symptoms of eye disorders
eye disorders
Sudden Vision Loss
Sudden loss of vision is an emergency. Most causes are serious. All people who experience a sudden loss of vision should see an ophthalmologist (a medical doctor who specialize in the evaluation and treatment—surgical and nonsurgical—of eye disorders) or go to the emergency department right away. Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause and the tests that may need to be done (see table). Doctors ask the person to describe when loss of vision occurred, how long it has been present, and whether if has progressed. People are asked whether loss affects one or both eyes and whether loss is total or affects only a specific part of the field of vision. Doctors also ask about other vision symptoms such as floaters, flashing lights, halos around lights, distorted color vision, jagged or mosaic patterns, or eye pain. Doctors ask about symptoms that are not related to the eyes and risk factors for disorders that may cause eye problems. The physical examination concentrates primarily on the eyes, but doctors may also do a general physical examination. For the eye examination, doctors first carefully check sharpness of vision (visual acuity), usually by having the person read letters on a chart, first while one eye is covered and then with both uncovered. Doctors check how the pupils narrow (constrict) in response to light and how well the eyes can follow a moving object. Color vision may be tested. Doctors examine the eyes and eyelids using a What Is a Slit Lamp? (an instrument that enables a doctor to examine the eye under high magnification) and measure pressure in the eye. Ophthalmologists, after instilling drops that dilate the pupils, examine the retina thoroughly with a slit lamp or light that is shone from a head lamp through a hand-held instrument. The presence or absence of pain helps narrow the list of possible causes of sudden vision loss considerably (see table). If vision returns quickly on its own, transient ischemic attack and ocular migraine are among the likely causes. Often findings during the eye examination provide enough information for doctors to diagnose the cause of loss of vision. Sometimes, however, testing is needed depending on what disorders are suspected. The following tests are of particular importance: Ultrasonography is done if the retina is not clearly visible during an ophthalmoscopic examination. Gadolinium-enhanced MRI of the orbit and/or the brain is done for some people with eye pain and certain other symptoms and when optic nerve swelling is seen during the eye examination. Erythrocyte sedimentation rate (ESR) and C-reactive protein level (blood tests that indirectly measure inflammation in the body) are done and the number of platelets in the blood (platelet count) are sometimes measured, particularly in people over age 50 who have headache. 