Vision tester is an instrument used to test certain visual functions of near and far viewing distances. It encompasses a slide projector for projecting a visual indication chart onto a curved display screen through a mirror rotated by a motor. The center of curvature of the curved display screen substantially coincides with the subject's eye. The rotation of the mirror causes an image of the visual indicator to be moved across the screen in a specific direction. When the subject provides a response to the moving image, the speed of image movement at the time of the response is detected and stored in a memory. The average of a plurality of such measurements is used to determine the subject's dynamic visual acuity.

A visual evoked potential is an evoked potential caused by sensory stimulation of a subject's visual field and is observed using an electroencephalography. It is very useful in detecting blindness in patients that cannot communicate, such as babies or non-human animals. Commonly used visual stimuli are flashing lights, or checkerboards on a video screen that flicker between black on white to white on black (invert contrast).

Video magnification systems can help improve quality of life for the visually impaired by dramatically enlarging printed text or photographs. It uses a video camera to project a magnified image of printed text, handwriting and photographs onto a video monitor, PC or TV screen.