Are there different types of glaucoma?
There are two main types of glaucoma, primary open-angle glaucoma (POAG) and primary angle closure glaucoma (PACG). Sometimes primary open-angle glaucoma is called chronic open-angle glaucoma (COAG), so you may see COAG on your medical chart if you have glaucoma. These different types of glaucoma refer to the status of the drainage angle in the front of the eye, where the eye fluid exits the eye to be reabsorbed by the body.
Primary open-angle glaucoma
This is the most common type of glaucoma. In primary open-angle glaucoma, the drainage angle is open but it is not working properly, like a clogged drain. This can result in an increase in eye pressure, which can lead to damage to the optic nerve. This type of glaucoma does not cause pain and most patients do not know they have it unless they see an eye doctor.
Chronic open-angle glaucoma
In chronic open-angle glaucoma, the drainage angle is physically closed. This can occur because the iris, the colored-part of the eye, bunches up and blocks the angle. Certain types of eyes are more prone to closure of the angle, including eyes that are smaller than average. Oftentimes far-sightedness, or hyperopia, is associated with smaller eyes and angle closure. Another common cause of progressive angle-closure is the formation of a cataract. This occurs because the lens, which becomes a cataract as it gets cloudy, also grows over time and ‘crowds’ the front of the eye. In cases such as this, cataract surgery can help open the drainage angle and lower the pressure inside the eye.