Here is a bit of info from the Kaiser-Permanente website:
"What Increases Your Risk
Risk factors for open-angle glaucoma include:
High pressure in the eyes. Open-angle glaucoma is often associated with higher-than-normal pressure in the eyes (intraocular pressure, or IOP). As many as 10% of people over age 40 have higher-than-normal IOP (pressure above 21 millimeters of mercury [mm Hg]). Some studies have indicated that among people with high IOP, only about 10% develop vision loss from glaucoma. Other studies indicate that 15% to 40% of people with high IOP develop some vision loss within 10 years. High pressure in the eyes is the one treatable risk factor for open-angle glaucoma. However, raised pressure in the eyes alone is not enough to diagnose glaucoma and does not always require treatment.
Age. The risk for glaucoma increases rapidly after a person reaches age 40. People age 70 and older are about 4 to 7 times more likely to develop glaucoma than people 40 to 50 years old.
Race. In the United States, blacks are 4 times more likely than whites to have glaucoma. Also, one study showed that blacks over age 30 had an increased risk of developing glaucoma at an earlier age than whites.9 Blacks with glaucoma are more likely than whites to develop severe damage to the optic nerve.
Family history of glaucoma. People who have family members with open-angle glaucoma are at greater risk of developing the condition. Relatives of people with primary open-angle glaucoma have about a 9 times greater risk of developing glaucoma. Changes within the eye (enlarged cup-disc ratio), not increased pressure in the eye, may be the first sign of glaucoma in these people.
Prior loss of vision in one eye from glaucoma. Damage in one eye from glaucoma is associated with a higher risk of future damage in the other eye. If untreated, the risk that damage will occur in the other eye within 5 years is about 29%."
Elsewhere on the site, it says that the success of different treatments depends a great deal on those factors such as age,race, etc. But it also says that glaucoma is very uncommon in people under 40.
Here's a link to the entire health article on the sie; there's lots of info there, I hope some of it helps.
Glaucoma Info