Anatomically narrow angles are a consequence of a narrow space between the iris and the cornea and can result in very high eye pressures and visual loss. Patients with progressive cataract as well as patients with shorter or hyperopic eyes are at increased risk of developing this condition. When it occurs, the normal path of fluid from the back of the eye to the front is blocked. Since this fluid needs to drain from the front via the angles, the blockage can result in very high eye pressures that result in rapid loss of vision. (Angle closure attack). By detecting anatomically narrow angles in the clinic, the risk of an angle closure attack can be prevented in two ways: 1. removal of the crystalline lens (cataract surgery) or 2. creation of a bypass channel or laser peripheral iridectomy (LPI). LPI is a common procedure that is generally safe. Common side effects are inflammation, bleeding and occasionally light leaking forward. These risks are weighed against the benefit of preventing an angle closure attack. In patients whose angles are 270 out of 360 degrees narrowed, an LPI or cataract surgery are recommended. If a patient has no signs of cataract, then the LPI procedure is the clear choice.