Scars slowly form between the iris and the drain, and the eye pressure will not increase until enough scar tissue forms to cover the drainage area. A sudden rise in eye pressure can occur within a few hours and become very painful. An acute attack is an emergency condition. If treatment is delayed, eyesight can be quickly and permanently destroyed. The trabecular meshwork can become scarred, resulting in chronic glaucoma, which is more difficult than open-angle glaucoma to control, and cataracts may form.
Many acute attacks occur in darkened rooms, such as movie theaters.
This further narrows the angle, perhaps triggering an attack. The pupil also dilates when someone becomes excited or anxious. Therefore, many acute glaucoma attacks occur during periods of stress. Some drugs can also dilate the pupil and lead to an attack. These drugs include anti-depressants, cold medications, antihistamines, and some drugs used to treat nausea.