Can the axis notation measurement of your eyes decrease over time?

June 4, 2011 2:48 PM

Four years ago the axis number for my left eye (I have astigmatism) was 52º, now it's 48º. Is this normal? I thought those numbers were supposed to always go up with age.

I recently went to get my eyes checked for a new pair of glasses. All my numbers went up slightly by a a couple of degrees since my last checkup (four years algo), the only measurement that didn't increase, but rather decreased, was the "Axis" on my left eye. Is this normal?

posted by Omon Ra to Health & Fitness (4 answers total)

IANAO, but mine tells me that it's not common, but it's not abnormal either. My axial correction changes regularly (sometimes to the point of needing a new 'script every 6 months), and neither my optometrist or opthamologist have ever made any mention of it being abnormal.
posted by jlkr at 3:33 PM on June 4, 2011

I thought those numbers were supposed to always go up with age.

If the axis is going to change, it can either go up or down. There's no reason for it to only go up.
posted by DarkForest at 4:08 PM on June 4, 2011

Best answer: The axis for astigmatism is largely based on the skill of the optometrist. I'd be very surprised if the degree of error on the axis for most optometrists was less than plus or minus 5 degrees and frankly I wouldn't be at all surprised if the degree of error for the vast majority of lens shops was greater than that when producing the lens.

The "numbers" that you probably are referring to are the diopters of correction for either the astigmatism or the main script. I doubt very much you'd be able to discern a difference of four degrees axis.
posted by Poet_Lariat at 4:12 PM on June 4, 2011

Seconding Poet_Lariat . My optemetrist mentioned this to me just a couple of months back, that the margin of error when measuring this was sufficiently large that you couldn't expect it be measured as 'the same' from time to time.
posted by southof40 at 5:42 PM on June 4, 2011