The adjustable nature of the second-generation LAL allows for improved visual and refractive outcomes in eyes with previous laser corneal refractive surgery.
Abstract
Purpose:
To evaluate the visual and refractive outcomes in eyes with a history of laser corneal refractive surgery implanted with the second-generation light-adjustable lens (LAL).
Setting:
Private practice, Sioux Falls, South Dakota.
Design:
Retrospective, consecutive case series.
Methods:
Eyes with a history of prior corneal refractive surgery that underwent cataract surgery with implantation of the LAL and were targeted for plano were included. Data on the type and number of prior refractive surgeries were collected, in addition to the timing and number of postoperative adjustments. The primary outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity, and the percentage (%) of eyes within ±0.25 diopter (D), ±0.50 D, and ±1.00 D of their refractive target.
Results:
76 eyes from 70 patients were included. A total of 45 eyes with a history of 1 prior refractive surgery and 31 eyes with a history of ≥2 refractive surgeries were included. 74% (n = 56) of all eyes achieved UDVA of 20/20 or better, 88% (n = 67) achieved 20/25 UDVA or better, and 93% (n = 71) were correctable to 20/20 or better postoperatively. For refractive outcomes, 66% of eyes (n = 50) were within ±0.25 D and 86% (n = 65) were within ±0.50 D of refractive target.
Conclusions:
Patients with a history of laser corneal refractive surgery achieved favorable visual and refractive outcomes with the LAL. This intraocular lens (IOL), which affords postoperative adjustability, is a promising option for patients with a history of corneal refractive surgery who maintain high expectations for functional uncorrected acuity after cataract surgery.
Cataract surgery continues to evolve with the advent of new intraocular lens (IOL) technology, formulas, and advanced diagnostics.1,2 The continued evolution has led to improved outcomes but also vaulted patient expectations. Despite the advent of new technology, patients with a history of corneal refractive surgery pose a number of unique challenges including most notably a reduction in accuracy and predictably of IOL power calculations.3 Recently, a new IOL technology was introduced known as the light-adjustable lens, or LAL (RxSight, Inc.). This new IOL is composed of a photoreactive silicone material that permits postoperative adjustment of the lens, allowing the refractive target to be tailored based on patients and their visual goals.4
Given the difficulty of achieving the desired refractive target after cataract surgery in patients with a history of corneal refractive surgery, the LAL has emerged as an appealing option in this patient population.5,6 The factors contributing to reduced IOL power calculation accuracy in this patient population are well established, and the advancement of formula and diagnostics have improved outcomes, but overall, there are minimal studies in which the percentage of eyes within ±0.50 diopter (D) of target exceeds or approaches 70%.3,7 As the only IOL that permits postoperative adjustment, the LAL is designed to provide enhanced refractive accuracy and precision. The LAL is made up of a photoreactive material that responds to UV light, and adjustments to the lens are delivered using a device known as the light delivery device, or LDD (RxSight, Inc.). Once the patient's desired refractive outcome is achieved, a “lock-in” treatment is delivered using the LDD to prevent further adjustment of the lens and stabilize the desired refractive power.
The LAL was initially approved by the U.S. Food and Drug Administration (FDA) in 2017, and the second-generation IOL (LAL with ActivShield) became commercially available in 2021 after FDA approval. Since its production and release, minimal data have been published evaluating the visual and refractive outcomes of the second-generation LAL.5,8 This study aims to evaluate the visual and refractive outcomes of the LAL in eyes with a history of prior corneal refractive surgery including laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). To collect data, a retrospective chart review was performed at a single site of all eyes with a history of prior corneal refractive surgery implanted with the second-generation LAL.
METHODS
A retrospective, consecutive case series was conducted at a single site (Sioux Falls, SD). The case series included eyes with a history of corneal refractive surgery that underwent implantation with the second-generation LAL after cataract extraction. A retrospective review was performed from August 2021 to May 2023. This study was performed in accordance with the tenets of the Declaration of Helsinki and was approved by the University of South Dakota Institutional Review Board.
