Novice with Cataract lens questions
Posted , 3 users are following.
I’m a 74-y/o male, who has used reading glasses from age 50, and distance glasses for driving (particularly at night) from 65.
My cataracts are slowly developing at roughly the same rate in both eyes, without any cloudiness. I am now having some night driving issues using glasses (stars and halos) so my eye surgeon is happy to go ahead with surgery.
Looking through past posts (and not finding an answer to my questions), I discovered just how many other novices go down the Google research worm hole! I’m sure my question below has been asked before, but I couldn’t find a suitable post. Apologies!
I have decided to elect for improved distance vision since I do a lot of night driving, and I’m happy with my cheap readers. My surgeon has recommended that I have toric IOLs since I have astigmatism. However, my astigmatism would seem to be slight. Numbers from my most recent exam (01/23) show OD cyl -0.25 axis 30 and OS -0.25 axis 120. Unsurprisingly, the cost difference is considerable monofocal $300 > toric $8,000.
When I research toric lenses, the information indicates that they are designed to correct astigmatism of greater than 0.75 (one brand) and 1.0 (second maker). If my astigmatism is slight, would toric lenses be beneficial?
The other fact that I gleaned from googling was that astigmatism is a compound measurement: corneal and lens. I have reached out to the surgeon for those respective numbers (repeatedly) … and they have never got back to me. Pity, I have use the practice for years, and now I am trying to take a life changing decision, they don’t call back! Is there an ophthalmic code for those measurements? If yes, I might be able to get from my records to help me decided … or is this just another rabbit hole!
Advice welcomed!
0 likes, 6 replies
RebDovid anthony66172
Edited
You're correct. By itself the degree of astigmatism you report doesn't justify toric lenses. You might ask for the surgeon's rationale.
RonAKA anthony66172
Edited
First off this sounds a bit suspicious. Have you had the detailed eye measurements done in preparation for cataract surgery? They are done with instruments like the IOLMaster and Pentacam, and are used to determine the IOL lens power you need, and how much cylinder there is to correct. As you say there can be astigmatism (cylinder) in both the natural lens and in the cornea. And, some of the astigmatism in the lens can be the result of the cataract itself.
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The pre-surgery eyeglass astigmatism is the total of the lens and cornea astigmatism. Because the effect has an angle the astigmatism in the lens can be at a different angle than that in the cornea. They can offset each other, or they also can be additive. That is why you need a predicted residual astigmatism after the lens is taken out of your eye and the lenticular astigmatism is gone. These instruments can do that. Until you get those measurement I would not make a decision. You should ask for the IOL Calculation Sheet which will have these numbers in it.
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My personal experience with both eyes was that my eyeglass astigmatism was significantly reduced with a non toric lens. In one eye my eyeglass cylinder went from -2.75 D down to -0.50 D after surgery. In the other it went from -1.25 down to -0.75 D. If your -0.25 D was to increase after surgery, it is possible, but I think highly unlikely.
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The other issue is as you have identified correctly is the minimum cylinder power of an IOL. Alcon (AcrySof IQ Toric) and B+L (enVista Toric) make lenses that have a minimum cylinder power of 1.0 D. This is at the lens plane, which translates into 0.75 D at the cornea or eyeglass plane. Other manufactures have a minimum power which is higher still as you note. The standard practice is to not over correct astigmatism, as it can flip the angular position of it. For that reason the minimum power corrected is -0.75 D or more, and only with the lower power lens like the Alcon and B+L ones.
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So as I say, I would not even think about going ahead with a toric unless they give you the predicted residual cylinder for each eye.
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As for cost I can tell you where I am in Canada the basic monofocal is free. The monofocal toric (Alcon AcrySof IQ Toric) is $1,100 CDN per eye. That is an extra cost over the monofocal. $8,000 US? for two torics sounds very very high.
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As I say this is suspicious. Perhaps time to get a second opinion from another surgeon...
anthony66172 RonAKA
Posted
Thanks, I did have a very comprehensive set of tests carried out, over a 90-minute period (I was told that this was essential if they were to determine the lens setting needed).
I am going to surgery this morning to ask for the residual values/cylinder for each eye.
With respect to costs, I did round up a tad: its $US 7782.14 for both in Wilmington, NC.
I post what I learn!
RonAKA anthony66172
Posted
If those are predicted residual cylinder values with no IOL toric correction, then there is no way a toric lens should be used. If you have -0.25 D at 30 deg and a 0.75 D effective toric is used then you will go, in theory, to -0.50 D at 120 deg. Your cylinder will be doubled and the angle flipped from 30 to 120. Not a good idea.
RonAKA anthony66172
Edited
If you can get an IOL Calculation printout and they are using an IOLMaster here is a document that will help you understand it. See pdf pages 5 and 7.
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IOLMaster 700 Quick Guide Printing Functions EN PDF
anthony66172
Posted
Hi RonAKA,
Thank you for such a comprehensive reply. The attachment didn't attached, but no worries, a quick google and I was able to d/load.
I did mention that I would provide feedback after my office visit. I didn't speak to the surgeon but one of her techs who could view the calculation spreadsheets. What I learned follows on ...