What You Should Know About Glaucoma

Just as hypertension is commonly called high blood pressure, glaucoma is simply high eye pressure that threatens vision. Glaucoma is the second leading cause of blindness in the whole world.

The eye has two segments that are filled with fluids; the anterior segment (contains aqueous humor) and the posterior segment (contains vitreous humor). The posterior segment contains an inert, transparent, jelly-like structure that is neither drained out of the eye nor replaced by new ones except when the body is hypertonic in which case, the water content of it is sucked out to neutralize the hypertonic body. This is the mechanism used by some antiglaucoma drugs (mannitol infusion) to lower the eye pressure in glaucoma.

The anterior segment contains slightly alkaline clear watery fluids (aqueous) that are continuously produced as well as drained.  The aqueous is drained out the eye through a small angle (anterior chamber angle). When this angle is narrow or blocked, the aqueous humor build up and exert pressure on the eye walls especially the small canal in the retina (the optic disc) through which nerves carrying visual information pass before they reach the brain.

The elevated eye pressure (intraocular pressure) causes irreversible damage on these nerves which diminishes the side vision of the individual involved (vision at the periphery is gradually reduced). If the eye pressure is not lowered in time, vision will continue to diminish peripherally until it reaches the central vision were it leads to total blindness.

There is also another case of glaucoma in which the drainage angle is widely open but the eye pressure is still high. Thus there two major types of glaucoma; “open-angle” glaucoma and “close-angle” (angle-closure) glaucoma.

Open-Angle Glaucoma; In this situation, the drainage angle is widely open but the intraocular pressure is high. This usually occurs when the rate of aqueous production is greater than its drainage. Open-angle glaucoma (chronic glaucoma) is the most common type, occurring in 90 percent of cases. It is asymptomatic in nature and the patient only notices it when his or her peripheral vision has diminished greatly. Open-angle glaucoma is called the “silent thief of sight” because loss of vision occurs gradually over a long period of time, with symptoms occurring in the advanced stage when the irreversible damage has already been done.

Close-Angle Glaucoma; This is the rare type, occurring in 10 percent of cases and requires immediate treatment (medical emergency). In angle-closure glaucoma (acute glaucoma), the drainage the drainage has been compromised giving rise to the following symptoms; sudden and severe eye pain, red eye, vomiting and tendency to vomit (nausea), seeing colored rings around light (halos), etc. 

There are treatment options available to lower the eye pressure but however, the vision that is already lost can never be regained because the nerves are irreversibly damaged. Thus medications (especially eye drops) are used to manage and monitor glaucoma progressions in order to prevent further damage. 

The first treatment option for glaucoma therapy is the use of topical (eye drops) and systemic medications (oral tablets and injections) that either reduces the aqueous production or increases their drainage and by doing so the pressure is lowered and further nerve damage is prevented.

When the use of medications fails to lower the eye pressure, another option of choice is surgery. The surgery is carried out, to open the narrow angle (or blocked angle) or to open a small hole close to drainage angle. This enables the aqueous to be drained efficiently.

Remember! The most common type of glaucoma does not have symptoms, thus regular eye check by an eye doctor will help in early detection of glaucoma.