Posterior capsular opacification (PCO), sometimes called “secondary cataract,” remains the most common long-term complication of modern cataract surgery, according to a recent article in Archives of Ophthalmology.
The problem develops when the posterior portion of the capsular bag — the structure which encloses the eye’s natural lens — begins to get cloudy. (The posterior portion of this bag is left intact during cataract surgery to prevent leakage of vitreous from behind the capsule, which could cause a detached retina.)
Posterior capsular opacification can occur months or years after cataract surgery, unlike most other cataract surgery complications that tend to occur during or soon after the procedure.
Within 2 to 5 years after surgery, PCO causes decreased visual acuity in 20 percent to 40 percent of eyes that have had cataract surgery, according to the report. The problem is age-dependent and occurs more frequently in young patients. The rate of PCO among children who have surgery to remove congenital cataracts ranges from 44 percent to 100 percent.
Opacification of the posterior capsule appears to be influenced by lens epithelial cells that are left behind in the eye during cataract removal. These cells multiply, migrate across the posterior lens capsule and undergo changes that cause fibrous or pearl-type opacities in the capsule. The exact mechanism is not completely understood, but it appears to be a aberrant would healing response to cataract surgery.
Currently, the only treatment of PCO is a type of laser surgery called Nd:YAG laser capsulotomy. In this procedure, a laser is used to create a central opening in the cloudy posterior capsule to restore sight. The procedure is quick and easy, but possible complications of laser capsulotomy include retinal detachment, damage to the intraocular lens (IOL), increase in intraocular pressure and other problems.
New surgical techniques for cataract surgery may reduce the risk of residual lens epithelial cells remaining in the eye and thereby may reduce the risk of posterior capsular opacification. Also, improvements in the design and materials used for intraocular lenses may also reduce the risk of PCO in the future.
Source: Posterior capsular opacification: A problem reduced but not yet eradicated. Archives of Ophthalmology. April 2009.