Abstract
Introduction
To compare the U.S. Food and Drug Administration (FDA) premarket approval (PMA) trials of topography-guided laser in situ keratomileusis (TG-LASIK) and ray tracing-guided LASIK (RT-LASIK) for the treatment of myopia and myopic astigmatism.
Methods
This comparative study was conducted between TG-LASIK (P020050/S012; Alcon Laboratories, Inc., Fort Worth, TX, USA) with Allegretto Wave Eye-Q laser and topography-guided custom ablation treatment planning software, and “WaveLight Plus” RT-LASIK (P020050/S043; Alcon Laboratories, Inc.) using the WaveLight EX500 excimer laser and InnovEyes Sightmap. Clinical outcomes were compared, including visual and refractive measures, astigmatic correction, mesopic contrast sensitivity, higher-order aberrations, and patient-reported outcomes.
Results
This analysis included 249 eyes (212 patients) that underwent TG-LASIK and 336 eyes (168 patients) that underwent RT-LASIK. At 12 months, uncorrected distance visual acuity of 20/16 or better (64.8% TG-LASIK vs. 70.2% RT-LASIK) and 20/20 or better (92.6% TG-LASIK vs. 94.4% RT-LASIK) did not differ statistically between platforms. However, more TG-LASIK eyes had 20/10 or better (15.7% vs. 2.5%, P < 0.001) and 20/12.5 or better (34.4% vs. 26.4%, P = 0.044) than RT-LASIK eyes. Both platforms demonstrated comparable refractive predictability and stability (P > 0.05). For preoperative cylinder between − 1.00 to − 4.00 D, RT-LASIK showed greater astigmatic overcorrection (P < 0.05). At 3 months, RT-LASIK showed higher mesopic contrast sensitivity at 3, 6, and 12 cycles per degree under glare, with more eyes achieving clinically significant gains compared to TG-LASIK (P < 0.001). Both platforms induced changes in total higher-order aberrations, although not clinically significant. RT-LASIK also reduced spherical aberration from baseline. Both procedures showed a reduction in symptom severity for glare, halos, starburst, double vision, and dry eye.
Conclusions
While TG-LASIK showed superior visual acuity outcomes, RT-LASIK was associated with higher contrast sensitivity; however, both platforms demonstrate excellent visual and refractive outcomes. The majority of published studies are consistent with FDA PMA trends, showing potential reductions in spherical aberration and higher rates of 20/20 or better visual acuity with RT-LASIK.
Keywords: Ray-tracing, WaveLight Plus, Contoura, VARIO, Wavefront-guided, Hartmann–Shack, High-order aberrations, Accommodation, Coma, Wavefront-optimized
Key Summary Points
| Why carry out this study? |
| Topography-guided laser in situ keratomileusis (LASIK) is a well-established platform that customizes treatment based on the unique corneal topography of an individual’s eye. In comparison, ray tracing-guided LASIK is a newer technology that creates customized ablation profiles using a single diagnostic device, the InnovEyes Sightmap, which incorporates Hartmann–Shack total eye wavefront analysis, Scheimpflug corneal tomography, and biometry (partial coherence interferometry). |
| The superiority of one ablation profile over the other is limited to a single published study with a 3-month follow-up, as the ray-tracing automated customization tool was introduced commercially only recently. |
| What was learned from the study? |
| Comparative analysis of the Food and Drug Administration (FDA) trials showed topography-guided LASIK achieved higher rates of 20/10 or better and 20/12.5 or better UDVA compared to ray tracing-guided LASIK. However, the proportion of eyes achieving 20/16 or better and 20/20 or better did not differ statistically between studies. |
| Ray tracing-guided LASIK showed more eyes with clinically significant gains in mesopic contrast sensitivity under glare but was also associated with greater overcorrection of cylinder. |
| Both platforms are safe and effective in the treatment of myopia and myopic astigmatism. Future studies using standardized reporting formats and uniform higher-order aberrations (HOA) analysis diameters are needed to better evaluate HOA changes, contrast sensitivity, and patient-reported outcomes, which may clarify the advantages of each platform and refine treatment planning. |
Introduction
Excimer laser treatments for refractive error correction have evolved considerably since Munnerlyn’s formula in 1988, which introduced the calculation for the ablation depth of myopic correction [1]. Modern platforms now achieve submicron precision to correct higher-order aberrations (HOAs) specific to each patient’s refractive needs [2]. Initially, custom correction of HOAs relied on aberrometry before the development of corneal topography, which enabled interactive elevation mapping [3]. In topography-guided laser in situ keratomileusis (LASIK; Alcon Laboratories, Inc., Fort Worth, TX, USA), the WaveLight Topolyzer VARIO topography system captures 22,000 points across the corneal surface to treat peripherally located irregularities, which account for most HOAs [4, 5].
In addition to topography-guided LASIK, wavefront-guided LASIK uses a customized ablation pattern to correct existing HOAs and minimize the induction of new aberrations [6]. Wavefront-guided ablation addresses all ocular aberrations in addition to the refractive errors, while topography-guided ablation primarily aims to treat corneal surface irregularities, defocus, and astigmatism [7]. Neither approach, however, precisely accounts for all refractive elements of the eye [8, 9].
Ray tracing-guided LASIK was developed to address these limitations by generating a customized optical eye model, or “eyevatar,” that simulates adjustments to the anterior corneal surface until the ideal wavefront is achieved [10]. This new algorithm tracks the directional changes of light passing through the eye to calculate both lower-order aberrations (spherocylindrical refraction) and HOAs [8, 11]. The WaveLight Plus software then creates an eye model using these measurements and automatically calculates a customized laser ablation profile [10]. Unlike its predecessors, the ray-tracing laser ablation pattern does not rely on subjective refraction but instead uses data from the three-in-one InnovEyes Sightmap (Alcon Laboratories, Inc.) diagnostic device [12].
Both topography-guided and ray tracing-guided LASIK have demonstrated safety and efficacy that meet the rigorous standards required by the U.S. Food and Drug Administration (FDA) [13, 14]. The superiority of one ablation profile over the other has yet to be established, as the ray-tracing automated customization tool was introduced commercially only recently.
This study aims to conduct a head-to-head analysis of two U.S. FDA premarket approval (PMA) trials, providing a detailed evaluation of approved excimer lasers by Alcon: topography-guided LASIK with the Allegretto Wave Eye-Q laser system, featuring the WaveLight Topolyzer and topography-guided custom ablation (T-CAT) software, and ray tracing-guided LASIK performed with the WaveLight EX500 laser and InnovEyes Sightmap device.
Methods
Visual and refractive outcomes of two FDA PMA studies were compared: (1) topography-guided LASIK performed with the Allegretto Wave Eye-Q excimer laser, WaveLight Topolyzer, and T-CAT treatment planning software (P020050/S012), approved in 2013, and (2) ray tracing-guided LASIK (WaveLight Plus) performed with the WaveLight EX500 excimer laser (P020050/S043) and using an ablation profile generated by the InnovEyes Sightmap, approved in 2025. In this analysis, the FDA PMA trials are referred to as the TG-LASIK and RT-LASIK studies.
