If one begins with the figures, glaucoma happens to afflict an astounding 70 million people globally. Of all the affected people, one-tenth are said to be suffering from bilateral blindness. The figures for India are equally worrisome with health officials suggesting glaucoma could afflict 12 million people. And this number is expected to rise to 16 million by the year 2020.

The disease — the second common cause of blindness — is not one disorder but a range of conditions in which the pressure inside the eye becomes too high. The mounting pressure within the eye — something the optic nerve (the nerve which takes the vision from the eye to the brain) cannot tolerate — results gradually into progressive vision loss. The vision goes from the sides with no other noticeable symptoms. In fact, the patient does not even realise that he is losing his vision. By the time a person feels disabled enough to notice that something is wrong, 90 per cent of the cases have already lost 50 per cent of their sight.
Every person above the age of 40 runs the risk of getting this disease. Also those with a family history of glaucoma, those with diabetes, hypertension, thyroid, high minus powered glasses, those who have had an injury or any surgery in the eye along with people who have been exposed to steroid use (which could be in the eye/in the form of tablets/ointments) — are at a higher risk of developing this disease. After 40 all individuals have a tendency to wear glasses for near work (presbiopia) for which most go to an optical shop and buy spectacles. If they went to an eye specialist instead, they would be benefited by being examined and detected at the earliest.

The detection
The tests are simple and non-invasive where the pressure of the eye is taken with an instrument, a visual field test which is like a video game takes place in a dark room while the optic nerve is examined manually. Sometimes you can be called in at different times of the day to check your eye pressure.
Usually, a lens is used to detect if the type of glaucoma is an open or closed angle type. If it is a closed angle type, people may actually end up at the doctor’s clinic earlier than normal as they could experience mild evening headaches or see coloured haloes around light in the evening. Persons with this sort of glaucoma have an acute attack of severe pain, vomiting, a red eye which will have diminished vision, or all the above. In these cases, medicines are prescribed and then a laser procedure is carried out to bypass the blocked internal channels of the eye. Despite laser treatment, however, almost half the patients may still require to be kept on life-long medication.
The other type called open angle glaucoma shows practically no symptoms but if one starts to have decreased night vision, difficulty in seeing objects coming from the sides and has to change his or her reading glasses very frequently (yearly), then one must suspect this disease. In this situation, usually a single medicine in the form of eye drops is to be started, which will have to be continued life-long. Later additional eye drops may be required and some laser procedures may also have to be carried out. Surgery may be the last resort to control eye pressure if other options fail.

The treatment
Surgery for glaucoma will reduce the eye pressure in a majority of cases. However, it can also have some side-effects and its efficacy may not last beyond a couple of years. For this reason, we conduct surgery on a glaucoma patient only if the eye pressure is not controlled by laser treatment and medicines, if the patient cannot afford medicines or is getting allergic to them. One must understand that even after surgery all patients must keep getting check-ups of eye pressure done every two to three months and a visual field examination every six to nine months to see if the disease is under control as is the schedule for all glaucoma patients on medications.
Do see an eye specialist every year if you are above 40 and/or have any of the risk factors spoken of above.

The writer is Director Glaucoma Services, Centre for Sight, New Delhi and President, Glaucoma Society of India