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by Dr Maria Hannah Pia de Guzman

One common type of glaucoma is primary angle-closure glaucoma. The term “primary” is used for diseases where there is no identifiable cause. The term “angle-closure” means that the anterior chamber angle (angle) is blocked by the iris (the colored part inside the eye). The angle is where the trabecular meshwork (TM) is located. The TM is the structure that constantly drains the fluid inside the eye. Think of it like the drain in a sink. Constant drainage is needed to balance the constant production of fluid by the ciliary body (like a faucet that is always open). If the faucet remains open but the drain is blocked the sink overflows. However, because the eyeball is a closed system, the fluid accumulation leads to elevation of the eye pressure in the same way that a ball that is pumped with too much air becomes hard. Elevated eye pressure can damage the optic nerve head thus leading to glaucoma.

Angle-closure can detected by the ophthalmologist in the clinic using a special lens in an examination called gonioscopy. There are also some special machines that can be used to view, measure, and document the angle.

A narrow angle or a recently closed angle can be opened using certain laser techniques. However, angles that have been closed for too long become stuck in the closed position and may no longer respond to laser and might need to be treated with surgery.