There are several eye diseases that can sometimes lead to vision loss. Glaucoma is the second leading cause of blindness in the world with approximately 65 million people affected. In the US, four million people are estimated to have the disease with 9-12% progressing to blindness. What makes glaucoma particularly important is its proportionately higher incidence amongst people of African descent. Research suggests that people of black heritage are five times more likely to suffer from glaucoma and are more than six times likely to become blind from the disease than people from other ethnic backgrounds. In addition to these statistics, African Americans tend to develop the disease at a younger age.
What is Glaucoma?
Glaucoma refers to a group of eye disorders that affect the optic nerve. This nerve is responsible for transmitting visual information from the eye to the brain for processing. In general, glaucoma occurs when there is an imbalance in the fluid production and drainage of the eye which can lead to increased pressure within the eye ball. An analogy that might help explain this is a hose pipe with water running through—so long as the end of the hose is open, tap water entering from the other end is squirted out with no problem. However, should a blockage occur within the pipe such that water cannot flow out, a back up occurs with a focal pressure point which continues to build up until the pipe blows up. In the eyes, this pressure pushes up against the optic nerve and over time leads to damage.
Who is at risk?
People with increased risk factors are those of African descent, over the age of 60, with family members who have glaucoma, use medications containing steroids (e.g. some asthma inhalers) and have comorbid diseases (e.g. diabetes and hypertension), should have a complete eye exam every one or two years.
Types of Glaucoma, symptoms and treatment
There are four main types of glaucoma:
a) Closed angle (acute) glaucoma – This occurs when blockage of the drainage canal occurs suddenly. Common symptoms include headaches, nausea and vomiting, severe eye pain, blurred vision, rainbow-colored halos and sudden vision loss. The sudden onset of blindness makes closed angle glaucoma a medical emergency usually requiring surgery to save vision in one or both eyes.
b) Open-angle (chronic) glaucoma — More common than closed angle glaucoma. Increased pressure occurs here because of a blockage within the drainage pipe as opposed to the end of it. Blockage occurs slowly over a longer period of time which usually results in gradual development of blindness. Usually, people have no symptoms until they lose their vision. Given its gradual nature, open-angle glaucoma can be treated with eye drops if detected early. Other people might require treatment such as laser or traditional surgery to open up the canal.
c) Congenital glaucoma – Diagnosed usually at birth resulting from improper development of the drainage canals of the eye. In most cases, the defect occurs in both eyes with boys more likely to be born with the disorder than girls. Symptoms include cloudiness of eye lenses, swelling and redness of eyes, excessive tearing and increased sensitivity to light. Treatment usually involves surgery.
d) Secondary glaucoma — As the name suggests, secondary glaucoma results from other injuries or diseases of the eye such as uveitis, diabetes and damage from drugs such as corticosteroids. Treating the underlying condition can sometimes prevent further damage to the optic nerve.
Screening and Testing
It is essential for prevention of blindness that glaucoma be detected early and treated. Current screening recommendations are eye tests:
- before age 40, every two to four years
- from age 40 to age 54, every one to three years
- from age 55 to 64, every one to two years
- after age 65, every six to 12 months
It is imperative that you talk to your doctor today about having your eyes checked if you have any of the risk factors previously mentioned in the article.
Sources
http://www.glaucoma.org/learn/
https://www.google.com/health/ref/Glaucoma