Individual left side optical lens to suit Reveal UltraFit mask. How to work out your correct diopter:
A typical prescription is written:



 
sphere
cylinder
axis


R
-3.00
-0.5
x180


L
-3.50
-1.00
x180



To work out which lenses you need, you’ll need to look at the first 2 aspects of your prescription.
sphere - is the main part of your prescription and will have a ‘–’ for short-sightedness or a ‘+’ for long-sightedness. If you have a ‘+’ then unfortunately our lenses will not work for you
cylinder - refers to the amount of astigmatism you have.
The diopter you order should be based on the amount of short-sightedness you have.
Our optical lenses don’t correct astigmatism but if it is less than 2.00 diopters and not the majority of correction, add half of this number to work out your power (examples below).
Here are some examples of how to work out the correct power for you:



sphere
cylinder
axis
recommended lens


-3.00
-1.00
x90
(-3.00 plus -0.50) = -3.50



-3.00
+1.00
x90
(-3.00 plus +0.50) = -2.50




Our lenses come in 0.5 steps from -1.0 to +3.0 so you may have to select the nearest power. It’s better to under-correct than over-correct. 
If you need any assistance please contact us with your prescription and we’ll do our best to help