Glaucoma

Glaucoma is characterized by increased intraocular pressure.  The front part of the eye is filled with a watery fluid, called aqueous humor.  When the aqueous humor does not drain properly, the fluid backs up and causes the pressure inside the eye to increase.  This can cause vision loss.  

There are two types of glaucoma:  acute glaucoma (or narrow angle or angle closure glaucoma) -- the pressure within the eye rises suddenly and immediate medical attention is necessary to preserve vision, and chronic open angle glaucoma -- the pressure within the eye rises gradually and vision loss progresses over a period of years.

In its early stages, the symptoms of glaucoma are almost non-existent.  Usually, the gradual increase of pressure inside the eye does not cause pain or discomfort.  However, as the disease progresses, vision begins to deteriorate, first affecting the peripheral vision and working inward.  If left untreated, the field of vision continues to shrink  until a person becomes completely blind.  The pictures below show how a person with glaucoma may see compared to someone with normal vision:

During regular eye examinations, pressure inside the eyes is usually checked by one of three methods.   In some cases, a puff of air is blown against the surface of the eye while an instrument measures how much air is deflected by the eye, thus giving an estimate of the pressure.  In others, the eye is numbed, and an instrument called a tonometer is lowered until it touches the surface of the eye, which measures the pressure.  A final method is called the applanation method.  Numbing drops and fluorescent dye are placed in the eye and the cornea is lit and the front part of the eye is touched by the tonometer, and the intraocular pressure is measured. 

Glaucoma is treated either by a surgical procedure or with the use of drops or medication to decrease fluid production in the eye or open the fluid drainage system.  There are many different surgical methods used to treat glaucoma.  These include laser trabeculoplasty, where a laser opens blockages by focusing on the clogged drainage channels, and trabeculectomy, where a new drainage system is created allowing the intraocular fluid leave the eye.  In addition to decreasing the pressure in the eye, this also reduces fluid buildup.

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