What is Glaucoma, and what is its current status in India?
Glaucoma is an eye condition where the optic nerve (nerve that carries information from our eyes to the brain) gets damaged usually due to raised pressure inside our eyes. What makes glaucoma dreadful among many other eye diseases is its covertness. By the time people realize that they are losing vision, most of the damage has already been caused. In most cases the optic nerve is damaged when the intraocular pressure inside the front of the eye rises. Glaucoma related eye damage can also occur when the intraocular pressure is normal. In most cases the optic nerve is damaged when the intraocular pressure inside the front of the eye rises. Glaucoma related eye damage can also occur when the intraocular pressure is normal. According to WHO statistics, the prevalence of glaucoma in India is 2.6%.
What are the most common types of glaucoma?
The most common types of glaucoma are “primary open-angle glaucoma” and “acute/angle closure glaucoma”. In “primary open-angle glaucoma” the fluid circulates freely in the eye with a slow rise in intraocular pressure over-time. “Acute angle glaucoma” is a less common form of glaucoma. It develops suddenly, causing eye-pain and redness.
What are the causes for glaucoma?
The exact causes for optic nerve damage from glaucoma are unknown; it involves mechanical compression and/or decreased blood flow of the optic nerve. Although high eye pressure sometimes leads to glaucoma, many people can develop glaucoma with “normal” eye pressure. The cause of secondary glaucoma is unknown. However, both “open-angle glaucoma” and “closed-angle glaucoma” can be a secondary cause due to:
- Medications such as corticosteroids
- Eye drops that dilate the eyes
- Uveitis which is an infection of the middle layer of the eye
- Eye injuries
Although “open-angle glaucoma” and “acute-angle glaucoma” cause blindness the symptoms are different. Symptoms of “open-angle glaucoma” are the following:
- Severe loss in vision
- Tunnel vision in advanced stages
Symptoms in angle-closure glaucoma are inconsistent; they may come and go or steadily become worse.
- Sudden, severe pain in one eye
- Decreased or cloudy vision, often referred to as “steamy” vision
- Nausea and vomiting
- Rainbow-like halos around lights, red eye
- Swelling sensation in eyes.
Diagnosis of glaucoma happens with different tests depending on the severity of the symptoms. Tests may include:
- Tonometry- Determines the pressure in the eye by measuring the tone or firmness of its surface.
- Pachymetry– Determines the thickness of cornea. Recent studies have shown that central corneal thickness can affect the measurement of intraocular pressure.
- Gonioscopy– Purpose of this test is to examine the filtering angle and drainage area of the eye.
- Nerve fiber analysis– This is a very important test for earliest detection of glaucoma where the thickness of retinal nerve fiber layer is measured. Since nerve layer fiber is earliest site of damage this test assumes importance in detecting glaucoma at earliest stage so that it can be treated early to arrest or slowdown further damage to the nerve.
- Visual-field testing– It is the best way to discover early signs of loss of peripheral vision. The visual-field machine draws a picture of where the person is able to see blinking lights.
How to prevent glaucoma?
Open angle glaucoma is un-preventable as most people do not show any signs/symptoms. However, vision loss can be prevented by
- Eating a healthy diet
- Limited use of caffeine
- Sufficient intake of fluids
- Regular exercise
Treatment of Glaucoma
Glaucoma can be treated with medication, eye drops, laser surgery, drainage implants or filtering surgery (trabeculectomy). Prognosis is dependent on the type of glaucoma, and the goal of any treatment is to prevent loss of vision, as vision loss due to glaucoma is irreversible.