Pressure of fluids within our eyeballs keeps them in shape, and ensures that our vision is not distorted. Sometimes, for one more reasons, that pressure builds up. This damages small blood vessels that feed the fibers of the optic nerve with oxygen and glucose, soon harming the delicate fibers themselves.
The condition is known as glaucoma, and few eye disorders are more dangerous. Its particular menace is that it steals a victim’s sight by stealth: the first sign of trouble may be partial or advanced blindness, and by then it is already too late. Only a regular examination, in which a doctor checks the pressure within each eye, will identify the disorder and avoid serious damage to the sight.
Why some people get glaucoma and others do not uncertain. The most common form, known as chronic simple, or open angle, glaucoma, tends to run in families. Anybody with history of glaucoma should take a routine test once a year. So should those aged forty or over, because chronic simple glaucoma is more prevalent among older people. It is found in some 2 percent of people over forty and rises to about 10 percent in those over the age of seventy.
A less’ common form, acute – or closed angle – glaucoma, gives some warning. A victim may feel sick, have severe pain in the eye and foggy vision. It is an emergency requiring instant attention which, after the immediate eyeball pressure is under control, usually involves surgery.
Chronic simple glaucoma is usually kept in check quite successfully with eye drops, but the treatment – usually just one or two drops a day in one or both medicines fail, an eye surgeon may try to relieve the pressure within the eye by opening the blocked drainage channel or creating a bypass for the fluid.