A B C D E F G H I J K L M N O P R S T U V W

CATARACT

What is a Cataract ?

A cataract is a clouding of the lens within the eye. The lens is just behind the coloured iris and pupil. It helps to bring any light coming into the eye to a focus. This gives a clear image or picture to the layer at the back of the eye called the retina. The lens is normally transparent and clear. Some loss of clarity may be normal or unimportant. When clouding is more marked, it interferes with vision. Patients notice blurring of objects and a loss of brightness in colours. Haloes may be seen around lights. In some cases, vision is especially bad in bright light. Often reading vision is more affected than distance vision. Opticians will often find changes in spectacle prescription while a cataract is developing.

How does a Cataract occur ?

Cataract formation is a normal part of ageing. All people are eventually affected to some extent. Diabetics seem to get cataracts considerably earlier than usual. Also people on certain drugs such as steroids can be affected. Often other diseases of the eye can cause cataract, including eye injuries. Some forms of radiation may even be responsible. Rarely, infants may be born with a cataract.

Treatment Involved for a Cataract

The only effective treatment of a cataract is surgical removal of the lens. Before this is recommended, your eye is examined carefully to be sure that the eye is otherwise healthy. If there is nothing else wrong with the eye, the operation has an excellent chance of restoring vision, but if other disease in the eye is found, then the result cannot be guaranteed. The most common other disease is age-change of the retina called macular degeneration. Also severe glaucoma (raised pressure in the eye) can reduce the chances of good vision after surgery. If the cataract is so dense that the surgeon cannot see through it, an ultrasound scan may be performed to find out whether the retina is detached. Such a retinal detachment would interfere with the result of operation.

The operation may be done under local or general anaesthetic. Local anaesthesia involves either an injection of anaesthetic into the eyelid are or simply application of anaesthetic eye drops. The local anaesthetic is usually well tolerated and often completely pain free. The operation is generally done as a day case procedure but occasionally as an overnight stay. Day patients are often asked to return the following day to be examined. The procedure itself involves removing the lens and replacing it with an implant – an intraocular lens implant. Modern cataract surgery is performed with the technique called phacoemulsification. A small incision (3mm.) is made into the cornea and the lens removed by sucking after the hard central core has been broken up with high frequency sound waves (ultrasonics).The intraocular lens is implanted into the "bag" created by the removal of the cataract. The implant is usually folded in half so that it can be inserted through the small corneal incision. Very shortsighted eyes however need special low power implants which require a larger incision. Fine corneal stitches are then required. A microscope is used for this operation as it is so delicate and precise.

After Treatment of a Cataract

Immediately after the operation, your vision should be improved and colours appear brighter. There should be no pain, only a little discomfort. The eye may be rather red for a few days, and bright light can be uncomfortable. It is usual to go home very soon after surgery. There will be drops to use about four times a day for up to a month. Do not use the drops for longer than recommended, as wound healing will be delayed. A protective shield should be taped over the eye when sleeping to prevent inadvertant rubbing of the eye. At least a week is usually recommended however the surgeon or nurse will advise you. The eye must not be rubbed at all.

The next attendance is often one week after surgery however with small incision surgery a final follow-up visit at one month may be all that is required. If the eye becomes painful, blurred and sticky before this visit, an urgent appointment will be necessary. A check will then make sure there is no infection in the eye. At the final visit an alteration of spectacles is recommended or prescribed. Corneal stitches if present would be removed at this appointment. This is a quick procedure done in the clinic. The skin or membrane behind the implant may gradually become opaque after some time, generally after about two years but occasionally within a few months. This condition called posterior capsular opacification. It is becoming less common with the latest generation lens implants. If it does happen, vision will gradually become blurred again. The surgeon can treat this easily by a procedure using a special laser, known by the initials, YAG. A small hole is cut in the thickened capsule in the middle of the pupil, then a clear path is made for the light to enter the eye. After this treatment, a short course of eye drops is given.

If a Cataract is Left Untreated

Left untreated, a cataract worsens and may make the eye almost completely blind. Rarely if neglected the cataract may begin to break up spontaneously within the eye causing severe inflammation and high pressure behind the eye (glaucoma).

Effects on Family of a Cataract

For the more elderly patient it may be necessary to have help for a few days. The eye drops may prove difficult to put in particularly for patients with arthritis. The modern operation does not impose restrictions on lifting or bending, however heavy lifting and vigorous exercise should be avoided for 3-4 weeks.