list of POMs available to optometrists (Table 1) hasonly been updated sporadically in the years since it wasfirst established. Since the last revision took place in 1978,the list has been in need of major review.
Several drugs in the list, for example, the antimuscarinichyoscine, the non-steroidal anti-inflammatory drugoxyphenbutazone and the miotics bethanechol,neostigmine and physostigmine, were no longercommercially available as ophthalmic formulations in theUK. In the case of antimicrobial preparations,chloramphenicol was the only POM available tooptometrists for treating superficial infections of the eye oras prophylaxis following ocular surface injury. Althoughframycetin sulphate was listed, it was of little clinical valueas its use was restricted to administration only. The legalprocess for amending POMs available to professionalgroups through exemptions involves a period of publicconsultation that is administered by the Medicines andHealthcare Products Regulatory Agency (MHRA), followedby consideration by the Committee for the Safety of
Medicines (CSM). The consultation document MLX 306summarised the rationale for updating the list andproposed removing framycetin and adding theantibacterial agent fusidic acid to the POMs available tooptometrists for sale and supply. The outcome of thisprocess was the establishment of an updated list which wasembodied in a new statutory instrument (SI 2005 766)which came into force on 7 April 2005 (Table 2).
Recent Changes in Medicines LegislationThat Affect OptometristsLucy C Titcomb 1 BSc MRPharmS MCPP and John G Lawrenson 2 BSc PhD MCOptom
1Birmingham & Midland Eye Centre, UK 2Department of Optometry and Visual Science, City University, London, UK Accepted for publication 26 January 2006
Address for correspondence: Mrs LC Titcomb, Pharmacy Department, Birmingham & Midland Eye Centre, Sandwell & West Birmingahm NHSTrust, Dudley Road, Birmingham B18 7QH, UK
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