How do I calculate what my regular contact lens prescription would be from my astigmatism lens prescription?
Question : How do I calculate what my regular contact lens prescription would be from my astigmatism lens prescription?
My tonic (astigmatism) contact lens prescription is:
-4.75 -0.75 x010 and
-5.00 -1.25 x170
what would my prescription be for regular contacts?
(I know that I wouldn’t be able to see as clear with regular contacts, but I would just like to know)
contact lens astigmatism
Best answer:
Answer by Pedestal42
Add half the amount of astigmatism to the first number, but allowing for the signs. Ignore the third number ( the direction of the astigmatism).
So:
-4.75 -0.75 x010 => -5.00 or -5.25
-5.00 -1.25 x170 => -5.50 or -5.75
If you are younger or do more driving, I’d opt for the higher power, older or do more office work, I’d opt for the lower.
But it’s a compromise.
(can be handy for single use throwaway lenses for swimming, for example)
For other people precriptions such as
+4.75 -1.50 x010 => +4.00
-5.00 +1.00 x170 => -4.50
You have to have your eye doctor determine this and write you a new prescription.