Light adjustable lenses (LAL)
Posted , 7 users are following.
Let's discuss these lenses that are under investigation by the FDA and which could be a new breakthrough in customized vision at all distances after cataract surgery.. The lenses have been in development since 1996 by Calhoun Vision (recently renamed to RxSight). The lenses are IOLs made of a silicone polymer material that reacts to ultraviolet light to change the power of the implanted IOL to provide optimal vision at near, intermediate and distance in a non-invasive manner - without the need for contact lenses or spectacles.
Reference:
http://www.20-20visionperfection.co.uk/eye-procedures/lens-implants/light-adjustable-lens
1 like, 15 replies
Sue.An Polyphemos
Posted
Only downside I see would be cost. A lot of individual attention - something in Canada I don’t see surgeons having time to dedicate to patients. Average cataract surgeon does about 20 per day at the hospital and sees them all next day for follow up visit then at 6 weeks. Perhaps in counties where there are many private clinics where they can charge what they want is where these new lenses once approved will be.
Just my thoughts - don’t see average person being able to afford them. But I would be curious to know how these lenses are for night vision: halos glare starbursts
pg128 Polyphemos
Posted
It's interesting but ultimately is just adjustable by surgeons and to be a multi-focal or mono-focal lens. The question is how good is it in either mode compared to fixed lenses and how long does it last?
Until we have reliable lenses that can adjust their power (e.g. FluidVision) then its all a compromise. One thing I would like to see is more lenses in 0.25D increments as most are 0.5D. Currently 0.5D in the IOL causes less refractive difference (0.35 to 0.4D) but 0.25D IOL increments would do a lot to help accuracy of targets, especially for people with low myopia and early cataracts who are easier to calculate for.
Sue.An pg128
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at201 pg128
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I know that Lenstec's Softec HD lens has come in 0.25D increments for years. May be, some others also come in 0.25D increments too. Please also note that the effective power increments (at the cornea) are smaller than these values.
Obviously, the surgeons don't pay much attention to this characteristic, probably because the eye measurements are not perfect any way.
pg128 at201
Posted
When I was looking at lens diameter some time ago (worried about looking around lens) I do remember seeing a lens with 0.25D increments, so presumably around 0.15D to 0.2D refractive change. However I never kept the details and all the lenses I've been recommend are 0.5D increments.
Being a little cynical, I expect in addition to cost saving if 0.25D increments were more common there would also be the concern of raising peoples expectation of accuracy.
Polyphemos
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at201 Polyphemos
Posted
This lens will definitely offer an advantage in letting the surgeon adjust the final IOL prescription after installation in the eye, but in principle have no advantage in having the surgeon select a good monofocal lens.
The FDA announcement does not mention any other advantage or disadvantage compared with the lenses of other material.
As a side comment, the "20-20 Vision Perfection" web site, mentioned by you in the first post, is another example of overselling of the product. Unlike the FDA announcement, it makes you think that the focus changes like a Crystalens or it has extended focus.
Night-Hawk at201
Posted
If it is not available in a toric version and doesn't allow adjustment of the cylinder, its not of any value to those with significant astigmatism either.
From my experience on my right eye, the surgeons can get the power pretty accurately (spot on in my case) but residual astigmatism is trickier since the cornea incision can introduce different astigmatism thats more unpredictable. So a toric IOL with adjustable cylinder after implantation would be a bigger deal for me...
Night-Hawk Polyphemos
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Are they only going to be available as a monofocal non-toric IOL?
at201 Night-Hawk
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It is possible that a toric version may be in the pipe line, but will have to wait for that.
The FDA Press Statement just says, "Six months after surgery, 75 percent also had a reduction in astigmatism." Considering that all cataract surgeries result in a change of astigmatism and a careful selection of the incision location can slightly decrease astigmatism, that statement may not say anything about the light-adjustable lens itself.
Night-Hawk at201
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Polyphemos Night-Hawk
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The better term to use for these LALs is "adjustable focus" versus the "fixed focus" of monofocal and multifocal IOLs. Don't think LALs come in monofocal or multifocal "flavours". The magic is in the LAL macromer material that allows for postoperative adjustment(s) to achieve sharp vision at near, intermediate and distance. When the patient is satisfied with the visual acuity, the settings are locked in permanently. LALs can achieve postoperative corrections for myopia, hyperopia and astigmatism for +/-2.0 diopters if I understood correctly.
at201 Polyphemos
Posted
Going by the FDA announcement says. "The magic is in the LAL macromer material that allows for postoperative adjustment(s) to achieve sharp vision at near, intermediate and distance." just means that one can pick any of the three distances after the cataract surgery, just like one can do with monofocal lenses up to the time of the cataract surgery.
Polyphemos at201
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"...at near, intermediate AND distance..." whereas a monofocal IOL maximizes visual acuity in only one of these.
at201 Polyphemos
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As I mentioned earlier, in my mind I would have more faith in the FDA announcement than the "20-20 Vision Perfection" web site, mentioned by you in the first post, which seems to be another example of overselling of the product.
Even the manufacturer's web site does not claim any more capability of any more focus capability than a monofocal lens with a precise prescription, stating that:
"During cataract surgery, physicians remove a patient’s cloudy lens and replace it with a clear artificial one. Even though they use the most modern lenses, it is difficult to predict the exact characteristics of the lens necessary to correct vision. Because of this prediction error, along with the potential for lens tilt or shift during the wound healing process, post-cataract surgery patients must often wear glasses for reading or distance vision.
To overcome the prediction problem, RxSight has developed the first intraocular lens that allows for in-office optimization after lens implantation and wound healing. Using a proprietary light treatment that produces modifications in lens curvature, the RxLAL enables surgeons to precisely reshape the lens based on the exact amount of visual correction and optimization needed to achieve desired vision after cataract surgery.
The RxLAL™ can be individualized for each eye and both eyes working together. When the best possible vision is achieved, and validated by the patient, the prescription is “locked in”. Patient participation throughout the normal healing process is integral to define personal vision goals, and effectively directs the precise application of light to create an individualized prescription lens."