This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.
The refractive inclusion criteria for the TG-LASIK study were myopia of up to − 9.00 D, astigmatism up to − 6.00 D, and spherical equivalent (SEQ) up to − 9.00 D in one or both eyes. The RT-LASIK study included patients with a sphere of up to − 11.00 D, with or without astigmatism of up to − 4.50 D (measured by the InnoveEyes Sightmap using wavefront objective refraction at a 4-mm analysis zone), and no more than − 12.00 D of SEQ in both eyes. Both studies enrolled patients aged 18 years or older. Exclusion criteria, described in detail in the PMAs [13, 14], were relatively similar between studies and included prior intraocular or corneal surgery, abnormal topography, eyes intended for monovision, predicted residual stromal bed thickness of less than 250 μm, as well as systemic autoimmune disease. The TG-LASIK study also excluded eyes with clinically significant lenticular astigmatism, while the RT-LASIK study excluded those with more than 0.75 D SEQ difference between cycloplegic and subjective manifest refractions. Although both studies had relatively broad enrollment criteria, the approved U.S. indications allow up to − 9.00 D of SEQ for TG-LASIK, with a maximum of − 8.00 D of sphere and up to − 3.00 D of cylinder, whereas RT-LASIK is approved for SEQ between − 1.00 and − 9.00 D, sphere up to − 8.00 D, and cylinder up to − 3.00 D. No nomogram adjustments were noted in either clinical trial.
Patients were followed for up to 12 months in both studies, including preoperatively and at 1 day, 1 week, 1 month, 3 months, 6 months, 9 months, and 12 months postoperatively. Preoperative assessments included cycloplegic and manifest refraction, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), slit-lamp biomicroscopy, dilated fundus examination, intraocular pressure measurements, patient questionnaires, and mesopic contrast sensitivity at 3 cd/m2 under glare and non-glare conditions across spatial frequencies 1.5, 3, 6, and 12 cycles per degree (cpd). Although photopic contrast sensitivity and 18 cpd were also assessed in the TG-LASIK study, our analysis compared only mesopic contrast sensitivity at 1.5, 3, 6, and 12 cpd. In the RT-LASIK study, aberrometry, biometry, keratometry, pachymetry, topography, and wavefront refraction were collected using a single diagnostic device, the InnovEyes Sightmap. In contrast, the TG-LASIK study required separate instruments: aberrometry data were obtained using the WaveLight Analyzer and Topolyzer, while topographic and keratometric measurements were obtained using only the Topolyzer.
Primary visual outcomes of both studies included efficacy using the cumulative postoperative UDVA and the difference in Snellen lines between preoperative CDVA and postoperative UDVA. Safety was assessed by changes in CDVA lines postoperatively compared to preoperative CDVA. Refractive stability was measured by changes in SEQ and cylinder over a 12-month period. Vector analysis was evaluated at the 3-month visit when refractive stability was achieved, which included correction ratio (CR), intended refractive correction, surgically induced refractive correction, error ratio, and error vector for the RT-LASIK study only. Axis shift, defined as the absolute difference between the preoperative and postoperative axes, was also performed in each study. Our analysis compared CR and axis shift between platforms, stratified by the amount of preoperative astigmatism. The two studies reported slightly different cutoff ranges for the refractive bins, ranging from 0.0 to − 6.00 D for TG-LASIK and 0.0 to − 4.50 D for RT-LASIK; only corresponding bins were included in our comparison.
For TG-LASIK, aberrometry data from the Topolyzer were recorded using a diameter 0.5 mm smaller than the treatment optical zone (OZ) at preoperative and 3 months. Most eyes were treated with a 6.5 mm OZ, although diameters of 6.0 and 7.0 mm were also included. The TG-LASIK study reported a mean root mean square (RMS) value for third- to eighth-order aberrations, with aberrations above the fifth order considered negligible. For RT-LASIK, HOA measurements were collected using the InnovEyes Sightmap at preoperative and 3 months, with diameters rescaled to represent pupil diameters of 4 mm and 5.5 mm. Given that the TG-LASIK study reported quantitative data at a 6.5 mm HOA diameter, we analyzed RT-LASIK data at a diameter of 5.5 mm to enable the most precise side-by-side comparison between platforms.
Patient-reported outcomes were assessed using the Patient-Reported Outcomes with LASIK (PROWL) questionnaire and Ocular Surface Disease Index (OSDI) scores for dry eye symptoms in the RT-LASIK study, and the TG-LASIK study used a 12-item self-administered visual symptoms questionnaire with a graded severity scale (none, mild, moderate, marked, and severe) and a Refractive Status and Vision Profile questionnaire (RSVP) to assess changes in vision-related health status (symptoms, functioning, expectations, and concern) [3, 15]. These were administered at all visits except the 1-month visit in the RT-LASIK study. Both FDA trials reported several categories of visual complaints, but only comparable data were analyzed in our study, including halos, glare, starburst, double vision, and dry eye symptoms. The RT-LASIK study reported outcomes in percentage of patients, while the TG-LASIK study reported percentage of eyes. Adverse events and complications were recorded at all postoperative visits.
Statistical Analysis
Statistical analyses were conducted using SPSS (version 30.0; IBM Corporation, Armonk, NY) and Microsoft Excel software (version 16.97; Microsoft Corporation, Redmond, WA). Due to the absence of raw data, normality tests such as the Shapiro–Wilk test and the Kolmogorov–Smirnov test could not be performed. However, normality of the sampling distribution was assumed based on the large sample sizes [16]. Welch’s t-test was used to compare continuous variables in demographic data. Categorical variables were assessed using Pearson’s chi-square test and Fisher’s exact test when appropriate. A P value less than 0.05 was considered statistically significant.
Results
Patient Characteristics
A total of 583 eyes underwent either TG-LASIK or RT-LASIK in the FDA clinical trials (Table 1). Of the 249 eyes (212 patients) in the TG-LASIK study, 93 (43.8%) were male and 119 (56.1%) were female, with a mean age of 34.0 ± 9.3 years. The RT-LASIK study enrolled 336 eyes (168 patients), with baseline data available for 334 eyes (167 patients), including 62 (37.1%) males and 105 (62.9%) females, and a mean age of 33.3 ± 7.0 years.
Table 1.
