Re: Calculating Add for computer work


"Mike" <turnpike_user@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote

My Add is +1.00 so is there a rule for working this out for computer work
with a screen that's about 70cm away?

To say your "add is +100" doesn't tell us much if we don't know what
distance it's calculated for. I'd guess you held the book about 50 cm.

As for the "rule", halving the add doubles the distance. If your +1.00 was
measured at 20" (50cm) then +050 should give 100 cm and +075 about 70 cm.

If the quarter-diopter step size forces you to choose between too much add
and too little, then less is better. Especially for younger presbyopes, eg
40-45 years old.

-MT, OD



.

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