Refractive outcomes of small lenticule extraction (SMILE) Pro® with a 2 MHz femtosecond laser

Three-Month Outcomes of SMILE Pro with the VISUMAX 800 for Myopic Astigmatism in a Large Population

Purpose

To report the visual and refractive outcomes of small-incision lenticule extraction (SMILE) Pro using a 2 MHz femtosecond laser for myopic astigmatism in a large population of Vietnamese patients.

Methods

This was a retrospective clinical study of subjects that underwent keratorefractive lenticule extraction (KLEx) with the VISUMAX 800 at Hong Son Eye Hospital (Ha Noi, Vietnam) between June 2023 and October 2023. Primary outcome measures of monocular uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and refraction, including vector analysis, were evaluated at 3-months postoperatively. Secondary outcome measures of intraoperative and postoperative complications were also recorded.

Results

A total of 765 eyes from 389 patients (60.66% women, mean age of 23.54±5.20 years) were analyzed 3 months after surgery. The mean preoperative spherical equivalent refraction was -5.98±2.26 D. The postoperative spherical equivalent refraction was within ±0.50 D of the intended target in 81% and within ±1.00 D in 97% of eyes. The mean spherical equivalent refraction was -0.11±0.45 D. UDVA was 20/25 or better in 92% and 20/32 or better in 97% of eyes. The mean postoperative UDVA and CDVA values were 0.05±0.09 and 0.00±0.02 logMAR, respectively. There was no change in CDVA in 99% of eyes. Efficacy index was 0.92, and safety index was 1.00. One eye (0.13%) had a suction loss, which resulted in a lenticule remnant. No other complications were reported during surgery or the postoperative follow-up period.

Conclusion

The current study, carried out on a large cohort of Asian patients, showed SMILE Pro with the VISUMAX 800 was safe and effective for treating myopic astigmatism.

Effect of Asymmetric Corneal Curvature on Optical Zone Decentration and Refractive Outcomes in SMILE for Myopic Astigmatism

PURPOSE

To investigate the effect of asymmetric corneal curvature on refractive outcomes and optical zone decentration at a 2-year follow-up after small incision lenticule extraction (SMILE) for myopic astigmatism.

METHODS

In this prospective study, 96 patients (169 eyes) with myopia and astigmatism (low astigmatism group [cylinder < -2.00 diopters (D)], 91 eyes; high astigmatism group [cylinder ⩾ -2.00 D], 78 eyes) were treated using SMILE. Two-year postoperative refractive outcomes and optical zone decentration were analyzed and compared between the groups.

RESULTS

Both groups achieved good visual and refractive outcomes. The mean postoperative cylinder in the low astigmatism group was significantly lower than that in the high astigmatism group (P < .05). The mean decentration in the low astigmatism group was lower than that in the high astigmatism group (P < .05). In the low astigmatism group, a weak positive correlation was observed between target induced astigmatism (TIA) and the arithmetic mean of angle of error (|AE|), difference vector (DV), and the arithmetic mean of magnitude of error (|ME|). Additionally, a weak positive correlation was observed between decentration and both the arithmetic mean of corneal front surface curvature asymmetry indices (|Sif|) and TIA. Within the high astigmatism group, TIA exhibited a weak positive correlation with |AE|, DV, and |ME|. Similarly, decentration demonstrated a weak positive correlation with |Sif|, TIA, DV, and |ME| (all P < .05).

CONCLUSIONS

SMILE surgery achieves good long-term refractive outcomes for correcting myopic astigmatism. However, there are still limitations to the accuracy of high astigmatism correction. Asymmetric corneal surface curvature may affect the astigmatism correction and optical zone decentration. [J Refract Surg. 2025;41(2):e173-e185.].

