ARTICLE

Comparison of anterior capsule contractionbetween 5 foldable intraocular lens modelsMayumi Nagata, MD, Hiroyuki Matsushima, MD, PhD, Koichiro Mukai, Wataru Terauchi,

Norihito Gotoh, MD, Eichiro Matsui, MD

Q 2008 A

Published

PURPOSE: To compare anterior capsule contraction in cataract patients having implantation of 1 of5 foldable intraocular lens (IOL) models and evaluate lens epithelial cell (LEC) adhesion to eachmodel.

SETTING: Department of Ophthalmology, Dokkyo Medical University, Tochigi, Japan.

METHODS: This study comprised 115 patients (126 eyes) without systemic or ocular complicationswho had phacoemulsification with IOL implantation. The eyes were randomly assigned to receive1 of the following IOLs: acrylic MA60BM (Alcon), SA60AT (Alcon), AR40e (Advanced MedicalOptics), or YA-60BBR (Hoya) or a silicone AQ310NV (Canon). Two weeks and 1, 3, and 6 monthspostoperatively, the anterior capsule opening area was measured using an anterior segmentanalysis system (EAS-1000, Nidek) and the percentage of anterior capsule contraction was com-pared for each postoperative period and IOL. Cell adhesion to each IOL type was evaluated usingLECs from albino rabbits.

RESULTS: The mean age of the patients was 73.6 years G 5.6 (SD). Eyes with the AQ310NV andAR40e IOLs had statistically significantly greater anterior capsule contraction. The rabbit studyshowed statistically significantly less LEC adhesion on these 2 IOL models.

CONCLUSIONS: Anterior capsule contraction was significantly greater with the AQ310NV andAR40e IOLs than with the other IOLs. Results indicate that cell adhesion to the IOL is an importantfactor in preventing anterior capsule contraction.

J Cataract Refract Surg 2008; 34:1495–1498 Q 2008 ASCRS and ESCRS

Advances in cataract surgery include the developmentof aspherical, tinted, and multifocal IOLs. These ad-vancements have improved optical characteristicsand postoperative visual function. However, anterior

Accepted for publication April 27, 2008.

From the Department of Ophthalmology, Dokkyo Medical Univer-sity, Tochigi, Japan.

No author has a financial or proprietary interest in any material ormethod mentioned.

Presented in part as a poster at the XXV Congress of the EuropeanSociety of Cataract & Refractive Surgeons, Stockholm, Sweden,September 2007.

Corresponding author: Hiroyuki Matsushima, MD, PhD, Depart-ment of Ophthalmology, Dokkyo Medical University, 880 Kitako-bayashi, Mibu City, Tochigi 321-0293, Japan. E-mail: hiro@dokkyomed.ac.jp.

SCRS and ESCRS

by Elsevier Inc.

capsule contraction continues to be an important post-operative complication that can reduce visual acuity1–3

and lead to refractive changes.4 Anterior capsule con-traction occurs after the creation of a continuous curvi-linear capsulorhexis (CCC). It is the result of fibrosisand collagen production that occur when residuallens epithelial cells (LECs) in the anterior capsulenear the CCC margin come in contact with an IOLthat is fixated in the capsular bag.5,6 However, theexact cause is unclear and the prevention of anteriorcapsule contraction remains difficult.

To further study the cause of anterior capsule con-traction, we evaluated and compared the percentageof anterior capsule contraction in eyes with 1 of 4 typesof hydrophobic acrylic IOLs or 1 type of silicone IOL.Analysis was stratified by postoperative period and byIOL. In addition, we evaluated IOLmaterial character-istics, specifically cell adhesion to the optic surface, toelucidate the role adhesion plays in the mechanism ofanterior capsule contraction.