Patient characteristics
| Parameter | Topography-guided n = 212 patients |
Ray tracing-guided n = 167 patients |
P |
|---|---|---|---|
| Age, yearsa | 34.0 ± 9.3 (18 to 65) | 33.3 ± 7.0 (21 to 56) | 0.401 |
| Sex, men/women, n (%) | 93 (43.9%)/119 (56.1%) | 62 (37.1%)/105 (62.9%) | 0.185 |
| SEQ (D)a | − 4.61 ± 2.43 | − 4.88 ± 2.89b | 0.221 |
| Sphere (D) | n = 249 eyes | n = 334 eyes | |
| All eyes | − 4.01 ± 2.57 | − 4.34 ± 2.45b | 0.118 |
| 0.00 to ≤ − 1.00 | 39 | 29 | 0.009* |
| > − 1.00 to ≤ − 2.00 | 41 | 47 | 0.423 |
| > − 2.00 to ≤ − 3.00 | 27 | 44 | 0.395 |
| > − 3.00 to ≤ − 4.00 | 33 | 35 | 0.302 |
| > − 4.00 to ≤ − 5.00 | 21 | 36 | 0.395 |
| > − 5.00 to ≤ − 6.00 | 27 | 41 | 0.594 |
| > − 6.00 to ≤ − 7.00 | 21 | 48 | 0.028* |
| > − 7.00 to ≤ − 8.00 | 23 | 34 | 0.705 |
| > − 8.00 to ≤ − 9.00 | 17 | 14 | 0.161 |
| > − 9.00 to ≤ − 10.00 | – | 6 | – |
| Cylinder (D) | |||
| All eyes | − 1.19 ± 1.23 | − 1.09 ± 0.94b | 0.285 |
| 0.00 to ≤ − 0.50 | 111c | 114 | 0.218 |
| > − 0.50 to ≤ − 1.00 | 45 | 96 | 0.004* |
| > − 1.00 to ≤ − 2.00 | 43 | 65 | 0.500 |
| > − 2.00 to ≤ − 3.00 | 29 | 40 | 0.903 |
| > − 3.00 to ≤ − 4.00 | 12 | 18 | 0.758 |
| > − 4.00 to ≤ − 5.00 | 7 | 1d | 0.009* |
| > − 5.00 to ≤ − 6.00 | 2 | – | – |
| > − 0.50 to ≤ − 4.00 | 129 | 219 | 0.003* |
SEQ spherical equivalent, D diopters
aValues expressed as mean ± SD (range for age)
bMean SEQ ± SD was approximated using the midpoint of each refractive bin, weighed by the number of eyes in each bin
c38 eyes with 0.00 D of cylinder were merged into 0.00 to ≤ − 0.50 D bin
dRefractive bin includes cylinder up to − 4.50 D
*Indicates statistically significant (P < 0.05)
In the TG-LASIK PMA trial, 19 eyes (7.6%) in 17 subjects were discontinued or lost to follow-up by 12 months, resulting in 230 eyes (92.4%) available for analysis. The RT-LASIK study reported that ten eyes (3.0%) were discontinued or lost to follow-up, leaving 326 eyes (97.0%) for the 12-month evaluation.
Despite varying inclusion criteria, the overall mean SEQ and cylinder were not statistically different between each FDA study (P > 0.05). However, stratifying by refractive bins, significant preoperative differences were observed between the TG-LASIK and RT-LASIK data in the following ranges: sphere 0.00 to − 1.00 D, and − 6.01 to − 7.00 D; and cylinder − 0.51 to − 1.00 D and − 4.01 to − 5.00 D (Table 1). Specifically, the TG-LASIK PMA trial had a greater proportion of eyes with simple myopia (P = 0.009), whereas the RT-LASIK study included more eyes with high myopia between − 6.01 to − 7.00 D (P = 0.028). In addition, more eyes in the TG-LASIK study had a preoperative cylinder between − 4.01 to − 5.00 D (P = 0.009), while the RT-LASIK study had more eyes in the − 0.51 to − 1.00 D cylinder range (P = 0.004). Merging all cylinder bins − 0.50 to − 4.00 D, the RT-LASIK study included a higher proportion of eyes with astigmatism compared to the TG-LASIK study (65.6% vs. 51.8%, P = 0.003).
Visual Acuity Analysis
All eyes included in the FDA trials were targeted for emmetropia. Across postoperative visits 3, 6, and 12 months, the TG-LASIK study demonstrated a higher proportion of eyes achieving a UDVA of 20/10 and 20/12.5 or better compared to the RT-LASIK study (Fig. 1). At 9 months, 12.7% of TG-LASIK eyes achieved a UDVA of 20/10 or better compared to only 2.2% of RT-LASIK eyes (P < 0.001) (Fig. 1C). By 12 months, 15.7% of eyes in the TG-LASIK trial and 2.5% of eyes in the RT-LASIK trial reached a UDVA of 20/10 or better (P < 0.001) (Fig. 1D). Similarly, 34.4% of TG-LASIK eyes and 26.4% of RT-LASIK eyes achieved a UDVA of 20/12.5 or better at 12 months (P = 0.044). The proportion of eyes achieving a UDVA of 20/16 or better (64.8% TG-LASIK vs. 70.2% RT-LASIK) and 20/20 or better (92.6% TG-LASIK vs. 94.4% RT-LASIK) was comparable between studies at 12 months (both P > 0.05).
Fig. 1.
Cumulative postoperative uncorrected distance visual acuity (UDVA) at A 3 months, B 6 months, C 9 months, and D 12 months between topography-guided and ray tracing-guided LASIK. *Indicates statistically significant (P < 0.05)
At 12 months, 89.2% of TG-LASIK eyes achieved a postoperative UDVA equal to or better than preoperative CDVA, compared to 90.1% of RT-LASIK eyes (Fig. 2D). However, more TG-LASIK eyes (30.9%) compared to RT-LASIK eyes (14.0%) demonstrated postoperative UDVA that was at least one line better than baseline CDVA (P < 0.001), including more eyes with improvements of more than two lines (3.0% vs. 0%, P = 0.002).
Fig. 2.
Difference between postoperative uncorrected distance visual acuity (UDVA) and preoperative corrected distance visual acuity (CDVA) for topography-guided and ray tracing-guided LASIK at A 3 months, B 6 months, C 9 months, and D 12 months. *Indicates statistically significant (P < 0.05)
When assessing safety parameters at 12 months, 10.4% of eyes in the TG-LASIK study gained two lines of CDVA (P < 0.001) and 3.0% gained more than two CDVA lines (P = 0.002), compared with 1.9% of eyes and no eyes in the RT-LASIK study, respectively (Fig. 3D). The TG-LASIK PMA reported four eyes (1.6%) that lost two or more CDVA lines at scheduled or unscheduled visits during the study. These were identified as transient, unrelated to the procedure, or resolved by the subsequent follow-up. In comparison, four eyes (1.2%) lost two CDVA lines in the ray-tracing-guided PMA across the 12 months, while no eyes lost more than two lines.
Fig. 3.
