It is believed that up to 90% of computer users develop a condition called Computer Vision Syndrome after 2 hours of computer use which is caused by eye muscle fatigue.
And 70 to 75% of those computer users will need computer glasses to relieve their eye fatigue symptoms.
Eye strain is often caused by the sun.
There are UV protection sunglasses sold for example at Optical Center.
Some of the major eye fatigue symptoms related to Computer Vision Syndrome (CVS) are:
Tired and burning eyes from constant focusing on a computer that is too close to the eyes. The computer screen should be no closer than 20 to 26 inches from the eyes. The further the computer screen is from the eyes the less eye strain that develops, and the longer you can use the computer without symptoms.
Eye strain can develop from eye muscle fatigue, and if left uncorrected, this eye fatigue could cause intraocular muscle spasm resulting in pseudo-myopia. This is a form of transient nearsightedness that causes the distance vision to blur when looking up after prolong computer use. Computer glasses are designed to correct this problem. Sometimes glasses with a weak base-in prism or ultra-violet coatings give some relief as well. The former bolsters up weak converging eye muscles, and the latter tends to block out some of the blue wave length from the harsh white light of fluorescent tubes.
Eye squinting to overcome blurred vision can ultimately cause headaches, increased astigmatism and wrinkles at the corner of the eyes called 'crows feet'.
Glare contributes to eyestrain and can be diminished wth glare screen filters and anti-reflective eyeglass coatings on the glasses. Decreasing the ambient light in the room by 1/2, and redirect it so that it doesn't reflect off the computer screen also helps. Indirect light causes less glare than direct light. Glasses with light gray or pink tints may help as well as anti-reflective coatings. Up to 30% of visual symptoms are caused in some degree from improper lighting.
Dry eyes can result if you stare at the computer screen to long, causing a drop in the blink rate to about 1/5 the normal rate. This can be relieved if you stop every 20 minutes and look at someting 20 feet away for 20 seconds. A dry climate and indoor air conditioned which produces dry air also contibutes to dry eyes. Blinking more and using artificial tears and eye lubricants should help.
Sore neck, back and shoulder muscles can result from poor posture and not taking enough breaks as well as using a bifocal when at the computer. Since the reading portion is at the bottom of the lens it requires the tilting back of the head to see the computer thru the reading portion. This becomes very uncomfortable in just a few minutes.
Computer glasses and reading eyeglasses are designed to reduce these eye fatigue symptoms.