Should possibly wrong axis values be of concern for upcoming cataract surgery?
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I'm scheduled for cataract surgery next week (PanOptix Toric) - left eye first and right eye 2 weeks later.
In February, my prescription from my optometrist was (sphere, cylinder, axis):
OD -6.5 -2.5 170
OS -7.5 -3.0 175
which was consistent with past prescriptions and is the prescription of my glasses.
In April, my prescription from my ophthalmologist was (sphere, cylinder, axis):
OD -6.75 -2.5 174
OS -7.75 -3.0 170
I had glasses made based on the latter prescription. However, I notice I see a tad better at distance with my old glasses.
I wonder if that is due to the change in the axis value? My axis value has always been higher in my left eye - always. I'm suspicious of the latest prescription that shows my right eye now with a higher axis. It almost appears that the technician got the numbers reversed.
My question - is this axis measurement for glasses used at all in determining the prescription of my toric iols? For all I know, the measurements for glasses and iols are totally independent.
If so, is this change in axis values significant enough that I should ask my ophthalmologist about it? Should I request another exam?
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RonAKA hello97801
Edited
The surgeon does not use the eyeglass prescription at all to my knowledge. They may look at it to get an idea of what they are dealing with. Some prism may be a bit of a flag. However they mainly use the measured shape of the cornea to determine what IOL power you need. I have not gotten real deep into the measurement methods they use but I believe they are a form of topographical measurements and can be done in different ways. My surgeon used two different methods and I guess they depend on their experience and skill as to which one to use or if they use an average of the two.
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The problem with the eyeglass prescription is that it includes your natural lens. Some of the error that you have that needs to be corrected with eyeglasses is in the lens, and some is in the cornea. And when you have a cataract that also distorts the shape of the lens, so some is to correct for that distortion too. But, when you get an IOL that lens including the cataract is removed, so that combined error is removed. The IOL only has to correct for the shape of your cornea.
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I believe in particular with astigmatism the error in your lens and cornea can be either additive or subtractive. With the lens removed you may need less astigmatism correction, or in some cases more. In my case I thought I had enough astigmatism to need toric lenses based on my eyeglass prescription, but when my measurements were taken the surgeon said that it was 0.4 by one measurement and 0 by the other. That is not enough to correct with a toric. Torics start to get used at about 0.7.
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So bottom line is that it all comes down to the measurements taken by the surgeon, not the correction indicated by using an eyeglass chart, and the resulting eyeglass prescription. They will however determine what the outcome is 6 weeks or so after your IOL is implanted by using the standard eyeglass chart method.
hello97801 RonAKA
Posted
Whew, that is reassuring - thanks!
RonAKA hello97801
Edited
The change you saw in your prescription is most likely due to the cataract changing the shape of your lens. I am on a long wait list for an IOL, that got even longer due to COVID. I had my eyes last tested and got new glasses about a year ago now. I can tell that my cataract eye has gotten significantly worse. I am now trying to decide if I go get another eye test and new glasses again, or just hold out until I get the IOL. My other eye has a cataract as well, but it is quite mild, and seems to also be stable compared to the bad one. My expectation is that I will have a long wait between my first eye and the second. I plan to use that time to decide what to do exactly with the second eye. I see it as a benefit to know what I actually get out of the first eye IOL before making the final decision on the second eye.
janus381 hello97801
Posted
My thoughts are:
Since this is clearly bothering you, and you are getting a Toric lens, there is no harm is asking your ophthalmologist about this. Most likely they will reassure you that they have the right measurement), but there is no harm in asking. There are no dumb questions, so don't hold back. Just ask if only to reassure yourself.