First question: I have been doing cm measurements off and on for the last week or two. My cm logs show fairly consistent measurements so far (within 0.5 to 1 cm day-to-day per eye). After adjusting for vertex distance, it looks like my base Rx is overprescribed by 0.5 D in one eye and 0.75 D in the other (comparing spherical equivalent values). So, when looking at ordering my first differentials, should I be using what the ophthalmologist measured or my own measurements for the full correction baseline (before reducing by 1.25 to 1.50 D for differentials)?
This seems like it could be important since the diopter gap from my opthalmologist is 0.25 D different than what I’m finding from cm measurements and I know we shouldn’t be messing with the diopter gap until we’re ready to start equalizing. Then again, that 0.25 may just be the difference in astigmatism correction.
Basically, should the cm measurement really be trusted for ordering lenses or just for tracking gains? I know it’s also used when determining the proper time to equalize, etc.
Second question: The EM site suggests that people with low astigmatism (< 1 diopter) can just drop the CYL from their differentials (potentially adding -0.25 SPH for every 0.50 elimination of CYL). However, in other places, the site says to reduce CYL in 0.25 increments in lieu of dropping SPH (for normalized and differentials).
I realize that at closer range, CYL is less necessary, so it is easier to drop it or reduce in the differentials than in the normalized lenses.
So I’m wondering whether it makes sense to just drop CYL altogether (differentials and normalized) when first starting out if it’s low enough? Otherwise, maybe just drop CYL from differentials and keep it in the normalized and drop a bit at a time over a couple of cycles?
I’m starting with -0.50 CYL in my right eye and -0.25 CYL in the left, so it’s almost negligible in my case. I know each person is different, and I can read (close up) without my glasses (no blurring or double vision), so I’m leaning towards dropping it completely (differentials a least, but maybe normalized too) and just adding -0.25 SPH to my right eye to compensate. I just wanted to validate that it makes sense before I shell out for glasses.
I’ve ordered a trial lens kit to help me validate some of these questions on my own, but I’m interested in the best practices. Plus the recommendations may be helpful to others too.