The basic cause of glaucoma is unknown, but a few factors have been identified. These include age, heredity, myopia (near – sightedness), general diseases such as early heart attack and stroke, and raised Intraocular Pressure (IOP).
Raised IOP is found in most types of glaucoma and is the main target for control of the disease. IOP is normal when there is a balance between fluid (aqueous) pumped into the eye and the amount that escapes from the eye. Raised IOP occurs when fluid outflow is obstructed. Visual loss in glaucoma is thought to be caused by raised IOP and other influences on the optic nerve, located at the back of the eye. The gradual loss of nerve function causes loss of peripheral or side vision painlessly and without notice.
Open–angle glaucoma is the most common form of glaucoma. Patients rarely notice any symptoms until the disease is very advanced, it is truly a “Silent blinding disease”. Those affected can drive, read and perform most tasks because the visual loss usually is not a black cloud or a blurring of the vision. This loss is permanent and cannot be reversed by treatment. Early detection and treatment is necessary to preserve remaining vision.
Treatment is begun with eye drops and sometimes pills, which decrease the IOP. It may be necessary to change from one type of drop to another. This lifelong disease must be constantly monitored to ensure the best treatment.
If control is not achieved with medication, laser therapy, performed during an outpatient visit, may be required to improve fluid drainage. If this also fails to decrease the IOP, surgery may be advised.
Less frequent than open–angle glaucoma. The sudden onset of dull, aching pain over one eye associated with a change in vision is the initial symptom. These changes may occur as blurring and haloes (rainbows) around lights. This usually happens very quickly (within a half–hour) and is an emergency! The aim of an acute attack is to decrease the IOP before permanent damage occurs. A small opening in the eye (iridectomy) is then made to prevent another attack.
If you stand to be at any of the risk factors (age, heredity, myopia, general disease such as early heart attack and stroke, and raised intraocular pressure), it is important to be aware of the possibility of glaucoma. Some drugs, such as cortisone (steroid) drops, can cause glaucoma. Any visual disturbance that cannot be corrected by glasses may be a sign of glaucoma.