Sunday, February 18, 2001		Keeping fit

Advancing age calls for greater care of the eyes. Regular visits to an eye specialist can help detect and prevent many sight-threatening diseases, say Prof Amod Gupta, Head, Department of Ophthalmology, PGI, and Dr B.K. Sharma.

THE first time the realisation dawns on you that age is really catching up, is around the age of 40, when imperceptibly but surely you start losing interest in the daily newspaper or you have difficulty sewing a button on your shirt. At this point of time, most people fail to appreciate fine print, especially in the evenings, or fail in simple activities like threading a sewing needle. People who are shortsighted find it more convenient to read without their spectacles. This is an indication of the onset of presbyopia due to failing accommodative power of the crystalline lens, a faculty which enabled one to see clearly the finest of prints in younger years. Clearly, one needs a pair of reading glasses and instead of heading to the nearest optical shop, this is high time you had your first detailed eye exam from a qualified eye specialist who will screen your eyes for a number of complications. It is important to realise that many sight-threatening diseases of the eye are asymptomatic and inapparent to the person himself till it is too late.

The commonest eye problem in the sixth decade and beyond is increasing cloudiness of the crystalline lens that starts interfering with the sharpness of vision, particularly during the evenings. Night driving may become hazardous because of the glare caused by the scattering of light by cataractous opacities. Some people who have these lens opacities in the dead centre of the light path may experience blurring of vision in the bright daylight instead and yet not feel anything abnormal while indoors. Till date, there is no medical cure for cataract. However, we know for sure that smokers are at least twice as likely to develop cataract as non-smokers. Healthy food habits that include fruits and leafy vegetables may help delay the onset of cataract. In the era gone by, when life was not very demanding, people waited for the cataract to turn white in colour before opting for its surgical operation. These days, anybody who finds that cataract is interfering in day-to-day activities such as reading, driving, watching television, socialising or interfering in general with the quality of life can opt for cataract surgery with implantation of an intraocular lens to replace the cataractous lens. While cataract surgery is the most common surgical procedure in the world and also has the highest success rate among all surgical procedures, it carries a small, acceptable but definite risk of losing vision forever should anything go wrong. The decision to undergo surgery, therefore, has to be carefully weighed keeping in mind the risk and benefits that would accrue. Cataract surgery does not require hospitalisation. While small incision surgery with ultrasonic phacoemulsification of cataract with implantation of foldable lens implants is fast catching up in urban India, expensive infrastructure that it requires, takes it out of the reach of the common man.

Unlike cataract, which is easily curable by surgery, glaucoma (kala motia in common parlance) causes irretrievable blindness if diagnosed late. While most of the diseases in man are symptomatic and alert a person well in time, glaucoma is by and large asymptomatic and by the time, the person notices declining vision, it is already too late. Glaucoma is the single most important reason why people above the age of 40 years should have their eyes screened. If detected in its initial stages, its progress can be halted by appropriate medical or surgical therapy. Till recently, high eye pressure alone was synonymous with the diagnosis of glaucoma, but now it is known that nearly one-third of the patients with glaucoma may have normal ocular pressure. Glaucoma is currently defined as a disease of the optic nerve (the nerve that conducts visual image from the eye to the brain) which produces characteristic losses in the field of vision. High ocular pressure is considered a modifiable risk factor. People who are shortsighted, diabetic or are related to someone who suffered from glaucoma should have periodic eye screening for glaucoma.

Macula or yellow spot is a highly-developed 0.5 mm area in the centre of retina, which is responsible for sharpness of vision, reading ability and seeing in colour. This is metabolically the most active tissue in the body. In the sixth decade of life and beyond the macula increasingly starts showing signs of wear and tear due to accumulation of metabolic waste products (dry type) resulting in gradual loss of central vision. Nearly 10 per cent of such people may develop abnormal blood vessels under the macula which may leak fluid or blood (wet form) and lead to sudden decline in visual function. Leafy vegetables and fresh fruits give protection against dry type of macular degeneration, while intake of vitamins and micronutrients in the form of pills or capsules have no such benefit. Smoking is a major risk factor. Very often involvement of one eye goes unnoticed and detected accidentally on closing the normal eye. People who have dry degeneration of macula in both eyes or already suffer from wet from in one eye are advised to regularly look at a grid (easily available from any eye specialist) with one eye closed to notice any distortions or disappearance of lines. Such an event would indicate the appearance of blood or fluid under the yellow spot. In early stages, laser treatment by a retina specialist can limit the extent of damage. At the very worst, an old person may lose central vision in both eyes which necessitates the use of magnifying glasses or even videomagnifier. Apart from difficulty in reading, recognising people, driving or crossing a busy road, there is no major handicap in moving around the house.

