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Eye Examinations: What to Expect

During an eye appointment several types of eye tests may be performed. In addition to a complete eye examination, your doctor may want to order one of the following special tests.

Applanation tonometry: A test that helps doctors diagnose glaucoma by measuring the amount of pressure needed to flatten a portion of the cornea. This is done by taking a thin strip of paper stained with the dye fluorescein. This dye stains the front of the eye and enables a better examination by the doctor. The patient is then given a local anesthesia in the form of drops and the pressure is measured using a tonometer.

Corneal topography: During this procedure, a computer is used create a "map" of the curvature of the cornea. The computer analysis will show any distortions of the cornea (e.g., scarring) as well as conditions such as astigmatism. This test is used to screen patients before they undergo any refractive surgery. It also can be used before contact fittings and corneal transplants.

Fluorescein angiography: This is a test used to evaluate the blood circulation in the retina. It is useful in helping to diagnose diabetic retinopathy and retinal detachment. During this test, a special dye called fluorescein is injected into a vein in the arm. The dye quickly travels to the blood vessels inside the eye. Once the dye reaches the eye, a specialized camera is used to photograph the fluorescein as it circulates though the blood vessels in the back of the eye. This will enable the doctor to diagnose any circulation problems, swelling, leaking or abnormal blood vessels.

Pupillary dilation test: During this procedure, the eye doctor places special drops in the eye, causing the pupil to dilate (expand). By dilating the pupils, your doctor can examine your retina for any signs of disease.

Refraction test: This test measures your ability to see objects at specific distances. It is often done by having the patient look at a chart at a fixed distance, usually 20 feet away. The patient tries to read the chart  while looking through a special instrument known as a phoropter. The phoropter moves lenses of different strengths into place for the patient to look through. This test is useful in helping to diagnose presbyopia, hyperopia, myopia, and astigmatism.

Slit-lamp exam: A test that looks at the front of the eye by shining a beam of light shaped like a small slit on the eye. The eye doctor may also dilate your pupils while you are undergoing this exam. The test can be used to help diagnose cataracts, retinal detachment, macular degeneration, injuries to the cornea and presbyopia.

Tonometry: This is a procedure used to help diagnose glaucoma. In tonometry, a small, smooth instrument known as a tonometer is lowered onto the surface of the eye in order to measure the pressure in the eye.

Ultrasound: An ultrasound uses sound waves to provide a picture of the eye’s internal structure. It is useful in evaluating ocular tumors and in evaluating the retina when it is being obscured by cataracts or a hemorrhage. This test is given as part of preoperative evaluation for cataract surgery.

Visual acuity testing: A test of your visual acuity, or ability to see sharply and clearly at near and far distances, will be performed. Various tests can be used to determine the visual acuity of infants, children, and adults. These are fairly simple and can be performed by an ophthalmologist, optometrist, technician, nurse, or optician. One common type of test used for children who cannot yet read is the Random E’s Visual Acuity Test. The patient is asked to identify the direction that the letter "E" opens to by holding out fingers to mimic the letter "E." This test is safe, there are no risks involved, and it works just as well as most other tests.

Visual field test: A test used to measure peripheral (side) vision. When given this test, you will be asked to stare at on object in the center of your line of vision (either the doctor’s eyes, on a screen or using a computer program). As you are looking at the object, you will be asked to note when you see an object moving into your peripheral vision. This test is done to diagnose glaucoma or possible damage caused by a stroke.

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 11/14/2008...#10738