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What eye doctors know about visual discomfort

6 June 2012


There are 2 types of eyestrain:

Internal symptoms

  • Ache or pain felt inside the eye
  • Caused by convergence and accommodative stress, refractive error
  • Caused by eye conditions

External symptoms (dry eye symptoms)

  • Dryness or irritation on the front of the eye
  • Caused by conditions that compromise the quality of the visual stimulus

What Eye Doctors Know:

  • Accommodative and/or vergence stress cause symptoms (internal)
  • Exophoria is typically more comfortable than esophoria
  • Convergence is much easier than divergence
  • There is considerable variation in phoria and ZSCBV across patients


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