What Happens in the Eye to Cause Glaucoma?
There is a gland behind the iris that normally produces a fluid called the aqueous humor in the eye. This fluid flows from the area behind the iris through the pupil to fill the space between the iris and the cornea. The fluid then flows through the trabecular meshwork and into Schlemm’s canal. It then makes its way into the blood system. There is a steady flow of fluid into the eye and a steady drainage of the fluid out of the eye. In open angle glaucoma, the trabecular meshwork partially obstructs the flow of fluid out of the eye causing the intraocular pressure (IOP) to rise. This high IOP causes damage to the optic nerve. In narrow glaucoma it is due the shape of the eye that allows the iris to block the trabecular meshwork not allowing any flow of fluid out of the eye and the IOP rises rapidly.
Risk Factors and Causes of Open Angle Glaucoma
People of African descent are four times more likely to develop glaucoma.
Family history significantly raises the risk of glaucoma.
There are several genes that have been found to contribute to the development of glaucoma.
Ocular blood flow around the optic nerve is now felt to cause the damage to the optic nerve. Factors affecting the blood flow can contribute to glaucoma damage. There is some evidence that fluctuations in blood flow may contribute to glaucoma. Hypotension at night may lead to glaucoma damage.
Causes of Acute Angle Closure Glaucoma
Women with their smaller eyes have a higher risk of angle closure glaucoma.
People who are farsighted are more likely to develop narrow angle glaucoma due to the smaller size of the eye.
Secondary Causes of Glaucoma
Long term use of cortisone or steroids
Injury to the eye damaging the outflow in the eye
Vascular causes include central retinal vein occlusion and diabetic retinopathy
Inflammation in the eye such as uveitis