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مخطط سنيلين للرؤية عن بعد للعين 20 قدم

KWD 7
– 1 +

مميزات خاصة

  • Designed for vision testing at 20 foot distance
  • Non-reflecting, matte finish eye charts
  • Eye chart measures 22 x 11 in.

وصف

The Snellen eye test uses the idea of a subtended 5 minutes of arc with a 20 foot distance. This became the "standard vision" measurement. Also, Snellen developed the idea of a 5x5 grid for a standard for his optotypes. Each optotype must meet certain percentage requirements in this grid before it is used for testing. This helps to make a uniform and equal vision chart. The Snellen eye chart is the basis for many other vision tests.

منتجات شبيهه

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