What is Glaucoma?
Disease of eye pressure can affect vision
Anna M. Walsh, M.D.
Chanping Liang, M.D.
Glaucoma, a disease that decreases vision, is a leading cause of blindness in patients over 60. It affects the optic nerve and side vision in the early stages. As the disease progresses, it impacts central vision as well. The optic nerve is like an electric cable between the eye and the brain that allows you to see. If your optic nerve is damaged, you develop blind spots in your vision. The blind spots that develop in glaucoma affect side vision first, so many people do not realize they are losing sight until a lot of vision is gone.
Unfortunately, glaucoma does not have a cure, but blindness from glaucoma can be prevented with early diagnosis, good follow-up care and consistent treatment with an eye care provider.
There is not an exact known cause of glaucoma, but glaucoma is a disease of eye pressure. Your eye makes fluid that needs to drain out to keep your eye pressure at a normal range, between 8 and 22. This fluid drains from the “angle,” where the cornea and iris meet. Anyone may develop glaucoma, but the likelihood increases with age. Individuals over the age of 40 or of African American, Hispanic or Asian heritage, as well as individuals who are nearsighted, farsighted, have experienced eye trauma, use steroids, have diabetes, migraines or high blood pressure, are at a higher risk for glaucoma.
There are two main kinds of glaucoma: open angle and closed angle. Open angle glaucoma is the most common type of glaucoma. It is a disease that happens slowly over time because the eye does not drain fluid normally. Because the eye’s drainage system does not work correctly, eye pressure builds up slowly, which damages the optic nerve and leads to vision loss. Patients with open angle glaucoma have no pain or vision loss at first. They often think they just need glasses, but in actuality, they are developing permanent vision loss. Regular eye appointments with an ophthalmologist are critical to catching glaucoma early.
Closed angle glaucoma is when the eye drainage system is blocked by the colored part of the eye, the iris. Most people have no symptoms until there is a considerable, quick rise in eye pressure. The symptoms of an acute attack can be blurry vision, haloes or rainbows around lights, headaches, eye pain, nausea or vomiting. An attack is very serious and can lead to permanent blindness in hours. Patients who experience this should go to the emergency department or an ophthalmology clinic to be seen immediately.
Glaucoma is diagnosed with an eye exam. There is more to an eye exam than getting a new pair of glasses, especially as you age. During an exam to test for glaucoma, your eye doctor will measure your eye pressure, look at the drainage system of the eye, look at the optic nerve, test your side or peripheral vision, take a picture of the optic nerve and measure the thickness of your cornea. These tests may happen at more than one visit.
Glaucoma is treated with eye drops, lasers and surgery. The eye drops for glaucoma contain medicines that lower eye pressure. As with any medication, there are potential side effects; drops used to treat glaucoma can irritate or burn the eyes. Talking to your eye doctor before stopping the eye drops prescribed is important. If you have glaucoma, make sure that after you put your eye drops in, you gently close your eye for 10 minutes to let the medicine soak in. Two main lasers are used to treat open-angle and closed-angle glaucoma. The laser for open-angle glaucoma makes the drainage system work better, so eye pressure is lower. This laser may not work for everyone, and the treatment may need to be repeated. The laser for closedangle glaucoma makes a small hole in the iris. This hole in the iris helps the fluid drain. After these treatments have been exhausted, surgery can be required to lower eye pressure and save vision.
What should you do if you are concerned about having glaucoma? Contact your ophthalmologist and make an appointment. When it comes to your vision, it is always best to be proactive.
Anna M. Walsh, MD, ophthalmology resident, LSU Health Shreveport. Chanping Liang, MD, MS, is a professor and clinical specialist of ophthalmology at LSU Health Shreveport.