Glaucoma is a leading cause of preventable vision loss and blindness in adults in the United States and the second leading cause of blindness in the World.
What is Glaucoma?
Glaucoma is actually a group of eye diseases that cause damage to the optic nerve due to an increase in pressure inside the eye or intraocular pressure (IOP). When detected in the early stages, glaucoma can often be controlled, preventing severe vision loss and blindness. However, symptoms of noticeable vision loss often only occur once the disease has progressed. This is why glaucoma is called “the sneak thief of sight”. Unfortunately, once vision is lost from the disease, it can’t be restored.
Treatments for glaucoma include medication or surgery that can regulate the IOP and slow down the progression of the disease to prevent further vision loss. The type of treatment depends on the type and the cause of glaucoma.
Prevention is possible only with early detection and treatment. Since symptoms are often absent, regular eye exams, which include a glaucoma screening, are essential, particularly for individuals at risk of the disease. While anyone can get glaucoma, the following traits put you at a higher risk:
- Age over 60
- Hispanic or Latino descent, Asian descent
- African Americans over the age of 40 (glaucoma is the leading cause of blindness in African Americans, 6-8 times more common than in Caucasians.)
- Family history of glaucoma
- People with severe nearsightedness
- Certain medications (e.g. steroids)
- Significant eye injury (even if it occurred in childhood)
Types of Glaucoma
Primary open-angle glaucoma (POAG) gradually progresses without pain or noticeable vision loss initially affecting peripheral vision. By the time visual symptoms appear, irreparable damage has usually occurred, however, the sooner treatment starts the more further vision loss can be prevented. When untreated, vision loss will eventually result in total loss of side vision (or tunnel vision) and eventually total vision loss.
Normal-tension glaucoma or low-tension glaucoma is another form of open-angle glaucoma in which the intraocular pressure remains within the normal level. The cause of this form of glaucoma is not known, but it is believed to have something to do with insufficient blood flow to the optic nerve, causing damage. Individuals of Japanese descent, women and those with a history of vascular disease, or low blood pressure are at higher risk.
Angle-closure glaucoma can be a sudden increase in eye pressure causing severe pain, blurred vision, halos, nausea, and headaches. The pressure is caused by a blockage of fluid at the front of the eye which is a medical emergency and should be treated immediately. Without prompt treatment to clear the blockage vision can be permanently lost.
Congenital glaucoma is an inherited form of the disease that is present at birth. These babies are born with a defect that slows the normal drainage of fluid out of the eye and is usually diagnosed by the time they turn one. In these cases, there are typically some noticeable symptoms such as excessive tearing, cloudiness or haziness of the eyes, large or protruding eyes or light sensitivity. Surgery is usually performed with a very high success rate of restoring full vision.
Secondary glaucomas are complications that develop from eye surgeries, injuries or other medical conditions such as cataracts, tumors, or a condition called uveitis which causes inflammation. Uncontrolled high blood pressure or diabetes can result of another serious form called neovascular glaucoma.
Pigmentary glaucoma is a rare form in which pigment from the iris sheds and clogs the drainage of fluid from the eye resulting in inflammation and damage to the eye and drainage system.
Glaucoma Diagnosis and Treatment
During a routine comprehensive eye exam to check for glaucoma, your eye doctor will examine the optic nerve for signs of glaucoma and will also measure the intraocular pressure (IOP) with an instrument called a tonometer. Since your IOP can fluctuate throughout the day and glaucoma can exist without elevated IOP this is not enough to rule out the disease. If there are signs of the disease, further testing will be performed.
A visual field test is designed to detect any blind spots in your peripheral or side field of vision. You will be asked to place your head in front of a machine while looking ahead and indicate when you see a signal in your peripheral field of view.
Your doctor may also measure the thickness of the cornea with an ultrasonic wave instrument in a test called pachymetry or use imaging techniques such as digital retina scanning or optical coherence tomography (OCT) to create an image of your optic nerve to look for glaucoma damage.
Treatment for glaucoma depends on the type and severity of the disease and can include medication such as eye drops or surgery.
Eye drops that lower IOP are often the first resort for controlling pressure-related glaucoma. These drops may have some uncomfortable side effects, such as dry eye, but compliance with the treatment plan is essential for preserving vision and halting the progression of the disease.
Surgical procedures are designed to control the flow of fluids through the eye by either decreasing the amount of fluid produced or improving the drainage. Your doctor may decide that a combination of surgery and medication will be the most effective in many cases.
It cannot be stressed enough that the most effective treatment for glaucoma happens when the disease is detected and treated early before significant vision loss occurs. Any vision that is lost cannot be restored. This is why the best prevention is awareness by knowing your risks and taking responsibility by having your eyes examined on a regular basis.