0886-3350/08/$dsee front matter 1495doi:10.1016/j.jcrs.2008.04.039

1496 ANTERIOR CAPSULE CONTRACTION WITH 5 FOLDABLE IOLs

PATIENTS AND METHODS

The study comprised 115 patients (126 eyes) having phaco-emulsification and IOL implantation at Dokkyo MedicalUniversity’s hospital. Inclusion criteria included no historyof systemic or ocular complications, successful creation ofa complete CCC, and IOL fixation in the capsular bag. Theeyes were randomly assigned to receive 1 of the followingIOLs: square-edged acrylic MA60BM (Alcon), SA60AT(Alcon), AR40e (Advanced Medical Optics), or YA-60BBR(Hoya) or a square-edged silicone AQ310NV (Canon).

Percentage of Anterior Capsule Contraction

Two weeks and 1, 3, and 6 months after surgery, diapha-noscopy was performed using an anterior segment analysissystem (EAS-1000, Nidek). The area of the anterior capsuleopening was determined by surface analysis software(Figure 1). To determine the percentage of anterior capsulecontraction with each IOL, the difference between the ante-rior capsule opening area 2 weeks postoperatively and theanterior capsule opening area 1, 3, and 6 months postopera-tively was calculated using the following formula: Percent-age contraction at 1, 3, and 6 months Z (anterior capsuleopening area at 2 weeks � anterior capsule opening area at1, 3, and 6months)/anterior capsule opening area at 2 weeks� 100. The data were analyzed by multiple comparisons us-ing the Fisher protected least significant difference (PLSD)test. The level of significance was P!.05.

Surface Cell Adhesion to the Intraocular Lens

To compare differences in IOL surface properties, LECadhesion to each IOL was evaluated. Lens epithelial cellswere obtained from the anterior capsules of albino rabbits,cultured, and treated with trypsin. The LECs in culture me-dia were adjusted to a cell density of approximately300 000 cells/mL. The cells were placed on each IOL, cul-tured for 3 hours (37�C, 5% carbon dioxide), washed, fixedin 10% formaldehyde, and stained with hematoxylin–eosin.The IOLs were examined by light microscopy (DP51, Olym-pus), and the number of LECs in a 1.0 mm2 area in the center

Figure 1. Measurement of the area of the anterior capsular openingusing an anterior segment analysis system.

J CATARACT REFRACT SUR

of each IOL was counted. The results were compared usingmultiple comparisons (PLSD test).

RESULTS

Themean age of the patientswas 73.6 yearsG 5.6 (SD).

Percentage of Anterior Capsule Contraction

Table 1 shows the percentage of anterior capsulecontraction with each IOL model. At all postoperativeexaminations, the percentage of anterior capsule con-traction was greatest with the AQ310NV and AR40eIOLs, with statisitcally significant differences betweenthese IOLs and the other 3 IOLs at 3 and 6 months.

Surface Cell Adhesion of Each Intraocular Lens

Figure 2 shows the cell adhesion test results. Lensepithelial cell adhesion was observed on each IOL sur-face, but there were few adherent cells on theAQ310NV andAR40e IOLs. Table 2 shows the numberof adherent LECs in a 1.0 mm2 area of each IOL. TheLEC adhesion was significantly less on the AQ310NVand AR40e IOLs.

DISCUSSION

In recent years, the optical characteristics of IOLs haveimproved. However, anterior capsule contraction stilloccurs and can affect visual function.1 Studies reportthat anterior capsule contraction is likely to occur inpatients with pseudoexfoliation, retinitis pigmentosa,or diabetic retinopathy7–10 and that IOL material andshape also play a role. Studies have found that anteriorcapsule contraction is more likely to occur with sili-cone IOLs than with acrylic IOLs11–14 and with plate-haptic IOLs15 or IOLs with a thin optic that causeless capsule dilation of the centrifugal haptics.16

In the present study, we compared the rate of ante-rior capsule contraction after cataract surgery and im-plantation of 1 type of silicone IOL or 1 of 4 types ofhydrophilic acrylic IOLs. Anterior capsule contractionwas marked with the AQ310NV, a silicone IOL.

