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    Eye Tests and Exams

    Refraction

    This eye test determines your eyeglasses prescription. During the test, you look at a chart, usually 20 feet away, or in a mirror that simulates 20 feet of distance, and try to read it while looking through a special instrument known as a phoropter. The doctor moves lenses of different strengths into place for the patient to look through. The doctor will ask you which of the choices looks clearer or more blurry, and based on these answers will determine the appropriate prescription for glasses or contacts. This eye test will also identify presbyopia, hyperopia, myopia, and astigmatism.

    Slit-Lamp Exam

    This test looks at the eye with a microscope shining an adjustable beam of light shaped like a small slit on the eye. The doctor may also dilate your pupils while you are undergoing this exam. The eye test can be used to help diagnose cataracts, glaucoma, retinal detachment, macular degeneration, injuries to the cornea, and dry eye disease.

    Non-Contact Tonometry

    This eye test is used to help diagnose glaucoma. An instrument known as a tonometer measures the pressure in the eye. The "air puff" tonometer measures the eye pressure indirectly by the eye's resistance to a puff of air.

    Applanation instruments can also be used to measure pressure. They are the most accurate, but they require local anesthetic.

    Ultrasound

    An ultrasound eye test uses sound waves to provide a picture of the eye's internal structure. It is useful in evaluating ocular tumors, as well as the retina when it is being obscured by cataracts or a hemorrhage. Measuring the length of the eye by ultrasound or other means is part of preoperative evaluation for cataract surgery and determination of the optimal cataract implant power.

    Visual Acuity Testing

    This is a test of visual acuity, your ability to see sharply and clearly at near and far distances. For children who cannot yet read, there is the Random E's Visual Acuity Test. The child is asked to identify the direction that the letter "E" opens to by holding out three or four fingers to mimic the letter. You can practice this at home with your child before the test. This eye test is safe, there are no risks involved, and it works just as well as most other eye tests.

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