Ophthalmology Glaucoma
Glaucoma Overview
Open angle glaucoma comprises about 90 percent of glaucoma cases in the United States, and is a slow, painless disease. Its effect on vision is often noticed only after it has progressed significantly. At first, open angle glaucoma has no symptoms. As it progresses, peripheral vision suffers. Eventually, it becomes tunnel vision, and, finally, blindness.
When detected early, most forms of glaucoma can be managed successfully. Glaucoma can be managed with medicines, lasers, or surgery. Although progression can be slowed or halted, vision already lost cannot be recovered, which is why early detection is critical. It can be detected by a series of tests, including tests for peripheral vision, eye pressure, examination of the optic nerve through dilated pupils, and measurement of cornea thickness.
If you are at risk, you should have a dilated-eye exam and a pressure measurement (tonometry) every year.
There are several other types of glaucoma. They include:
- Closed angle glaucoma is more rare (although less so among Asians), and may happen much more suddenly and painfully.
- Low-tension (or normal-tension) glaucoma is optical nerve damage that occurs despite intraocular pressure that is not elevated. Often, this is also treatable by reducing pressure.
- Angle-closure glaucoma is a medical emergency. It is caused by the occlusion by the iris of the trabecular meshwork, causing a sudden increase in pressure. Symptoms include severe pain, nausea, redness of the eye, and blurred vision. Blindness can result in a day or two, but prompt treatment can clear the blockage.
- Congenital glaucoma occurs in children born with defective drainage.
- Secondary glaucoma develops as a complication of other eye maladies, like injury or advanced cataracts.
Glaucoma Tests and Screenings
- Dilated eye exam
- Pressure measurement
- Visual field testing
Glaucoma Risk Factors
- Age
- Family history of glaucoma
- African-American ancestry
Treating Glaucoma with Medicines
Medicines are the most common early treatment for glaucoma. They reduce intraocular pressure either by curtailing the eye's production of fluid, or by helping fluid drain through the trabecular meshwork. They may be eye drops, or rarely pills, and may have side effects, which can often be avoided by changing medicines.
Treating Glaucoma with Surgery
Surgery physically opens the trabecular meshwork in the eye, allowing the fluid to drain more easily. Laser trabeculoplasty makes several burns in the trabecular meshwork, stretching its drainage holes, and is performed under topical anesthesia. It reduces pressure quite well, but its effects can diminish over time.
Conventional surgery is done after medicines and laser surgery have failed to control intraocular pressure. Under local anesthetic, a small piece of the trabecular meshwork is removed to create a channel for the fluid to drain. Conventional surgery is 60-80 percent effective at lowering eye pressure, and may be repeated. It may have side effects, including cataract, inflammation, and infection. If vision has already been lost due to glaucoma, there are various low-vision services available to make the most of remaining vision.