Visual Field Testing
A visual field test measures the range of your peripheral or “side” vision to assess whether you have any blind spots (scotomas), peripheral vision loss or visual field abnormalities. It is a straightforward and painless test that does not involve eye drops but does involve the patient’s ability to understand and follow instructions.
An initial visual field screening can be carried out by the optometrist by asking you to keep your gaze fixed on a central object, covering one eye and having you describe what you see at the periphery of your field of view. For a more comprehensive assessment, special equipment might be used to test your visual field. In one such test, you place your chin on a chin rest and look ahead. Lights are flashed on, and you have to press a button whenever you see the light. The lights are bright or dim at different stages of the test. Some of the flashes are purely to check you are concentrating. Each eye is tested separately and the entire test takes 15-45 minutes. These machines can create a computerized map out your visual field to identify if and where you have any deficiencies.
Glaucoma testing involves measuring internal eye pressure and a detailed scan of the retina for signs of disease.
If you’ve discovered you might need vision correction during your eye examination, it’s vital to determine just how “much” your eyes need to be corrected with lenses or contact lenses. This is called measuring your “refraction.
Autorefractors automatically measure this value during an eye examination.
While seated with your chin in a stabilizing chinrest, you’ll be asked to focus on an image or point of light. The autorefractor automatically determines the correction needed to place your “focus point” on top of the retina, the light-sensitive area at the back of the eye responsible for correctly processing images.
The measurement taken by an autorefractor can be translated into a prescription for eyeglasses.
In eye exams for small children, or for people with special needs who may have trouble sitting calmly during an extended exam, or verbally describing their vision problems—autorefractors give highly accurate measurements used to determine vision correction needs, automatically.
How Do Autorefractors Work?
Autorefractors only take a few moments to determine each measurement for each eye. What’s more, autorefractors are quite reliable and are sometimes used in conjunction with a machine called a phoroptor to manually switch lenses in front of your eyes to provide ideal vision correction.
Special thanks to the EyeGlass Guide, for informational material that aided in the creation of this website. Visit the EyeGlass Guide today!
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