Comparison Between Topographic-Based and Manifest-Based Astigmatism Corrections in the Second (Visumax 800)-Generation Keratorefractive Lenticule Extraction Surgery: A Real-World Study

Objectives: To evaluate the effectiveness of astigmatism correction between topographic- and manifest-based methods in individuals who underwent second-generation keratorefractive lenticule extraction (KLEx) surgery. Methods: This study was conducted with participants who underwent second-generation KLEx surgery. After exclusion, there were 46 and 43 participants in the manifest and topographic groups, respectively. The main outcomes were postoperative uncorrected distance visual acuity (UDVA), spherical equivalent (SE), and residual astigmatism. The independent T-test and generalized estimate equation were used to investigate differences between the two groups. Results: Three months postoperatively, UDVA was 0.02 ± 0.04 in the manifest group and 0.00 ± 0.06 in the topographic group which also revealed no significant difference (p = 0.155). Also, the SE value in the two groups three months postoperatively was statistically similar (-0.57 ± 0.48D versus -0.63 ± 0.62D, p = 0.574). The final residual astigmatism was -0.26 ± 0.27 in the topographic group which was significantly lower than the -0.51 ± 0.40 in the manifest group (p < 0.001). Moreover, the amplitude of astigmatism change was significantly lower in the topographic group (p = 0.002). In the subgroup analysis, UDVA and residual astigmatism were significantly better in the topographic group than in the manifest group (both p < 0.05). Conclusions: The topographic-based method represents a better astigmatism correction than the manifest-based method in second-generation KLEx surgery, especially in the low astigmatism population.

Comparison of Clinical Outcomes and Patient Satisfaction Following SMILE Performed With the VisuMax 800 in One Eye and VisuMax 500 in the Contralateral Eye

PURPOSE

To compare the clinical outcomes, surgical workflow, and patient satisfaction following small incision lenticule extraction (SMILE) performed with the VisuMax 800 in one eye and the VisuMax 500 in the contralateral eye (both Carl Zeiss Meditec).

METHODS

This was a prospective, single-site clinical study of patients undergoing SMILE for myopia and myopic astigmatism between February 2022 and August 2023. Each patient underwent bilateral treatment using the VisuMax 800 (VM800 group) in one eye and the VisuMax 500 (VM500 group) in the contralateral eye. Intraoperative docking time, suction time, laser time, and surgical time were noted. Patient satisfaction and laser preference was evaluated immediately after treatment. Visual and refractive outcomes, contrast sensitivity, and quality of vision were assessed at the 3-month postoperative visit.

RESULTS

A total of 30 patients undergoing bilateral SMILE were included. The mean docking time and surgical time were significantly lower in the VM800 group (46.53 ± 11 sec and 4.52 ± 2.33 min, respectively) compared to the VM500 group (68.25 ± 15 sec and 6.22 ± 2.04 min, respectively) (P < .001). No significant differences were observed at the 1-day or 3-month visit for uncorrected distance visual acuity, corrected distance visual acuity, spherical equivalent, higher order aberrations, Objective Scatter Index, modulation transfer function, and contrast sensitivity. Patient scores regarding subjective symptoms were comparable. However, overall satisfaction with the surgical experience was rated significantly better in the VM800 group, with 80% of patients preferring the VM800 eye. No complications occurred for eyes in either group.

CONCLUSIONS

No significant differences were observed in clinical outcomes between the two laser systems. However, the surgical workflow and patient-reported intraoperative experience favored the VisuMax 800. [J Refract Surg. 2025;41(1):e14-e21.].

Comparison of Visual and Refractive Outcomes Between Refractive Lens Exchange and Keratorefractive Lenticule Extraction Surgery in Moderate to High Myopia

Background/Objectives: To evaluate the visual and refractive outcomes of keratorefractive lenticule extraction (KLEx) surgery and refractive lens exchange (RLE) surgery in moderate to high myopia patients. Methods: A retrospective cohort study was performed, and patients receiving KLEx or RLE surgeries with myopia within -3.00 to -10.00 diopter (D) were enrolled. A total of 19 and 35 patients were put into the RLE and KLEx groups after exclusion. The main outcomes are postoperative uncorrected visual acuity (UDVA), the spherical equivalent (SE), and residual astigmatism via vector analysis. Fisher's exact test and the Mann-Whitney U test were utilized for the statistical analysis. Results: The percentages of patients who reached UDVA results of more than 20/25 and 20/20 were statistically similar between groups (both p > 0.05), and the percentages of patients who reached SE results within ±0.50 D and ±1.00 D were statistically similar between groups (both p > 0.05). The change in SE in the KLEx group was lesser compared to that in the RLE group (p = 0.021). The vector analysis showed a lower DV and ME and a higher CoI in the KLEx group than in the RLE group (all p < 0.05). The percentage of patients who reached specific UDVA and SE thresholds were statistically similar between groups with different myopia degrees (all p > 0.05). Conclusions: The postoperative visual and refractive outcomes between RLE and KLEx surgeries are grossly comparable, while the KLEx may have a slight advantage in astigmatism correction.

