If you're looking for the cause of irritated eyes, the obvious suspect may not always be the culprit.
Last week, Twitter co-founder Christopher Isaac "Biz" Stone had a message for those who stare at their Twitter feed for hours on end: "It's not healthy." Stone says people should visit the popular site, but not dedicate their lives to it.
Beyond the social repercussions of constantly looking at a screen, Stone's statement carried some greater weight -- our eyes could be harmed as well.
Some experts agree, but say the actual screen may not be what's causing the damage. "While computers have no known harmful effects on eyesight, computer users do often complain of eye-related symptoms like eye strain, headaches, fatigue and difficulty focusing," says Surjinder Sahota, president of the British Columbia Doctors Of Optometry. "These symptoms, however, are caused not by the computer screen itself, but rather by the conditions surrounding the computer screen."
Sahota says poor lighting, improper placement of computer equipment and even computer furniture may all cause our eyes to be irritated after staring at a screen too long.
Our eye muscles function like any other muscle in our body. When muscles become fatigued, the eyes may feel uncomfortable or ache and vision may start to blur, Sahota says.
But if your profession requires you to stare at a screen all day, there are techniques to overcome eye irritation -- it's the rule of 20.
"Look away from your computer at least every 20 minutes and gaze at a distant object 20 feet away for 20 seconds," she says.
And size also matters. LCD screens can cause less eye strain than older screens and adjusting your text size for comfort can also help.
Last year, scientists found that our inability to focus on smartphone screens and determine how far away the content should actually be from our eyes, is the reason why they may feel sore after texting.
In the short term, there are ways we can improve our eyesight by making a trip to the grocery store. Here are 10 foods that can help to preserve your vision.
Like all leafy green vegetables, collards are high in the carotenoid nutrient lutein. Eating foods rich in carotenoids, particularly lutein and zeaxanthin, is associated with reduced risk of developing age-related macular degeneration.
Another food rich in lutein and zeaxanthin. Lutein and zeaxanthin help by protecting the central retina (also known as the macula) from blue and ultraviolet light. Consumption of zeaxanthin, with lutein, has been found in studies to reduce the likehood of developing cataracts.
Broccoli and broccoli sprouts have been found to protect the retina from free radical damage. This may be due to a compound in broccoli called sulphoraphane which naturally boosts the body's own defense system against free radicals.
Eggs are rich in cysteine and sulphur, two components of glutathione, a protein that acts as an antioxidant for the lens of the eye. This may explain why sulphur-containing compounds have been found to protect from cataract formation. Egg yolks also contain lutein and diets high in lutein lead to reduced risk of developing age-related macular degeneration.
Sulphur-rich garlic and onions are important for the production of glutathione, an important sulphur containing protein that acts as an antioxidant for the lens of the eye. Raising glutathione levels can be instrumental in both prevention and resolution of visual problems like macular degeneration, glaucoma or cataracts.
Tomatoes contain two eye-healthy nutrients -- lycopene and lutein. Both of these phytochemicals are carotenoids, found to be helpful for vision. Lycopene has been well documented as effective in cancer-protection, but its antioxidant capabilities also act to protect the eyes from sun damage.
The old axiom that carrots are good for the eyes is not just a myth. Carrots are rich in betacarotene (precursor to vitamin A, a necessary nutrient for vision), lycopene (a phytonutrient antioxidant protective of UVB radiation in the eye) and lutein (a protective phytonutrient found in high concentrations in the macula which protects it from free radical damage).
Eating blueberries has been associated with the reduction of eye fatigue. As well as having the eye-healthy carotenoids lutein and zeaxanthin, blueberries contain anthocyanins, eye-nourishing phytonutrients which have been shown to improve night vision. They also contain flavonoids like rutin, resveratrol and quercitin which may have preventative effects on macular degeneration. Blueberries also contain minerals necessary for proper vision including selenium and zinc.
Apricots are rich in both beta-carotene and lycopene, two phytochemicals that promote good vision. Beta-carotene is converted by the body to vitamin A, an important antioxidant that resists oxidative stress damage to the lense of the eye, helping to prevent cataracts and macular degeneration.
Cold-water fish such as salmon, tuna, cod, haddock as well as sardines are rich in the healthy Omega-3 oils. Fish are especially high in EPA and DHA, two Omega-3 fats which are important for cellular health. DHA makes up 30 percent of the fatty acids that comprise the retina.
With files from the Canadian Press