Opthamalogist Tools for Eye Exam
Ophtalmologists use a variety of tools to physically examine the eye without pain and to assess your visual acuity. You will feel much more at ease in the exam room if you familiarize yourself with these tools, since this gives you an explanation of why the doctor is doing what he is doing even if he doesn't tell you outright.
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Charts
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The Snellen chart is the chart which hangs on the wall in the exam room and has different letters on it. The letters are arranged in lines, with the largest letters on top. The doctor asks you what letters you can see from each line, and depending on the form of the chart, what way the letters face. This gives the ophthalmologist a rough idea of what your vision is like without any physical exam and therefore is used as a starting point for using other tools. Your ophthamologist may use other charts such as the Amsler grid to test for blind spots and check your peripheral vision.
Lights
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Your ophthalmologist will want to examine the structures of your eyes in order to make sure they are working properly and are of the right dimensions. Bright lights make it easier for the ophthalmologist to see how your eye is built and is functioning. The two main lights the ophthalmologist may use are the hand-held ophthalmoscope (also called a funduscope), which is a tiny flashlight with a magnifying lens, and the sit lamp, which is a big, bright lamp attached to a support on which you rest your chin.
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Tonometers and Autorefractors
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An instrument called a tonometer measures eye pressure, usually with a painless puff of air over the eye. Autorefractor machines detect how your eye is refracting light. Based on the refraction percentage calculated by the machine, the doctor determines how to build your contacts or lenses, or whether to proceed with a corrective eye surgery. Ultrasound machines sometimes are used alone or in conjunction with these machines to get an idea of the eye shape.
Drops and Dyes
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The eye doctor may put drops in your eyes to relax or numb the eye muscles. If the doctor needs to view the blood vessels in the back of the eye more clearly, he may give you a simple shot of a dye called fluorescein, which travels through all areas of your body and therefore shows up in your eyes.
Computers
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As technology improves, ophthalmologists are utilizing computers and computer software more frequently to run tests more easily. More programs and computer aided machines will allow for less invasive and more accurate eye exams.
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