We have noticed a daily influx of clients with eye strain associated with computer use. More people are using computer screens for longer periods with little incentive to take a break. The increased time spent looking at a screen at around 40 cm can lead to eye strain.
How much strain depends on your age and how good your distance vision is. If you have perfect sight for distance your eye muscles have to refocus for closer up vision. in this case the amount of refocusing your eye needs to do is about 1.5 units of power. If you are farsighted and don’t have a prescription for this yet, you can add that amount of focussing power to the 1.5 units. If you are nearsighted you may be able to see the computer screen comfortably, especially if you are about 1.5 units nearsighted.
Can you correct for 1.5 units of power without straining your eyes ? Well that depends on your age. A young person can correct a few units of power without too much effort or strain. The focussing correction is called accommodation.
Most people don’t have the same focus in each eye, so there is an imbalance which your eyes can not correct for. Your eyes can only refocus by the same amount in each eye, so whatever imbalance there is between the two eyes stays.
If you also have astigmatism in your eyes, and most people have some, your eyes can not correct for this. A small amount does not usually give rise to eye strain. A larger amount, over one unit of power, invariably contributes to eye strain and is worth correcting with a spectacle lens.
All the above focussing issues can be corrected with a spectacle lens or with contact lenses. Contact lenses may dry out a bit using the computer screen. Not because anything ‘harmful‘ is emitted from the screen but because we tend to blink less when concentrating. This drying out of the eye and lens can give rise to blurred vision, distortion of the contact lens and malposition of the lens. Your vision will be more stable with a spectacle lens for computer use.
Vocational or Occupational lenses are designed specifically to reduce eye strain for close up computer work. You can just wear a lens suitable for screen distance only. But think about the other distances you need to see too. Do you have paper or notes closer up, that would require a different power lens. Or do you have to see a display in the distance clearly too ? For both of those cases you’d want your lens to have two focussing areas, suitably set up to cope with the wearers requirements. So why not just wear a normal varifocal lens ?
A normal varifocal lens has the top part of the lens dedicated for distance vision so you can see the road signs. Then a small section lower down for 40 cm use and a slightly bigger section further down for closer up reading. Hm that is not much use when you are using a computer for long periods. You need a lens that has a much wider area for the computer screen so you don’t have to lift your chin or move your head from side to side to see clearly.
The newer digitally designed vocational or occupational lenses can be designed in a variety of ways to suit the wearer. One design is set up with the whole of the top half for computer use, and the whole of the lower part for closer up vision. Different manufacturers use their own trade names, Zeiss calls these lenses Officelenses and they give excellent comfort when worn for computer and desk work.
These lenses designed for desktop computer use will work just as well for a laptop, mobile phone or other arms length and close up vision, contact us for further details.
We can supply and fit these lenses for you in a new frame or fit the lenses into your existing frames.