KASHSURG Snellen Color Eye Chart Non-Reflective Matte Finish Wall Eye Chart 20 Feet : Industrial & Scientific

Description

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 5 x 5 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. Statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease or health condition. To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyzed reviews to verify trustworthiness.

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