All surgery was performed at a single site (Vance Thompson Vision, Sioux Falls, SD). Before the procedure, initial IOL power selection was based on ocular biometry and power calculation was selected using the Barrett True-K formula, a formula specially developed and used for eyes with prior refractive surgery.9 Patients with a history of radial keratotomy (RK) were excluded. Patients with a history of any concurrent eye pathology (eg, epiretinal membrane) that would limit the ability to achieve a best-corrected 20/20 visual acuity postoperatively were excluded from the study. Patients with a history of prior small-incision lenticule extraction (SMILE) were not excluded, but there were no prior patients included in this study with a history of previous SMILE.
This study included eyes that had been targeted for emmetropia (plano) before their lock-in. This is inclusive of eyes that had been initially targeted for a near target (eg, −0.50 or greater) but elected to maximize distance vision and modified their target to plano (0.00 D). Of note, patients were not intentionally left with any degree of with-the-rule or against-the-rule astigmatism. The outcome measures of interest included the percentage of eyes achieving uncorrected distance visual acuity (UDVA) of 20/20, 20/25, and 20/30 or better, the average monocular UDVA, and the percentage of eyes within ±0.25 D, ±0.5 D, and ±1.0 D of refractive target at the date of final lock-in. To evaluate refractive accuracy, this study followed the recent correspondence piece published by Kozhaya et al. and defined treatment error as the difference in refraction (spherical equivalent) between the last LDD target and the final lock-in.5 Patient eyes were further subdivided based on refractive history, specifically those eyes with a history of only 1 prior refractive procedure vs eyes with a history of multiple prior corneal refractive surgeries.
Adjustment Protocol
A standard surgical technique was used for cataract extraction and implantation of the LAL including a 2.75 mm temporal corneal incision. Postoperatively, adjustments were typically performed starting at 6 to 8 weeks postoperative, which is extended beyond the typical recommended timeline of starting approximately 3 weeks postoperative (∼17 days per manufacturer recommendation). This practice pattern evolved from experience with the LAL and allowing patients with a history of corneal refractive surgery to stabilize from a refractive standpoint before proceeding with light adjustments. Overall, patients were treated with up to 3 light adjustments followed by 2 lock-in treatments.
RESULTS
This retrospective study included 76 eyes from 70 patients. Demographics of the patient population included in this study is presented in Table 1. All patients had a history of prior corneal refractive surgery, and only eyes targeted for plano (≤−0.25 D) at their final LDD adjustment before their lock-in were included in the case series. The mean age was 64.4 ± 6.4 years. Of the 70 patients, 29 were male and 41 were female. Of the 76 eyes analyzed in this study, 45 had a history of 1 prior laser refractive surgery (88.9% LASIK, 11% PRK), while the other 31 had a history of 2 or more prior refractive procedures.
Table 1.
Baseline characteristics
| Parameter | |
| Age (y), mean ± SD | 69.4 ± 6.6 |
| Gender (M/F) | 33/43 |
| IOL power (D), mean | 19.4 |
| Light delivery device treatments | |
| Time to first treatment (d), mean ± SD | 50 ± 14.3 |
| Time to lock-in (d), mean ± SD | 66 ± 20.2 |
| Number of adjustments, mean ± SD | 1.5 ± 0.6 |
| Refractive surgery history | |
| No. of prior refractive surgeries, mean ± SD | 1.5 ± 0.6 |
| Primary LASIK (n) | 67 |
| Primary PRK (n) | 9 |
| Initial ablation type (myopic/hyperopic) | 72/4 |
PRK = photorefractive keratectomy
The visual and refractive outcomes for all 76 eyes are displayed in Figure 1. Overall, for UDVA, 36% were 20/15 or better, 74% were 20/20 or better, 88% were 20/25 or better at last collected follow-up (Figure 1). The overall mean UDVA (logMAR) was 0.0 ± 0.1, which is equivalent to ∼20/20. Of all eyes included, 93% were correctable to 20/20 postoperatively and 100% were correctable to 20/25 or better. For all eyes, the UDVA was the same or better than the corrected distance visual acuity (CDVA) in 68% of eyes and the UDVA was within 1 line of CDVA in 91% of eyes.
