Per the Occupational Safety & Health Administration: The preferred viewing distance for VDTs ranges between 18 and 24 inches (45.72 and 60.96 centimeters, respectively). FEATURES AND BENEFITS Filters 100% of the most damaging low-level blue and nearly 40% high energy visible light from tablets, phones, TV, computers and more. Our lenses code is BB40 for the Eyekepper violet block glasses. Anti fatigue Anti jet lag blue blocker Get maximum protection with ourpatented, multi layer coating designed specifically to reduce glare, reflect blue light away from the user and relieve long term eye strain caused by excess electronic device use. Whether you are looking for computer glasses for the office or a late night Netflix binge. Eyekepper glasses will give you the premium protection you are looking for If you are unfamiliar with blue light it's right next to UV light on the spectrum of light. It is comprised of very high energy and a low wavelength very similarly to UV light. All of our electronic devices with a back-lit screen give off large quantities of blue light (Iphones, Ipod, Laptop, Computer TV.) This blue light messes with our internal clock making us think it's mid day when really it can be closer to night and stops our body from naturally producing the melanin that helps us fall asleep late at night CARE To avoid damage, never clean your computer glasses with paper towels or clothing or alcohol, and also avoid using household detergents or soaps. While a few mild soaps don't harm lenses, today's extra strength soaps are powerful enough to slowly disintegrate lens coatings.