The most common type of glaucoma is called primary open angle glaucoma. This is when the drainage channel (located between the iris and the cornea) is open. When the drainage channel closes, the iris moves forwards and against the cornea, blocking the pathway to the drainage channel and causing the pressure in the eye to rise. If this pressure remains high for a period of time, the optic nerve can be damaged, which then leads to primary angle closure glaucoma.
Some eyes have a shallow anterior chamber and narrow angle due to the iris and lens being close to the cornea. This is often found in people with smaller eyes or who are long-sighted (hypermetropic).
There are a number of conditions that are closely related to primary angle closure:
Primary angle closure suspect – This is when tests show that the drainage channel in your eye is narrow and is at high risk of closing up at any time. This is more common in people with smaller shaped eyes where the iris is naturally closer to the cornea.
Acute angle closure – Primary angle closure is usually painless and occasionally causes symptoms of mild headache. However, if the drainage channel suddenly closes and the pressure suddenly becomes very high, the signs and symptoms are usually severe. This is called acute angle closure.