What Causes Computer Vision Syndrome?
Computer eye strain and computer vision syndrome are caused by our eyes and brain reacting differently to characters on a computer screen than they do to printed characters. Our eyes have little problem focusing on printed material that has dense black characters with well-defined edges. But characters on a computer screen don’t have the same degree of contrast and definition. Words on a computer screen are created by combinations of tiny points of light (pixels), which are brightest at the center and diminish in intensity toward their edges. This makes it more difficult for our eyes to maintain focus on these images. Instead, our eyes want to drift to a reduced level of focusing called the “resting point of accommodation” or RPA. Our eyes involuntarily move to the RPA and then strain to regain focus on the screen. This continuous flexing of the eyes’ focusing muscles creates the fatigue and eye strain that commonly occur during and after computer use.
CVS is caused by the increased demands of computer-generated images on our eyes and visual systems and by the prolonged and/or repetitive nature of computer work. Our eyes have little problem focusing on most printed material, which is characterized by dense black characters with well-defined edges. Characters on a computer screen, however, don’t have the same high contrast or well-defined borders. The luminous elements (pixels) that create images on a computer screen are brightest at the center and diminish in intensity toward their edges. This makes it more difficult for our eyes to accurately focus on computer-generated images compared to images printed with ink in a book or magazine. As our eyes struggle to gain and maintain focus on images on a computer screen, this continuous flexing of the eyes’ focusing muscles creates fatigue and the burning, tired-eyes feeling that is so common after long hours at the computer. In addition, it’s common for computer users to fall into bad post