Comparison of Visual and Refractive Outcomes of Keratorefractive Lenticule Extraction for Compound Myopic Astigmatism Between VisuMax and VISUMAX 800

Purpose

To evaluate the visual outcomes of keratorefractive lenticule extraction using a new version of a femtosecond laser platform with semi-automated cyclotorsion compensation in comparison to the previous generation without cyclotorsion control.

Methods

This was an ambispective study of consecutive eyes treated by SMILE with the VisuMax and VISUMAX 800 femtosecond lasers at the Uma Eye clinic, Chennai, India between June 2022 and July 2023. Inclusion criteria were myopia up to -10 D and astigmatism between 1.5 D and 5 D. Data was retrospectively collected from patients that underwent SMILE using the VisuMax without cyclotorsion compensation and prospectively collected from patients undergoing SMILE using the VISUMAX 800 with Oculign and Centralign software aids.

Results

Data was collected from a total of 220 eyes that underwent routine SMILE; 115 eyes with VisuMax (VM500 group) and 105 eyes with VISUMAX 800 (VM800 group). The mean attempted spherical equivalent was -4.82±2.16 D in the VM500 group and -4.80±2.24 in the VM800 group. At the 3-month postoperative visit, 94% of eyes in the VM500 group and 98% of eyes in the VM800 group had an UDVA of 20/20 or better. Accuracy of the SEQ showed that 71% of eyes were within ±0.50 D and 100% were within ±1.00 D of target in the VM500 group and 96% of eyes were within ±0.50 D and 100% were within ±1.00 D of target in the VM800 group. There were no reported cases of suction loss or any other intraoperative complication in either group.

Conclusion

SMILE with the VisuMax and VISUMAX 800 provided excellent visual and refractive outcomes for subjects with myopic astigmatism. The VISUMAX 800, using Oculign and Centralign aids, demonstrated better accuracy when correcting cylinder greater than 2 D compared to the VisuMax without using manual cyclotorsion compensation.

The outcomes of first-generation (visumax 500) and second-generation (Visumax 800) keratorefractive lenticule extraction surgeries for astigmatism

To evaluate the efficiency, predictability, and residual astigmatism between first- and second-generation keratorefractive lenticule extraction (KLEx) surgeries in a prominent astigmatism population. A retrospective cohort study was conducted, and individuals who underwent first- and second-generation KLEx surgeries were enrolled. A total of 31 and 35 eyes were categorized into first and second KLEx groups, respectively. Visual acuity, refraction, topographic parameters, and surgical indices were recorded. Independent t tests were used to compare the postoperative uncorrected distance visual acuity (UDVA), spherical equivalent (SE), and residual astigmatism between the two groups. The difference in UDVA was not significant three months after KLEx surgery (P = 0.509), and the SEs three months after surgery also presented similar values between the two groups (P = 0.552). The first KLEx group demonstrated greater residual astigmatism than did the second KLEx group throughout the three-month follow-up period (all P < 0.05). The values of surgically induced astigmatism (SIA), difference vector (DV), magnitude of error (ME) and correction index (CoI) were significantly better in the second KLEx group via vector analysis (all P < 0.05). Old age, high steep keratometry (K), high topographic cylinder, large angle kappa, and a small optic zone were correlated with greater residual astigmatism in the first KLEx group (all P < 0.05), whereas only a small optic zone was significantly correlated with greater residual astigmatism in the second KLEx group (P = 0.047). The second-generation KLEx is correlated with a lower risk of residual astigmatism.