Change in corrected distance visual acuity (CDVA) at A 3 months, B 6 months, C 9 months, and D 12 months between topography-guided and ray tracing-guided LASIK. *Indicates statistically significant (P < 0.05)
Refractive Analysis
The RT-LASIK PMA data did not report postoperative refractive means. In contrast, the mean SEQ with TG-LASIK improved from − 4.61 ± 2.43 D preoperatively to 0.06 ± 0.33 D at 3 months, and to 0.00 ± 0.27 D by 12 months. From 3 to 12 months, 91.9% or more eyes in this group were within ± 0.50 D of the intended SEQ (Table 2). Similarly, at least 90.9% of RT-LASIK eyes were within ± 0.50 D of the target. Both groups demonstrated stable results postoperatively with minimal changes over the 12 months that were not statistically significant. However, between 3 and 6 months, the mean SEQ shift was more myopic for TG-LASIK eyes (P = 0.003).
Table 2.
Predictability and stability outcomes between topography-guided and ray tracing-guided LASIK across 12 months
| Parameter | Topography-guided | Ray tracing-guided | P | Topography-guided | Ray tracing-guided | P | Topography-guided | Ray tracing-guided | P | Topography-guided | Ray tracing-guided | P |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Predictability (% of eyes) |
3 months | 6 months | 9 months | 12 months | ||||||||
| n = 247 | n = 326 | n = 244 | n = 330 | n = 237 | n = 320 | n = 230 | n = 322 | |||||
| SEQ within ± 0.50 D | 91.9 | 92.0 | 0.958 | 93.0 | 90.9 | 0.359 | 93.3 | 90.9 | 0.322 | 94.8 | 94.4 | 0.849 |
| SEQ within ± 1.00 D | 98.8 | 98.5 | 0.747 | 98.8 | 98.2 | 1.00 | 99.2 | 99.1 | 1.00 | 99.6 | 99.7 | 1.00 |
| SEQ stabilitya | 1–3 months | 3–6 months | 6–9 months | 9–12 months | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n = 227 | n = 326 | n = 227 | n = 326 | n = 227 | n = 316 | n = 227 | n = 314 | |||||
| Change in SEQ (D) | – 0.008 ± 0.07 | – 0.011 ± 0.306 | 0.864 | – 0.044 ± 0.06 | 0.010 ± 0.323 | 0.003* | – 0.017 ± 0.06 | – 0.018 ± 0.295 | 0.953 | 0.014 ± 0.06 | 0.0 ± 0.267 | |
| Cyl stabilitya | 1 to 3 months | 3 to 6 months | 6 to 9 months | 9 to 12 months | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n = 191 | n = 326 | n = 191 | n = 326 | n = 191 | n = 316 | n = 191 | n = 314 | 0.370 | ||||
| Change in Cyl (D)b | 0.037 ± 0.08 | 0.026 ± 0.270 | 0.493 | 0.012 ± 0.06 | 0.004 ± 0.249 | 0.581 | – 0.013 ± 0.06 | – 0.017 ± 0.237 | 0.775 | – 0.005 ± 0.04 | 0.021 ± 0.211 | 0.034* |
D diopters, SD standard deviation, SEQ spherical equivalent, Cyl cylinder
aValues expressed as mean ± standard deviation
bRay tracing-guided study reported values as the change of absolute cylinder
*Indicates statistically significant (P < 0.05)
Astigmatic Correction
At all preoperative cylinders from − 0.50 to − 4.00 D, RT-LASIK showed greater correction of cylinder than TG-LASIK (Table 3). Although the cylinder ranges of − 0.50 to − 1.00 D and − 4.00 to − 5.00 D were statistically different between groups at baseline, all other preoperative cylinder bins were similar (Table 1). Specifically, for preoperative cylinders ranging from − 1.00 to − 4.00 D, RT-LASIK showed a correction ratio (CR) between 1.11 to 1.13, which was significantly greater than that of TG-LASIK (0.93 to 0.96; P < 0.05).
Table 3.
Comparison of correction ratios between topography-guided and ray tracing-guided LASIK at 3 months
| Preoperative cylinder (D) | Topography-guided n = 129 eyesa |
CR = SIRC / IRC (mean ± SD) |
Ray tracing-guided n = 181 eyes |
CR = SIRC/IRC (mean ± SD) |
P |
|---|---|---|---|---|---|
| > – 0.50 to ≤ – 1.00 | 45 | 1.02 ± 0.25 | 76 | 1.15 ± 0.35 | 0.019* |
| > – 1.00 to ≤ – 2.00 | 43 | 0.93 ± 0.18 | 57 | 1.13 ± 0.29 | < 0.001* |
| > – 2.00 to ≤ – 3.00 | 29 | 0.93 ± 0.15 | 31 | 1.13 ± 0.19 | < 0.001* |
| > – 3.00 to ≤ – 4.00 | 12 | 0.96 ± 0.15 | 17 | 1.11 ± 0.15 | 0.012* |
D diopters, CR correction ratio, SIRC surgically induced refractive correction, IRC intended refractive correction, SD standard deviation
aPreoperative cylinder bins 0.00 to – 0.50 D (n = 72), – 4.00 to – 5.00 D (n = 7), and – 5.00 to – 6.00 D (n = 2) from the topography-guided study are excluded from the analysis, as the ray tracing-guided study had preoperative cylinder values ranging from – 0.50 to – 4.50 D
*Indicates statistically significant (P < 0.05)
The mean postoperative cylinder was not reported in the RT-LASIK study. In contrast, the TG-LASIK clinical trial showed improvement from − 1.19 ± 1.23 D at baseline to − 0.19 ± 0.32 D at 3 months, which remained stable at 12 months (-0.19 ± 0.30 D). Between 9 and 12 months, the magnitude of cylinder change was − 0.005 ± 0.04 D in TG-LASIK eyes, whereas RT-LASIK eyes had a greater residual cylinder of 0.021 ± 0.211 D (P = 0.034) (Table 2). Cylinder changes remained stable at all other time points from 1 to 9 months for both studies (P > 0.05). Regarding axis shift at 3 months, 7.1% of TG-LASIK eyes and 2.8% of RT-LASIK eyes had an absolute axis shift between 15° and 30°, which was marginally significant (P = 0.049) (Table 4).
Table 4.
Absolute axis shift stratified by residual astigmatic magnitude at 3 months
Values expressed as number of eyes (% of eyes)
aAstigmatic myopia is defined as eyes with a preoperative manifest refraction cylinder of > – 0.5 D
bAxis shifts are defined to be zero for eyes with zero residual cylinder magnitude
*Indicates statistically significant difference between the total number of eyes for each platform (P < 0.05)
Contrast Sensitivity
For both platforms, 3-month mesopic contrast sensitivity improved from baseline across all four spatial frequencies under both glare and non-glare conditions (Table 5). There was a small but statistically significant difference between platforms at 3, 6, and 12 cpd with glare and 1.5 cpd without glare. Specifically, RT-LASIK showed a greater improvement at 3 cpd (P = 0.018), 6 cpd (P = 0.015), and 12 cpd (P < 0.001) with glare, while TG-LASIK showed a greater improvement at 1.5 cpd without glare (P = 0.032). Eyes unable to detect any contrast level were excluded from both studies, which was noted to inflate mean values and reduce standard deviation in the TG-LASIK study.
