An addition to my previous reply: I found an article in an online magazine for Optometrists which gives a couple more clues about your query (http://www.optometry.co.uk/ articles/docs/April%2018%2008%20Clinical.pdf).
-- On page two, they note that not only different optometrists may get different results, but the same optometrist could get a different result on a different day: "Subjective refraction results, even when performed by experienced practitioners will vary, and although most vary by 0.25D or less (~80%), others can differ by up to 0.50D (95%)...Subjective refraction results are therefore not an absolute value and will vary from test to retest separated by even a few days." So that cylindrical value did not necessarily change all that much (provided a D = 1.00 on the optometrist's prescription); it sounds like 0.25 different is actually pretty negligible. -- Section 3 on page 2 talks about changing cylindrical power. I'm not sure if it directly applies to your case or not, though. They do confirm the approximate equivalence between cylindrical and spherical measurements: "lowest cylinder power (with appropriate spherical equivalent) providing reasonable visual acuity." 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
