Observations from a new discussion between two ophthalmologists:
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- Doctor advises against monovision, and steers patients to multifocal lenses instead. He says you need anisometropia of 2.5 D to get satisfactory reading vision in monovision, and that that much anisometropia can cause problems, including the possibility of insufficient binocular vision for driving - even with corrective lenses! I’d never heard that one before, but the interviewer ophthalmologist seemed to agree. My own experience is different - my driving vision was both legal and sufficient with much greater anisometropia in recent years than 2.5 D, but my experience is only one guy’s experience.
- If a patient insists on monovision, the doctor uses EDOF lenses. For both eyes, I think, to better cover the full range of distances with both eyes.
- This one surprised me (and it surprised the doctors, too, at first): Doctor generally targets slight hyperopia - up to 0.15 D. Whereas most surgeons target emmetropia or slight myopia in an effort to minimize the risk of hyperopia. The reason was interesting, and was supported by research published by a colleague on actual results for a large number of patients. Even with an artificial lens, when you attempt to focus on an object that is out of focus, hyperopia produces miosis (constriction of the pupil/iris) and better vision, whereas myopia produces the opposite - relaxation of the iris (mydriasis) and poorer vision.
- Regarding blue/violet/ultraviolet light filtering - Doctor says his patients show a strong preference for vision with clear lenses over vision with the yellowish lenses that filter out bluish light. He generally uses the clear lenses, and tries to avoid mixing types on the two eyes of the same patient.
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There was also a lot of technical stuff that I was less interested in. Some food for thought as I consider my remaining cataract treatments.
Google " Kevin miller ophthalmologist interview"
It's the first video. He's very distinguished but I am sure there are equally distinguished ophthalmologists who would disagree with some of his views about blue light and monovision.
Thanks Lynda111. There's also an article entitled What Is Better-Tolerated After Cataract Surgery: Residual Hyperopia or Residual Myopia? that points to the primary research. It looks like this was an ancillary finding of the study, not the stated main purpose. But the study used outcomes from over 17,000 patients, so the conclusion may be highly credible. I have not studied the paper, so can't say for sure. Regardless, it's intriguing.
My first thought is that these two "opthalmologists" are borderline incompetent.
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"He generally uses the clear lenses, and tries to avoid mixing types on the two eyes of the same patient."
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Sounds like he must have done it. How else would he know that patients prefer clear lenses?
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I wouldn't put any stock in their opinions. Seems like they are mostly interested in selling premium priced lenses to make more money.
These ophthalmologists views reminded me of one of the many article I have saved on monovision. A quote from the article
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"In the United States, there is economic incentive for surgeons to use multifocal IOLs in lieu of mini-monovision with monofocal IOLs because the physician can legally make a surcharge to the patient for the use of a premium multifocal IOL, which is typically an out-of-pocket expense for patients [7]. High patient out-of-pocket expenses for premium multifocal IOLs is common in many counties. Physicians may also be able to charge additional fees for necessary testing prior to cataract surgery for mini-monovision; however, these fees run considerably less than charges for the premium multifocal IOLs."
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The link to the article:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6230294/
Imagine if you had a pair of blue light filtering glasses with one yellow lens removed-- who would want to wear those all day?
Based on a retrospective study of patients where one clear and one blue light filtering IOL was implanted inadvertently, 80% did not even notice the difference until after they were told about it. None found it bothersome.
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" Four of five patients had no spontaneous color vision complaints. When these patients were informed of the unintended mismatch, all remarked that they could perceive a color vision difference, but that it was not bothersome. One of the five patients reported "beige" vision. None of the patients wanted an IOL exchange."
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https://pubmed.ncbi.nlm.nih.gov/16678519/
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The blue light filtering in IOLs is very slight. It is only done to restore the colour balance of the natural lens. It is more important for those doing photographic digital dark room work and want to get the colour balance right especially for paying customers that have natural vision eyes.
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I went 18 months with one eye done (with a blue light filtering lens) and the other eye with a minor cataract. To me there was a very obvious difference in the colour balance. The cataract eye was much more warmish yellow. I had not noticed it until after the surgery and I had something to compare to. When looking at people's faces on TV I decided that the warmer cataract coloured eye was more flattering to their appearance. But I would only notice this difference when closing one eye, and then closing the other eye. With both eyes open what I saw was a blend of the colour balance.
