What is Glaucoma?

ID-10020472Glaucoma is a group of eye disorders where there is rise in intra-ocular pressure (pressure inside the eye due to presence of liquid inside eye, known as aqueous humor and vitreous humor), of multifactorial causes, which lead to optic neuropathy. Glaucoma is raised intra-ocular pressure more than normal limit of 21 mm Hg. Normal intra-ocular pressure is 12-21 mm Hg. If left untreated, glaucoma can lead to permanent blindness. In fact, glaucoma is one of the leading causes of blindness (second leading cause of blindness, only after cataract).

Glaucoma is sometime called “ocular hypertension”, because there is raise in intra-ocular pressure, especially in case of patients with raised intra-ocular pressure (glaucoma), but there is no damage to optic nerve and there is effect on vision. Sometime there may be damage to optic nerve without any increase in intra-ocular pressure, which may be normal or even low.

The only known cause of glaucoma is raised intra-ocular pressure, although the cause of intra-ocular pressure is not clearly known.

What are the types of glaucoma?

There are two types of glaucoma, namely primary open angle glaucoma (commonest type and unknown cause) and closed angle glaucoma or angle closure glaucoma. The angle here refers to the area (angle) between the iris and cornea and known as iridocorneal angle. If the angle narrows the outflow of aqueous humor is blocked (reduced), which lead to accumulation of aqueous humor inside the eye and rise in intra-ocular pressure and glaucoma. This occurs in case of closed angle glaucoma. The angle-closure glaucoma usually appears suddenly and it is a medical emergency, due to blockade of aqueous humor outflow due to narrowing of the iridocorneal angle and tremendous rise in intra-ocular pressure quickly. Prompt and appropriate measures are required to treat this condition and to save vision of the patient. If intra-ocular pressure is not reduced promptly, there may be permanent damage to optic nerve and ultimately permanent loss of vision. 

In case of open angle glaucoma, there is no narrowing of the angle, hence the cause of raise intra-ocular pressure is not known. This is the common form of glaucoma, which requires life-long treatment to keep the intra-ocular pressure under control (normal). Open angle glaucoma may not have any symptoms initially and may be diagnosed only during routine eye examination. Open angle glaucoma is a common health problem affecting 1 in 200 individuals below 50 years of age, but affect as many as 1 in 10 in individuals above 80 years of age.

Visual problems caused by glaucoma are usually not reversible, but early intervention can prevent or reduce visual problems and this is the aim of treatment of glaucoma.

“Image courtesy of Pixomar / FreeDigitalPhotos.net”.

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