Continuous curvilinear capsulotomy is the most common technique for opening the anterior lens capsule during phacoemulsification. Postoperatively, however, a small-diameter capsulorhexis may result in progressive shrinkage or complete closure of the anterior capsule opening as a result of lens epithelial cell proliferation and fibrosis. This phenomenon has been termed capsule contraction syndrome.1 Associated conditions include pseudoexfoliation syndrome and other diseases of zonular weakness such as high myopia, uveitis, pars planitis, myotonic dystrophy, diabetes mellitus, advanced age, and retinitis pigmentosa.
We report a 69-year-old myopic patient with pseudoexfoliation syndrome who developed capsule contraction syndrome in both eyes 2 months after successful cataract surgery with implantation of an endocapsular ring and an acrylic intraocular lens (IOL).
A 69-year-old man was diagnosed with pseudoexfoliation syndrome and cataract in both eyes. The refraction was −7.50 −2.00 × 80 in the right eye and −7.75 −0.75 × 135 in the left eye. In both eyes, the best corrected visual acuity was 20/30 and the intraocular pressure, 17 mm Hg. Slitlamp examination showed a cortical and nuclear cataract in both eyes and signs of pseudoexfoliation. Phakodonesis was not evident in either eye.
The patient had bilateral phacoemulsification under topical anesthesia with 1 month between surgeries. Because of the phakodonesis associated with the pseudoexfoliation syndrome, an endocapsular ring (model 14-A, Morcher) and an AcrySof® MA30BA acrylic IOL (Alcon) were implanted in both eyes. There were no intraoperative complications, and all cortical material was removed. Both eyes received the standard postoperative antiinflammatory treatment of prednisolone acetate every 4 hours tapered over 1 month.
Two months after the surgery, the patient reported blurred vision in the left eye. Slitlamp examination revealed anterior capsule contraction in both eyes and a fully closed capsulorhexis opening in the left eye. In the left eye, the IOL was centered but completely enclosed, with numerous linear fibrous folds radiating from the thick central fibrosis (Figure 1). In the right eye, the endocapsular ring could be seen at the pupil edge (Figure 2).
A neodymium:YAG (Nd:YAG) circular anterior capsulotomy was performed. Several Nd:YAG laser shots to the center of the fibrosis were needed to reopen the anterior capsule in the left eye. The treatment consisted of 18 pulses at 5 to 10 mJ. The summit of the capsulotomy was just above the intended visual axis, and its radial limbs extended peripherally. At the end of the procedure, no pits were noted on the IOL's anterior surface (Figure 3). Visual acuity was restored to 20/20 in both eyes.
Although the pathogenic mechanisms responsible for excessive capsule fibrosis and contracture are not well understood, several histopathologic studies have identified the cell types associated with pseudophakic fibrosis.2 Metaplasia of residual epithelial cells and fibrosis contribute to the purse-string contracture and closure of the anterior capsulotomy. This response may be exaggerated when unopposed by normal zonular tension such as in cases of pseudoexfoliation syndrome. Contraction of the anterior capsulorhexis is supposedly related to an imbalance between centrifugal and centripetal forces that act on the zonules and the capsulorhexis edge.
Some studies suggest that the IOL optic material may influence the development of anterior capsule fibrosis. Specifically, optics made of acrylate copolymer (AcrySof) are probably better at maintaining large capsulorhexis diameters than silicone optics. Cochener and coauthors3 found intense contraction in 70% of eyes with a silicone IOL and 32% with a poly(methyl methacrylate) (PMMA) IOL. No differences were reported between PMMA and acrylic IOLs.
In our patient, we implanted an endocapsular ring and an acrylic IOL in both eyes because he had pseudoexfoliation syndrome and the presence of phakodonesis during surgery. Two months after surgery, however, he presented with total capsule contraction syndrome in the left eye and mild capsule contraction syndrome in the right eye.
Cochener and coauthors3 report that retraction was significantly greater at 30 to 150 days with continuous progression for 5 months postoperatively, suggesting late stability of the capsulorhexis.3 Hayashi and coauthors4 report stability at 3 months.
In cases of progressive zonular disease such as pseudoexfoliation syndrome or Marfan's syndrome, a capsular tension ring (CTR) is often implanted at the time of surgery to stabilize the bag during phacoemulsification and provide better and more symmetric capsular bag support than the haptics alone can provide. In such cases, the CTR may limit bag contraction.
Both the original CTR and the modified endocapsular tension ring consist of an open, flexible PMMA filament; however, a PMMA fixation element or hook is joined to the loop of the modified ring. This hook extends from the loop centrally and courses anteriorly into a second plane, where it turns peripherally. At the free end of the hook is an eyelet for manipulation and suture placement. When the modified endocapsular tension ring is implanted in the capsular bag, the hook wraps around the capsulorhexis edge and comes to rest on the anterior surface of the anterior capsule rim.5
Nagamoto and Bissen-Miyajima6 showed that an open PMMA CTR inhibits fibrotic capsule shrinkage, although not completely. Strenn and coauthors7 implanted a silicone IOL and a CTR that had a 10.0 or 12.0 mm diameter depending on globe length in 19 eyes. They quantified capsule bag shrinkage by measuring the anterior chamber depth, iris-lens distance, and distance between the eyelets of the CTR. The capsular bag circumference was deduced from these measurements. They found a significant decrease in the circumference during the first 3 months after cataract surgery. No significant difference was found between the 2 types of CTRs. Although the change in the capsular bag circumference was similar with both ring types from 1 week to 1 month, capsule contraction continued for 2 months with the smaller ring but ceased with the larger one.
After the diagnosis of capsule contraction syndrome, we performed an Nd:YAG laser anterior relaxing capsulotomy in the left eye. The patient recovered a visual acuity of 20/20. We did not find IOL displacement or secondary complications
In conclusion, we suggest avoiding silicone IOL implantation in eyes with risk factors for contraction. In such cases, placement of an intracapsular ring may limit contraction of the bag, although it does not completely prevent anterior capsule contraction. Moreover, intracapsular ring implantation can inhibit lens decentration. Eyes with apparent or suspected zonular compromise should be closely monitored postoperatively to minimize the consequences of anterior capsule fibrosis.
1. Gallagher SP, Pavilack MA. Risk factors for anterior capsule contraction syndrome with polypropylene or poly-(methyl methacrylate) haptics. J Cataract Refract Surg 1999; 25:1356-1361
2. Davison JA. Capsule contraction syndrome. J Cataract Refract Surg 1993; 19:582-589
3. Cochener B, Jacq P-L, Colin J. Capsule contraction after continuous curvilinear capsulorhexis: poly(methyl methacrylate) versus silicone intraocular lenses. J Cataract Refract Surg 1999; 25:1362-1369
4. Hayashi K, Hayashi H, Nakao F, Hayashi F. Reduction in the area of the anterior capsule opening after polymethylmethacrylate, silicone, and soft acrylic intraocular lens implantation. Am J Ophthalmol 1997; 123:441-447
5. Cionni RJ, Osher RH. Management of profound zonular dialysis or weakness with a new endocapsular ring designed for scleral fixation. J Cataract Refract Surg 1998; 24:1299-1306
6. Nagamoto T, Bissen-Miyajima H. A ring to support the capsular bag after continuous curvilinear capsulorhexis. J Cataract Refract Surg 1994; 20:417-420
7. Strenn K, Menapace R, Vass C. Capsular bag shrinkage after implantation of an open-loop silicone lens and a poly(methyl methacrylate) capsule tension ring. J Cataract Refract Surg 1997; 23:1543-1547