1-Piece vs 3-Piece IOLs?
Posted , 3 users are following.
3-Piece design is often mentioned in regards to zonular issues and complicated cases. In terms of optical outcome, something like the 3-piece ZA90003 and the 1-piece ZCB00 seem to be much the same.
I imagine the 3-piece IOLs are more complicated to insert, thus probably more costly.
Are there any other caveats?
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PS: I have retinitis pigmentosa, though no zonular weakness was diagnosed yet. I am however in my early 40s and thus wary what happens if I develop an issue down the road or have some complications from surgery such as capsular bag contraction.
0 likes, 9 replies
RonAKA BrianCyberEyes
Edited
I believe there is a higher probability of PCO with three piece IOLs. To my knowledge they are largely not used in North America. PCO will require future YAG laser treatments. The Alcon material is also associated with a lower frequency of PCO compared to Tecnis. Clareon claims to have even lowered the frequency over the AcrySof. If my surgery goes as planned next week, I will get a blue light filtering Clareon monofocal lens.
BrianCyberEyes RonAKA
Posted
I take it that a 3-Piece IOL nowadays is more of a special tool mostly used in special cases where a 1-Piece would not be suitable (implanted outside the bag, for example) and not really opted for by the patient.
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As for PCO, seems it depends on what study one follows, I just read "A comparison of posterior capsular opacification after implantation of three different hydrophobic square edge intraocular lenses", which concluded the opposite. Design and material of any of those lenses is probably so similar that differences are down to small sample size and error margin (or what the author tries to portrait).
RonAKA BrianCyberEyes
Posted
You can find other studies which show that the AcrySof lens design and material has a lower YAG rate than the Tecnis lenses. More recently, Alcon claim that the Clareon is even better than the AcrySof material and design for resistance to PCO. Google this report for more detail.
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Comparison of Visual Outcomes and Patient Satisfaction Following Cataract Surgery with Two Monofocal Intraocular Lenses: Clareon® vs AcrySof® IQ Monofocal Smita Agarwal, Erin Thornell
BrianCyberEyes RonAKA
Edited
Alcon claims that both the material as well as a new square edge design contribute to lower PCO. There's a cadaver study where they measured cell growth on both IOL materials (Clareon and AcrySof) and the results were only slightly different.
As for edge design, however, the study I posted noted that the 360-degree square edge present in the Tecnis and enVista likely contributed to the much better results compared to the AcrySof. I wouldn't be surprised if the new design in the Clareon is more similar to the other IOLs'.
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Would be great to see a study between Clareon and some other manufacturer (preferably one that doesn't list "member of advisory board for alcon" under Conflicts of Interest) as the two studies were clearly conducted with different methodologies and difficult to compare. Alcon might just have followed suit in design or taken a great lead, hard to say - a result of 0% in a small sample size study isn't terribly representative by itself, but given that the same patients who had PCO in the AcrySof didn't develop any in the Clareon is definitely interesting.
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Edit: A stydy with 110 patients, published last year ("Comparison of posterior capsule opacification between Clareon CNA0T0 and Tecnis ZCB00 intraocular lenses") concluded that "There are no differences in slit-lamp pictures or visual function between both IOLs during the first 12 months after implantation."
RonAKA BrianCyberEyes
Posted
Another study to check out:
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Visual function improvement using photocromic and selective blue-violet light filtering spectacle lenses in patients affected by retinal diseases
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On a more simplistic basis it makes no sense to me that in situation where the retina is not healthy you would want to expose the retina to abnormal higher amounts of blue-violet light.
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On the PCO there are a number of studies which shows the AcrySof is more resistant. But it comes down to how many studies do you want to look at, and which ones do you believe.
BrianCyberEyes RonAKA
Posted
I'm not ultra skeptical, but with studies that lean heavily in favor of a particular manufacturer I tend to first look at the Conflicts of Interest section. I believe the one in regards to PCO/YAG is "5 year incidence of YAG capsulotomy and PCO after cataract surgery with single-piece monofocal intraocular lenses: a real-world evidence study of 20,763 eyes"? I've only read the abstract, but, I'll put it that way - if a study sponsored by Coca Cola and conducted by Coca Cola employees, comes to the conclusion that Coca Cola tastes best, I am not immediately sold 😉
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Doesn't really matter though, as I'd pick Clareon over AcrySof anyways. Plus, with my RP I probably will develop PCO and need YAG regardless of IOL, so there's that for me 😉
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As for blue light, I think you have a really good point there.
RonAKA BrianCyberEyes
Posted
I am also skeptical about manufacturer conducted studies. But, the issue is that they are the ones that have the money to fund the studies. Same as with drug companies. I suspect that they fund many studies that never see the light of day when the results do not favour their product. If the results are good they publish it. If bad then then they downplay that aspect of the product or take it off the market. I suspect there are enough checks and balances that they do not outright cheat or publish fictitious data.
ad12345 RonAKA
Posted
The truth is most people develop PCO. What they won't tell you is that IOLs are design to postopne it, not to eliminate it. You'll develop it with any lens if you're young enough and/or a surgeon doesn't clean you eye in 100%, which is not possible.
RonAKA ad12345
Posted
I am only about 1.5 years into having an AcrySof IQ IOL, and have had no issues yet. Keeping fingers crossed.