Glaucoma
Glaucoma is a group of eye disorders that lead to progressive damage to the optic nerve. It is characterized by loss of nerve tissue that results in vision loss. People with glaucoma can lose nerve tissue, resulting in vision loss. These eye disorders include:
- Primary open-angle glaucoma – This is the most common form of glaucoma. Damage to the optic nerve is slow and painless. Those affected can lose a large portion of vision before they notice any vision problems.
- Angle-closure glaucoma – This is a medical emergency that can cause vision loss within a day of its onset. It occurs when the drainage angle in the eye (formed by the cornea and the iris) closes or becomes blocked.
- Secondary glaucoma – Results from an injury or another eye disease. It may be caused by a variety of medical conditions, medications, physical injuries, and eye abnormalities.
- Normal-tension or low-tension glaucoma – In this form of glaucoma, eye pressure remains within the “normal” range, but the optic nerve is damaged nevertheless. It is not known why this happens.
Causes & Risk Factors
There are many theories about the causes of glaucoma, but the exact cause is unknown. Although the disease is usually associated with an increase in fluid pressure inside the eye, other theories include a lack of adequate blood supply to the nerve.
The following factors can increase the risk of developing glaucoma:
Race. African Americans are significantly more likely to get glaucoma than Caucasians, and they are much more likely to suffer permanent vision loss. People of Asian descent and Native Alaskans are at higher risk of angle-closure glaucoma. People of Japanese descent are more likely to develop low-tension glaucoma.
Family history of glaucoma. Having a family history of glaucoma increases the risk of developing glaucoma.
Medical conditions. Some studies indicate that diabetes, high blood pressure, and heart disease may increase the risk of developing glaucoma.
Physical injuries to the eye. Severe trauma, such as being hit in the eye, can result in immediate increased eye pressure. Internal damage from such a trauma can also cause future increases in pressure. Injury can also dislocate the lens, closing the drainage angle and increasing pressure.
Other eye-related risk factors. Certain features of eye anatomy, namely thinner corneas and optic nerve sensitivity, indicate an increased risk for developing glaucoma. Conditions such as retinal detachment, eye tumors, and eye inflammations may also trigger glaucoma. Some studies suggest that high amounts of nearsightedness may also be a risk factor for glaucoma.
Corticosteroid use. Using corticosteroids (including cortisone, hydrocortisone, and prednisone) for prolonged periods of time appears to put some people at risk of getting secondary glaucoma.
Symptoms
The first indication that a person has glaucoma may occur after some vision has been lost. However, the signs or symptoms of glaucoma can vary depending on the type.
Primary open-angle glaucoma often develops slowly and painlessly, with no early warning signs.
Acute angle-closure glaucoma results from a sudden blockage of drainage channels in the eye, causing a rapid buildup of pressure. In this form, a patient would have blurred vision, the appearance of halos or colored rings around lights, and pain and redness in the eye.
Diagnosis
Treatment
Glaucoma treatment is aimed at reducing pressure in the eye. While there is not yet a cure for glaucoma, early diagnosis and continuing treatment can preserve eyesight.
Treatments may include:
Medications – A number of medications are currently available to treat glaucoma. Typically, medications reduce elevated pressure in the eye. A single medication or a combination of medications may be prescribed.
Surgery – Procedures include laser treatment, making a drainage flap in the eye, inserting a drainage valve, or destroying the tissue that creates the fluid in the eye. Surgery cannot reverse vision loss.
Laser surgery – Laser trabeculoplasty helps fluid drain out of the eye. A high-energy laser beam stimulates the structure that drains fluid from the eye (the trabecular meshwork) so that fluid drains more efficiently. The results may be somewhat temporary, and the procedure may need to be repeated in the future.
Conventional surgery – If eye drops and laser surgery aren’t controlling eye pressure, the patient may need a trabeculectomy. This filtering microsurgery creates a drainage flap. Fluid can then percolate into the flap and later drain into the vascular system.
Drainage implants – Drainage valve implant surgery may be an option for adults with uncontrolled glaucoma or secondary glaucoma or for children with glaucoma. A small silicone tube is inserted in the eye to help drain fluid.
Treatment for acute angle-closure glaucoma
Acute angle-closure glaucoma is a medical emergency. Those affected can take medication to reduce eye pressure as quickly as possible. They will also likely undergo a laser procedure called laser peripheral iridotomy. In this procedure, a laser beam creates a small hole in the iris to allow fluid to flow more freely into the front chamber of the eye where it then can drain.
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