eye disorders
Glaucoma
Diagnosis of Glaucoma
A doctor's examination of the eyes If doctors suspect glaucoma (for example, based on what they find during a routine eye examination), they do a comprehensive eye examination for glaucoma. There are five parts to a comprehensive eye examination for glaucoma: Measurement of eye pressure Evaluation of the optic nerve Visual field testing Gonioscopy Measurement of the corneas Doctors measure pressure in the eye. This measurement is taken painlessly with an instrument called a Tonometry . Normal eye pressure readings are in the range of 11 to 21 millimeters of mercury (mm Hg). In general, eye pressure readings greater than 21 mm Hg are considered high. But measuring eye pressure is not enough because a third or more of people with glaucoma have eye pressure in the average range, and some people have a high eye pressure reading that is not caused by glaucoma. So doctors also use an What Is an Ophthalmoscope? and sometimes other instruments (such as In addition, Visual Field Testing (peripheral vision testing) allows a doctor to detect blind spots. Most often, visual field testing is done with a machine that determines the person’s ability to see small dots of light in all areas of the visual field. Doctors may also use a special lens to examine the drainage channels in the eye, a procedure known as gonioscopy. The gonioscope allows the doctor to determine whether the glaucoma is of the open-angle or closed-angle type. Doctors also measure the thickness of the corneas. If the corneas are thin, glaucoma is more likely to develop. However, a thin cornea does not mean that glaucoma is present. Medications that cause anticholinergic effects (for example allergy, cold, or sleep medications that contain an antihistamine) can widen the pupils, so before older people take these medications, their eyes should be checked to see whether development of closed-angle glaucoma is likely. Because the most common types of glaucoma can cause slow and silent loss of vision over years, early detection of the disease is extremely important. All people at high risk of glaucoma (see the Glaucoma ) should have a routine comprehensive eye examination every 1 to 2 years. 