It is said that one should have a clear vision so that he can excel and achieve his objectives accordingly. Sometimes, however, this is not the case in the literal meaning of the phrase.

It happens when the lens, lying just behind the coloured portion of eye, that helps to converge and focus the light rays onto the retina located at the back of the eye, allowing us to see things clearly, becomes cloudy. The lens is mostly made of water and protein; the protein is arranged in a way that keeps the lens clear and lets light pass through it. But as we age, some of the protein may clump together and start to cloud a small area of the lens. This clouding is known as cataract and gradually grows larger covering more and more of the lens, making it harder to see.

According to the World Health Organisation, cataract accounted for 20 million people or 51 per cent of the entire blind population globally. It occurs gradually without causing any immediate significant disability. Initially the person may experience impaired, fuzzy and blurred vision; later symptoms include difficulty in night vision, increased light sensitivity, haloes around light and double vision. An individual who might be developing cataract is likely to feel the need for changing his contact lens and eye glasses frequently. Increase in size of the developing cataract, while involving more of the lens, obstructs the light pathway and impedes clear vision. Resultant scattered light rays form ill-defined images.

Cataract is the most common cause of vision loss in people over 40 years of age and is the leading cause of blindness in the world

Cataract is not contagious, but can develop in both the eyes. The chances of developing cataract increases exponentially with age due to the age-related changes in the lens. Past eye surgery, genetic disorders, chronic steroid intake, injuries or even metabolic disorders like diabetes and certain radiations predisposes to developing cataract. Alcohol consumption, increased exposure to sunlight, family history, high blood pressure, smoking and even obesity may increase the chances.

Cataracts may be classified based upon the type (congenital or acquired), causes (age-related, traumatic, associated with other eye diseases or surgeries, associated with metabolic disorders like blood pressure or diabetes), position of the cataract on the lens and even on the stage of the senile cataract where the lens thickens gradually. The problem progresses from immature, to mature and to hyper-mature cataract; however, is better not to prolong the cataract to the mature stage as if left untreated it may lead to blindness.

There are no medicines for curing cataract; temporary relief might be a possibility in a few conditions. The treatment for cataract is only surgery. The decision for cataract surgery depends on the extent of cloudiness and how slow or fast it is progressing; depending upon the extent the ophthalmologist might delay surgery for years. But once diagnosed the patient should stay in touch with the doctor as (s)he would perform some basic eye tests to gauge the extent, condition and stage of the cataract. If the vision cannot be improved with the help of glasses and the quality of life is being compromised, especially with respect to difficulty during driving, reading and night vision, then it is considered an indication for surgery.

After assessment, surgery is performed with the sole purpose to remove the affected lens. The lens with cataract is removed and replaced with an artificial lens, called intraocular lens (IOL). In some cases, lens may not be replaced and instead external contact lens and spectacles are advised for complete vision correction. Laser phacoemulsification is the most common procedure these days performed by ophthalmologists in which the lens is broken down into small pieces by ultrasound waves. It is an Out Patient procedure and do not require hospital admission. Extra capsular cataract extraction (ECCE) is another surgery with relatively longer healing time, in which comparatively bigger incision is made while extracting the complete lens in one piece. Both surgeries are safe and conducted under local anaesthesia. The complete healing time might be 10-15 days. In case of cataract in both eyes, the second eye is operated on after a gap of two to four weeks.

Different types of IOLs are available. Less in demand, Rigid IOLs are currently used mostly in the remote areas and eye camps. Foldable lens category is in much demand. Depending upon the ability to focus and provide different range of vision, these lenses are available in monofocal, bifocal, trifocal and multifocal types.

Toric IOL is another type used in Astigmatism (a condition where light rays are prevented from meeting at a common focus) correction. Foldable IOLs are preferred over Rigid IOLs because of their reduced healing time and smaller incision requirement. Even smaller incision is required in Rollable IOLs and Preloaded IOLs that are placed with the help of special injections designed specifically for this purpose.

Annual visit to ophthalmologist is important, especially after 40 years of age. This is even more critical in case of those individuals who may experience any change in their normal routine vision from their previous visit. Wearing sunglasses, avoiding direct sunlight exposure, eating healthy food, smoking cessation and controlling diabetes are likely to decrease the progression speed of a cataract formation.

The writer is a physician and tweets @Ali_Shahid82

Published in Dawn, Sunday Magazine, November 15th, 2015

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