Blue Light
Posted , 6 users are following.
There's been some discussion in other threads about blue light and the significance, if any, of the fact that Alcon IOLs, e.g., the AcrySof and Clareon materials, filter some blue light while Tecnis IOLs, or at least the Eyhance, do not. In particular, t's unclear whether blue light indeed should be a concern in choosing an IOL.
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Here's an illustration from Shamir, designer of advaqnced spectacle lenses and lens treatments, showing the different sources of blue light.
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And here's a Shamir chart showing (what they say are) harmful high energy visible light frequencies.
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But is blue light harmful, or harmful in a way that matters for IOL selection? A March 10, 2021, on-line publication from the American Academy of Ophthalmology--Should You Be Worried About Blue Light?--has as its "bottom line": "taking preventive measures against blue light even though there is no evidence of damage could be more harmful than the blue light itself. 'It’s premature to take preventative action against blue light—there could be unintended consequences'”.
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On the other hand, an August 3, 2022, article by the principal optometrist at the UC Davis Eye Center--"How blue light affects your eyes, sleep, and health"--after noting the beneficial impacts of blue light, also says: "there is concern about long-term effects of screen exposure from digital devices. This is especially true when it comes to too much screen time and screens too close to the eyes....Since our eyes are not good at blocking blue light, nearly all visible blue light passes through the front of the eye (cornea and lens) and reaches the retina, the cells that convert light for the brain to process into images....Constant exposure to blue light over time could damage retinal cells and cause vision problems..."
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And Alcon itself--in its white paper, "Blue Light Filtering IOLs and Occular Health"--is somewhat equivocal. Here are the conclusions: "There is much experimental evidence showing that blue light poses a hazard to macular health induces retinal toxicity and damage. Clinical evidence shows that there is no interference with visual performance or circadian rhythms with blue-light filtering IOLs. Clinical evidence also shows that BLF
IOLs reduced photostress recovery time and reduced glare disability. However, current clinical studies have not definitively demonstrated a protective benefit of blue-light filtering lenses on macular health. More well-designed studies are necessary."
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In these circumstances, it's not clear whether choosing an IOL for its blue light filtering is a case of better safe than sorry or simply taking chances with one's eyes. When choosing eyeglasses a few years ago, I chose Shamir Workspace 'computer' glasses on their merits and then also chose Shamir's Blue Zero treatment because of concerns about digital eye strain and because my primary use is in front of the computer, and because the additional cost was minimal. But the Blue Zero treatment wouldn't have bound me to Shamir if I'd reason to prefer, for example, the Hoya or Zeiss computer lenses.
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Bringing it back to IOLs, I think that currently we don't know enough to say whether Alcon's blue-light filtering should weigh in the balance when making a choice.
0 likes, 12 replies
RonAKA RebDovid
Posted
All the information on blue light filtering for eyeglasses is irrelevant. For eyeglasses it is basically a big scam. For IOLs it is much more significant issue, because your natural lens which has significant blue light filtering is being totally removed for the rest of your remaining life.
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If I had AMD I would certainly choose blue light filtering just to be safe.
RebDovid RonAKA
Posted
But does the natural human lens have significant blue light filtering? Not according to the American Optometric Association. In a July 11, 2019, on-line article entitled Blue-light hype or much ado about nothing?, the AOA says: "While anterior structures of the eye block and absorb most UV rays from reaching the retina, visible blue light (specified by the AOA as 420-480 nm) passes through the cornea and on to the light-sensitive tissue."
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If the AOA is correct, then cataract surgery would not seem to increase our risk from exposure to blue light. (The risk from UV rays is another matter, but I believe that both Alcon and J&J IOLs, and probably those from other companies, are made from UV-blocking materials.)
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If you have contrary authoritative sources that you can share, I'd be grateful.
adam06539 RebDovid
Posted
It's pointless to discuss the case with RonAKA. With all due respect, he's in love with Alcon, so you will always get the same anwser.
billy111 adam06539
Posted
I think RonAKA is probably the most knowledgeable and helpful member of this forum. He has had good results with his Alcon IOL, but I don't see any bias toward other IOLs. There is no one perfect IOL brand, and I am sure he is well aware of that. He and I were quibbling a week or two ago about whether the Eyhance was a monofocal, but I think we both ended agreeing that is a monofocal but with an extended depth of focus.
soks adam06539
Posted
adam what iol do you have?
adam06539 soks
Posted
Tecnis 1
soks RebDovid
Posted
on another thread you mentioned why -1.5D is the myopic sweetspot for near and distance. can you please point me to the article you had referred?
RebDovid soks
Posted
I don't think I was referring to an article about 1.5 D as such. I arrived at that target from a combination of considerations. First, I'm most likely going to follow my surgeon's recommendation of Eyhance, and am seriously considering mini-monovision. Second, from reading several posts and articles, up to a 1.5 D difference in the IOLs seems to be reasonable in terms of successful adaptation, also without sacrificing 3D vision. Currently, I'm trying it with contact lenses. Third, all going well, targeting a 1 or 1.25 D under-correction seems prudent because surgeons often miss on either side of the target, and I don't want to end up with too great an under-correction. Fourth, my surgeon's choice for a basic Eyhance target is -0.50 D. Fifth, my study of the seven Eyhance defocus curves I've fond on-line suggests that a combination of that in my distance eye and -1.50 D in my near eye would indicate mean visual acuity of 20/25 at distance, and better than that to 17.3". Sixth, while -1.75 D could be even better closer, I'm averse to risking too great a difference. Seventh, my limited contact lens trial has me valuing better intermediate/moderately near vision over 20/20 distance. Eighth, the latter point is reinforced by my wife's recent Eyhance experience with the same surgeon. She's at -0.50/-0.50 and 20/25, which she experiences as clear and sharp.
The fly in the ointment is the inability of surgeons to guarantee hitting what they target and that the same correction can yield different results in different people--defocus curves report mean visual acuities, generally accompanied by standard deviation data. I hope to achieve greater clarity from reading here, seeing where my first eye ends up, and talking more with my surgeon in light of first eye results and my contact lens trials.
soks RebDovid
Posted
thanks. i am planning on just keeping my symfony with -0.25 and getting eyhance set for -1D.
currently with PCO the symfony eye is 20/50 and unoperated eye is 20/60 or worse. with both eyes i am 20/40.
how good is your wife's near with both eyes at -0.5D?
RebDovid soks
Posted
I need to apologize doubly. First, I just saw your post regarding my wife's near vision. Second, I can only provide a qualitative answer, namely, that it's not good enough for her to read her smartphone or a book comfortably without readers. In contrast, she doesn't need readers to use her MacBook computer.
sue78611 RebDovid
Posted
It sounds cool
RonAKA RebDovid
Posted
There is an interesting annual article that reports on a survey of ophthalmologists that are doing cataract surgery, primarily on what IOLs they are using. Some interesting results.
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The most popular monofocal by far is the Alcon IQ Aspheric which typically has blue light filtering.
J&J have come out with new lenses that are called Optiblue with InteliLight. They are using a violet light filter which is right next to a blue light filter. It was first brought out with their Synergy lenses and now is being used on the Symfony and Symfony Toric lenses.
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The also asked what Attributes in an IOL that they value the most. The top three priorities were:
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Review of Ophthalmology Cataract Surgeons Embrace New Options Walter Bethke, Editor in Chief PUBLISHED 10 JANUARY 2023