Abstract
Purpose
To evaluate whether LASIK induces axial elongation comparable to or less than that observed with continued soft contact lens (SCL) wear in myopic eyes.
Design
A prospective, randomized-controlled within-person clinical trial.
Participants
Forty-two eyes from 21 patients (11 males, 10 females; mean age: 26 ± 4 years) with myopia or compound myopic astigmatism.
Methods
In this contralateral-eye, randomized clinical trial, each participant underwent wavefront-guided (WFG) LASIK in 1 randomly assigned eye, while the fellow eye continued SCL wear. Axial length (AL), spherical equivalent (SE), higher-order aberrations (HOAs), visual acuity, and contrast sensitivity were assessed preoperatively and every 6 months for 2.5 years. The primary outcome was axial elongation from 6 months to 2.5 years postoperatively. Data were analyzed using linear mixed-effects models.
Main Outcome Measures
Axial elongation.
Results
The mean preoperative SE in LASIK-treated eyes was –6.23 ± 1.95 diopters. In the early postoperative phase, a significant reduction in AL exceeding corneal thinning was observed, suggesting true axial shortening. From 6 months to 2.5 years, axial elongation did not significantly differ between the LASIK and SCL eyes. Although HOAs at a 6-mm pupil diameter increased more in LASIK-treated eyes, most participants reported subjectively superior visual quality in those eyes.
Conclusions
LASIK was associated with early axial shortening and did not accelerate long-term axial elongation compared with SCL wear. These results suggest a potential modulatory effect of WFG-LASIK on AL progression and support the need for further longitudinal studies.
Financial Disclosure(s)
The authors have no proprietary or commercial interest in any materials discussed in this article.
Keywords: Higher-order aberration, Axial length, Within-person clinical trial, Myopia
Myopia continues to increase worldwide, increasing the risk of future visual impairment,1 and because the classification of myopic maculopathy in the META-analysis of Pathologic Myopia study shows that more advanced cases are more likely to progress,2 it makes sense to prevent myopia from progressing as far as possible.3 Several studies have reported that myopia progression4 and axial elongation5 may continue beyond adolescence into adulthood. It is reported that hyperopic blur to the peripheral retina is the cause of axial elongation,6 and hyperopic blur with ordinary glasses7 or soft contact lenses (SCLs)8 may accelerate the progression of myopia. Defocus incorporated multiple-segment spectacle lenses,9 multifocal SCLs,10 and orthokeratology11 have been recognized as promising treatment options to reduce the peripheral hyperopic blur for suppressing the axial elongation.12
Since 2000, LASIK has become the world-standard surgical procedure for the correction of myopia.13,14 Since the latter part of the 2000s, wavefront-guided (WFG) LASIK15 was developed as a cutting-edge surgical procedure aimed at eliminating optical aberrations16 obseved after conventional myopic LASIK. Although WFG-LASIK has largely resolved issues related to visual function, higher-order aberrations (HOAs) increase as the analysis pupil diameter expands.17 This increase in HOAs causes more myopic defocus in the peripheral retina.18 This suggests that LASIK may exert an inhibitory effect on axial elongation due to a decrease in the peripheral hyperopic blur.
Axial length (AL) and central corneal thickness are fundamental biometric parameters. Although some studies have reported a potential association between AL and central corneal thickness,19,20 no clear or consistent correlation has been established. Except in cases involving corneal deformation, such as keratoconus, a thinner cornea does not lead to axial elongation.
The purpose of this prospective study was to clarify whether AL changes after WFG-LASIK surgery differ from those resulting from SCL wear in patients with myopia. To achieve this, 1 eye of each myopic patient who regularly used SCLs was randomly selected to undergo WFG-LASIK, utilizing a high-resolution wavefront aberrometer21 and a femtosecond laser for flap creation.22 The second objective was to evaluate AL changes in the WFG-LASIK eye up to 6 months postoperatively. Additionally, the visual function between the WFG-LASIK eye and the contralateral SCL-wearing eye in the same patients from 6 months to 2.5 years after surgery was compared.
Methods
This study was a single-center, within-person, randomized, prospective clinical trial. It was approved by the Clinical Research Review Board of Kyoto Prefectural University of Medicine, Kyoto, Japan (ERB-C825-2), and registered with the Japan Registry of Clinical Trials (https://jrct.mhlw.go.jp/) under Registration No. jRCTs052180173. The study adhered to the principles of the Declaration of Helsinki, and informed consent was obtained from all participants. Wavefront-guided LASIK surgery was performed at Baptist Eye Clinic (Kyoto, Japan) between October 2016 and June 2019. Participants were patients with myopia or compound myopic astigmatism who wore SCLs and provided informed consent to undergo WFG-LASIK in 1 eye, with the contralateral eye scheduled for surgery 2.5 years later.