Table 5.
Changes in Log10 mesopic contrast sensitivity from preoperative to 3 months
| Parameter | Topography-guided n = 247 eyes |
Na | Ray tracing-guided n = 330 eyes |
Nb | P |
|---|---|---|---|---|---|
| Without glare | |||||
| 1.5 cpd | 0.061 ± 0.181 | 243 | 0.018 ± 0.298 | 330 | 0.032* |
| 3 cpd | 0.037 ± 0.495 | 243 | 0.050 ± 0.261 | 330 | 0.714 |
| 6 cpd | 0.083 ± 0.251 | 239 | 0.118 ± 0.373 | 330 | 0.179 |
| 12 cpd | 0.043 ± 0.310 | 204 | 0.074 ± 0.417 | 330 | 0.323 |
| With glare | |||||
| 1.5 cpd | 0.065 ± 0.227 | 239 | 0.096 ± 0.459 | 330 | 0.283 |
| 3 cpd | 0.050 ± 0.232 | 239 | 0.115 ± 0.413 | 330 | 0.018* |
| 6 cpd | 0.090 ± 0.303 | 226 | 0.168 ± 0.451 | 328 | 0.015* |
| 12 cpd | 0.018 ± 0.317 | 176 | 0.174 ± 0.476 | 326 | < 0.001* |
SD standard deviation, cpd cycles per degree
Values expressed as mean ± standard deviation
aNumber of eyes represents the paired difference between preoperative and postoperative; patients were excluded from the mean calculation if they could not see any contrast level
bEight eyes were excluded from the mean calculation at a particular spatial frequency, as they were unable to see the reference pattern
*Indicates statistically significant (P < 0.05)
A clinically significant change in contrast sensitivity is defined as ≥ 0.30 log unit decrease (loss) or increase (gain) at two or more spatial frequencies compared to baseline. At 3 months, more eyes treated by RT-LASIK than TG-LASIK showed a clinically significant increase in contrast sensitivity with glare (40.0% vs. 23.8%, P < 0.001), but not under non-glare conditions (25.2% vs. 20.5%, P = 0.210). The rate of clinically significant contrast sensitivity loss did not differ between RT-LASIK and TG-LASIK, both with glare (15.8% vs. 11.9% of eyes, P > 0.05) and without glare (10.0% vs. 7.1% of eyes, P > 0.05).
HOA Analysis
Direct statistical comparisons of HOAs could not be performed between studies due to variation in analysis diameters. In the TG-LASIK study, both the WaveLight Analyzer aberrometer and the WaveLight Topolyzer were utilized for whole eye and corneal HOA measurements, respectively. The WaveLight Analyzer showed a significant decrease in defocus and astigmatism RMS magnitudes at 3 and 6 months (P < 0.05). TG-LASIK induced significant coma, while trefoil, spherical aberrations, and tetrafoil were relatively unchanged at 3 and 6 months. When measured with the Topolyzer at a 6.5 mm diameter, total HOAs (2nd- through 5th-order) decreased slightly to 0.0537 ± 0.0034 μm at 3 months from 0.0589 ± 0.0022 μm at baseline (Fig. 4A) [3]. Similarly, RT-LASIK at a diameter of 5.5 mm showed an increase in absolute total HOAs from 0.254 ± 0.071 μm preoperatively to 0.314 ± 0.127 μm at 3 months, due to a slight induction of coma (Fig. 4B). Spherical aberrations also decreased in magnitude; however, similar to TG-LASIK, trefoil remained relatively unchanged.
Fig. 4.
Comparison of total higher-order aberrations (HOAs) from preoperative to 3 months following A topography-guided LASIK at an HOA analysis diameter of 6.5 mm or B ray tracing-guided LASIK at 5.5 mm. Topography-guided LASIK data includes 2nd- through 5th-order aberrations, as all terms through the 8th order were considered negligible to the total root mean square (RMS) value. Values are expressed as mean ± standard deviation
Patient-Reported Outcomes
The prevalence of visual symptoms at the preoperative and 12-month visit for each study is shown in Fig. 5. TG-LASIK data (Fig. 5A) represent changes in the percentage of eyes reporting moderate to severe symptoms from baseline to 12 months. The RT-LASIK data (Fig. 5B) reflect symptom prevalence responses from the PROWL questionnaire and the distribution of OSDI scores for dry eye symptoms, both expressed as a percentage of patients. Differences in questionnaires and data reporting formats between platforms made a statistical comparison not feasible. The FDA PMA for TG-LASIK reported changes in severity using two categories: none to moderate and marked to severe. This showed a statistically significant reduction in the severity of glare, halos, and starbursts from baseline. Conversely, our analysis for both platforms showed significant reductions in the severity of double vision and dry eye, in addition to glare, halos, and starbursts at 12 months (all P < 0.05).
Fig. 5.
Comparison of visual symptoms from baseline to 12 months postoperatively between A topography-guided LASIK (reported as % of eyes) and B ray tracing-guided LASIK (reported as % of patients). All visual symptoms for the topography-guided study were quantified on a 5-point scale: none, mild, moderate, marked, and severe. The number of patients who reported moderate to severe symptoms was summed and reported. For the ray tracing-guided study, the incidence of dry eye symptoms reflects the total number of patients who reported mild (13–22), moderate (23–32), or severe (33–100) responses, based on the Ocular Surface Disease Index scores from 0 to 100. *Indicates statistically significant (P < 0.05). †One patient omitted rating for starbursts at 12 months, n = 229 eyes
Complications
Of the 336 eyes treated with RT-LASIK, 37 eyes (11.0%) experienced ocular complications over the 12-month study, including corneal flap complications in 11 eyes (3.3%), dry eye symptoms in three eyes (0.9%), punctal plug insertion in two eyes (0.6%), and diffuse lamellar keratitis (DLK) in three eyes (0.9%). Serious adverse events occurred in four eyes (1.2%) of three patients, including two eyes (0.6%) with a retinal tear.
In the TG-LASIK study, 12 eyes of 249 (4.8%) developed DLK, including four eyes that were documented at unscheduled visits. In addition, 33 eyes of 247 (13.4%) had dry eye requiring punctal plugs or ocular lubricants at three months or later, six of which were documented at unscheduled visits. No corneal flap complications occurred at 1 month or later, including miscreated flaps, melting flaps, or any corneal defect involving the keratectomy site. Two of 244 eyes (0.8%) in the same subject developed retinal detachments at approximately 6 months postoperatively, which was deemed unrelated to the TG-LASIK treatment. Neither study reported any retreated eyes during the 12 months.