Sudden appearance of cobwebs in front of eyes in old age can be quite startling. While very often these cobwebs are a benign separation of the vitreous jelly from surface of retina, in nearly 5 per cent of the individuals it may herald the onset of a tear in the retina which could lead to detachment of the retina and subsequent loss of vision. Flashes of light somewhat similar to lightening streaks may accompany and indicate local tug on the retina by the separating vitreous jelly. People who have been short sighted all their life, have had surgery for cataract or have a family member who suffered from retinal detachments, are particularly prone to develop retinal detachment. Appearance of cobweb thus mandates an early and thorough retinal examination to detect any retinal holes/tear. These retinal holes can be easily closed with a laser before the occurrence of retinal detachment that would necessitate a major surgery to reattach the retina.

Eyes get affected in nearly 95 per cent of patients of diabetes after 20 years of suffering from the disease. Sadly, however, the eye is an organ that is most often neglected both by the patient and the physician. Over the years, diabetes causes damage to the small vessels and capillaries of the retina, leading to accumulation of fluid and fat in the yellow spot and development of abnormal vessels on the retina that can cause haemorrhage in the eye with eventual blindness. Till the very late stages, changes in the eye occur so slowly that they are inapparent to the patient even to an unsuspecting eye specialist. It is mandated that all diabetics should be screened to detect changes that are likely to threaten vision and preempt blindness by application of appropriate laser treatment. When detected early and treated, blindness can be prevented in over 95 per cent of the patients. All Type I diabetics, who have completed 5 years and Type II diabetics at diagnosis (since they may have remained undiagnosed for a number of years) should undergo a thorough dilated retinal examination every year till diabetic changes appear in the eyes when examination could be as frequent as every 3 to 6 months. At the most appropriate time, laser photocoagulation is advised to prevent sight-threatening complications. Appearance of any cobweb in front of eyes is a red flag signal in diabetics, as it may indicate the beginning of a haemorrhage in the eye and needs urgent attention. When eyes get affected, other organs, particularly the kidneys and peripheral nerves, also start getting affected. This is also the high time that a patient should be under the care of a competent physician and not indulge in self-treatment.

It has been shown beyond doubt that round-the-clock meticulous control of diabetics can delay (but not always prevent) and reduce the severity of eye changes. However, it is important to consult an eye specialist within weeks of changing any treatment regimen. All diabetic women planning a pregnancy must have their eyes checked, as pregnancy can lead to acceleration of diabetic changes in the eye if these existed before the onset of pregnancy.

While most lay people easily identify and are familiar with heart attack (occlusion of coronary artery) and stroke (occlusion of cerebral artery), they are not able to come to terms with similar events occurring in other organs, including the eyes. The cardiovascular risk factors such as smoking, high blood pressure, diabetes, and high blood cholesterol levels etc are universal for all ischaemic events. In the eyes, these could lead to temporary or permanent stoppage of blood supply to either retina or the optic nerve, with a consequent visual deficiency that could range from minimal to absolute. A word of caution for patients who take their blood pressure pills just before bed time. During sleep, even normal people experience a dip in their blood pressure and this phenomenon may become more pronounced if blood pressure medicines are taken before sleep. If the blood pressure falls below a critical level, the blood supply to the optic nerve head may stop, resulting in a stroke of the optic nerve head. The person wakes up in morning almost completely blind. So, stop smoking today and achieve a round-the-clock control of blood pressure, blood sugar and cholesterol levels to prevent the occurrence of these vascular complications.

Finally, it bears repetition that there is overwhelming evidence that smoking significantly increases the risk of cataract formation, macular degeneration and vascular occlusions. All these may lead to complications in old age when your eyes may be your sole companions and you need them the most.