Glaucoma causes damage to the optic nerve. Most commonly, this occurs due to increasing internal pressure in the eye because of problems with the flow or drainage of fluid within the eye. It can also occur when the internal pressure of the eye does not increase (normal tension glaucoma), but there is not enough blood flow to the optic nerve. There are no early symptoms in the most common form of glaucoma, but the first signs of damage are defects in side (peripheral) vision and difficulty with night vision. If diagnosed early, it can be treated with drugs, or sometimes surgery can minimize vision loss.

Cause of Glaucoma - illustration of cross-section of eye labels the lens, pupil, anterior chamber, iris, and cornea, showing where fluid forms inside the eye, flowing to the anterior chamber where it exits through the angle at the bottom

view from the point of view of a person with glaucoma - a photograph of two young boys holding balls has a halo effect with all areas outside of the halo dark

Images credit: National Eye Institute, NIH

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