Discussion
The U.S. FDA PMA data show superior visual outcomes with TG-LASIK compared to the recently introduced RT-LASIK, reporting more eyes achieving a UDVA of 20/10 and 20/12.5 or better (Fig. 1D), and greater improvements in postoperative UDVA relative to preoperative CDVA (Fig. 2D). Although impressive, both TG-LASIK and RT-LASIK studies demonstrated excellent results overall, with more than 25% of eyes reaching a UDVA of 20/12 or better, 64% with 20/16 or better, 94% with 20/20 or better, and 24% gaining one line of CDVA (Tables 6 and 7).
Table 6.
Summary of postoperative visual outcomes from published literature of topography-guided LASIK
| Study (year) | Country | Eyes | Follow-up (m) | Efficacy | Predictability | Safety | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UDVA 20/12.5 or better | UDVA 20/16 or better | UDVA 20/20 or better | UDVA same or better than preop CDVA | SEQ ± 0.25 D | SEQ ± 0.50 D | Cyl ± 0.25 D | Cyl ± 0.50 D | Loss 1 line of CDVA | No change in lines of CDVA | Gain 1 line of CDVA | Gain ≥ 2 lines of CDVA | ||||
| Published studies | |||||||||||||||
| Tan et al. (2012) [20] | Singapore | 2051 | 3 | 1.8% | 41.5% | 73.5% | 86.9% | – | 86.1% | – | 97.9%c | 12.7% | 62.9% | 22.1% | 1.9% |
| Kim et al. (2019) [31] | South Korea | 43 | 3 | 25.6% | 60.5% | 90.7% | – | – | 65.1% | 62.8% | 86.1% | – | – | – | – |
| De Stefano et al. (2019) [32] | US | 256 | 3 | – | 81.4%d | 95.7% | – | – | 98.4% | – | – | 2.3% | – | 25.6%f | – |
| Lobanoff et al. (2020): MRx [17] | US | 317 | 2 to 5 | – | 41.3% | 94.0% | 78.0% | 84.9% | – | ~ 83.0% | 96.0% | 0% | ~ 55.0% | 30.3%f | – |
| Lobanoff et al. (2020): PAE [17] | US | 323 | 2 to 5 | – | 62.5% | 94.0% | 85.0% | 81.4% | – | ~ 81.0% | 96.0% | 0% | ~ 52.0% | 42.7%f | – |
| Cao et al. (2024)a [23] | China | 42 | 3 | 5.0% | 90.0% | 98.0% | 95.0% | – | 95.2% | 52% | 76.2% | – | – | – | – |
| Stulting et al. (2022): PAE [21] | US | 130 | 3 | 28.0% | 89.0%d | 100% | 92.0% | – | 100% | 99.0% | 100% | 1.0% | 53.0% | 40.0% | 6.0% |
| Sachdev et al. (2023): MRx [19] | India | 30 | 3 | 0% | 0% | 70.0% | – | 87.0% | 90.0% | 73.0% | 90.0% | 0% | 83.3% | 10.0% | 6.6% |
| Sachdev et al. (2023): PAE [19] | India | 30 | 3 | 0% | 0% | 70.0% | – | 87.0% | 94.0% | 77.0% | 87.0% | 3.3% | 90.0% | 6.6% | 0% |
| Rush et al. (2023): PAE [29] | US | 92 | 6 ± 0.9e | 87.0% | 100% | 100% | – | 96.7% | – | 92.4% | 97.8% | 0% | 17.4% | 69.9% | 13.0% |
| Saleh et al. (2024) [18] | US | 60g | 12 | 27.0% | 67.0% | 96.0% | 67.0% | 48.0% | 96.0% | – | – | 19.0% | 40.0% | 25.0% | 12.0% |
| Mean (Published studies) | 21.8% | 57.6% | 89.3% | 84.0% | 80.8% | 90.6% | 77.5% | 91.9% | 4.3% | 56.7% | 30.2% | 6.6% | |||
| U.S. FDA PMA (2013) (P020050/S012) [13] | US | 249 | 12 | 34.4% | 64.8% | 92.6% | 89.1% | – | 94.8% | 77.0%b [3] | 90.0%b [3] | 2.2% | 57.0% | 27.0% | 13.4% |
UDVA uncorrected distance visual acuity, SEQ spherical equivalent, D diopters, CDVA corrected distance visual acuity, Cyl cylinder, PAE Phorcides Analytic Engine, MRx manifest refraction, m months
aProspective contralateral eye study
bReported from Stulting et al. at 6 months [3]
cOut of 2009 eyes
dReported as 20/15
eConverted from weeks (26 ± 4 weeks)
fGain of 1 or more lines
g52 eyes at 12-month follow-up
Table 7.
Summary of postoperative visual outcomes from published literature of ray tracing-guided LASIK
| Study (year) | Country | Eyes | Follow-up (m) | Efficacy | Predictability | Safety | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UDVA 20/12.5 or better | UDVA 20/16 or better | UDVA 20/20 or better | UDVA same or better than preop CDVA | SEQ ± 0.25 D | SEQ ± 0.50 D | Cyl ± 0.25 D | Cyl ± 0.50 D | Loss 1 line of CDVA | No change in lines of CDVA | Gain 1 line of CDVA | Gain ≥ 2 lines of CDVA | ||||
| Published studies | |||||||||||||||
| He & Bala (2023): OD [10] | Australia | 200 | 3 | 54.0% | 90.0% | 100% | 85.0% | 59.0% | 97.0% | 84.0% | 97.0% | 6.0% | 46.0% | 41.0% | 7.0% |
| He & Bala (2023): OS [10] | Australia | 200 | 3 | 47.0% | 89.0% | 100% | 83.0% | 54.0% | 96.0% | 80.0% | 96.0% | 4.5% | 46.5% | 39.4% | 9.1% |
| Kanellopoulos (2024) [24] | Greece | 40 | 24 | 25.0% | 87.5% | 100% | – | – | 95% | ~ 47.0% | ~ 85.0% | 0% | 17.5% | 65.0% | 17.5% |
| Cao et al. (2024)a [23] | China | 42 | 3 | 48.0% | 98.0% | 100% | 100% | – | 90.5% | 52.0% | 85.7% | – | – | – | – |
| Kanellopoulos et al. (2024) [26] | Multicenterb | 222 | 3 | 48.0% | 82.5% | 98.1% | 96.0% | 74.1% | 92.0% | 86.0% | 99.0% | 0.5% | 63.7% | 32.1% | 3.8% |
| Khoramnia et al. (2025) [9] | Germany | 30 | 3 | 23.0% | 83.0% | 100% | 90.0% | 83.3% | 100% | 88.5% | 100% | 0% | 87.0% | 13.0% | 0% |
| Luo et al. (2025) [27] | China | 77 | 3 | 14.0% | 66.0% | 100% | 86.0% | – | 97.0% | 83.0% | 97.0% | 0% | 39.0% | 55.0% | 6.0% |
| Yuan et al. (2024)a [28] | China | 34 | 3 | 32.0% | 94.0% | 100% | 91.0% | – | 88.0% | 71.0% | 85.0% | 6.0% | 47.0% | 47.0% | 0% |
| Mean (Published studies) | 36.4% | 86.3% | 99.8% | 90.1% | 67.6% | 94.4% | 73.9% | 93.1% | 2.4% | 49.5% | 41.8% | 6.2% | |||
|
U.S. FDA PMA (2025) (P020050/S043) [14] |
US | 334 | 12 | 26.4% | 70.2% | 94.4% | 90.1% | – | 94.4% | – | 83.6% | 1.9% | 71.1% | 24.8% | 1.9% |
UDVA uncorrected distance visual acuity, SEQ spherical equivalent, D diopters, CDVA corrected distance visual acuity, Cyl cylinder, OD right eye, OS left eye, m months
aProspective contralateral eye study
bInternational, multicenter study including Germany, Australia, and Greece
