Water Goggles

[Alvaro Cordova]

I was curious if anyone knows how to compensate, if necessary, a prescription that will be used underwater? My intuition says you have to change something because it would be
(| = lens)

water | air

instead of

air | air

How would I convert an Rx depending on the medium?

[Darryl Meister]

You would essentially substitute (n - 1.333) / r for the power of the front surface instead of (n - 1) / r.

[Alvaro Cordova]

Thanks. I vaguely remember my teacher mentioning that the 1 in that equation was to factor out air.

[Darryl Meister]

Yes. The power of a refracting surface is given by,

F = (n' - n) / r

where n' is the refractive index of the lens material and n is the refractive index of the surrounding medium.