What is Glaucoma?
Glaucoma is one of the leading causes of blindness in people over the age of 40. It is a group of diseases that lead to vision loss. Vision loss occurs when the optic nerve is damaged by the pressure inside the eye. The higher eye pressure compresses the optic nerve causing damage. It represents the area where optic nerve fibers have been damaged or lost. As the nerve fibers are lost, so too is the vision. This process is referred to as glaucoma.
The eye’s pressure is maintained by a balance between fluid production and fluid outflow. The fluid leaves the eye through drainage channels in the “angle” of the eye where the iris meets the edge of the cornea; these channels are called the trabecular meshwork and filter eye fluid to small blood vessels leading into the systemic circulation.
High eye pressure is not related to high blood pressure, but glaucoma is found along with other vascular diseases like hypertension and diabetes. It can also occur after a severe eye infection or trauma. Glaucoma is not a contagious disease but can be hereditary.
Example of Vision with Glaucoma
Following a careful and comprehensive eye examination and measurement of eye pressure, your eye doctor will examine the drainage tube of the eye with a special contact lens. The retina, and specifically the optic nerve, will also be closely examined to look for any glaucoma changes. A patient should expect visual field tests at least once a year, and maybe twice a year in the more severe cases. Special pictures of the optic nerve will also be obtained on a routine basis to help the doctor detect any subtle changes from glaucoma.
Open-Angle vs. Closed Angle
Chronic open-angle glaucoma progresses at a slower rate and is often not noticed until there is a significant loss of vision. Eye pressure being above normal levels is not the reason all people have open-angle glaucoma, however decreasing eye pressure has been proven to forestall the progression of glaucoma even in the cases where elevated pressure does not occur. Peripheral vision tends to be affected first, and if not treated open-angle glaucoma will lead to a total loss of entire vision.
Closed-angle glaucoma is often painful and sudden, characterized by visual loss (that progresses quickly) and discomfort (that often leads people to seek medical attention before permanent damage occurs). Closed-angle glaucoma is diagnosed when aqueous fluid cannot reach the anterior chamber angle. It accumulates and forces the iris to obstruct the trabecular meshwork. Contact between the iris and the trabecular meshwork may ultimately damage the function of the meshwork so that it fails to respond to aqueous fluid production leading to an increase of IOP (intraocular pressure). Scars called synechiae form, causing an irreversible block in aqueous outflow. Most cases of closed-angle glaucoma do not reveal themselves through symptoms. In the cases where symptoms do occur patients experience eye pain and redness, blurred vision, headaches, vomiting, and the appearance of halos. In addition to these symptoms doctor’s look for mid-dilated pupils, lack of response to light, cloudy corneas and reduced vision to diagnose closed-angle glaucoma.
How is Glaucoma Treated?
Although there is currently no cure for glaucoma, and lost vision cannot be restored, many studies have shown that with control of eye pressure, further damage can be slowed or prevented. Hence, it is very important to control your eye pressures. The main goal of glaucoma treatment is the prevention of further optic nerve damage if possible.
Lowering eye pressure can be attained in many ways including medical drops, laser, and surgical options. The decision on a treatment plan is based on your discussion with your eye doctor.