However, the remarkable visual outcomes achieved by the U.S. FDA in the TG-LASIK PMA study were not reproducible in routine clinical practice. Following its FDA approval in 2013, clinicians observed discrepancies when comparing the magnitude and axis of astigmatism between manifest refraction and Topolyzer VARIO topographic data [17]. This may have been attributed to the exclusion of eyes with either an abnormal topography or large disparities between manifest and topographic cylinder magnitudes. As a result, the study’s population predominantly included patients with simple myopia and low astigmatism. Alternative strategies were proposed to address this limitation and determine the appropriate entry for spherocylindrical treatment planning. Among these was the Phorcides Analytic Engine (PAE; Phorcides LLC, North Oaks, MN, USA), a software that compiles refractive vectors from anterior and posterior corneal astigmatism, topographic irregularities, and internal ocular astigmatism to provide a more responsive ablation pattern that accounts for corneal asymmetry [17–19]. In 2020, Lobanoff et al. found that 62.5% of 323 eyes treated with PAE achieved 20/16 UDVA, and 42.7% gained one or more lines of CDVA, compared with treatment based on manifest refraction (Table 6) [17]. Despite discrepancies between the cylinder magnitude and axis in their patient population, they were still able to achieve favorable outcomes.
It is still difficult to overlook the extensive planning required to perform TG-LASIK with Contoura Vision, despite its potential for higher rates of 20/12.5 and 20/10 UDVA. The calculation is finalized only after several steps with high-quality, reproducible scans using the Topolyzer VARIO. Scan quality requires time and depends on the absence of artifacts (e.g., eyelids, lashes, tear film), completeness of data within the planned OZ (≥ 70% analyzed area), and proper horizontal alignment [20]. Four to eight maps with the lowest median absolute deviation are averaged, then exported to the T-CAT software. PAE planning may simplify the process by adjusting the spherical component and compensating for mid-periphery ablation effects [21]. However, even with meticulous preparation and an ideal candidate, TG-LASIK treatment might still not be feasible. Clinicians may have to revert to wavefront-optimized LASIK by simply using their well-refined nomograms. For these reasons, TG-LASIK has not been widely adopted, and refractive surgeons continue to favor wavefront-optimized approaches due to its ease of preparation and established reliability in routine LASIK procedures.
Although TG-LASIK addresses the disadvantages of conventional spherocylindrical ablation, this method does not correct all optical errors of the eye [21]. RT-LASIK may offer greater potential by reconstructing individual eye models from all optically relevant structures and performing calculations automatically without nomogram adjustments. This single device integrates multiple diagnostic measurements, including Hartmann–Shack total eye wavefront analysis, Scheimpflug corneal tomography, pachymetry, and axial length data (partial coherence interferometry) [10]. Though the new ray-tracing software was introduced to the United States in 2025, the algorithm was first applied a decade ago in a study of 127 eyes with moderate to high myopic astigmatism [22]. The authors reported that UDVA was 20/20 or better in 83.8% of eyes and 20/16 or better in 61.3%. Since then, the algorithm has been redesigned with improved laser-spot surface distribution and sequence [23]. The FDA PMA data and published literature reflect these improvements through the use of the diagnostic device, InnovEyes Sightmap (Table 7). Interestingly, these studies show more RT-LASIK eyes achieving a UDVA of 20/12.5, 20/16, and 20/20 or better, contrary to the FDA study that showed superior visual outcomes for TG-LASIK (Fig. 1). The study by He and Bala demonstrated the most favorable outcomes, which may be explained by lower preoperative myopia compared with the FDA report [10]. Few studies have assessed contrast sensitivity using the ray tracing-guided approach; however, results are consistent with the FDA studies, demonstrating improved contrast sensitivity across 1.5, 3, 6, and 12 cpds at both 6 months and 24 months [11, 24].
RT-LASIK theoretically aims to achieve zero total ocular HOAs by addressing both the corneal aberrations targeted by TG-LASIK and spherical aberration [23]. The RT-LASIK study reported a marginal increase in total HOAs from baseline, while the TG-LASIK FDA trial found a slight, nonsignificant reduction. Despite this, neither platform met the clinically significant threshold, defined as an absolute change of ≥ 0.1 μm from baseline (Fig. 4) [25]. Published data assessing HOAs across these platforms are limited to non-comparative studies with varying analysis diameters, making direct comparison difficult (Figs. 6 and 7) [9, 10, 26–35]. Nevertheless, specific trends are evident. Multiple studies, including the FDA PMA, have shown consensus on a reduction in spherical aberration with RT-LASIK [9, 10, 14, 23, 26]. The optimized excimer ablation in RT-LASIK may explain these findings, as it integrates both total eye refractive data and ocular HOAs into its customization [11]. Similar reductions in spherical aberration with RT-LASIK were observed by Thananjeyan and Bala, independent of the degree of preoperative myopia (Fig. 7) [36]. For coma, previous studies tend to show an increase with both platforms, whether statistically significant or not. Cao et al. reported an increase in vertical coma using both TG-LASIK and RT-LASIK [23]. Regarding trefoil, Luo et al. found a statistically significant decrease using RT-LASIK; however, the general trend in the literature is relatively inconclusive [27]. Although the TG-LASIK FDA study did not report coma or trefoil outcomes (Fig. 6), the literature shows a relative reduction in trefoil compared with the trend observed for RT-LASIK.
Fig. 6.
Comparison of changes in corneal higher-order aberrations (HOAs) between the topography-guided LASIK FDA PMA and published studies across diameters of 5.0-, 5.5-, 6.0-, and 6.5-mm. FDA Food and Drug Administration, RMS root mean square. Coma for Cao et al. (2024) and El Awady et al. (2011) and trefoil for El Awady et al. (2011) were calculated using the RMS equation of their vertical and horizontal components. * Indicates wavefront aberrations, — indicates not noted
Fig. 7.
