Glaucoma is a disease in which the optic nerve is damaged, leading to progressive, irreversible loss of vision. It is often, but not always, associated with increased eye pressure. One person may develop nerve damage at a relatively low pressure, while another person may have high eye pressure for years and yet never develop damage. Untreated glaucoma leads to permanent damage of the optic nerve and can result in peripheral visual field loss, which can progress to blindness if untreated.
OPEN ANGLE AND NARROW/CLOSED ANGLE GLAUCOMA
Glaucoma can be divided roughly into two main categories, “Open angle” and “Narrow/Closed angle” glaucoma. Open Angle Glaucoma tends to progress at a slow rate and a patient may not notice that they have lost vision until the disease has progressed significantly. Narrow/Closed angle glaucoma can appear suddenly and is often painful. Visual loss can progress quickly but the discomfort often leads patients to seek medical attention before permanent damage occurs.
Glaucoma has been nicknamed the “sneak robber of sight” because the loss of vision normally occurs gradually over a long period of time and is often only recognized when the disease is quite advanced. Once lost, this damaged visual field cannot be recovered. Worldwide, it is the second leading cause of blindness. It is also the first leading cause of blindness among African Americans. Glaucoma affects 1 in 200 people aged fifty and older, and 1 in 10 over the age of eighty. If the condition is detected early enough it is possible to arrest the development or slow the progression with medical and surgical means.
NORMAL OR LOW TENSION GLAUCOMA
Eye pressure is normal or even low in this type of glaucoma. It is thought that not enough blood reaches the tiny arteries in the optic nerve. This is rather like having a low water pressure in a house… not enough water comes out of the tap. Without its blood supply, the nerve becomes damaged, and sight will be reduced. An alternative explanation is that there is a fault with the blood vessel oxygen extraction process.
When a person develops Glaucoma with angle-closure and open-angle mechanisms in the same eye, he/she is diagnosed as having “combined glaucoma”.