What is glaucoma and how can it be treated?

By Nnaemeka Meribe

Glaucoma is a leading cause ofirreversible blindness in the world. It is a group of diseases of the eye that causes permanent blindness by destroying the optic nerves at the back of the eye. Optic nerves take information from the retina of the eye to the brain for interpretation.

• Illustration of intraocular pressure in the back of the eye due to damage to the optic nerve. Photo credit: www.allaboutvision.com

Who is at risk?

While anyone can develop glaucoma at any time, some people, more than others, are predisposed to developing glaucoma, particularly chronic glaucoma. People over 40 years and above fall into this. In addition to increasing age, race is another predisposing factor.

Black people are at ahigher risk of developing glaucoma than any other race. People whose relations have been diagnosed with glaucoma are also at risk. The risk is higher if they are above 40 years. Other risk conditions include high myopia or short-sightedness, diabetes and hypertension. People who are on medications containing corticosteroid, especially eye drops, over a long period are also likely to develop glaucoma.

What are the causes?

The cause of glaucoma is not completely known. But raised pressure in the eyeball has been frequently linked with glaucoma. Inside the eyeball is fluid which gives the eyeball its shape and assists in its function by exerting some pressure within the eyeball.  When this pressure exerted by the fluid goes beyond acceptable range, damage to the optic nerve occurs. The extent of the damage is determined by the magnitude of the pressure, with higher pressure resulting in much more damage and the duration of the pressure determined by how much damage is done to the optic nerves.

What are the symptoms?

At the onset, the disease could be chronic or acute.  Chronic cases develop slowly without symptoms over the years. This is why glaucoma is often referred to as ‘thief of the eye’. Acute cases are rare but are sudden and associated with sharp pain and irreversible loss of vision. Glaucoma could also be a result secondary to another condition or factor and congenital glaucoma has been seen in newborns and associated with incomplete development of the visual system at formation.

In most cases of glaucoma, there are no appreciable symptoms reported until advanced stages of the disease. It starts with narrowing of the visual field to tunnel vision. Other symptoms like sharp pain, reduced and blurry vision, haloes around bright light, poor contrast and red eye (in acute glaucoma) etc. occur at advanced stage of the disease.

• Illustration of malignant glaucoma. Photo credit: www.eyeworld.org

Can it be treated

In managing glaucoma, early detection is key.  A study is currently going on inAustralia to improve early detection. Yearly comprehensive eye check by an optometrist is recommended. For those identified as being at higher risk, comprehensive eye check twice every year is recommended. Generally, early detection and treatment will ensure minimized risk and damage to the eye, since vision loss is irreversible. The goal of the treatment is to reduce the pressure in the eye and improve blood circulation to the optic nerves.

If the disease was detected late and significant vision has been already lost, much can still be done to stop further loss and help maximize the remaining partial vision. Low vision devices can be helpful where drugs, surgery and other optical devices have failed or could not help. Contact an optometrist for further details.