The stealthy & silent thief of sight

Glaucoma typically exhibits no symptoms until the advanced stages, at which point the prognosis is dismal, Watch out for tunnel vision or blotchy spots in peripheral vision, warns Dr Chetana T Nayak

Glaucoma, also known as the “silent thief of sight”, is an eye condition that gradually and painlessly results in permanent vision loss. It is an eye condition that causes irreparable damage to the optic nerve. Glaucoma is the second most common cause of blindness in India, affecting at least 12 million people and leaving approximately 1.2 million of them legally blind. Cataracts are the primary cause of blindness in the country. Contrary to glaucoma, cataract-related blindness can be easily treated surgically.

Glaucoma typically exhibits no symptoms until the advanced stages, at which point the prognosis is dismal. To maintain improved visual fields, diagnosis at an early stage is essential. Early glaucoma symptoms are essentially undetectable, but as the disease worsens, individuals may have tunnel vision or see blotchy spots in their peripheral vision. The warning indicators to watch out for are halos around lights, tunnel vision, slow loss of peripheral or side vision, and blurred vision.

What is glaucoma?

The intraocular pressure (IOP), or fluid pressure inside the eye, rises in glaucoma. The optic nerve may gradually deteriorate due to this pressure rise, and nerve fibres may be lost. The optic nerve is a collection of nerve fibres that carries visual information from the retina to the cerebral cortex. Even those with healthy ocular pressure occasionally experience glaucoma. Primary open-angle glaucoma is the most prevalent type of disease. It steadily grows and typically exhibits no symptoms. Many people don’t realise they have a problem until they have severe vision loss. Primarily affecting side or peripheral vision, glaucoma can eventually cause considerable vision loss in both eyes and even total blindness if untreated. The following factors can increase the risk of developing glaucoma:

Age: People over the age of 60 are at increased risk for glaucoma.

Race: African Americans are significantly more likely to get glaucoma.

Family history: Having a family history of glaucoma increases the chances of developing glaucoma.

Medical conditions: Some studies have indicated that diabetes, high blood pressure and heart disease may increase the risk of developing glaucoma.

Injuries to the eye: Severe trauma like being hit in the eye can result in immediate increased eye pressure. Internal damage due to such trauma can also increase eye pressure in the future.

Corticosteroid use: Using corticosteroids for prolonged periods of time can increase the risk of getting secondary glaucoma.

There are many tests used by an eye doctor for detecting glaucoma. These tests are:
Intraocular pressures (IOP): There are many methods of measuring IOP like air puff test, Goldmann tonometry, Perkins applanation tonometry, and a few others. But the Goldman method may be considered the gold standard for measuring eye pressure.

Visual Fields Test: Here, a computerised mapping of the patient’s visual field is done. It enables the doctor to measure the range of the patient’s peripheral vision and detect any abnormalities in the visual field.

Optical Coherence Tomography (OCT) scan: This is a non-invasive, radiation-free computer-based diagnostic device that provides colour-coded, cross-sectional images of the retina, allowing early detection and treatment of glaucoma.

How can glaucoma be treated?

Glaucoma can only be controlled, it cannot be cured completely. While there is no way to prevent glaucoma, there are several treatment options that can slow down damage to the eye and vision loss.

Eye drops are prescribed for the early stages of glaucoma. These drops are used to improve fluid drainage from the eye or help to decrease the amount of fluid the eye produces thereby reducing eye pressure.

Oral medications are used when drops alone are ineffective in reducing eye pressure.

Laser therapy or laser trabeculoplasty helps the fluid easily drain from the eye and is used to treat open-angle glaucoma while laser peripheral iridotomy is used in cases of narrow-angle glaucoma.

Apart from eye drops and lasers, surgery is an option especially when eye pressure is not controlled.

(The author is a consultant in general ophthalmology.)