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Contrast Vision Deficiency (2A)

Contrast discrimination is the ability to differentiate between light and dark (contrast).

Luminance ratio is the measure of how much contrast the parts of an image should have for easy discrimination. Problems with contrast discrimination make visual processing difficult and more time consuming as students need to view content longer to process the parts of an image. Depending on the luminance ratio and the degree of the visual impairment, a student may not be able to process the image at all. There are standards set by the ADA regarding the luminance ratio for accessible visual information (3 to 1 ratio is the minimum requirement for accessibility). Students have particular problems in poorly lit environments.

Formal Diagnostics

Contrast vision deficiency may be diagnosed by medical personnel.

Intake Questions

  • Do you have difficulty reading or understanding visual information if shading is used or there are not clear contrast differences?
  • Is your vision such that you require high contrast to read or understand visual information?
  • Do you have difficulty reading in low light?
  • What accommodations or strategies have been effective in the past?


The Building Accepting Campus Communities (BACC) project was funded by the US Department of Education Office of Secondary Education grant #P333A080070-09. The University of Nebraska does not discriminate based on gender, age, disability, race, color, religion, marital status, veteran's status, national or ethnic origin, or sexual orientation.