The Risk Factors for Myopia Undercorrection in Second-Generation (Visumax 800) Keratorefractive Lenticule Extraction Surgery: A Retrospective Case-Control Study

In this study, we aim to evaluate the risk factors of myopia undercorrection in recipients of second-generation keratorefractive lenticule extraction (KLEx) surgery. A retrospective case-control study was performed, and patients who received second-generation KLEx surgery were enrolled. The cases with myopia undercorrection were matched to non-myopia undercorrection cases with a 1:4 ratio according to age, and a total of 22 and 88 eyes were categorized into the undercorrection and control groups, respectively. Demographic, refractive, topographic, and surgical data were collected preoperatively. A generalized linear model was operated to evaluate the potential risk factors for myopia undercorrection. The uncorrected distance visual acuity (UDVA) at three months postoperation was significantly better in the control group (p = 0.006), and residual myopia and SE were significantly higher in the undercorrection group during the whole follow-up period (all p < 0.001). The UDVA value showed a trend of improvement in the control group (p < 0.001), and the changes to SE and residual myopia were significantly lower in the control group (both p < 0.001). Regarding the risk factors for myopia undercorrection in the whole population and the high-myopia population, a higher manifest sphere power, higher steep keratometry (K), higher topographic cylinder, lower central corneal thickness (CCT) at apex, higher CCT difference and lower residual stromal thickness (RST) correlated to myopia undercorrection (all p < 0.05). In the low-myopia population, only higher myopia and lower RST correlated to myopia undercorrection (both p < 0.05). In conclusion, a high-sphere power and irregular topographic pattern correlated to myopia undercorrection after the second KLEx surgery, especially for individuals with high myopia.

The Efficiency, Predictability, and Safety of First-Generation (Visumax 500) and Second-Generation (Visumax 800) Keratorefractive Lenticule Extraction Surgeries: Real-World Experiences

We aimed to evaluate the postoperative visual and refractive outcomes between the first- and second-generation keratorefractive lenticule extraction (KLEx) surgeries. A retrospective cohort study was conducted and patients who had received first- and second-generation KLEx surgeries were enrolled. A total of 80 and 80 eyes were categorized into the first and second KLEx groups after exclusion, respectively. The primary outcomes were the postoperative uncorrected distance visual acuity (UDVA), spherical equivalent (SE), and safety indexes. An independent t-test and generalized estimate equation were implemented to compare the primary outcomes between the two groups. After the KLEx surgery, the UDVA showed no significant difference between the two groups throughout the study period (all p > 0.05), and the postoperative SE and safety index were also statistically identical between the two groups during the follow-up interval (all p > 0.05). There was a similar trend of visual recovery between the two groups (aOR: 0.967; 95% CI: 0.892-1.143; p = 0.844), while the amplitude of the SE change was significantly lower in the second KLEx group (aOR: 0.760; 95% CI: 0.615-0.837; p = 0.005). Nine and two unintended initial dissection of the posterior plane (UIDPP) occurred intraoperatively in the first and second KLEx groups, respectively, and the second group showed a lower risk of UIDPP (p = 0.032). In conclusion, the efficiency, predictability, and safety are similar between first- and second-generation KLEx surgeries.

Comparison of early visual outcomes after SMILE using VISUMAX 800 and VISUMAX 500 for myopia: a retrospective matched case-control study

VISUMAX 800 was introduced to improve the patient experience and clinical outcomes of small incision lenticule extraction (SMILE). This was a retrospective, matched, and case-control study (1:2) controlled for preoperative central corneal thickness and refractive error that compared early refractive and visual outcomes after SMILE using VISUMAX 800 and VISUMAX 500 to treat myopia. We included 50 eyes that underwent the VISUMAX 800 SMILE and 100 eyes that underwent the VISUMAX 500 SMILE. SMILE using VISUMAX 800 was performed using the CentraLign aid for vertex centration. Cyclotorsion was controlled by an OcuLign assistant in the VISUMAX 800 group after corneal marking. Corneal higher-order aberrations (HOAs) were evaluated using a Pentacam 1 month after surgery. No differences were observed in the pre- and post-operative refractive and visual outcomes at 1 day, 1 month, and 6 months after surgery. VISUMAX 800 induced less total HOAs than VISUMAX 500 (P = 0.036). No statistically significant differences were observed in the amounts of induced spherical aberrations or vertical and horizontal comas. No differences were observed in the 1 month and 6 months refractive and visual outcomes between two SMILE procedures, except for VISUMAX 800, which resulted in lower postoperative total HOAs than VISUMAX 500.