Figure 1.
Visual and refractive outcomes for all eyes. A shows the percent of eyes achieving 20× or better for UDVA and CDVA. B demonstrates the difference between UDVA and CDVA. C demonstrates the spherical equivalent refractive accuracy. D highlights the breakdown of postoperative refractive cylinder.
For refractive outcomes, the mean refractive spherical equivalent (MRSE) was −0.04 ± 0.4 D. For spherical equivalent refractive accuracy and percentage of eyes within target, 66% of eyes were within ±0.25 D, 86% of eyes were within ±0.50 D, and 99% of eyes were within ±1.00 D of target. For astigmatism correction, 61% of eyes had ≤0.25 D of postoperative refractive cylinder and 100% had ≤1.00 D of postoperative refractive cylinder. Overall, the mean cylinder after final lock-in was −0.3 ± 0.3 D. The astigmatism and MRSE data were also evaluated based on the change after LDD adjustments by comparing the manifest refraction before and after adjustments. Figure 2 compares the SE obtained before the first LDD adjustment compared with the refraction obtained after the lock-in procedure. The percent of eyes within ±0.13 D of target increased to 54% from 17% before the first adjustment, and the percent of eyes within ±0.50 D of target increased from 68% to 87% after adjustments. For change in astigmatism, Figure 3 shows 2 double-angle plots comparing the refractive astigmatism at similar points including the refractive astigmatism obtained before the first LDD adjustment vs the refractive astigmatism obtained after the lock-in procedure.
Figure 2.
Refractive accuracy before and after LDD adjustments. This graph compares the manifest refraction spherical equivalent obtained prior at the visit before the first LDD adjustment with the manifest refraction spherical equivalent obtained after adjustments. LDD = light delivery device
Figure 3.
Double-angle plots of refractive astigmatism before and after LDD adjustments. Double-angle plots are shown comparing the refractive astigmatism before the first LDD adjustment (left) vs the refractive astigmatism after the series of adjustments with the LDD (right). The centroid values, standard deviation, and 95% confidence ellipses are also shown. LDD = light delivery device
The results were also stratified based on the number of prior refractive surgeries, and these results are demonstrated in Figure 4. In eyes with a history of 1 prior refractive surgery, 47% achieved 20/15 or better and 84% were 20/20 or better. Overall, 91% of eyes with 1 prior refractive surgery were correctable to 20/20 or better and 100% were correctable to 20/25 or better. In eyes with ≥2 refractive surgeries, 58% achieved UDVA of 20/20 or better and 81% were 20/25 or better. For CDVA, 97% were 20/20 or better and 100% were 20/25 or better. For refractive outcomes, 91% of eyes with a history of 1 prior refractive surgery were within ±0.50 D of target. In eyes with a history of 2+ prior refractive surgeries, 75% were within ±0.50 D of target. For outliers, there was 1 patient included that ended up with an SE of +1.13 despite undergoing 3 adjustments with a plano (0.00 D) target; this participant's history was notable for prior myopic LASIK followed by a LASIK enhancement in the same eye. The patient's corneal topography was consistent with a prior myopic ablation with a high degree of total corneal higher-order aberrations (HOAs) (>0.6 μm).
Figure 4.
Visual and refractive outcomes stratified by refractive surgery history. A shows the percent of eyes achieving 20× or better for UDVA and CDVA in eyes with 1 prior refractive surgery. B shows the percent of eyes achieving 20× or better for UDVA and CDVA in eyes with ≥2 prior refractive surgeries. C demonstrates the spherical equivalent refractive accuracy of eyes with 1 prior refractive surgery. D demonstrates the spherical equivalent refractive accuracy of eyes with ≥2 prior refractive surgeries.