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I suspect the difference between a cataract eye "warm" is much more dramatic than the difference between an IOL clear lens and a blue light filtering lens. I would have no hesitation if the circumstances warranted to have a blue light filtering lens in one eye and clear in the other. That said, I have blue light filtering in both eyes as I want a natural colour balance. Back when we used florescent lighting I always preferred the warm daylight tubes to the cold bluish light tubes.
The surgeon is only identified by the initials M.G.? The differential iol range of -.75 to -1.75 D of myopia would not be appropriate for me and many others. It goes from the upper limit of mini to full monovision. Several unique variables here, like small sample size, twice the number of females, and no control group. Even included a lens exchange.
There is no standard for what mini-monovision is called. My opinion based on many different studies and articles is that mini-monovision goes from -1.25 to -1.75, with -1.50 the nominal ideal differential between the eyes. There is good evidence to support that. And don't forget that if your distance eye, done first, comes out at the ideal -0.25 D then the ideal for the near eye goes up to -1.75 D. A range of -1.50 to -1.75 is a realistic target considering the inaccuracy inherent in the power calculation.
Based on the reports of 'refractive surprise' outcomes, I have concluded that it is prudent to use the same the same brand of iol in each eye, target distance with no or small difference in lens power, and avoid MF and EDOF lenses based on manufacturer warnings on suitability/contraindications. I am personally concerned with the safety of LAL with UVL directed to eyes in adjustments.
PCO prevention needs a solution. It appears to occur from the surgery trauma itself and not just the friction of the iols. How to clear out the epithelial cells before lens placement without damaging the capsular bag?
Yes, I think it is a good idea to use not only the same brand, but the same lens model in each eye to get the most consistent accuracy from the IOL power calculation. But, sometimes larger differences in the eyes can drive the choice to different lenses due to power availability by brand and model type.
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Lens power required is going to be driven by the eye measurements and you cannot choose to use the same power in each eye unless you are willing to live with a different outcome refraction in the eyes. Normally the eye measurement and target for outcome drives the power choice. It would be unusual to use the same power in each eye.
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According to RxSight the LAL has a UV resistant coating on the back side of the lens, and none on the front side. This allows the use of the UV adjustment to change the power of the lens without damaging the eye behind the lens. For this reason the lens must be installed properly and not back to front, as it would not be possible to adjust the lens with the UV blocking coating on the front side.
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I don't think the causes of PCO are fully understood. Alcon have produced some studies that show their specific material is more resistant to PCO (lower YAG rate). Sharper lens edges also seems to help prevent PCO. And surgeon proficiency is cleaning the capsule without damaging it is a factor too. I have even seen a study which found that diabetics taking metformin for treatment have lower PCO rates than those not taking metformin. But, that does not seem to have worked for me. I have been taking metformin for many years and I now seem to have indications of PCO in both eyes. Both are Alcon material, one has sharper edges (Clareon) than the other (AcrySof IQ). So despite having all the right things in place it still can happen. I think the other issue with PCO is that YAG can be used as a bit of a "cure-all" for patient complaints, and I suspect it is done in many cases when it was not really necessary. I was relieved when I got a second opinion on my PCO diagnosis and the laser specialist recommended against doing it until it starts to impact my vision.
One of the really interesting findings in the Juvene studies is essentially no PCO in any study participants years after surgery. It may be the bag-filling nature of the implant that prevents PCO. Filling the bag completely keeps it closer to it's natural state. I suspect the shrink wrapping effect with current IOLs which results in the two inner faces of the bag touching each other may be what causes PCO.
Ron… have you considered that it may have been the cataract itself in you natural lens that was causing it to have such a pronounced "warm" colour compared to your IOL eye between surgeries? I remember coming home once after an appointment before I'd had any surgery done and my pupils were extremely dilated and everything wasn't just warm but very unnaturally brownish. Not warm… brown. That didn't seem natural and I assume it was from my cataracts.
A plausible explanation. Beware of the wrinkles there and elsewhere.
