Q: My vision has been blurring over the last several months. I thought I just needed new eyeglasses but the ophthalmologist told me I have cataract and that I need to undergo an operation to restore my vision. What causes cataracts?  How safe and effective are operations for cataracts? I am 63 years old already. --Fleridaq@yahoo.com

MANILA, Philippines — A: Cataracts refers to clouding or opacity of the lens of the eye. The lens is the structure that focuses light rays on the retina, where the cells that are sensitive to light (photoreceptors) are located. It is normally clear and transparent despite the fact that it contains a considerable amount of proteins. Sometimes, however, for one reason or another, the proteins clump up and the lens gets cloudy. Light that enters the eye has to pass through the lens hence any opacity of the lens will result in blurred vision.

Although cataracts are associated with some risk factors such as smoking, alcohol intake and prolonged exposure to ultraviolet light from the sun (sunlight) and X-rays, most are age-related and develop without any apparent cause—15 per cent of people above 50 years old have cataracts, albeit in varying degrees. A few are secondary to an infectious or inflammatory eye disease, trauma, a systemic disease like diabetes mellitus and intake of certain drugs such as steroids. A handful are congenital in nature (i.e., present at birth) and are either inherited or secondary to a maternal illness during pregnancy such as German measles, syphilis, cytomegalovirus infection or toxoplasmosis.

As a rule, cataracts, especially those that develop with aging, do not appear overnight. They develop slowly, over a period of many years. In its early stages, a cataract will not cause any visual impairment, but as it increases in size there is gradual and progressive loss of vision.

There are no known effective preventive measures against cataracts, although avoiding or controlling the known risk factors for the condition may help a little. Hence, non-smoking, drinking in moderation, avoidance of exposure to ultraviolet radiation including consistent use of sunglasses, and adequate control of diabetes mellitus (if a person has this disease) may reduce one’s risk for the condition.

How are cataracts treated? For early cataracts, new eyeglasses, better lighting and sunglasses that reduce glare are good temporary measures.

There are also many pharmacological agents available that claim to delay, prevent or even reverse cataract formation. Many eye specialists (ophthalmologists) prescribe them liberally, but these agents are largely ineffective. At present, the only definitive treatment for cataracts is surgery.

Outside of some medical indications like the danger or presence of secondary glaucoma, the only time cataracts should be operated on is when it already produces functional impairment of vision, i.e., if there is loss or significant diminution in the person’s ability to perform his/her vocation and avocation, something only the person with cataracts can tell.

Cataract surgery is one of most effective and safest of surgeries. In over 95 percent of cases, the procedure results in improved vision and complications like glaucoma, hemorrhage, retinal detachment and infection rarely occur.

Cataract surgery is usually performed under local anesthesia and on an outpatient basis. The surgical techniques that are currently being used in cataract surgery involve removal of the lens. After lens removal, an artificial plastic lens—called an intraocular lens (IOL)—is usually implanted.

If there is a contraindication for the implantation of an IOL, the error of refraction that occurs following removal of the lens is corrected with the use of glasses or soft contact lenses.

By the way, if both eyes require cataract surgery, the surgery is performed on each eye at separate times, usually two to eight weeks apart.

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