What is Glaucoma?
Glaucoma is a disease in which the optic nerve is damaged through mechanisms that are not completely understood. It is a leading cause of blindness in Americans aged 60 and over.
The optic nerve connects the retina — a layer of light-sensitive tissue lining the inside of the eye — to the brain. At this time, we don’t have a good means to repair damage to the optic nerve and thus the treatment for glaucoma is directed toward protecting the optic nerve from further damage. Currently, the only known means of protecting the optic nerve from damage due to glaucoma is to lower the eye’s pressure. Eye pressure is assessed by the firmness of the eye itself just like the pressure of a basketball can be assessed by the firmness of the basketball.
A clear fluid called aqueous humor circulates inside the front portion of the eye, and its circulation determines the eye’s pressure. Eye pressure is lowered when less aqueous is produced or when the aqueous fluid can leave the eye more easily, and only by lowering eye pressure can the danger from glaucoma be reduced.
All current treatments for glaucoma–drops, pills, lasers and surgery work by reducing the eye’s pressure. Regular exercise also seems to lower eye pressure.
Because most types of glaucoma develop slowly, and because visual changes are almost never noticed early in the course of the disease, many people don’t know they have glaucoma until significant, irreversible, optic nerve damage that seriously threatens the remaining vision has occurred.
- Types of Glaucoma
- Causes of Glaucoma
- Symptoms of Glaucoma
- Diagnosis of Glaucoma
- Treatment of Glaucoma
- Open angle is the most common form of glaucoma. It occurs in eyes with normal appearing aqueous drainage systems.
- Narrow angle (also called Angle closure) occurs when the iris causes a structural blockage of fluid drainage from the eye. It is most common in females, Asians, and far sighted individuals and can lead to rapid permanent vision loss.
- Congenital is a rare form of glaucoma found in infants and young children. Congenital glaucoma can cause permanent blindness if not diagnosed and treated early.
- Secondary occurs as the result of another eye condition or disease, including tumors or eye injuries.
In open angle glaucoma the fluid drainage system looks normal and eye pressure can be normal or elevated.
Structural abnormalities can cause glaucoma:
- Angle closure glaucoma
– A blocked drainage angle
– Scar tissue between the iris and cornea
- Congenital glaucoma
– affects children before age 3
- Secondary glaucoma
– Eye injury
– Eye surgery
– Use of steroids
Different forms of glaucoma can have different symptoms. However, with all forms of the disease, vision is threatened, and if not treated, can lead to permanent blindness.
Only rarely does glaucoma cause early symptoms
- Open angle glaucoma and secondary glaucoma
– There are usually no symptoms until very late in the course of the disease
– Missing spots in the vision and loss of peripheral vision are eventually noticed
– Complete loss of vision can follow early symptoms with surprising speed
- Narrow angle glaucoma
– May be initially asymptomatic and progress slowly like open angle glaucoma
– May present with sudden, severe blurring of vision accompanied by headache, nausea and a red painful eye
- Congenital glaucoma
– Cloudy eye or eyes
– Watery eyes
– Eyes that look especially large (Due to a build-up of pressure)
– Significant rubbing of the eyes in infants
During a glaucoma screening, tests that are performed include:
- Tonometry. Eye pressure is measured with one or more instruments.
- Optic nerve examination. The optic nerve head is evaluated with a lens and a special microscope. (Dilation of the pupil is usually required.)
- The depth of the anterior chamber (the front part of the eye) is assessed with a special microscope.
- If any sign of glaucoma is detected, additional testing can be done to determine the risk to the vision and to guide further evaluation and treatment of the condition.
Glaucoma treatment is selected to have maximum impact on eye pressure while minimally affecting lifestyle. An increase in regular exercise and an elimination of activities such as inversion therapy or SCUBA diving are useful in lowering pressure in some patients with open angle glaucoma. Anti-glaucoma eye drops and even pills can often very effectively lower eye pressure. There are also multiple procedures used to treat glaucoma. These treatments include: