Working your eyes too hard can lead to eyestrain, that must-close-my-lids sensation often accompanied by blurred vision, headaches and neck pain, says Avnish Deobhakta, MD, assistant professor of ophthalmology at New York City's Icahn School of Medicine at Mount Sinai. Perk up tired peepers by following this advice:

See an eye doc. 
Visit an optometrist to rule out presbyopia, a condition that affects your ability to clearly view nearby objects, leading to eyestrain. Everyone develops some degree of presbyopia by the time they're 50, thanks to age-related hardening of the eye's lens, says Gardiner. If diagnosed, you'll need reading glasses or bifocals (over-the-counter or prescription, depending on severity). Pick a pair you'll enjoy wearing, since they can help your eyes see—and feel—better.

Space out. 
When you look at your computer screen, the ciliary muscle in your eye changes the shape of your lens to bring emails or spreadsheets into focus. And just like any other muscle, the ciliary gets fatigued if engaged for too long, Deobhakta says. At least once an hour, give it a break by gazing off into the middle distance (as if daydreaming) for two to three minutes.

Set a blink reminder. 
Each time you bat your lashes—typically, every four seconds—you refresh the nerve-packed surface of the cornea with tears. But concentrating puts the brakes on your blink rate, which may lead to dry, irritated, sleepy eyes, says Matthew Gardiner, MD, director of ophthalmology emergency services at Massachusetts Eye and Ear. Stick a "Blink!" note on your monitor—no, seriously, do it—suggests Stephanie Marioneaux, MD, a clinical spokesperson for the American Academy of Ophthalmology. And keep artificial tears on hand in case blinking doesn't do the trick.

Fight glare. 
The ciliary muscle has to work overtime to focus the eye against too-bright light, says Deobhakta. Fiddle with the brightness, position, and tilt of your screen to see whether it makes a difference in how your eyes feel.