Overall, eyes in this study underwent a mean number of 1.5 ± 0.6 light adjustments before the final lock-in procedures which included 2 additional light treatments to finalize the target. The mean refractive target from the IOL calculation sheet was −0.6 ± 0.5 D; 4 of 76 eyes initially had a near target (−0.50 D or greater) but with adjustments switched to a plano target. The mean time between surgery and the initial light treatment was 50.4 ± 14 days, and the mean time between surgery and the final lock-in was 66 ± 20 days. No eyes in this case series underwent an IOL exchange within the 3-month postoperative period. There were no intraoperative or postoperative complications of eyes included in this case series.
DISCUSSION
The challenges of cataract surgery in eyes with a history of laser corneal refractive surgery are well established, and many of these patients are now presenting for cataract surgery. These patients characteristically are motivated to retain functional uncorrected acuity after cataract surgery. Despite the continued advancements in IOL power formulas and corneal imaging, which have enhanced our ability to achieve targeted postoperative refractive outcomes, the predictability remains inferior to patients without a history of corneal refractive surgery.2 The LAL represents a promising form of IOL technology that enables postoperative adjustment and therefore presents an exciting option for this patient population.5,6,8
To the authors' knowledge, this is the largest study to date evaluating the second-generation LAL in eyes with a history of corneal refractive surgery. In this study, eyes with a history of prior corneal laser refractive surgery achieved excellent visual and refractive outcomes with 71% of eyes achieving UDVA of 20/20 or better and 91% of eyes achieving 20/25 or better. For refractive outcomes, 67% of eyes were within ±0.25 D and 87% of eyes were within ±0.50 D. These results compare favorably with what has been reported thus far with the first-generation and second-generation LAL in eyes with prior laser corneal refractive surgery. Folden et al. reported 100% of eyes (n = 20) were within ±0.50 D of target and also reported 95% had 20/20 or better UDVA evaluating a series of eyes with the first-generation LAL.8 A comparative, retrospective study by Moshirfar et al. reported outcomes from the first-generation LAL and reported 55% of eyes were within ±0.50 D of target and 31% of eyes had 20/20 or better UDVA.6 More recently, another small series was published by Kozhaya et al. that included 23 eyes with prior laser corneal refractive surgery.5 In this study, they found 96% were within ±0.50 D of target and 56% were 20/20 or better.
These results also compare favorably with the accuracy of IOL power calculations for patients with a history of prior laser corneal refractive surgery.10 Although a number of formulas have been developed specifically for this population, it is rare for the percentage of eyes within ±0.50 D of target to exceed 70%.7,10,11 Before the first adjustment, the percentage of eyes within ±0.50 D of target was 68%; after adjustments with the LDD, this number rose to 86%, which demonstrates the advantage of adjustability with this population of patients. Overall, this study, in addition to what has been published thus far in the literature, highlights the appeal of the LAL in eyes with a history of prior corneal refractive surgery.
In addition to postrefractive patients, previous case reports have also reported unique uses of the LAL to leverage the adjustable optics of the IOL. A small case series by Eisenbeisz et al. described a combined Descemet membrane endothelial keratoplasty with cataract surgery with implantation of the LAL and reported excellent visual outcomes.12 Another case report described intrascleral haptic fixation of the LAL, which takes advantage of the 3-piece design of the LAL.13 Although isolated case reports, each of these studies highlights the value of postoperative adjustment with the IOL in situations in which the refractive predictability is reduced. Additional situations where an adjustable lens such as the LAL could be helpful are in eyes with advanced cataracts limiting biometry measurements, outliers of axial length where IOL power calculation accuracy is further reduced and in eyes with prior RK.
