The natural lens of the eye is held in place by a thin clear membrane called the lens capsule. The capsule completely surrounds the lens and separates it from the thick fluid in the back of the eye, called the vitreous, and the thinner fluid in the front of the eye, called the aqueous.
Cataract surgery is necessary when the natural lens become cloudy and must be removed. When cataract surgery was originally performed, surgical techniques were not as refined as today, and both the natural lens and the capsule were removed during surgery. Newer techniques allow the capsule to remain in the eye and hold the implanted lens (or intraocular lens, IOL) in place. Leaving the capsule in place during surgery is a great advancement because it allows the vision after surgery to be more stable and provides for less surgical complications.
Sometimes the posterior, or back, portion of the capsule becomes cloudy after cataract surgery. The reasons for this cloudiness are unknown. If the posterior capsule becomes so cloudy that it detrimentally effects vision, then a capsulotomy is performed.
A capsulotomy involves a yttrium aluminum garnet laser (YAG laser) to create an opening in the center of the cloudy capsule. The opening allows clear passage of the light rays and eliminates the cloudiness that was interfering with the vision. A laser beam is used to create this opening. This procedure is painless, very safe and typically the results can be seen immediately. For capsulotomy, as with any surgery, rare complications can occur, such as swelling or retinal detachment. These complications can cause loss of vision.
A cloudy capsule will often appear the same way as the original cataract. The vision is cloudy or hazy and the patient is heavily bothered by glare. In fact, vision is so similar that some patients think that the cataract has come back or regrown. This is impossible, cataracts cannot return once the natural lens has been removed.
If your vision is getting worse after cataract surgery, it could be that your capsule is becoming cloudy. Your eye doctor should give you a thorough eye examination to determine the cause of your vision loss. If your capsule is becoming cloudy, your eye doctor can then determine whether a capsulotomy is necessary to improve your vision.