CVS stands for Computer Vision Syndrome. This is a disorder that is caused by staring at a computer display or VDT (Video Display Terminal). This page will focus on the effect of CVS on eBook Readers.
 American Optometric Association
This is an organization devoted to Optometry and associated vision issues. They have created several pages to explain CVS. These include:
http://www.aoa.org/x5253.xml Causes at work. Has links to:
- What causes Computer Vision Syndrome?
- How is Computer Vision Syndrome diagnosed?
- How is Computer Vision Syndrome treated?
http://www.aoa.org/x5374.xml Occupational Issues. Has links to:
- Computer Vision Syndrome Symptoms
- The Relationship of Computer Vision Syndrome to Musculoskeletal Disorders
- Impact of Computer Use on Children's Vision
- The Effects of Video Display Terminal Use on Eye Health and Vision
- Criteria for Determining Whether the Need for Eyeglasses or Other Treatment is Related to Computer Use.
 Display Factors
Settings can be adjusted to combat contrast and glare issues, color choices can be adjusted. However some things are inherent in the display itself.
- a CRT generally has a thick glass in front, which forces the eye to refocus from the front to the back of the glass constantly, contributing to eyestrain.
- LCD monitors have less of a boundary between LCD pixels and the front of the screen, causing the eye to work less to focus.
- Both CRTs and LCDs have screen refresh - There can be a flickering effect that places undue strain on the eyes, causing fatigue. This can be exacerbated by florescent lights being used in a room where the display is being used.
- E-Ink generally is reported to have the least eye strain. Some attribute this to lack of refresh and others to lack of backlight.
- PixelQi sunlight readable displays allow the user to control the LCD's brightness thereby reducing "screen glare". It can be turned completely off allowing a "vision easy" display where text and graphics are sharp and clear while not glaringly bright.
 Anecdotal Evidence
While scientific study does not prove many of the claims of users there are enough claims to provide a few tips to minimize the problems that some people experience.
- Decrease the backlight level to the minimum acceptable (This will also increase battery life on portable devices).
- Increase the Font size to reduce eye strain.
- Change the color choices to something that is pleasant to view. Experimentation is required.