Some people are at higher risk for glaucoma, such as those with a family history of vision loss from glaucoma, people with a history of trauma to the eye (even as long as 20 years prior), or those taking certain medications, such as prednisolone (cortisone). People at higher risk should certainly be screened at least yearly.
Glaucoma is a disease of the optic nerve, the cable at the back of the eye that takes the picture to the brain. In glaucoma, the cable “loses its wires.” When enough of the “wires” have been lost, blank areas develop outside of the central area of the vision, similar to losing pixels from a computer screen. These blank areas can be discovered by an examination known as a visual field test, and the number of wires remaining in the cables can be estimated by a computerized scan of the optic nerves known as optical coherence tomography (OCT).
In most cases, optic nerve damage is related to the pressure exerted upon the optic nerve by the internal fluid that fills the eye. The intraocular pressure (IOP) is determined by how much internal fluid is produced and how much leaves the eye via the internal drain, called the trabecular meshwork, a structure that circles the eye in the space where the iris (the colored part of the eye) and the wall of the eye meet, known as the “angle” of the eye. In most cases of glaucoma, the angle is open, meaning not blocked by other structures of the eye. IOP rises due to the drain not functioning properly. In a smaller percentage of cases, the angle becomes physically blocked by the iris, a condition known as “angle closure.” In rare circumstances, angle closure can occur suddenly, leading to pain, headache, intense redness, blurred steamy vision, and even nausea and vomiting. Acute angle closure is an emergency and requires immediate professional attention to prevent permanent vision loss.
The exact mechanism by which IOP leads to optic nerve damage is unknown. What has been established is that elevated IOP is a risk factor for the development of glaucoma or its progression, and that adequate reduction of IOP can either prevent the development of glaucoma or its worsening, even in cases where the IOP was not outside of the normal range.
An eye examination for glaucoma consists of risk assessment through careful questioning of medical, eye, and family history, determination of visual acuity, measurement of IOP, assessment of the state of the angle, and a dilated examination of the optic nerve. Additional testing will be obtained if necessary.
Treatment of Glaucoma
It should be understood that if glaucoma is a disease in which the optic nerve is damaged, there is no treatment to restore this damage. The optic nerve cannot be regrown. Therefore, treatment is directed as reducing risk for glaucoma either developing or becoming worse, and all such treatments involve reducing the IOP. Initial treatment is usually by prescription eyedrops. Many such medications are available, highly effective, and may only need to be taken once daily.
Other IOP lowering options involve treating the angle of the eye with laser, either to widen the space if narrow or closing, or to stimulate the drainage tissue to function more efficiently to drain the fluid from the eye.
Finally, surgical options are available to create a new “drain,” bypassing the natural drain that is not functioning properly or is physically blocked. These procedures can be done using the tissue of the eye to form a controlled hole for the fluid to seep out into the space under the tissue that lines the eye, or by implanting a microscopic drainage tube. IOP can also be lowered by reducing the amount of internal fluid that is produced, a procedure known as cyclophotocoagulation.
With proper detection and management the risk of permanent vision loss or blindness from glaucoma is quite small. The key is timely and thorough eye examinations to detect problems before they become advanced.
Contact Our Glaucoma Treatment Team
Learn more about glaucoma by scheduling an appointment with our ophthalmologists. Please contact Eye Care of San Diego today.