COMPUTER VISION SYNDROME

DR KUNAL MANDLIKAravind Eye Hospital, Pondicherry

INTRODUCTION

• Computer Vision Syndrome (CVS) is the number one occupational hazard of the 21s' century. Defined as 'Complex of eye and vision problems that are experienced during and related to computer use; it is a repetitive eye strain disorder that appears to be growing rapidly. "50-90% experience CVS in some or another form r while 22% have musculoskeletal disorder.

PATHOPHYSIOLOGY• Characters displayed on a computer screen or video display terminal (VDT) is made

up of many, many small dots or pixels. The eyes have a very hard time focusing on the pixel characters

• There is a significant difference in the glasses prescription required for focusing on a standard printed near card (called a Snellen card) and focusing on the image of a typical computer screen, both at a viewing distance of 20 inches.

PATHOPHYSIOLOGY

• Starting around age forty, the condition called presbyopia, the conventional bifocal correction (general purpose bifocals) is not recommended for working with a computer. Wearing bifocal glasses forces a computer user to tilt the head back and move closer to focus on the screen to see through the lower part of the bifocal lenses. Such a position can cause neck and shoulder pain, as well as back pain and headaches.

• Eyes focus on the screen and relax to a point behind the screen, called the Resting Point of Accommodation (RPA) or dark focus.

PATHOPHYSIOLOGY• Blinking of eyes is 22 times per minute when looking at a paper which reduces to

7 blinks per minute while looking at a computer screen, leading to dry eyes.• Discomfort glare is largely caused by large disparities in brightness in the field of

view, the largest single factor in the workplace causing cvs.• Improper lighting can account for up to 30% of the visual symptoms computer

users' experience

SYMPTOMS• Eyestrain• Headaches• Neck Pain• Blurred vision• Burning sensation• Colour distortion• Photophobia• Double vision• Dry eyes• Back pain• Slow refocussing

TREATMENT• Anti-reflective (AR) coating: reduces reflections on the front and back surfaces of

eyeglass lenses that cause glare and interfere with your ability to focus on images on your screen.

• Lightly tinted lenses: They filter out the unwanted effects of certain colors (blues in fluorescent lighting) which have been known to cause discomfort and eyestrain for computer users. The most common tints used are beige (the PRIO tint), gray, and pink.

• Ergonomics is important — changing your computer workstation to facilitate good posture can certainly help.

• Get the light right: In the ideal environment, all objects in the patient’s visual field should be equal in brightness. The light should never be behind the video display terminal

TREATMENT

• Adjust the monitor: To further minimize the drying, recommend that the patient position his video display terminal 10 to 20 degrees below eye level.

• Practice 20/20 rule: Close your eyes from time to time and roll them to relax your eye muscles. Every 20 minutes take 20 seconds and look at least 20 feet away to relax your eye muscles.

TREATMENT• Lubricating drops: These are a simple and effective therapy for the inevitable reduction of an

individual’s blink rate and tear film. • Correct refractive errors:

• Glasses prescription:A bifocal designed for computer use (higher-than-normal segment height; lower-than-normal add) Occupational lenses or readables (the Sola Access lens or the Zeiss R lenses) that are a modified type of progressive lenses work the best for presbyopic computer users. Half-eye glasses, Flip-down lenses clipped to the distance treatment, Plus inserts, Clip-on magnifiers, Prisms for binocular abnormalities.