Online Tool Help Test Vision Parameters

An online vision screening tool enables internet users to test their visual acuity (VA), contrast vision, and color vision.

Developed by Carl Zeiss Vision (Aalen, Germany), the website provides instructions that enable the user’s computer monitor to be configured to optimize the accuracy of the test, including instructions on how to achieve the correct settings for screen calibration, gamma calibration (brightness), and how far the eyes should be from the monitor.


Results from the tests, designed for people who wear glasses or contacts as well as for those who do not, come back within five minutes or less to let the user know if their vision is good, average, or poor.

The online vision screening is divided into three parts. The first is a visual acuity check, which measures the spatial resolution of the visual processing system. VA is tested by requiring the person whose vision is being tested to identify characters--such as letters and numbers--on a chart from a set distance. The distance between the person's eyes and the testing chart is set at a sufficient distance to approximate infinity in the way the lens attempts to focus.

The second part is a contrast vision check, which examines the ability to differentiate between light and dark (contrast). Contrast sensitivity is a very important measure of visual function, especially in situations of low light, fog, or glare, when the contrast between objects and their background often is reduced. Driving at night is an example of an activity that requires good contrast sensitivity for safety.

The third part is a color vision check, which checks for color blindness. Color blindness in humans is the inability to perceive differences between some of the colors that most people can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage, or due to exposure to certain chemicals. There are two major types of partial color blindness: those who have difficulty distinguishing between red and green, and who have difficulty distinguishing between blue and yellow. Total color blindness is much less common than partial color blindness.

The Zeiss online vision screening is only intended to be used as a guide to help determine the urgency of getting a professional eye exam.

Related Links:
Carl Zeiss Vision
The Zeiss online vision screening tool