Thoughts on refraction with phoropter before/after dilation, with added reference to RxLAL adjust.
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These are my thoughts, and are not distilled from studies.
When refracting for eyeglasses, are different opinion on which is better, with some refracting before dilation and checking after if the exam includes dilation for some reason. My RxLAL settings were determined based solely on un-dilated.
It seems to me that doing refractions before and after would be better, especially with RxLAL adjustments. Some phoropter measurements give no difference observed between two lens combinations. Phoropter results have a 0.25 D resolution. I think the norm in that case is to go with the lower absolute number. I think that even if you thought the non-dilated exam should be the one to use for RxLAL adjustment, I would at least let ties be resolved in favor of the dilated refraction.
A dilated refraction would seem to magnify the effects of differences (make it more obvious which is better). An undilated refraction, even when you are going to get dilated anyway, would seem to imply that they are likely to come up with a different number, and that the undilated refraction was preferable to use.
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RonAKA trilemma
Posted
I am pretty sure all my autorefractor and phoropter tests have been done only before dilation. At least in theory the phoropter is done under very controlled lighting conditions and the pupil should be adjusting to that standard of light.
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The issue that may be of more concern is repeatability if you have any dry eye issues. This may be something to discuss with the clinic. It may be important if you are using dry eye drops to take them in a consistent manner before the testing.