Written by Anjum Cheema, MD
Narrow Angle Glaucoma
The eyeball is continually producing and draining fluid, called aqueous humor. This aqueous humor is produced by cells that lie behind the iris, or colored part of the eye. This fluid then circulates through the pupil into the front of the eye and drains out of the eye through a complex circular drainage structure in the “angle,” that is, the angle formed between the iris and the cornea, the clear front covering of the eye.
In some eyes, this angle is more acute than usual, and is called “narrow angle.” Eye’s with narrow angles are at risk of developing “angle closure” in which access to the drain is closed off completely and fluid that is being produced in the eye is trapped and cannot escape the eye, leading to a sudden increase in eye pressure to dangerous levels, sometimes leading to permanent vision loss in a short amount of time.
Most patients who have narrow angles are hyperopic, or “far sighted.” Typically these are individuals who have never needed glasses to see clearly, with the exception of reading glasses after the age of 40 or so. Hyperopic eyes tend to be shorter and smaller than the average eye, so everything is condensed in the eye, including the angle. Besides hyperopic patients, elderly patients who have not had cataract surgery are also at risk because as a cataract develops, it pushes the iris forward, narrowing the angle.
Typically, narrow angles are asymptomatic – that is they don’t cause any noticeable problem to the patient. On the other hand, angle closure if it develops often leads to dramatic symptoms – an unbearable pressure like headache, blurry vision, nausea, vomiting, redness, extreme eye pain. Occasionally, patients with narrow angles suffer from intermittent episodes of angle closure attacks, and these are usually associated with a mild or moderate headache in dark light conditions, blurring of the vision for a few hours, redness, and sometimes nausea and vomiting.
There are several options for narrow angles, and your doctor will review which option is the best depending on the overall health of the eye. In general, treatment involves either laser surgery or cataract surgery. Laser surgery typically involves making an iridotomy, which is a small hole in the iris that causes the angle to become less acute, and to open further. If one has narrow angles as well as a cataract, cataract surgery can sometimes be performed since it will both improve the vision and usually cure the narrow angle as well.
If you are far sighted, you should have an annual eye exam to ensure that you have not developed a narrow angle. If you have any of the other symptoms described earlier – headache worse in dark lighting, episodic blurry vision, eye pain, or redness – seek attention urgently.