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Variable Contrast Optotypes

App for measuring the Visual Acuity and Contrast Sensitivity with dynamic Charts at multiple distances and for Normal or Low Vision Patients.
 
 
AmblyopiaVA - Manuel Rodriguez Vallejo

This App is not available for Android due to the great variations in luminance properties between different tablets. The app allows personalizing the calibration values even though it is not strictly required if you are using an iPad third generation.

Normal Vision

  • ETDRS Charts for presenting at 0.40, 0.67, 0.80, 3 and 4 meters.
  • 3 Different packages of letters for avoiding memorization.
  • Contrast Variation from 0 to -2.3 log units in -0.1 log unit steps for measuring visual acuity at different conditions of contrast.
  • Isolated Crowded Sloan letters for measuring poorer visual acuity values than the limited for the screen size in an ETDRS chart.
  • Contrast Variation from 0 to -2.3 log units in -0.1 log unit steps for measuring contrast at a fixed value of visual acuity.

Low vision

  • ETDRS Chart for presenting at 1 meter. From 0.2 to 1.1 logMAR [20/32 to 20/253]
  • Contrast Variation from 0 to -1.9 log units in -0.1 log unit steps for measuring visual acuity at different conditions of contrast.
  • Isolated Crowded Sloan letters for measuring poorer visual acuity values than the limited for the screen size in an ETDRS chart. Up to 1.6 logMAR [20/800]

Special characteristics

  • These issues makes the app the most proffesional in terms of personalization to maximize reliability.
  • Tablet's pixels per inch. The dots per inch (dpi) from your device is automatically recovered from the deviced and displayed in the screen (Possibility to change if the app is recovering incorrectly the dpi, particularly in android tablets.
  • Gamma correction. Optimize the contrast of the letters in your device by means of inserting your own calibration data.