Posterior capsule opacification

Posterior capsule opacification following extracapsular cataract extraction is a manifestation of proliferation of anterior lens epithelium onto the posterior capsule. In addition to Elschnig pearl formation, vision is decreased in two ways. Multiple layers of proliferated epithelium produce a frank opacity. Also, the lens cells show myofibroblastic differentiation and their contraction produces numerous tiny wrinkles in the posterior capsule resulting in visual distortion. Because the cells that proliferate are anterior lens epithelial cells and because proliferation begins at the site of apposition of anterior capsular flap and the posterior capsule, a wide anterior capsulectomy should help reduce the risk of and delay the onset of visual loss from this complication of extracapsular surgery. Polishing the posterior capsule at the time of surgery will not help in this regard unless there is a complicated cataract with pre-existing posterior migration of lens epithelium. The presence of a potential cleavage plane between the proliferating epithelium and the posterior capsule provides a therapeutic alternative to surgical or laser discission.

We performed a prospective study evaluating the incidence of angiographic cystoid macular edema (CME) following extracapsular cataract extraction and posterior chamber intraocular lens implantation. Of the 162 eyes in the study, 141 were randomized into either a primary capsulotomy or a capsule intact group. The remaining eyes were not randomized due to intraoperative surgical complications, but they were included in the follow-up studies. Six weeks after surgery, angiographic CME was documented in 24% of the capsulotomy group and in 16% of the capsule intact group. The differences were not statistically significant. Including nonrandomized cases reduced the overall incidence of angiographic CME and the difference between the two groups. Angiographic CME was usually not extensive, and it was associated with a visual acuity less than 20/40 in 2.5% of eyes six weeks postoperatively. A subgroup of 120 eyes was followed up for approximately six months, when angiographic CME was present in 4% of the capsulotomy and capsule intact groups.