Eye pressure is called intraocular pressure. It is a measure of the fluid pressure in the eye. According to the International Glaucoma Association, the fluid is called aqueous humor and is meant to flow through the eyes' drainage system. When this flow is hindered, blindness can occur.
Hypotony
Low eye pressure is also called hypotony. It commonly occurs after any eye surgery, as the flow of fluid returns to its normal level. However, chronic or long-term hypotony is a sign of a serious condition.
Significance
Long-term low eye pressure means something is interrupting the production of eye fluid, or that there is an eye fluid leak.
Other Causes
Low eye pressure can also be caused by an injury to the eye that cuts off eye fluid production. A tumor in the eye can also cause hypotony.
Low Pressure Measure
Eye pressure is measured in millimeters of mercury, or mm Hg. Normal eye pressure is between 10 and 20 mm Hg. Low eye pressure is considered hypotony at 5 mm Hg.
Consequences
If left untreated, low eye fluid can lead to problems with eyesight or even blindness. Hypotony is the opposite of glaucoma, which is increased eye pressure and also can cause blindness.