Glaucoma is a condition where the optic nerve is subject to damage--usually, but not always, because of excessively high intra-ocular pressure (pressure within the eye--also called IOP). If untreated, the optic nerve damage results in progressive, permanent vision loss, starting with unnoticeable blind spots at the edges of the field of vision, progressing to tunnel vision, and then to blindness.
Glaucoma is actually a class of diseases--there are at least twenty different forms that can be divided into two categories: open-angle glaucoma and narrow-angle glaucoma. To understand what glaucoma is and what these terms mean, it is useful to understand eye structure.
Glaucoma occurs if the aqueous humor is not removed rapidly enough or if it is made too rapidly, causing pressure to build-up. The high pressure distorts the shape of the optic nerve and destroys the nerve. Destroyed nerve cells result in blind spots in places where the image from the retina is not being transmitted to the brain.
Open-angle glaucoma accounts for over 90% of all cases. It is usually chronic and progresses slowly. In narrow-angle glaucoma, the angle where aqueous fluid drainage occurs is narrow, and therefore may drain slowly or may be at risk of becoming closed. A closed-angle glaucoma attack is usually acute, occurring when the drainage area is blocked. Glaucoma is also a secondary condition of over 60 widely diverse diseases and can also result from injury.
The cause of eye damage in some otherwise healthy eyes is a raised pressure within the eye, (the intra-ocular pressure), that can damage the nerve over a period of time and this damage results in poor blood supply or weak end eye structure.
Some of the risk factors for Glaucoma are:
- Persons who have had eye surgery or an eye injury earlier in life.
- People with very near sightedness or far sightedness.
- Diabetes and certain other chronic diseases.
- African-Americans are more prone to this condition.
- Anyone over the age of 60 are most susceptible.
- People with a family history of glaucoma.
- Persons with heart disease or conditions resulting in sluggish blood flow to the eye are at an increased risk for developing glaucoma.
- Obesity has been identified as a risk factor associated with glaucoma.
Glaucoma is an insidious disease because it rarely causes symptoms, however some glaucoma's do have signs like :-
- Loss of side vision.
- Extreme eye pain and headaches.
- Difficulty in adjusting to a dark room.
- Nausea and vomiting.
- Watering and increased sensitivity to light, with appearance of halos around lights.
- Blurring of vision.
- Need for frequent changes of glasses.
Because glaucoma may not initially result in symptoms, the best form of prevention is to have regular eye exams.
Patients with narrow angles should avoid certain medications (even over-the-counter medications, such as some cold or allergy medications). Any person who is glaucoma-susceptible (i.e. narrow angles and borderline IOPs) should read the warning labels on over-the-counter medicines and inform their physicians of products they are considering taking. Steroids may also raise IOP, so patients may need to be monitored more frequently if it is necessary to use steroids.
Not enough is known about the underlying mechanisms of glaucoma to prevent the disease itself. However, prevention of optic nerve damage from glaucoma is essential and can be effectively accomplished when the condition is diagnosed and treated. As more is learned about the genes that cause glaucoma, it will become possible to test DNA and identify potential glaucoma victims, so they can be treated even before their IOP becomes elevated.