Cataract refers to the condition where the lens of the eye – a transparent, biconvex structure behind the iris that focuses light onto the retina so that we see things as they are – develops cloudy patches. These patches usually increase in area over time, subsequently affecting one’s vision. Cataract may develop in only one or both eyes and does not spread from one eye to the other. It usually occurs in people over the age of 55 years, although it may occasionally occur in babies or children due to various reasons.
Cataract may manifest as:
- nuclear cataract – occurs at the center, or nucleus, of the lens, which tends to darken from clear to yellow (and sometimes even brown) with age
- cortical cataract – occurs on the layer surrounding the nucleus, giving it a wedge- or spoke-like appearance
- posterior capsular cataract – occurs on the back outer layer and usually develops more rapidly than the other two
Common symptoms of cataract include one or more of the following, which usually increase over time:
- blurry, hazy or misty vision
- colours seeming faded or less intense
- increased sensitivity to lights, particularly at night
- increased difficulty seeing in low light
- needing to frequently get eyeglass prescription changed
If left untreated, cataract progressively worsens eyesight, eventually making it challenging to carry out day-to-day activities that one might have previously been used to. Basic things such as reading, judging the shape, distance and colour of objects may be distorted. This could make certain activities such as driving potentially dangerous.
The lens of the eye is largely made up of water and proteins. Cataract occurs when changes take place in these proteins, thereby affecting the lens fibres and causing clouding of the lens.
While most cataracts are age-related, there are several risk factors associated with the development of cataract. These include:
- a family history of cataract
- diabetes mellitus
- long-term use of certain drugs such as steroids
- high alcohol consumption
- eye injury or long-term exposure to ultra-violet radiation
- nutritional deficiencies such as vitamin C, vitamin E and carotenoids
- after-effect of surgery for other eye conditions, such as glaucoma
Cataracts in infants or children may be associated with the following:
- a hereditary condition passed down from the parents
- genetic conditions, such as Down’s Syndrome
- infections in the mother such as chickenpox and rubella during pregnancy
- post-natal injury to the eye
An ophthalmologist would carry out a comprehensive eye exam if they suspect that your symptoms may be related to cataract – particularly if you have a known family history of the condition or can relate to the other risk factors mentioned above. The test usually measures several parameters that include visual acuity (clarity of vision), keratometry/topography (curvature of the cornea), refraction (how lens focuses light on the retina), eye focusing, teaming and movement. Further investigations may be carried out, as required.
There is no definite means of preventing the incidence or progress of cataract. The best option is to treat the condition before it progresses to the point of impairing one’s daily routine and activity. In addition, it also helps to maintain a healthy lifestyle that includes a balanced diet, limited alcohol intake and no smoking.
In cases where a cataract is still in its early stages and only minimally affects the patient’s vision, an ophthalmologist might recommend no treatment, and may instead advise the patient to come for regular check-ups to monitor its progress.
The ultimate solution for cataract is surgery. This may be done by:
- small-incision surgery, where a tiny probe is inserted through a small incision in the cornea and ultrasound is used to disintegrate the lens, the remains of which are sucked out (known as phacoemulsification)
- extracapsular surgery, where a larger incision is made in the cornea to enable the lens to be removed as a whole
An intraocular lens (IOL) is then implanted (unless this is not possible due to other eye conditions, in which case eyeglasses or contact lenses may be recommended) to replace the removed natural lens.
The surgery itself should ideally take no more than a few minutes, to the trained hand. Post-surgery medication usually continues for about six weeks.
Cover illustration adapted from 123RF
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thankyou for the explanation. very useful.