Many innovations have come to cataract surgery in the 25 years since Barry Emara, MD, opened his clinic in southwestern Ontario, but the fundamentals of the procedure have remained the same: inserting a probe in the front lens compartment of the eye, extracting the cloudy and calcified natural lens, then inserting a new, clear, prosthetic lens through the same probe. The operation takes about 10 minutes from start to finish — and has become one of the most performed surgeries in the industrial world, with roughly 4 million of the procedures annually in the United States alone. 

Typically, the surgeon takes a series of measurements of the patient’s vision and eye before and during surgery to select an intraocular lens (IOL) that would best meet the patient’s vision needs — and hope the patient likes the result. If not, however, short of extracting the IOL lens and trying a new one, patients are generally stuck with the outcome.

But one fundamental that has changed for Emara and thousands of cataract surgeons like him is an IOL that can be adjusted after implantation. Known as the Light Adjustable Lens, or LAL (RxSight). The product was approved by the FDA in 2017. 

Since he started using the LAL in 2024, Emara told Medscape Medical News, he has implanted about 200 of them, contributing to the 300,000 LAL implant milestone reached in the past few months. 

How It Works

The LAL, and a newer version called LAL+, is a component of a system that includes a light-delivery device. Once the IOL is implanted, the eye takes 2-4 weeks to heal and for the IOL position to stabilize. Then the surgeon, with patient input, applies the light-delivery device to fine-tune the desired refractive outcome. 

The patient undergoes up to three procedures in which the light-delivery device applies ultraviolet light onto specific areas of the IOL to activate light-sensitive polymers within it and essentially reshape the LAL before the final refractive error is “locked in,” in the parlance of the surgeons who used the device. 

"The beauty of Light Adjustable Lens is the fact that once the eye is healed and all those moving parts have settled into place and the lens is now healed into place, then we can measure the eye starting 3-4 weeks after surgery,” Emara said. “Based on those measures, we can change the shape of the actual Light Adjustable Lens while it's in the patient’s eye."

The Patient Experience: More Visits, Higher Costs, Greater Satisfaction 

One thing that makes the LAL different from non-LAL IOLs is what the patient must do after the operation. “Over the first 90 days, LAL patients spent an average of 14 hours and 23 minutes in clinic compared with 8 hours and 14 minutes for monofocal IOL patients,” said Kendall Donaldson, MD, MS, a corneal surgeon at Bascom Palmer Eye Institute in Plantation, Florida, who led a study of postoperative care of the two IOL types. “They also required more visits, averaging nine visits vs six, and each visit was longer on average.”

Patients also must wear UV-blocking glasses continuously after the LAL is implanted until the final lock-in visit to prevent UV light from altering the lens. 

Those additional visits and the technology involved in manufacturing the LAL add costs compared to standard cataract surgery and IOL implantation. Compared to the standard single-focus IOL, which Medicare covers minus the deductible, the LAL can cost up to $2000 more per eye, according to SurgeryCostGuide.com. In his practice, Emara charges $5000 Canadian per eye, about $3600 U.S., which he said is about two to 2.5 times more than the price of a nonadjustable IOL. 

But the price can vary depending on the practice. “It's typically $500 maybe to $1000 more than they might charge for other kinds of lens implants,” said Douglas Koch, MD, a corneal surgeon at Baylor College of Medicine in Houston. “Some practices will charge everybody the same just to keep the pricing simple and to help patients make decisions based not on price but on the optics.”

In Donaldson’s experience, patients so far think the higher cost is worth it. “Patients can trial and refine different refractive targets after surgery rather than committing entirely to a preoperative target,” she said. “Additionally, patients maintain higher-quality distance vision while extending the range of vision.” Patients with the LAL typically need small amounts of correction for near vision in the nondominant eye to rely on glasses less than they would otherwise, she said.

The Evidence So Far

The existing evidence of the LAL shows excellent outcomes compared to conventional lenses, with 90% or more of patients getting to with .5 diopters of their target refraction after the correction is locked in. In his experience, Koch said, the difference is about.25 diopters, which to a lay person would mean missing one letter on one line of the Snellen eye chart. 

