Glaucoma is a degenerative disease in which the optic nerve is damaged, usually due to abnormally high pressure in the eye (intraocular pressure or “IOP”).
Increased IOP occurs when the eye’s drainage system, called the “angle” does not allow sufficient outflow of the eye’s natural fluid, called aqueous humor. Fluid therefore builds up and presses on the optic nerve. The optic nerve, a bundle of nerve fibers at the back of the eye, is responsible for carrying images from the retina to the brain. Increased IOP causes the optic nerve to deteriorate resulting in blind spots that usually start in the periphery of vision and then expand toward the center.
Glaucoma is sometimes called “the silent thief” because it can slowly steal sight without being perceived until substantial damage has occurred. Left untreated, glaucoma may lead to irreversible blindness in both eyes.
How Common is Glaucoma?
Glaucoma is the 2nd leading cause of blindness in the United States. It is estimated that 2.5 million Americans have it, and more than half of those with it experience at least some vision loss. Open-angle glaucoma (versus closed-angle glaucoma) is the most common form accounting for approximately 85% of glaucoma cases.
What Causes Open-angle Glaucoma?
While certain factors don’t always “cause” one to get glaucoma, there are a number of risk factors which increase your chances of getting glaucoma. These risk factors include:
- Aging – with increased age comes reduction of the size of the eye’s drainage angle, and consequently increased intraocular pressure. Risk of getting glaucoma increases substantially for whites over age 60, and blacks over age 40.
- Genes and Heredity – family history greatly increases risk, and certain genes are associated with glaucoma
- Nitric oxide deficiency – this can damage blood vessels, which elevates I.O.P.
- Nutritional deficiencies - this can damage the optic nerve.
- African-American descent – glaucoma is significantly more common in African-Americans than in Caucasians.
- Hispanic descent – recent studies indicate an increased risk for those of Hispanic versus European ancestry
- Steroid Use – some evidence links steroid use to glaucoma
- Eye Injury – blunt injuries (injuries that “bruise” the eye) and injuries that penetrate the eye can damage the drainage system resulting in glaucoma
- Medical Conditions – certain conditions including Diabetes, high blood pressure, heart disease, and brain chemical abnormalities (e.g. over production of neurotransmitter, glutamate) increase risk.
- Nearsightedness – being nearsighted increases the likelihood of getting glaucoma.
What are the Symptoms of Primary Open-angle Glaucoma?
Primary glaucoma refers to glaucoma in which the cause is unknown (e.g. not an injury).
It is very important to have regular eye exams because primary open-angle glaucoma progresses with little or no symptoms until is has reached an advanced stage. As the disease damages the optic nerve, peripheral vision worsens. If left untreated, it can result in tunnel vision and eventually all eyesight. Open-angle glaucoma usually effects both eyes, but can result in vision loss in one eye first.
How is Open-angle Glaucoma Treated?
Treatment is focused on reducing IOP. It cannot cure the disease, but can dramatically slow or temporarily stop its progress. Medication is usually prescribed, and if this fails, surgery is the second line of treatment.
Medication
Topical medications
These include eye drops, ointments, and inserts. Topical medication categories include Miotics, Epinephrines, Beta-blockers, Carbonic-anhydrase inhibitors, alpha-adrenergic agonists, and prostaglandin analogs.
Oral medication
Carbonic anhydrase inhibitors such as Daranide®, Diamox®, and Neptazane® are the most commonly prescribed oral medications for glaucoma.
If topical and/or oral medications do not yield results, then the Ophthalmologist may recommend glaucoma surgery.
Selective Laser Trabeculoplasty (SLT)
This in-office procedure takes approximately 10-20 minutes. You’ll be given an anesthetic eye drop. You will then be seated at a slit lamp and fitted with a lens on your eye. The doctor will aim a laser through the lens at the trabecular meshwork, a structure in the eye that controls fluid flow. The procedure increases outflow of the aqueous humor in the area surrounding the laser’s spot, and this reduces IOP. You can typically resume normal activity immediately afterwards without discomfort. The Dr. will treat the eye with anti-inflammatory drops post-operatively, and you will most likely go in for follow-up visits.
The Results
Your eye pressure may decrease as quickly as one day after surgery. It can take weeks for results to stabilize. IOP is reduced in 60-70% of patients that have SLT procedures performed. While surgery reduces IOP, it may begin to increase again over time. Glaucoma management is a lifelong process requiring regular examinations as recommended by your doctor.
Conventional Surgery
If topical treatments and laser surgery do not effectively reduce eye pressure, you may need a conventional surgical procedure called a trabeculectomy which is performed in a surgical facility. In this procedure, the Ophthalmologist uses intruments to open the white of the eye and remove a small piece of the trabecular meshwork.