The LAL offers unique appeal as an advanced technology IOL in postrefractive cataract surgery patients owing to the postoperative adjustability and ability to achieve superior refractive outcomes. As previous work has demonstrated, residual refractive error after cataract surgery is a major driver of dissatisfaction and residual astigmatism ≥0.75 D has been shown to negatively degrade uncorrected visual acuity.14,15 Currently, the use of excimer laser enhancements remains the only option for adjusting and/or addressing residual refractive error or astigmatism after cataract surgery. Many cataract surgeons, however, do not have access to or do not perform keratorefractive procedures. Furthermore, in older patients—specifically in those with a history of prior refractive surgery—laser enhancements may be technically challenging and/or less predictable. Previous research has also demonstrated that laser enhancements after cataract surgery are more accurate with LASIK vs PRK, and there are known technical challenges and/or risks with lifting an old LASIK flap.16 Moreover, patients with a history of a large ablation or multiple laser corneal refractive procedures may not be candidates for additional laser correction owing to the risk of additional surgery and limitations of corneal tissue.
In this series, patients with 1 or less prior corneal refractive surgery achieved superior visual and refractive outcomes. In comparison with those eyes with ≥2 refractive procedures, the rate of eyes achieving 20/20 or better was higher in the group with 1 prior refractive procedure in addition to improved refractive outcomes. We suspect that additional refractive procedures introduce additional corneal HOAs that negatively affect the predictability of the refractive outcome and ultimately affect visual outcomes using the LAL despite the adjustable optics. To the authors' knowledge, this is first study to stratify outcomes based on the number of prior refractive procedures and the variability in results from other studies could be attributable to this history.
The results of this study support the LAL as an attractive lens option in the postrefractive population, but patient selection remains paramount for achieving favorable postoperative outcomes. Although the LAL affords postoperative adjustability, it does not account for or minimize preexisting HOAs present in the cornea from prior corneal refractive surgery. Thus, it is critical to evaluate the degree of irregular astigmatism and HOAs before surgery and carefully evaluate patient candidacy before surgery. Corneal topography is an essential component of the preoperative evaluation, and in patients with an irregular ablation pattern and suspected irregular astigmatism, patients should be evaluated with a gas permeable overrefraction to assess the contribution of the cornea to visual degradation relative to the lens.17
Despite the significant strengths of this study, certain limitations should be acknowledged. This is a retrospective study, which carries inherent limitations including the lack of a control group and no subjective questionnaire. Furthermore, this study does not have long-term data, and the long-term stability of the LAL remains unclear. Despite these limitations, this is the largest study to date evaluating the second-generation LAL in patients with a history of corneal refractive surgery and provides meaningful data to guide cataract surgeons implanting this IOL in this patient population. Future study should explore the use of this IOL in patients with prior RK, which has previously been reported in isolated case reports or case series.18
The introduction of the LAL represents a significant advancement in IOL technology and a solution to some of the challenges posed by patients electing to undergo cataract surgery with a history of corneal refractive surgery. Overall, the favorable visual and refractive outcomes of this study favor the use of the LAL in eyes with prior corneal and refractive surgery.
WHAT WAS KNOWN
IOL power calculations remain less accurate in postrefractive eyes despite advancements in diagnostics and formulas.
The light-adjustable lens (LAL) is the first IOL that enables power adjustment postoperatively and offers potential for improving outcomes in postrefractive eyes.
WHAT THIS PAPER ADDS
The second-generation LAL enhances the predictability of refractive outcomes in eyes with a history of prior corneal refractive surgery.
The LAL is a promising option for patients with a history of prior corneal refractive surgery who are motivated to retain excellent uncorrected visual acuity after cataract surgery.
Footnotes
Supported by an investigator-initiated trial grant from RxSight, Inc.
Disclosures: T.J. Ferguson reports research funding from RxSight, Inc. J.P. Berdahl and V. Thompson are consultants and report ownership with RxSight, Inc. None of the other authors have any financial or proprietary interest in any material or method mentioned.
First author:
Marlee Jones, BS
University of South Dakota Sanford School of Medicine, Sioux Falls, South Dakota
Contributor Information
Marlee Jones, Email: Marlee.Jones@coyotes.usd.edu.
Daniel C. Terveen, Email: daniel.terveen@vancethompsonvision.com.
John P. Berdahl, Email: john.berdahl@vancethompsonvision.com.
Vance Thompson, Email: vance.thompson@vancethompsonvision.com.
Brent A. Kramer, Email: brent.kramer@vancethompsonvision.com.
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