Emara helped conduct one of the largest studies of the LAL to date: a systematic review of 819 implanted lenses and 609 patients. The study found 91.5% of patients got to within.5 diopters of their target refraction after their LALs were locked in. Eighty-five percent had an uncorrected distance vision of 20/20 or better, and long-term follow-up demonstrated good visual acuity and refractive outcomes that held steady even after seven years. 

Emara said between 80% and 85% of his patients with nonadjustable lenses achieve such outcomes, with 85% or more getting to 20/25 vision or better. 

Koch led a study that found LAL outcomes after the first and second light treatments in eyes that had undergone previous refractive surgery were not far off the targeted refraction compared with eyes that did not have refractive surgery — “virgin corneas,” as Koch called them. 

For example, in virgin corneas the average treatment errors were.02 ±.29 diopters for distance and.21 ±.49 for near targets; in nearsighted eyes that had previous laser-assisted in situ keratomileusis or photorefractive keratectomy, the average errors were.03 ±.35 and.2 ±.44 diopters, respectively, his group found.

“Overall, it reinforced how impressed we are with what a powerful tool this is and how accurate it is in daily practice,” Koch said.

A study of 30 patients who had LALs implanted in both eyes found they had excellent binocular uncorrected vision at near, intermediate, and distance vision, said Jonathan Davidorf, MD, a cornea and cataract surgeon in Los Angeles and an assistant clinical professor at UCLA’s Stein Eye Institute. The average distance vision was 20/20 in the group. “Basically, everybody could see up close and everybody wanted clear distance vision, so everyone had what they considered good distance vision,” he said. 

Another phenomenon that can bother patients after they have cataract surgery are higher-order aberrations — errors that aren’t necessarily detectable on an eye exam but can impact quality of vision nonetheless. By contrast, lower-order aberrations, particularly nearsightedness, farsightedness, and astigmatism, are measurable on an eye exam.

“Some of the concern with the Light Adjustable Lens was that we can fix the actual prescription, we can fix the nearsightedness or the farsightedness or the astigmatism, but is that having a negative impact on these higher-order aberrations?” said Drew Dickson, MD, a corneal surgeon in Omaha, Nebraska, and Des Moines, Iowa, who led a retrospective chart review of 56 eyes from 32 patients to examine that question.

The study found that use of LALs did not lead to a clinically significant amount of higher-order aberrations, Dickson said. The study used the iTrace device to measure corneal, internal, and total higher-order aberrations before each light treatment and at the final lock-in visit. “I think there still needs to be some follow-up studies, including a randomized controlled trial,” he said.

Patient Selection and Expectations

Success with the LAL comes down to patient selection and patient expectations, Donaldson said. 

“The LAL is especially well-suited for patients who want a high degree of refractive precision and are motivated to reduce dependence on glasses,” she said. That would include patients who have had refractive surgery, but also those “with more challenging refractive calculations” because the postsurgery adjustments can help refine the final visual outcome. 

“It is also a strong option for patients interested in blended vision or monovision who would like to customize the amount of near vision after surgery,” Donaldson added.

However, even with 90%-plus rates of reaching the target refraction, some patients who get the LAL will not be satisfied with their vision. Reddit has a few reports of extremely unhappy patients, but quantifying those experiences is difficult, experts said. 

“Like every other lens, there are certain patients who, for whatever reason, don't get the outcome they want and of course, that's frustrating,” Koch said. Surgeons who use the LAL must prepare to deal with that, even to the point of exchanging it for a different kind of IOL, he said. “There's no lens that you can put in the eye that's perfect for every patient.”

But so far, he said, the LAL is as close as he has come. 

Emara reported no relevant financial relationships. Koch reported financial relationships with Carl Zeiss Meditech, Johnson & Johnson, PerfectLens, and VirtuaLens. Donaldson reported financial relationships with Alcon, Allergan/AbbVie, LensAR, Tissue Tech/BioTissue, Johnson & Johnson, Bausch + Lomb, Lumenis, Versea, BVI, iOR, Rayner, and Carl Zeiss Meditech. Dickson and Davidorf report financial relationships with RxSight. 

Richard Mark Kirkner is a medical journalist based in Philadelphia.