Cataract

Cataract is the term used to describe clouding of the lens of the eye (as opposed to the common misconception that cataract relates to a 'film' on the front of the eye). Although cataract can occur as a complication of disease, the majority of cataracts are caused by the aging process. It is unusual not to have developed some cataract by the age of 70.

The prime symptom of cataract is misty vision, though related symptoms include dazzle and glare, particularly in sunshine or when driving at night. Some cataracts can affect colour perception.

The only treatment for cataract is surgery. The correct time for surgery depends upon the needs of each patient. Patients who require excellent vision (drivers, pilots, artists, musicians etc) often request surgery at an early stage. Maintaining vision adequate for driving standards is perhaps the most common reason to undergo cataract surgery nowadays.

Surgery is normally undertaken under local anaesthetic and takes under 20 minutes. The cataract is removed using ultrasound (phaco-emulsification), before an artificial lens is implanted in its place. The lens implant is manufactured from a flexible clear plastic, which allows it to pass through a small incision (3mm or less), thereby enabling surgery to be undertaken without need for sutures. By calculating the power of the implant and the position of the incision it is possible to correct long and short sightedness and astigmatism at the time of cataract surgery. Most cataract operations will result in a return to normal vision although this may not be true where other eye disease is already present e.g. macular degeneration.

Complications of cataract surgery include unpredicted long and short-sightedness and astigmatism (which can usually be corrected with glasses). More serious complications include retinal swelling (macula oedema), which can reduce sight. Very rarely, severe post-operative infection can cause total loss of sight in the eye undergoing surgery (occurring in approximately 1 in 1000 cataract operations).