My eyes, they are a-changin'
May 29, 2010 9:42 AM   Subscribe

Help me read my contact lens prescription.

YANAD, but I'm curious and am having bad Google-fu with this one. I'm curious if a change in my contact lens prescription a year ago is related to some neurological issues I've been having more recently. It was something that made me go "Huh, weird," and then forget all about it until these other issues surfaced in the past few months.

I actually meant to mention it at my last doctor's appointment and forgot, and will mention it next week, but in the meantime, I'm just curious.

I've been mildly nearsighted, with astigmatism, for 20 years (I'm in my mid-30s). Right eye has always been a bit more myopic than the left.

Last year when I went to the optometrist to get my contact lens prescription updated, they checked my eyes and for the first time ever, my left eye was worse than my right. The eye doctor didn't remark on it and I didn't realize what the new prescription meant until I happened to compare it to my old one. I feel pretty confident that my prescription is correct because I haven't had any of the headaches or eyestrain that I usually notice when it's time to get my rx updated.

A few months ago I started to have some neurological symptoms on my left side, and I'm now under care for that, although there is no diagnosis yet. All this to say, I'm curious whether the eye thing was the first symptom. I don't have any stake in whether it is or not--I'm not going to sue the optometrist for not catching it or anything, I'm just curious.

If you care, or are an optometrist, the differences in the prescriptions over the past 4 years are:

Right: power is the same, cylinder increased by .75
Left: power increased 0.5, cylinder increased by .5

The result is that both eyes are now the same power for the first time, and the cylinder on the left is now .5 higher than the right, whereas before it was .5 lower.

I'm wondering what it means for the power to increase vs. just the cylinder, and what parts of the eye anatomy affect these measurements, etc.

Thoughts?
posted by anonymous to Health & Fitness (3 answers total)
 
I'm not an optometrist, but I'm fairly sure that power is to correct nearsightedness, and cylinder is to correct astigmatism.
posted by insectosaurus at 11:32 AM on May 29, 2010


Agreed with insectosaurus. It sounds like you've had the nearsightedness and astigmatism for many years, and they just got a little worse, as they tend to do. I don't think this is related to a new medical issue.
posted by treehorn+bunny at 1:38 PM on May 29, 2010


I am an optician, so maybe I can fill in a little bit.
Some actions the eye performs are muscular, so it's possible that any neurological issues are affecting vision.
Having said that, a quick primer on Eyeglass/ Contact lens prescriptions:
They probably are not identical.
The power in both fields is measured by .25 increments, so .50 is two steps of change.
If you are looking exclusively at your CL RX, the power of the cylinder portion prescribed could be a function of the brand of Toric CL the Dr. prescribed. Typically, toric cl's are manufactured in 3-4 different astigmatic levels, such as -0.75, -1.25, -1.75, and maybe -2.25.So if the Dr. changed your CL brand ( for more comfort ) the cylinder ( astigmatism correction) may have changed to something else.
FYI, axis is the degree the astigmatism is corrected at- 1-180. Most CL's offer the axis at 5 or 10 degree difference , so that number may have changed, as well.

Finally, consider this: when the Dr. is refracting you, and he says " Which is better, one or two?" , he is changing the power in .25 increments- and lots of times, the two look almost identical, don't they? I just want to put you at ease over the RX change- it really isn't that drastic.
Hope this helps, and this is my first post.
posted by Stellaboots at 6:30 PM on May 29, 2010 [1 favorite]


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