Causes of glaucoma

What causes glaucoma?

This is a complicated question which many researchers, including those at Casey, are trying to understand. From ongoing research, we know that genetics, eye pressure and blood flow are all involved. The term "glaucoma" also encompasses a spectrum of diseases which behave differently from each other.

While high eye pressure (over 21 mm Hg) is commonly associated with glaucoma, it is not part of the definition of glaucoma. A person can develop glaucoma at normal eye pressures (13 to 20 mm Hg). For this reason, optic nerve examination is the key to diagnosis.

What are the risk factors?

The number of people who develop glaucoma varies with age and race. African Americans are 4 times more likely to develop glaucoma than whites, especially at younger ages. Glaucoma is also more common in Hispanics. 

Age (years) White Black Hispanic Asian
< 50 0.8% 2.9% 1.32% 0.6%
70-90 3.3% 11.2% 11% 2.5%
80-89 6.6% 16.9% 14% 3.8%

In addition, a family history of glaucoma and high eye pressure (over 21 mm Hg) are risk factors.

Based on this information, the American Academy of Ophthalmology considers the following groups at high risk for developing glaucoma and recommends that they should have a screening eye exam:

  • Anyone with a family history of glaucoma
  • African Americans over 40 years of age
  • Everyone over 60 years of age, especially those of Hispanic background