I'm not an optometrist or an optician, but I think I can help with this based on an explanation that an experienced optician gave me yesterday about my own prescription (and a course in general optics that I took). He indicated that the strength of the glasses (overall) comes from the addition of the spherical and cylindrical (which is applied at an angle, the axis) values. In my case, I had asked why I have -9.00 in one eye and -7.75 in the other (for the spherical); he pointed out that the -1.00 and -1.75 for cylindrical on my prescription balanced it out, as it turns out more like a total of -10.00 on one side and -9.50 in the other.
To apply this to your question, you had -2.25 and -2.00 total. Now you have something like -2.50 and -3.00. So, basically, they moved one of the correcting forces off from the side, onto the front, at least as I understand it, so your overall prescription went up. I likened it to vectors to see if I was understanding it the same way as the optician at the store did, but he didn't really confirm the application of this analogy one way or the other. Check out something on vector addition for more detail on this explanation, which may be correct. On Aug 12, 7:51 pm, phillo <[email protected]> wrote: > I visited 2 optometrists 1 year apart and now need to order new > glasses but when I compared the newer prescription to the older 1 this > particular difference jumped out but doesn't make sense: > > old script - OD-CYL:-2.00 > > new script- OD-CYL:-1.75 > > I'm assuming that closer to 0 = less correction so -2.00 should be the > newer prescription/more correction but I'm having a hard time > validating or negating this assumption online and I'm in contact with > neither of the optometrists that examined me. If anyone could clarify > I'd really appreciate it. > > FYI COMPLETE PRESCRIPTIONS > > Old script: > ____________ > OD-SPH:-0.25 > OD-CYL:-2.00 > OD-AXIS: 95 > --------------------- > OS-SPH:-.50 > OS-CYL:-1.50 > OS-AXIS: 80 > > New script: > ____________ > OD-SPH:-0.75 > OD-CYL:-1.75 > OD-AXIS: 95 > --------------------- > OS-SPH:-1.25 > OS-CYL:-1.75 > OS-AXIS: 80 -- Check us out at the oft-updated http://glassyeyes.blogspot.com! You received this message because you are subscribed to the Google Groups "GlassyEyes" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/glassyeyes?hl=en
