A Sloan-letter distance acuity screening, properly sized to your screen and viewing distance. The same logMAR progression used in the clinic — adapted for the desk at home.
Built by Dr. Ryan Evans, OD
i.Calibrate
ii.Distance
iii.Test
iv.Result
Calibrate the screen
First we need to know how large a millimetre is on your display. Choose a method:
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CALIBRATION CARD
0000 · 0000 · 0000
Resize until it matches a real credit card. Current: — px/mm
Align your face inside the oval, then start.
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Viewing distance
Sit a measured distance from the screen. Standard testing distance is 10 ft (3 m); shorter distances are valid if your screen is small.
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Tip. Use a tape measure or a known length (a US dollar bill is 156 mm; a credit card is 86 mm). Sit so your eyes are level with the screen.
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Right eye — cover the left
Cover your left eye gently with your palm (don't press on the eyeball). Read the letters aloud. Tap each letter you can identify, or type it. If unsure, guess — partial credit counts.
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Right eye (OD)
Cover your left eye. When ready, the test will begin at the largest line and progress smaller.
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Your results
Best uncorrected acuity (better eye)
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Right (OD)
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Left (OS)
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Educational use only. This screening is not a substitute for a comprehensive eye examination. Refractive error, cataract, glaucoma, and retinal disease can produce 20/20 results yet still require treatment. If you notice any change in vision, schedule an exam with a licensed eye care provider.