Glaucoma is a disease in which the optic nerve (the nerve that connects eye with brain) is damaged, leading to progressive, irreversible loss of vision. It is often, but not always, associated with increased pressure of the fluid in the eye.

It is one of the leading causes of blindness worldwide.

Rays of light enter the eye through the pupil (the opening of the eye), passes through the lens and is focused onto the retina (the innermost layer of the eye). From here; the optic nerve carries the images to the brain.

The front part of the eye is filled with a fluid called ‘aqueous humor’. This fluid not only nourishes different parts in the front portion of the eye, also helps to maintain the shape of the eyeball. It is constantly produced, circulated and drained outside the eye through drainage canals. When there is a problem in the drainage, the fluid pressure in the eye increases, damaging the optic nerve and resulting in glaucoma.

There are two most common types:

1. Open-angle (also called primary open-angle glaucoma or chronic glaucoma) – Open angle accounts for 90 percent of all glaucoma cases and occurs when the drainage canals are blocked and the fluid pressure within the eye builds up gradually.

2. Closed angle (also called angle closure glaucoma or acute glaucoma) – Closed angle accounts for about 9 percent of all glaucoma cases and occurs when the drainage opening becomes narrow and the fluid pressure within the eye builds up very quickly.

Family history of glaucoma in parents or siblings

Age advances beyond 45 years

Medical history of diabetes, high blood pressure

Myopia (nearsightedness), which is the inability to see distant objects clearly

History of raised pressure of fluid in the eye (intra ocular pressure)

Injury to the eye

Use of cortisone (steroids), either in the eye or systemically (orally or injected)

Early diagnosis of glaucoma is very important as it has no symptoms in the early stage and the damage to the optic nerve is irreversible. Early diagnosis can help preserve the vision. It can be done by the doctor using,

Tonometry - After the eye has been numbed with anesthetic eye drops, an instrument called a tonometer is used to measure fluid pressure in the eye (intra ocular pressure).

Ophthalmoscopy - After dilating the pupil with the eye drops, the doctor can examine the inside of the eye and the optic nerve with the help of an instrument called ophthalmoscope.

Perimetry - A special computerized test is done to analyze the field of vision of the patient.

Gonioscopy - A test to check whether the drainage area of the eye is open or narrow, blocking the drainage of the aqueous fluid out of the eye.

Pachymetry - A new test used to determine the thickness of the cornea. Thin corneas may be an additional risk factor for glaucoma.

There is no cure for glaucoma, but it can be controlled. Ophthalmologists use medication, laser or surgery to prevent further loss of vision.

Medication

Nearly all glaucoma can be treated successfully with medications such as eye drops or eye ointments or oral medications (taken by mouth).

One or more types of eye drops may have to be used several times a day. These drops lower intraocular pressure either by reducing the production of the aqueous fluid or by increasing the drainage of the fluid out of the eye.

Certain oral medications also help in lowering intra ocular pressure by reducing the aqueous fluid flow into the eye.

Each type of therapy has its benefits and potential complications.

There are several forms of laser therapy for glaucoma.

Trabeculectomy is the most commonly performed glaucoma surgery and the most effective means of lowering the eye pressure.

While glaucoma cannot be prevented, here are some tips for its early detection.

• Individuals with the age of 40- 65, should have an eye examination every 2-4 years
• have an eye examination every 1-2 years if
1. have age of 65 years or more
2. have family history of glaucoma
3. have diabetes
4. have history of eye injury
5. are taking steroids.

Regular eye checkups and compliance with medication can go a long way in preserving the vision.