Pdf Eye Diagram Based Evaluation Of Rz And Nrz

Eye graph testing method

Eye charts have different uses. Standardized eye test results are vital for accurate vision testing. They help doctors. Visual screening tests involve reading letters, numbers, or symbols of different sizes on a chart-like structure placed at a distance (usually 20 feet away). A Hess test or Hess chart is used to map the amount of underaction or overaction of the extraocular muscles. It was made by Hermann Snellen in 1862. Refractive errors and conditions that cause blurry reading vision include astigmatism, hyperopia (farsightedness) and presbyopia (loss of near focusing ability after age 40). Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula developed by his professor Franciscus Cornelius Donders.

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