Comparison of changes in ocular higher-order aberrations (HOAs) between the ray tracing-guided LASIK FDA PMA and published studies across diameters of 4.0-, 4.5-, 5.0-, 5.5-, and 6.0-mm. FDA Food and Drug Administration, OD right eye, OS left eye. Coma for Cao et al. (2024) was calculated using the RMS equation of their vertical and horizontal components
A recognized challenge using the new ray-tracing algorithm is the tendency to accommodate during data acquisition, which may exclude potential candidates [37]. Consequently, there is a relative myopic shift greater than 0.50 D with the wavefront measurements compared to manifest refraction [38]. Although the RT-LASIK FDA study did not address this concern, a recent study proposed two strategies to mitigate this issue, including utilizing cycloplegic wavefront data for treatment planning or making surgeon-based adjustments [37]. Regarding the former approach, it is often time-consuming [38], controversial in adult refraction [39], and may alter corneal vertex positioning [37]. In the latter approach, the authors specifically adjusted the spherical component to ensure that the wavefront SEQ at a 4.0 mm pupil diameter was within 0.50 D. Another strategy involves effectively using the automatic fogging function on InnovEyes Sightmap, although some patients may be insensitive to this feature [40]. Further research is warranted to refine treatment planning and to overcome the impact of accommodation.
In terms of astigmatic correction, RT-LASIK showed greater overcorrection for astigmatism ranging from – 1.00 to –4.00 D (Table 3). Cylinder overcorrection was also observed across multiple studies using this approach, ranging from 1.08 to 1.12 [10, 26–28]. To address this, a 10–15% magnitude reduction of the planned astigmatic treatment may be required. Our preliminary experience with the ray-tracing approach has not only shown overcorrection of cylinder, but also that it removes more corneal tissue per diopter of correction compared to both TG-LASIK and wavefront-optimized LASIK. Previous authors have made similar observations, with one study noting 18.5% more tissue ablation in RT-LASIK compared to the Custom-Q ablation algorithm [28]. This is believed to result from the ablation pattern algorithm to avoid altering lower-order aberration components during the correction of HOAs, while also precompensating for expected corneal remodeling [23, 24]. Therefore, a large effective OZ is achieved, which in turn contributes to more corneal tissue ablation [23, 28].
Regarding patient-reported outcomes, the authors cannot draw definitive conclusions between the two platforms, as the RT-LASIK PMA study used the PROWL questionnaire and OSDI scores to report outcomes as a percentage of patients. In contrast, the TG-LASIK study used a 12-item questionnaire and an RSVP questionnaire to report outcomes as a percentage of eyes. However, according to the FDA reports, both studies demonstrated reductions in the severity of visual symptoms, including glare, halos, starbursts, double vision, and dry eye (Fig. 5). The FDA PMA studies also reported patient-satisfaction rates of 98.4% for TG-LASIK and 100% for RT-LASIK, with the latter group being somewhat, very, or completely satisfied with their outcomes at 12 months. These findings are quite preliminary for RT-LASIK, as only one study has evaluated visual symptoms using a different assessment tool [24]. Additional studies using standardized, validated questionnaires are needed to assess whether the effort to correct a greater amount of HOAs translates to an improvement in subjective symptoms.
The present study has additional limitations that should be acknowledged. The two PMA trials had different inclusion criteria, with TG-LASIK allowing up to − 9.00 D of SEQ and RT-LASIK up to − 12.00 D. Despite these variations, both groups did not differ statistically in terms of overall preoperative mean SEQ nor mean cylinder (Table 1). The TG-LASIK study also excluded clinically significant lenticular astigmatism, which may have contributed to the greater cylinder overcorrection observed in RT-LASIK compared to TG-LASIK. It is important to note that the outcomes from both FDA studies may not fully reflect real-world outcomes, where disparities between corneal and refractive astigmatism may extend beyond the inclusion criteria for TG-LASIK. Additionally, the influence of accommodation responses observed with RT-LASIK may be mitigated to improve outcomes.
Conclusions
Technical refinements in ablation algorithms have expanded the pool of candidates eligible for corneal refractive surgery. TG-LASIK has become the preferred approach for patients who are otherwise good candidates for refractive surgery but have primarily irregular corneas or other asymmetric corneal abnormalities [5]. Now, patients who may not qualify for TG-LASIK could still be eligible for refractive correction treatment with RT-LASIK. While promising, this new platform still has potential for further optimization. Across both platforms, the FDA PMA clinical trials and published literature have consistently demonstrated excellent refractive predictability and efficacy. As advancements continue to progress in refractive error correction and visual acuity outcomes, the new challenge lies in determining which procedure is the most appropriate for each patient.
Author Contributions
All authors adhered to ICMJE guidelines and contributed to the study conception and design. Formal analysis and investigation: Mina M. Sitto, Majid Moshirfar, and Philip C. Hoopes. Validation: Mina M. Sitto, Majid Moshirfar, and Triston B. Crook. Data curation: Mina M. Sitto and Triston B. Crook. Writing—original draft preparation: Mina M. Sitto and Majid Moshirfar. Writing—review and editing: Mina M. Sitto, Majid Moshirfar, Triston B. Crook, and Philip C. Hoopes. Visualization: Mina M. Sitto and Triston B. Crook. Supervision: Mina M. Sitto, Majid Moshirfar, and Philip C. Hoopes. All authors have read and agreed to the published version of the manuscript.
Funding
No funding or sponsorship was received for this study or publication of this article.
Data Availability
All data generated or analyzed during this study are included in the following published sources: 1. United States Food and Drug Administration. Summary of safety and effectiveness data (P020050/S012). Accessed July 2, 2025. Available at: https://www.accessdata.fda.gov/cdrh_docs/pdf2/P020050S012B.pdf. 2. United States Food and Drug Administration. Summary of safety and effectiveness data (P020050/S043). Accessed July 2, 2025. Available at: https://www.accessdata.fda.gov/cdrh_docs/pdf2/P020050S043B.pdf. The analyses performed in the current study, based on these publicly available data, are available from the corresponding author on reasonable request.
Declarations
Conflict of Interest
Majid Moshirfar is an Editorial Board member of Ophthalmology and Therapy. Majid Moshirfar was not involved in the selection of peer reviewers for the manuscript, nor any of the subsequent editorial decisions. Mina M. Sitto, Triston B. Crook, and Philip C. Hoopes declare that they have no competing interests.
Ethical Approval
This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
All data generated or analyzed during this study are included in the following published sources: 1. United States Food and Drug Administration. Summary of safety and effectiveness data (P020050/S012). Accessed July 2, 2025. Available at: https://www.accessdata.fda.gov/cdrh_docs/pdf2/P020050S012B.pdf. 2. United States Food and Drug Administration. Summary of safety and effectiveness data (P020050/S043). Accessed July 2, 2025. Available at: https://www.accessdata.fda.gov/cdrh_docs/pdf2/P020050S043B.pdf. The analyses performed in the current study, based on these publicly available data, are available from the corresponding author on reasonable request.