The Effect of Capsulorhexis Size on Posterior Capsular Opacification: One-Year Results of a Randomized Prospective Trial EMMA J. HOLLICK, BA, FRCO PHTH , DAVID J. SPALTON, FRCP, FRCS, FRCO PHTH , AND WILL R. MEACOCK, BS C, FRCO PHTH ● PURPOSE: Posterior capsular opacification is the most common surgically related cause of reduced vision after cataract surgery. We studied the effect of capsulorhexis size on the pattern and severity of posterior capsular opacification. ● METHODS: In this prospective study 75 patients under- went standardized phacoemulsification with capsulorhexis and in-the-bag placement of a 5.5-mm polymethylmethac- rylate intraocular lens implant. The patients were randomly assigned to receive either a small capsulorhexis of 4.5 to 5 mm to lie completely on the intraocular lens optic or a large capsulorhexis of 6 to 7 mm to lie completely off the lens optic. Patients were examined at days 1, 14, 30, 90, and 180 and at year 1 with logMAR visual acuity assessment, Pelli-Robson contrast sensitivity testing, anterior chamber flare and cell measurement, and high-resolution digital retroillumination imaging of the posterior capsule. The pattern of posterior capsular opacification was determined, and the percentage area of posterior capsular opacification was calculated for each image with dedicated image analysis software. ● RESULTS: Large capsulorhexes were associated with significantly more wrinkling of the posterior capsule and worse posterior capsular opacification than small capsu- lorhexes. At 1 yearthe average percentage areaof posterior capsular opacification was 32.7% forsmall capsulorhexes (95% confidence interval, 19.8 to 45.6) and 66.2% for largecapsulorhexes (95% confidence interval, 57.7 to 74.6) (P 5 .0001). The patients with large capsulorhexes had significantly poorer visual acu- ities and a trend toward worse contrast sensitivities. ● CONCLUSION: This study demonstrated significantly greater wrinkling and opacification of the posterior ca sule and worse visual acuity with large capsulorhexes than with small capsulorhexes. In cataract surgery wi polymethylmethacrylate intraocular lens, a small capsu- lorhexis with the edge completely on the surface of th implant is preferable to a large capsulorhexis in reduc posterior capsular opacification. (Am J Ophthalmol 1999;128:271–279. © 1999 by Elsevier Science Inc. Al rights reserved.) C ONTINUOUS CURVILINEAR CAPSULORHEXIS HAS become a routine part of cataract surgery since its introduction by Gimbel and Neuhann in 1990 1,2 because it allows true capsular bag fixation of the intraoc- ular lens with better centration. 3–5 An intact capsulorhexis reduces the severity of the blood–aqueous barrier break- down and the foreign-body cellular reaction on the in- traocular lens surface 6,7 and prevents contact between the intraocular lens and uveal tissue. It also produces a safer environment during phacoemulsification and may result in a more predictable refractive outcome. 8 There is,however, much debate as to what the ideal diameter of the capsulorhexis should be. Smaller capsulo- rhexesare easier to perform but make removal of the cataract more difficult and have the major disadvantage that the anterior capsular opening can shrink, leading to phimosis, which causes decreased vision. 9 –11 Large capsu- lorhexesmake the subsequent phacoemulsification and removal of soft lens matter easier and enable a fuller fundal view, which is an important consideration when undertak- ing surgery for patients with diabetes or patients at risk of retinal detachment. The effect of the size of the capsulorhexis on posterior capsular opacification is unclear. Posterior capsular opaci- fication iscaused by residual lensepithelialcellsthat remain in thecapsularbagaftercataractsurgeryand proliferateand migrateoverthe capsuleto produce Elschnig pearls or transform into myofibroblasts to cause capsular fibrosis. 12,13 After surgery, these residual cells are Accepted for publication April 14, 1999. From the Department of Ophthalmology, St Thomas’ Hospital, Lon- don,United Kingdom. This article was supported by a research grant from the Iris Fund for the Prevention of Blindness, London,United Kingdom, and an open grant from Alcon Laboratories. Reprint requests to Mr. D. J. Spalton, Department of Ophthalmology, St Thomas’ Hospital, Lambeth Palace Road, London,SE1 7EH,United Kingdom; fax 144 171 922 8157. ©1999 BY E LSEVIER S CIENCE INC. ALL RIGHTS RESERVED . 0002-9394/99/$20.00 271 PII S0002-9394(99)00157-9