A silent thief of the precious gift of sight, glaucoma is the second leading cause of blindness world-wide. Yet, timely detection can help protect your vision, says Kamala Thiagarajan

Our eyes are our windows to the world. And yet, we remain unaware of potential threats that can rob us of our vision.

Glaucoma refers to several diseases that ravage the optic nerve of the eye, first causing a loss of peripheral vision. If left to progress unchecked, it has the potential to blind you completely. And the statistics are staggering. While 11 million Indians above the age of 40 currently suffer from glaucoma, (according to estimates gleaned from the Chennai Glaucoma Study, conducted by Sankara Nethralaya, Chennai), in almost 10 million of these cases, the disease rages on undetected. Today, it is believed that 1 in 9 Indians (an estimated 40 million people) are at risk and may not even know that they are in imminent danger of losing their eyesight.

Glaucoma: Understanding the disease: "The front part of the eye is filled with a clear liquid called the aqueous humor," says Dr Ronnie George, Senior Consultant, Glaucoma Services, Sankara Nethralaya. "This clear liquid is produced where the iris (the colored part of the eyeball) meets the eye. It circulates through the eye, nourishing it. Normally, the fluid should drain away from the eye through regular channels or pathways. However, some conditions can prevent the proper draining away of this fluid. This causes excessive pressure to build up within the eye, creating a problem we call glaucoma."

A majority of sufferers have primary open-angled glaucoma--a condition in which there is a slow clogging of drainage channels, usually because of a structural defect of the eye that you are born with. This creates a silent build-up of pressure over a period of time. "This glaucoma has no symptoms, so the sufferer can be completely unaware of the condition, until activities that require peripheral vision, such as driving, become difficult," says Dr Ronnie George. "However, if caught early, it responds well to medication, so while it cannot be cured, eyesight can be saved." Primary open angled glaucoma is a chronic disease, one that requires life-long medication (with medicated eyedrops) and frequent follow-up check-ups, but it can be controlled and managed.

In angle closure glaucoma however, the pressure within the eye builds up dangerously and at a rapid pace because the fluid from the eye is suddenly prevented from draining away since the angle between the iris and the cornea is narrowed or closed. You will experience redness, swelling and pain and this is a medical emergency.

Co-genital glaucoma can develop at birth or usually during the first few years of life. "In children, one eye is usually larger than the other in such cases," says Dr Ronnie George.

Secondary glaucoma however, is caused by a sudden injury to the eye or can even be triggered by a bad lifestyle. "Just as in the heart, blood vessels in the eye too can be blocked because of excessive smoking, alcohol consumption and fat intake, leading to glaucoma at a later stage," says Dr N. Kasinathan, senior consultant ophthalmologist, Chennai. "Poorly controlled diabetes is a risk factor, especially if you've been a diabetic for over ten years. If you experience a frequent change in power (eye glass prescriptions), every three months instead of the usual one or two years, then it can be a warning signal for glaucoma. Any vague sensation of discomfort around the eyes, extreme sensitivity to light, frequent headaches should be investigated. Long term use of steroid drugs and steroid creams can put you at risk as well."

Families ties & treatment: "Glaucoma does run in families, so if any family member is diagnosed, it increases your risk three-fold," says Dr Ronnie George. "Regular and comprehensive eye evaluations are absolutely essential in such cases," says Dr Kasinathan. "Every six months, a dilated retina evaluation for those with a family history is recommended." For others above the age of forty, annual check-ups are required.

Glaucoma, though a chronic condition, can be managed through life-long use of medicated eyedrops. However, sufferers may experience several side-effects while using medication. Laser surgery is often an option in some cases, but frequent follow-up with your ophthalmologist is required as the results are often unpredictable and will last only a few years. Regular and timely evaluation is crucial in managing glaucoma. Remember, protecting your eyesight will go a long way towards ensuring the quality of your life, especially during those golden years.