Can blindness due to glaucoma be prevented?
Regular and appropriate diagnostic examinations by an ophthalmologist are the key to preventing loss of vision due to glaucoma. Ophthalmologists are medical doctors, specialists in eye care, trained to examine and treat eye diseases. Although there is no way currently to reverse optic nerve damage, if glaucoma is diagnosed and treated early, blindness almost always is preventable. The important issue in preventing blindness from glaucoma is early detection before the vision is seriously threatened and appropriate treatment to prevent further damage once glaucoma is diagnosed.
What are the symptoms of glaucoma?
Over 50% of individuals who have the disease in the United States do not know they have it. In most cases, glaucoma is asymptomatic and the patient is unaware of a problem. By the time an individual experiences noticeable decreased vision, the disease is frequently in its latter stages. Since early warning signs of glaucoma are rare, it is important, especially for those at increased risk, to have medical eye examinations at the appropriate intervals as described in the risk factors section.
Symptoms depend on the type of glaucoma the individual has. The reason why patients who have chronic glaucoma may not be aware of any symptoms is because the disease usually develops so slowly that patients rarely notice loss of peripheral vision even though it may in fact be significant. This is quite different from the symptoms of cataract or macular degeneration, which affect the central vision first making the patient aware fairly early on of a vision problem.
An interesting exception to these generalizations of most forms of glaucoma is acute angle closure glaucoma. Even before a full blown acute angle closure attack, patients often experience intermittent symptoms of an impending serious problem. Symptoms of early acute angle closure glaucoma include:
- Blurry vision when it starts to get dark or after an emotional upset.
- Halos around lights
- A headache around the eye or on the brow accompanied by blurry vision and halos
- Nausea with the above symptoms.
These symptoms are often mistaken for a migraine headache or other non-glaucoma related vision problem. They can also be precipitated by certain medications a patient may be taking. Some ingredients in many over the counter cold symptom relief medications and prescription medications for various conditions can make a susceptible patient more likely to suffer acute angle closure glaucoma. Patients with these symptoms need a careful evaluation of the drainage angle of their eyes to determine if they are at risk for angle closure glaucoma.
How does glaucoma affect the eye?
The eye has an internal pressure created by production of a clear fluid called aqueous humor. This fluid is necessary to maintain the shape of the eye and it acts to maintain the function of the optically clear parts of the eye including the lens and cornea. This fluid circulates through the eye and exits through the anterior chamber angle and ultimately drains into the blood stream through blood vessels outside of the eye. In most forms of glaucoma, the aqueous humor outflow is obstructed, resulting in increased eye pressure, and eventually, optic nerve damage. However, glaucoma is not a disease of high pressure in the eye alone. Glaucoma is an optic nerve disease and high pressure within the eye is one of the major risk factors. The vision loss from glaucoma is the result from the death of the structures making up the optic nerve, the nerve fiber layer, which conveys the visual information gathered from the eye to the brain, which is interpreted as vision. The characteristic pattern of damage to the nerve fiber layer in glaucoma produces the patterns of visual field defects that are characteristic of the disease.