Eligibility criteria included males and females aged 18 to <35 years with a bilateral spherical equivalent (SE) refractive error of ≤ –3.5 diopters (D). Inclusion criteria were normal corneal shape, a residual corneal stroma bed of ≥250 μm, and a corrected distance visual acuity (CDVA) of ≥1.0 decimal visual acuity (VA). Exclusion criteria included anisometropia and astigmatism of ≥3.0 D. It should be noted that initially, the inclusion criteria were an SE of ≤ –6.0 D SE and an age of <29 years, while the exclusion criteria included anisometropia and astigmatism of ≥1.5 D. However, due to low enrollment during the first year of recruitment, criteria were revised to the current thresholds. There were no restrictions on the type of SCLs worn by participants, either preoperatively or postoperatively.
The dominant eye of each patient was determined preoperatively using the Dolman method.23 Simple randomization was then performed using a computer-generated random number table created by K.Y. prior to the start of participant enrollment. This table specified whether the dominant eye or the nondominant eye would undergo surgery. The randomization table was maintained by a third party within the hospital and was used at the time of patient registration to determine which eye would be designated as the surgical eye.
The WFG-LASIK surgery with femtosecond-laser flap creation was performed under topical anesthesia on 1 randomly selected eye in all patients. The surgery was conducted using the iFS Advanced Femtosecond Laser (Johnson & Johnson Vision), the iDesign Refractive Studio Wavefront Aberrometer (Johnson & Johnson Vision), and the STAR S4 IR (Johnson & Johnson Vision) excimer laser.
Uncorrected distance VA (UDVA) after LASIK or habitual SCL-wearing VA was adjusted to be ≥1.0 decimal VA during the follow-up period. If the UDVA of the operated eye was <1.0 decimal VA postoperatively, enhancement surgery was performed to achieve a UDVA of ≥1.0. In cases where undercorrection occurred in the habitual SCL-wearing eye, appropriate SCL power was adjusted accordingly.
The primary outcome measure was the amount of AL elongation of LASIK and SCL eyes in the same individual over 2 years, starting from 6 months post-LASIK, which is the period when LASIK postoperative results stabilize, as previously reported.24 Axial length was measured using the IOL Master 700 (Zeiss) preoperatively and at 6 months, 1 year, 1.5 years, 2 years, and 2.5 years postoperatively for both eyes. Measurements for the SCL-wearing eyes were taken after the contact lenses were removed. To observe changes in AL of LASIK eyes from preoperative to 6 months postoperative, the LASIK eye was measured preoperatively and 1 week, 1 month, 3 months, and 6 months postoperatively and compared with changes in corneal thickness measured simultaneously using the same instrument.
To compare the visual function of both eyes, UDVA after LASIK, SCL-wearing VA, and CDVA were measured at 6 months, 1 year, 1.5 years, 2 years, and 2.5 years postoperatively. Higher-order aberrations were measured at 6 months, 1 year, 2 years, and 2.5 years; contrast sensitivity (CS) was measured at 6 months, 1.5 years, and 2.5 years; and dilated CS was measured at 6 months, 1 year, 2 years, and 2.5 years postoperatively. Higher-order aberrations, CS, and dilated CS were measured with contact lenses in non-LASIK eyes. The question of which eye could see better was asked at 6 months, 1 year, 1.5 years, 2 years, and 2.5 years postoperatively. In order to avoid sensory bias caused by wearing contact lenses and to compare the individual's eyes and hear their subjective impressions, we asked the question, “Which eye can see better—the right or the left?” Participants answered “right,” “left,” or “the same.”
Visual acuity was assessed using a standard decimal VA chart under photopic conditions and subsequently converted to logarithm of the minimum angle of resolution units. Ocular HOAs were measured with the KR-1W Wavefront Analyzer (Topcon Corporation) under natural pupil conditions, using analysis pupil diameters of 4 mm and 6 mm. From these measurements, total HOAs, coma-like aberrations, spherical-like aberrations, and spherical aberrations were then calculated. Contrast sensitivity was evaluated using an auto-calibrated vision-testing device (CSV-1000; VectorVision) under both natural and pharmacologically dilated pupil conditions. Dilation was achieved using Mydrin-P ophthalmic solution (Tropicamide, Phenylephrine Hydrochloride; Santen Pharmaceutical). In the preoperative phase, measurements of the SCL eyes were taken without lenses, whereas postoperative assessments were conducted while the subjects were wearing SCLs.
Using EZR software for the calculation of the required sample size for comparing the means of 2 paired groups, the expected mean difference between the groups was set at 0.05 mm. The 95% confidence limit of the noncontact AL measurement device is 0.024 mm.25 In adult eyes with pathologic myopia, the annual axial elongation is approximately 0.065 mm,26 whereas in myopic LASIK patients, the change is only about 0.01 mm.27 Therefore, in adult myopia, a difference of 0.05 mm can be considered clinically meaningful. The common standard deviation is at 0.08 mm, based on interocular differences observed in our previous data. With a 2-tailed test, an alpha level of 0.05, and a power of 0.80 (1 – beta), the required sample size was calculated to be 23 eyes.
