Manuel Molina
Post count: 19

To get my differential prescription, I’ll start from my centimeter measurements to get my distance prescription then add 1.5. (I know I don’t have to get the distance prescription just yet, it’s just to arrive at the differential prescription)

Right eye: 24.6, so 4.00 diopters
Left eye: 20.8, so 4.75 diopters

That leaves me with a distance prescription of:
SPH 3.25 – CYL 1.75
SPH 3.75 – CYL 2.25
(Leaving astigmatism the same as my current prescription)

So for differentials I subtract 1.5 diopters (option A):
SPH 1.75 – CYL 1.75
SPH 2.25 – CYL 2.25

You said I should replace 0.5 diopters of cylinder for 0.25 of spherical, so that would be (option B):
SPH 2.00 – CYL 1.25
SPH 2.50 – CYL 1.75

I could order the option B prescription right away and go from there. I can just return it if it doesn’t work, because like you said it’s just a guess. Maybe try it out with my test lens kit before I order it. However, does it seem weird to you how my current prescription allows me to see 20/70 and blurry 20/50, and yet the all of the three prescriptions I calculated here, based on my centimeter measurements, are that much higher? It kinda makes me question if I did the cm measurements wrong. Also, what do I do with the axis, leave it the same?