This technique is used to treat acute glaucoma, in which pressure in the eye rises suddenly due to blockage in the outflow of fluid. The pressure is reduced using eyedrops, intravenous drugs, and, sometimes, oral drugs. Anaesthetic eyedrops are then put into the eye, and a thick contact lens is placed in front of it to focus a laser beam onto the iris. The laser cuts a small hole in the iris, releasing the fluid behind it. The iris flattens, opening the drainage angle and letting trapped fluid out. The hole remains in the eye with no ill effects.
A thick contact lens is held in front of the eye, and a laser beam is focused through it onto the iris. The laser then cuts a small hole right through the iris.
Fluid trapped behind the iris flows through the hole. The iris returns to its normal shape, and the drainage angle opens, allowing the eye to drain normally.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.