Visual impairments

Astigmatism

An irregularity in the curvature in either the cornea or the inner lens of the eye.

Astigmatism prevents light from properly focusing on the retina. Astigmatism can exaggerate optical glare.

The irregular shape of the cornea causes refracted light to have focal points inset and behind the retina. The irregular shape of the cornea causes refracted light to have focal points inset and behind the retina.

How it affects UI design

Astigmatism can cause or exaggerate chromatic aberration. Be sensitive to juxtaposing highly saturated reds and blues, as they will create a "vibration" appearance called chromostereopsis. This can be unpleasant and causes text legibility issues.

Astigmatism causes lowered visual acuity (blurring) and is typically accompanied with myopia or hyperopia.

Sources:

  1. What is astigmatism. American Academy of Opthalmology. https://www.aao.org/eye-health/diseases/what-is-astigmatism
  2. Astigmatism. . https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/astigmatism
  3. Astigmatism. American Optometric Association. https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/astigmatism
  4. Astigmatism. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/astigmatism/symptoms-causes/syc-20353835
  5. Astigmatism. Wikipedia. https://en.wikipedia.org/wiki/Astigmatism