A cataract is a cloudy or opaque area in the normally clear lens of the eye. Depending upon its size and location, it can interfere with vision. Most cataracts develop in people over age 55, but they occasionally occur in infants and young children. Usually cataracts develop in both eyes, but one may be worse than the other. The lens is located inside the eye behind the iris, the colored part of the eye. The lens focuses light on the back of the eye, the retina. The lens is made of mostly proteins and water. Clouding of the lens occurs due to changes in the proteins and lens fibers. Increasing age, UV light exposure, and some medications like Prednisone contribute to the formation of cataracts.
The lens is composed of layers like an onion. The outermost layer is called the lens capsule. The layer inside the capsule is the cortex, and the innermost layer is the nucleus. A cataract may develop in any of these areas and is described based on its location in the lens:
- A nuclear cataract is located in the center of the lens. The nucleus tends to darken changing from clear to yellow and sometimes brown.
- A cortical cataract affects the layer of the lens surrounding the nucleus. It is identified by its unique wedge or spoke shaped appearance.
- A posterior subcapsular cataract is found in the back layer of the lens. This type often develops more rapidly than other types of cataracts.
Normally, the lens focuses light on the retina, which sends the image through the optic nerve to the brain. However, if the lens is clouded by a cataract, light is scattered so the lens can no longer focus it properly, causing vision problems.
Cataracts generally form very slowly. Signs and symptoms of a cataract may include:
- Blurred, hazy, or cloudy vision
- Reduced intensity of colors
- Increased sensitivity to glare from lights, particularly when driving at night
- Increased difficulty seeing at night and with reading vision
- Change in the eye’s refractive error
While the process of cataract formation is becoming more clearly understood, there is no clinically established treatment to prevent or slow their progression. In age-related cataracts, changes in vision can be very gradual. Some people may not initially recognize the visual changes. However, as cataracts worsen vision symptoms tend to increase in severity. Fortunately, modern day cataract surgery is a quick and painless procedure. Both Drs. Liu and Beers specialize in cataract surgery. In fact, Dr. Beers teaches the cataract procedure to the ophthalmology residents in training at Stanford University, and Dr. Liu has taught these procedures to ophthalmology residents at UC Irvine.