Table 1. Percentage of anterior capsule contraction with eachIOL.

Percentage G SD

IOL 1 Mo Postop 3 Mo Postop 6 Mo Postop

AQ310NV (n Z 18) 9.38 G 6.68 18.80 G 11.27 22.19 G 6.70*AR40e (n Z 23) 9.90 G 6.71 20.23 G 7.70* 21.16 G 8.16*MA60BM (n Z 30) 6.52 G 4.57 14.69 G 9.56 15.95 G 10.94SA60AT (n Z 24) 9.01 G 6.02 13.40 G 7.01 14.52 G 9.00YA-60BBR (n Z 31) 9.26 G 8.26 13.13 G 9.07 14.14 G 11.17

IOL Z intraocular lens*Significantly low compared with other IOLs (P!.05)

G - VOL 34, SEPTEMBER 2008

1497ANTERIOR CAPSULE CONTRACTION WITH 5 FOLDABLE IOLs

Figure 2. Results of cell adhesiontesting using LECs (bar Z 500 mm).

Furthermore, the rate of anterior capsule contractionvaried between the 4 acrylic IOLs, with contractionsignificantly greater in eyes with an AR40e IOL.A previous study12 found no marked difference in an-terior capsule contraction between 2 acrylic IOLs withdifferent optic shapes. Therefore, we focused on thecharacteristics of IOL optic materials and comparedsurface adhesion between IOL models in an experi-mental study. We found that cell adhesion to the 2IOLs with the greatest anterior capsule contraction(AQ310NV and AR40e) was significantly lower thanadhesion to the other IOL models. This shows thateven when 2 IOLs have the same material, anteriorcapsule contraction is likely to be great if surface adhe-sion is low.

Intraocular lens surface adhesion also plays a role inthe onset of posterior capsule opacification (PCO).17

The results in the present study suggest that whenan IOL with high surface adhesion is implanted,a sharp bend is created in the lens capsule at the rect-angular, sharp posterior optic edge of the IOL (bendformation) soon after surgery.18,19 This suppresses

Table 2. Number of LECs after adhesion test.

IOL Mean Cells/mm2 G SD

AQ310NV* 5.0 G 3.5AR40e* 54.0 G 8.3MA60BM 141.0 G 15.4SA60AT 153.7 G 17.3YA-60BBR 103.3 G 10.7

IOL Z intraocular lens*Significantly low compared with other IOLs (P!.05)

J CATARACT REFRACT SUR

PCO formation and anterior capsule contraction.However, with IOLs with low surface adhesion, thelens capsule and IOL are less likely to adhere. Thismakes proliferation of LECs and fibroblasts morelikely, increasing the risk for PCO and anterior capsulecontraction (Figure 3). Thus, good surface cell adhe-sion is an important IOL characteristic in preventinganterior capsule contraction.

REFERENCES1. Davison JA. Capsule contraction syndrome. J Cataract Refract

Surg 1993; 19:582–589

2. Masket S. Postoperative complications of capsulorhexis.

J Cataract Refract Surg 1993; 19:721–724

3. Hansen SO, Crandall AS, Olson RJ. Progressive constriction

of the anterior capsular opening following intact capsulorhexis.

J Cataract Refract Surg 1993; 19:77–82

4. Nishigaki S, Inaba I, Minami H, Inoue T, Ichioka H. [The postop-

erative change of depth of anterior chamber, refraction and an-

terior capsulorhexis size after intraocular lens implantation].

[Japanese] Nippon Ganka Gakkai Zasshi 1995; 100:156–158

Figure 3. Characteristics of the IOL surface, PCO, and anterior cap-sule contraction (hypothesis). Strong adhesion of the IOL surface cre-ates a bend between the IOL and lens capsule, preventing PCOformation and anterior capsule contraction caused by LEC prolifer-ation and migration. However, weak adhesion to the IOL surfacedoes not prevent early postoperative LEC proliferation and migra-tion, promoting the development of PCO and anterior capsulecontraction.