Yes, for sure the warm colour was coming from the cataract in my natural lens. The colour it induces in the vision is very striking compared to the slight yellow tint in a blue light filtering lens.
Filling the bag also means no wrinkles. And no shifting of the lens position either (effective lens position). There will be a lot of benefits when these next generation bag-filling (and often accommodating) designs finally become available.
I am not so sure about the bag filling theory being the key to preventing PCO. The Alcon AcrySof material has been found to be more resistant to PCO than other materials. The refractive index of AcrySof material is the highest of all commonly used material for IOLs. This makes for the thinnest lenses for a given power and the least bag filling potential.
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https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0220498
These two views align with my own situation. Refreshing to see this stated here, with all the recommendations for targeting residual myopia.
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"If a patient insists on monovision, the doctor uses EDOF lenses. For both eyes, I think, to better cover the full range of distances with both eyes...
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Doctor generally targets slight hyperopia - up to 0.15 D."
He says that his patients tend prefer clear lenses so that is what he generally uses. I didn't get the impression that he recommends them over blue light filtering ones. He doesn't believe in mixing them in the same patient,
My surgeon's views were very different.
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1. Yes, there are some theoretical benefits from using EDOF lenses with monovision. I carefully reviewed it all and concluded that what really made sense was to use a monofocal in the distance eye to get the best distance vision especially at night. The EDOF I considered was the Vivity and it gains about 0.6 D in depth of focus. But, there is a hit to the peak visual acuity and a big hit to the contrast sensitivity. Google Vivity Patient Insert PDF. My plan was to use it only in the near eye to get the extra depth of focus and to take advantage of that to target it at -1.0 instead of -1.50 D. The theory was that the monofocal would give me the distance and night vision contrast sensitivity to make up for the loss in the Vivity eye. And targeting -1.0 instead of -1.5 would close the gap between the two lenses for intermediate vision without giving up any near vision due to the EDOF of 0.60 D. My surgeon disagreed. He said he had another patient that had considered similar and had higher expectations for vision. This patient was disappointed with the Vivity outcome. He thought I was similar in expectations and I would be disappointed too. He recommended a monofocal in both eyes, and that is what I did. As it turned out there is no intermediate vision gap, and I can see the whole range of vision from about 8" on a computer monitor to the moon.
2. This statement of targeting hyperopia convinced me that this surgeon is incompetent. Nobody that is at all informed does that. I had a power option to get me very close to 0.0 D and my surgeon recommended I go to the next step more myopic which was about -0.375, which is where I ended up, and still have 20/20+ vision in this eye. He said that outcomes are not always predictable and nobody ever thanks him for leaving them hyperopic. Being hyperopic means a loss in distance vision and a loss in near vision. The near vision in the distance eye helps close the intermediate gap. And if you end up at -0.25 D in the distance eye you can target as much as -1.75 D in the near eye to get better near vision without exceeding the recommended maximum anisometropia guideline of 1.50 D.
3. Benefits from blue light filtering are controversial. Using blue light filtering is the "do no harm" option as the Alcon lenses use it to restore the colour balance of a young person's natural eye. Clear lenses expose the eye to a much higher level of blue light than the retina has ever seen in your lifetime. What I find is that surgeons that use Alcon lenses use the blue light filtering option because Alcon has it. Surgeons that are in bed with J&J use clear lenses and of course recommend them. Until very recently J&J had no blue light filtering option. Not sure if it was a patent issue or what but they have now come out with an OptiBlue option on some lenses. I think it is slightly different in filtering with more of bias to violet, but I suspect that may be due to patent infringement avoidance. Just a guess.
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This said I think a case can be made, particularly in younger patients to use a hybrid mini-monovision with an EDOF in the near eye, if one can accept the optical risks associated with the EDOF technology. A younger person typically has larger pupils and at least until they get older do not benefit from the pinhole effect of smaller pupils which adds to the useable depth of focus. The article below talks about using hybrid monovision in younger patients with good success. This article convinced me it was worth considering, and I was going to do it, right up until the surgeon discouraged me.
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Clinics in Surgery 2018 | Volume 3 | Article 2027
Monovision Strategies: Our Experience and Approach on
Pseudophakic Monovision Published: 16 Jul, 2018
Misae Ito CO* and Kimiya Shimizu