Glaucoma represents a group of eye diseases that can silently steal your vision without any warning or pain. It has been estimated that over 4 million Americans have glaucoma and half of these people are unaware of it. Glaucoma is the second leading cause of blindness in the world, and the leading cause of blindness among African-Americans. You are at a greater risk to develop glaucoma if you are over the age of 60, African-American, have a family history of glaucoma, highly nearsighted, or have diabetes.
Glaucoma is usually caused by an increase in pressure (intraocular pressure or IOP) inside the eye. This is often due to a reduction in the drainage of fluid within the eye. This fluid (aqueous humor) is produced behind the colored part of your eye (iris), moves through the pupil and drains out a mesh-like channel (trabecular meshwork) in the front of the eye. Recent research has found that IOP readings vary with the thickness of the cornea. For this reason, a pachymeter (ultrasound device to measure thickness of cornea) is necessary to measure the variable corneal thickness of glaucoma patients, especially in those who have had refractive surgery (PRK, LASIK) where the corneal thickness is purposely changed.
It is believed that an elevated intraocular pressure (IOP) causes damage to the optic nerve if left untreated. Unfortunately, even if the IOP is normal, glaucoma can still develop (low tension or normal tension glaucoma). Low tension glaucoma is poorly understood and may be more an issue of reduced blood flow to the optic nerve rather than elevated IOP.
Glaucoma rarely presents with overt symptoms. In the early stages of the disease, loss of peripheral vision is detectable only with sensitive visual field devices (specialized machines that test your peripheral vision by flashing spots of varying intensity lights throughout your peripheral field of view). With moderate to advanced stages, you may notice tunneling or loss of vision. Occasionally, there are rapid increases in IOP, which can create significant pain, haloing of lights, nausea or even make the eyes look hazy or cloudy.
Currently, there is no cure for glaucoma. However, there are multiple treatment options available, including medications and laser or microsurgery that are successful in slowing or preventing the progression of vision loss. Steadfast compliance with a treatment plan and regular eye examinations are essential in managing glaucoma.
The California Optometric Association recommends annual eye examinations for people at risk for glaucoma (your doctor may, depending on your condition, recommend more frequent examinations). A comprehensive optometric examination will include a tonometry test to measure the pressure in your eyes, an examination of the inside of your eyes and optic nerves, and a visual field test, as necessary, to check for changes in the central and peripheral vision.
Vision lost to glaucoma cannot be restored… but, if diagnosed and treated early, the disease can be controlled. Talk with your optometrist to find out more information about this and other vision threatening diseases.