The Silent Thief of Sight
It is estimated that glaucoma is threatening the vision of two out of every hundred persons age 35 and over. Glaucoma can result in blindness, and is one of the leading causes of blindness in the United States today.
We refer to glaucoma as the "silent thief" because glaucoma typically has no symptoms until partial vision loss has occurred. Loss of vision due to glaucoma is irreversible.
Early diagnosis and treatment of glaucoma may prevent blindness and loss of vision. For this reason, it is important that persons over age 35 undergo eye examinations, at least every 2 years, and persons with a family history of glaucoma may need examinations more often.
What is Glaucoma?
Simply stated, glaucoma is elevation of the pressure inside the eye. Glaucoma destroys vision in this way: As the pressure inside the eye increases, the optic nerve is damaged. The optic nerve is comprised of millions of nerve bundles which transmit light images to the brain where they are translated into what we know as sight. When these nerve bundles are damaged, blind spots in areas of vision develop. With early glaucoma, these blind spots occur in the side (peripheral) vision and go undetected. Typically, there is no pain associated with the most common form of glaucoma. If the pressure inside the eye goes unchecked for a period of time, the damage increases and becomes permanent, and blindness results.
The 4 Types of Glaucoma
The aqueous humor is a clear, transparent liquid that continually circulates throughout the eye. When this circulation becomes restricted for one reason or another, pressure inside the eye begins to rise. Typically, there are four general types of glaucoma:
Chronic open-angle glaucoma
Chronic Open-Angle Glaucoma
By far the most common type of glaucoma, chronic open angle glaucoma, occurs when the exit of aqueous humor from the eye is restricted by inadequate drainage. Chronic open-angle glaucoma develops slowly over a long period of time and results in the quiet loss of vision, because no symptoms occur until the optic nerve is extensively and permanently damaged.
If the front of the eye, or the angle between the iris and cornea, is narrow or crowded, pressure inside the eye may rise chronically or suddenly. This chronic or sudden blockage of the eye's outflow system is called narrow angle or angle-closure glaucoma. Patients may or may not complain of blurred vision or halos around lights, severe pain, nausea and vomiting. Unless the pressure is brought under control rapidly, complete blindness may result in a very short time.
If the outflow system of the eye exhibits abnormalities from the time of birth, congenital glaucoma may result. Infants born with glaucoma may be extremely sensitive to light and tear excessively, or the front of the eye may be enlarged or cloudy. This condition fortunately is uncommon. An eye examination is advised even for newborns if such symptoms are noted.
Glaucoma may result from trauma or injury, diabetes, or previous stroke in the eye, or may happen as a result of certain medications or inflammation. These are all conditions which may lead to blockage of aqueous drainage from the eye and high intraocular pressures.
Glaucoma And Your Blood Pressure
Patients often ask if their blood pressure rises, will the pressure inside the eye also rise. The answer is no. The drainage of aqueous humor from the eye functions independently of the body's vascular/circulatory system. Good control of blood pressure does not mean good glaucoma control.
Glaucoma can sometimes be controlled by topical medications (eye drops), or by oral medications. These medications assist the outflow of fluid or may decrease the amount of fluid produced within the eyes. All eye drops and oral medications have potential side effects. If medications are not effective in the control of glaucoma, laser may be indicated in order to decrease the pressures and preserve vision.
During an eye examination, the pressure inside the eye is taken. An ophthalmoscope is used to examine the back of the eye to ensure the health of the optic nerve and to look for possible damage. Several other risk factors are a consideration in developing glaucoma including a family history of glaucoma, general health problems, including diabetes, anemia, or hardening of the arteries. It is important to understand that while treatment and surgery can usually prevent further vision loss, there is no way to restore vision already lost due to glaucoma.