G - VOL 34, SEPTEMBER 2008

1498 ANTERIOR CAPSULE CONTRACTION WITH 5 FOLDABLE IOLs

5. Frezzotti R, Caporossi A, Mastrangelo D, Hadjistilianou T,

Tosi P, Cintorino M, Minacci C. Pathogenesis of posterior capsu-

lar opacification. Part II: histopathological and in vitro culture

findings. J Cataract Refract Surg 1990; 16:353–360

6. Nishi O, Nishi K. [Fibrosis and constriction of capsular opening

following continuous curvilinear capsulotomy]. [Japanese] IOL

& RS 1995; 9:2–7

7. Namiki M, Yamamoto N, Tagami S, Yamazaki K, Tatibana H,

Kobayashi S, Toba Y. [Risk factors for anterior capsular shrink-

age in intraocular lens implantation]. [Japanese] Rinsho Ganka

1991; 45:1828–1831

8. Namiki M, Tagami Y, Morino I, Kano M, Sugiura T. [Findings

from slit lamp and histological examination of the anterior cap-

sule in patients with severe anterior capsular shrinkage and

opacities after implantation of intraocular lenses]. [Japanese]

Nippon Ganka Gakkai Zasshi 1993; 97:716–720

9. Hayashi K, Hayashi H, Matsuo K, Nakao F, Hayashi F. Anterior

capsule contraction and intraocular lens dislocation after implant

surgery in eyes with retinitis pigmentosa. Ophthalmology 1998;

105:1239–1243

10. Hayashi H, Hayashi K, Nakao F, Hayashi F. Area reduction in

the anterior capsule opening in eyes of diabetic mellitus patients.

J Cataract Refract Surg 1998; 24:1105–1110

11. Hayashi K, Hayashi H, Nakao F, Hayashi F. Reduction in the

area of the anterior capsule opening after polymethylmethacry-

late, silicone, and soft acrylic intraocular lens implantation. Am J

Ophthalmol 1997; 123:441–447

12. Hayashi K, Hayashi H. Intraocular lens factors that may

affect anterior capsule contraction. Ophthalmology 2005; 112:

286–292

13. Cochener B, Jacq P-L, Colin J. Capsule contraction after contin-

uous curvilinear capsulorhexis: poly(methyl methacrylate)

J CATARACT REFRACT SUR

versus silicon intraocular lenses. J Cataract Refract Surg

1999; 25:1362–1369

14. Park TK, Chung SK, Baek NH. Changes in the area of the ante-

rior capsule opening after intraocular lens implantation. J Cata-

ract Refract Surg 2002; 28:1613–1617

15. Gonvers M, Sickenberg M, van Melle G. Change in capsulo-

rhexis size after implantation of three types of intraocular lenses.

J Cataract Refract Surg 1997; 23:231–238

16. Sickenberg M, Gonvers M, van Melle G. Change in capsulo-

rhexis size with four foldable loop-haptic lenses over 6 months.

J Cataract Refract Surg 1998; 24:925–930

17. Matsushima H, Iwamoto H, Mukai K, Obara Y. Active oxygen

processing for acrylic intraocular lenses to prevent posterior

capsule opacification. J Cataract Refract Surg 2006; 32:

1035–1040

18. Nishi O, Nishi K, Sakanishi K. Inhibition of migrating lens epithe-

lial cells at the capsular bend created by the rectangular optic

edge of a posterior chamber intraocular lens. Ophthalmic Surg

Lasers 1998; 29:587–594

19. Sacu S, Menapace R, Buehl W, Rainer G, Findl O. Effect of

intraocular lens optic edge design and material on fibrotic

capsule opacification and capsulorhexis contraction. J Cataract

Refract Surg 2004; 30:1875–1882

First author:Mayumi Nagata, MD

Department of Ophthalmology, DokkyoMedical University, Tochigi, Japan

G - VOL 34, SEPTEMBER 2008