New Article on Low Level of Astgmatism
Posted , 3 users are following.
Healio has a new article stating even at low levels of residential astigmatism can degrade visual acuity after IOL Surgery.
According to the study:
"The odds of not achieving 20/20 vision in eyes with 0.25 D to 0.5 D of residual astigmatism, compared with eyes with 0 D of residual astigmatism, increased by a factor of 1.7 with monofocal IOLs and 1.9 with multifocal IOLs"
and
" In eyes with 0.75 D to 1 D of residual astigmatism, the odds ratio for not achieving 20/20 vision was 6.1 with monofocal IOLs and 6.5 with multifocal IOLs "
Article in Helio titled:
"Low-level residual astigmatism can degrade visual acuity after intraocular surgery"
0 likes, 6 replies
RonAKA rwbil
Edited
My post IOL surgery with an AcrySof IQ Aspheric lens has left me with 0.00 D Sphere, 0.75 D Cylinder. I still can read the 20/20 line easily and about half of the 20/15 line. This is a higher residual astigmatism than the surgeon was expecting. He was suggesting the residual would be less than 0.40 D, which is too little to correct with a toric.
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On the more positive side, I can read a computer screen at about 20". Some of that may be due to the residual astigmatism.
BrianCyberEyes RonAKA
Posted
May I ask, what was your corneal astigmatism before the surgery? Did the surgeon perform limbal relaxing incisions, or was the astigmatism changed just by the regular surgery incisions?
RonAKA BrianCyberEyes
Posted
Unfortunately my surgeon does not like to be technical in his explanations and gets defensive when you ask for more detail. As best as I can figure it he used two different methods to measure my astigmatism before surgery. According to one method there was 0.0 astigmatism, and according to the other it was -0.4 D. He said that his experience is that the true number is somewhere between the two methods, so I was expecting about -0.25 D or so. It came out at -0.75 D. He does not do LRI and I am not sure he made the surgical incision to minimize the induced astigmatism, but that is the standard practice. There are formulas used to determine the optimum location for the cataract removal and lens insertion incision. Bottom line is that there must have been some induced astigmatism, or the measurements were wrong. A complicating factor is that my astigmatism is irregular rather than the standard hourglass or bow tie shape. That makes it more difficult to measure.
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On my second eye due to be done next week, I am expecting astigmatism to be -1.0 D or possibly worse. I am prepared to get Lasik or PRK to reduce it, if my vision is not as good as it needs to be. My surgeon did not inspire my confidence in selecting a toric lens. He flip flopped on it a couple of times, and I decided I did not want to risk it. The astigmatism is clearly in the cornea and if you use a toric IOL to correct it, you are using astigmatism in the lens plane to correct in astigmatism in the cornea plane. Seems to me that the most direct way to correct it, is in the same plane as the source of the issue.
BrianCyberEyes RonAKA
Edited
As far as I understand surgically induced astigmatism is the norm, even if surgeons like to downplay it. Though if the surgery was recent, yours can change over time postop going closer to pre-op levels.
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Your surgeon probably operated from the temporal position while your astigmatism would have benefitted from a superior position - also possible though that he wanted to reduce the chance of changing the astigmatism from negative to positive (-.4D would probably be safe, but given that it could have been -.2D or lower, it would be cutting it close).
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You're still very lucky with the 20/20 results and good DoF.
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I too would rather have the astigmatism fixed where it is rather than having a complex lens fitted to counteract it. Haven't really considered Lasik, but I think I will if after LRI I'm left with too much astigmatism (mine is about -1D in one eye and -1.5D or a bit more in the other). My RP also makes me not want to get a Toric lens in fear of tilt.
RonAKA BrianCyberEyes
Posted
I have had my IOL eye tested at 6 weeks and 1 year later. I got identical refractive readings in the eye for sphere and cylinder. So, it seems to be stable. But since I am seeing well down to 18-20" along with 20/20 vision in the distance I don't want to mess with it. I am quite happy with it, the way it is.
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My non operated eye has -1.25 D cylinder at 77 deg. The surgeon says he is predicting -1.0 D cylinder after the surgery. I am expecting that is going to affect my near vision as we have agreed on -1.25 D sphere as the target. He is expecting -1.30 D sphere with a 18.5 D power lens. That is going to leave me with a total equivalent of -1.80 D which I think will be too much for the optimum monovision. But I will see what it is like first, and also give it time to settle down. If it needs to be done, I will go with what the surgeon is recommending, which I expect will be Lasik. And, if he misses on the sphere, it will be an opportunity to correct that at the same time. Still my best case wish is that it is fine without Lasik. That may require some good luck!
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Here is an article I found interesting if you want to google it.
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CRSToday FEATURE STORY JUN 2012 Correcting Residual Astigmatism After the Implantation of a Toric IOL John Berdahl, MD
BrianCyberEyes RonAKA
Posted
It's great to have options. For me, I will definitely have to talk about laser correction with my doctor - with my RP and Glaucoma they will probably caution me to do as few procedures as possible on my eyes.