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Editor,—Anterior capsular phimosis is one of the complications of continuous curvilinear capsulorhexis (CCC). It was first described by Hansen and the term “capsule contraction syndrome” was coined by Davison in 1993.1 2 Capsular contraction has previously been reported to occur with poly(methylmethacrylate) (PMMA) and with silicone intraocular lenses (IOLs), particularly plate haptic silicone IOLs.3 4Several authors have reported that the anterior lens capsule is more stable when in contact with an acrylic IOL (AcrySof) compared with PMMA and silicone lenses.5-8 To our knowledge this is the first case report of anterior capsular contraction following implantation of an AcrySof IOL.
A 77 year old white woman underwent uncomplicated phacoemulsification with insertion of a foldable acrylic (AcrySof, Alcon Laboratories, Hemel Hempstead) IOL (23.0 dioptre, 6.0 mm optical diameter, model number MA60BM) through a superiorly sited scleral tunnel (June 1998). The capsulorhexis diameter was between 5.0 and 5.5 mm. No attempt was made to remove anterior lens epithelial cells (LECs) during irrigation aspiration of lens cortex. Ophthalmic history was negative for uveitis, pseudoexfoliation, and myopia. Postoperatively she made a good recovery, achieving an unaided visual acuity of 6/9. Three months later she presented again because of reduced vision (6/24 corrected). Dilated examination revealed fibrosis as well as marked phimosis of the anterior capsular opening (Fig 1A). The contraction was symmetrical and no decentration or tilting of the lens was noted. There was no posterior capsular opacification of note. Nd:YAG radial anterior capsulotomy (193.5 mJ TE) was carried out (Fig 1B). She regained a visual acuity of 6/9 when reviewed 1 month later (Fig1C).
The advent of CCC has led to the presentation of specific complications of this technique. These are capsule contraction syndrome, capsular bag distension, and LEC migration and proliferation onto the posterior capsule. It is now well recognised that capsule contraction syndrome is due to proliferation of residual anterior LECs that leads to fibrous metaplasia and eventual reduction of the capsular opening. Electron microscopy studies have revealed these to be cells resembling fibrocytes surrounded by a dense collagen matrix.9
Vision can be impaired not only because of opacification of the media but also because of tilting, decentration, and buckling (foldable only) of the IOL. In severe cases the zonular traction may lead to IOL dislocation and retinal detachment.2 Anterior capsular shrinkage occurs more rapidly in the first 6 weeks postoperatively but continues slowly thereafter.4
Sickenberg et al have claimed that the stronger centrifugal force of the AcrySof IOL’s haptics confer a greater stability to the anterior capsule compared with other foldable IOLs.6
Ursell and co-authors have analysed anterior capsular stability in AcrySof IOLs, and found this to be greater in contrast with PMMA and silicone IOLs.7 In nearly all cases, the anterior capsular opening enlarged with time, probably because large capsulorhexes were made for extracapsular cataract surgery. The implant designs were similar so the authors argued that this difference was due to the difference in biomaterials. An interesting in vitro study on the adhesiveness of collagen to AcrySof lenses by Nagataet al hypothesised that the anterior capsule adheres more strongly to the IOL optic thus preventing LECs from undergoing fibrous metaplasia.8
We do not know why this rare complication should have occurred in our patient, but it may be that the capsulorhexis opening was too small for this particular lens capsular bag zonular apparatus complex. In any case, clinicians should be alerted by our case which shows that anterior capsular phimosis can occur with AcrySof lenses. The risk of anterior capsular phimosis may be increased with smaller capsulorhexis diameter independently of IOL biomaterial.10