Factors increasing the risk for angle closure glaucoma

As with open angle glaucoma, older persons are more likely to have angle closure. We have seen people in their twenties with the disease, but that is rare. The rate peaks around age 60, at least in part because the natural tendency is for eyes to get shorter (slightly smaller) with time. By contrast with open angle glaucoma, angle closure affects women probably 50% more often than men. The reasons for this aren’t completely settled, but we do know that women have smaller eyes and that is one of the contributors.

For reasons that aren’t yet fully understood, Asian and east Indian persons have a lot more angle closure than everyone else in the world. Asians don’t have more of the other risk factors; at least present research says that their eyes don’t have more of the other contributing factors, such as having smaller eyes. Asian eyes look a little different from Europeans because they have different eyelid structure, not because their eyes themselves are a different size. The contribution of family history to angle closure is just as strong as it is for open angle glaucoma. No actual mutations or DNA code mistakes in particular genes are known that are associated with angle closure yet. Without question, if you have a close blood relative with angle closure, you are 10 times more likely to develop it as well.

Angle closure glaucoma is more a disease of higher than normal eye pressure than is open angle glaucoma. As discussed in a previous section, the process of angle closure means that the iris moves to block the trabecular meshwork, raising eye pressure and causing damage. This can happen either suddenly (an acute angle closure crisis) or more commonly as a silent but off-and-on process that gradually plugs up the meshwork with iris stuck to it, leading to a chronic disorder. The dominant reason for the iris to block the meshwork is that it starts out close to the outflow area in the first place in smaller eyes. Smaller eyes are often “far-sighted” (hyperopic). Persons with hyperopia develop the need for eyeglasses in mid-life and become unable to read print without glasses earlier than everyone else. When we measure the length of their eyes, they are shorter than average, with crowding of the structures together. This slows the movement of aqueous humor from where it is produced behind the iris (at the ciliary body) through the pupil (between the iris and lens) and into the front chamber (anterior chamber) of the eye. Because the block of aqueous movement is at the pupil, doctors call it pupil block. If there were an opening in the iris, the fluid couldn’t be blocked. So, the first treatment for angle closure is to make a hole where there isn’t one naturally. This is done in the office with a laser, painlessly, with only eyedrop anesthesia (laser iridotomy, see section Laser glaucoma surgery: iris holes and angle treatment).

More detail about the risk of developing angle closure glaucoma and treatment or no treatment for suspects for angle closure is included in the section Why isn’t glaucoma either there or not there—what makes you an angle closure suspect?

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