Scotopic sensitivity is a condition which affects the way in which the brain processes and interprets visual information. The symptoms can be wide ranging from problems with reading and writing, depth perception, headaches, comprehension problems and extreme light sensitivity. Although its symptoms suggest that it is an optical problem it is actually called a perceptual processing disorder as it is the brains inability to properly process the information it receives through the eyes that causes issues.
In terms of digital accessibility people with scotopic sensitivity can have problems with text appearing to move or blur or disappear on a screen due to the high contrast between text and background (ie black text on white background) This condition can be helped with either colour tinted glasses or colour tinted screen overlays which will reduce the contrast between the elements on the screen.
Overlays have also been found to be helpful for people with dyslexia.