Glaucoma

“Glaucoma,” a Principal Cause of Blindness. Glaucoma is one

of the most common causes of blindness. It is a disease

of the eye in which the intraocular pressure becomes

pathologically high, sometimes rising acutely to 60 to

70 mm Hg. Pressures above 25 to 30 mm Hg can cause

loss of vision when maintained for long periods.

Extremely high pressures can cause blindness within

days or even hours. As the pressure rises, the axons of

the optic nerve are compressed where they leave the

eyeball at the optic disc.This compression is believed to

block axonal flow of cytoplasm from the retinal neuronal

cell bodies into the optic nerve fibers leading to

the brain. The result is lack of appropriate nutrition of

the fibers, which eventually causes death of the involved

fibers. It is possible that compression of the retinal

artery, which enters the eyeball at the optic disc, also

adds to the neuronal damage by reducing nutrition to

the retina.

In most cases of glaucoma, the abnormally high pressure

results from increased resistance to fluid outflow

through the trabecular spaces into the canal of Schlemm

at the iridocorneal junction. For instance, in acute

eye inflammation, white blood cells and tissue debris

can block these trabecular spaces and cause an acute

increase in intraocular pressure. In chronic conditions,

especially in older individuals, fibrous occlusion of the

trabecular spaces appears to be the likely culprit.

Glaucoma can sometimes be treated by placing drops

in the eye that contain a drug that diffuses into the

eyeball and reduces the secretion or increases the

absorption of aqueous humor.When drug therapy fails,

operative techniques to open the spaces of the trabeculae

or to make channels to allow fluid to flow directly

from the fluid space of the eyeball into the subconjunctival

space outside the eyeball can often effectively

reduce the pressure.

Glaucoma is a condition of increased fluid pressure inside the eye. The increased pressure causes compression of the retina and the optic nerve which can eventually lead to nerve damage. Glaucoma can cause partial vision loss, with blindness as a possible eventual outcome.