Background characteristics were summarized as means ± standard deviations. Paired t-tests were used to evaluate differences between the LASIK-treated eyes and SCL-wearing eyes. Changes in AL and corneal thickness in LASIK-treated eyes up to 6 months postoperatively were also assessed using paired t tests. For the primary outcome and additional endpoints, mixed-effects models were used to estimate least square means and between-group differences at each timepoint. The covariates included group (SCL-wearing eye or WFG-LASIK eye), dummy variables of time point, and interactions between group and time point as fixed effects, with subject specified as random effects. P values from the mixed-effects models for the between-group differences and the interactions were reported. A 2-sided P value <0.05 was considered statistically significant. In the nonoperated eye, UDVA, CDVA, and SE after LASIK were assessed with the subject wearing an SCL.
Results
A total of 22 subjects were randomized; 22 eyes of 22 patients underwent surgery. One participant discontinued the study at 3 months post-LASIK due to pregnancy. The study ultimately included 21 patients (11 males and 10 females) with a mean age of 26 ± 4 (mean ± standard deviation) years at baseline (Fig 1). No statistically significant differences were observed between the LASIK and non-LASIK eyes in any preoperative measurements. Baseline characteristics, including sex, age, UDVA, CDVA, SE, keratometry (K) values, corneal thickness, AL, intraocular pressure, ocular HOAs, and CSs under both natural and dilated pupils, are summarized in Table 1. At 4 months post-LASIK, 1 eye underwent enhancement with an additional 20.4 μm of corneal ablation. Contact lenses were replaced in 5 eyes a total of 6 times: once at 3 months, 3 times at 6 months, once at 1 year, and once at 2 years postoperatively.
Figure 1.
Flowchart of patient enrollment and follow-up in this study.
Table 1.
Demographic Characteristics of Patients
| Baseline Data | Operated Eye | Nonoperated Eye | P Value |
|---|---|---|---|
| Sex (male:female) | 11:10 | ||
| Mean age: (±SD) (range: years) | 26 ± 4 (19–32) | ||
| Eye (right:left) | 11:10 | 10:11 | 1.00 |
| UDVA (logMAR) | 1.24 ± 0.20 | 1.26 ± 0.14 | 0.49 |
| CDVA (logMAR) | –0.14 ± 0.05 | –0.13 ± 0.05 | 0.32 |
| SE (D) | –6.23 ± 1.95 | –6.23 ± 1.62 | 1.00 |
| K-value (D) | 43.21 ± 0.96 | 43.27 ± 0.96 | 0.78 |
| Corneal thickness (mm) | 555.0 ± 37.1 | 553.8 ± 38.7 | 0.56 |
| Axial length (mm) | 26.41 ± 0.84 | 26.39 ± 0.76 | 0.79 |
| Intraocular pressure (mmHg) | 13.03 ± 2.35 | 13.29 ± 2.49 | 0.21 |
| Total ocular HOA in 4 mm (μm) | 0.11 ± 0.05 | 0.10 ± 0.05 | 0.24 |
| Coma-like aberration in 4 mm (μm) | 0.10 ± 0.04 | 0.08 ± 0.04 | 0.11 |
| Spherical-like aberration in 4 mm (μm) | 0.05 ± 0.03 | 0.05 ± 0.02 | 0.93 |
| Spherical aberration in 4 mm (μm) | 0.01 ± 0.02 | 0.02 ± 0.03 | 0.39 |
| Total ocular HOA in 6 mm (μm)∗ | 0.36 ± 0.16 | 0.35 ± 0.13 | 0.63 |
| Coma-like aberration in 6 mm (μm)∗ | 0.28 ± 0.14 | 0.28 ± 0.11 | 0.76 |
| Spherical-like aberration in 6 mm (μm)∗ | 0.21 ± 0.10 | 0.19 ± 0.10 | 0.35 |
| Spherical aberration in 6 mm (μm)∗ | 0.13 ± 0.11 | 0.10 ± 0.11 | 0.06 |
| CS 3 CPD (log unit CS) | 1.71 ± 0.17 | 1.71 ± 0.17 | 0.97 |
| CS 6 CPD (log unit CS) | 1.99 ± 0.11 | 1.99 ± 0.19 | 0.82 |
| CS 12 CPD (log unit CS) | 1.75 ± 0.19 | 1.77 ± 0.18 | 0.49 |
| CS 18 CPD (log unit CS) | 1.37 ± 0.18 | 1.33 ± 0.17 | 0.35 |
| CS 3 CPD with mydriasis (log unit CS) | 1.74 ± 0.16 | 1.73 ± 0.16 | 0.72 |
| CS 6 CPD with mydriasis (log unit CS) | 1.94 ± 0.20 | 1.92 ± 0.16 | 0.67 |
| CS 12 CPD with mydriasis (log unit CS) | 1.62 ± 0.20 | 1.63 ± 0.21 | 0.82 |
| CS 18 CPD with mydriasis (log unit CS) | 1.13 ± 0.28 | 1.26 ± 0.19 | 0.06 |
CDVA = corrected distance visual acuity; CPD = cycles per degree; CS = contrast sensitivity; D = diopters; HOA = higher-order aberration; log CS = logarithm of contrast sensitivity; logMAR = logarithm of the minimum angle of resolution; SD = standard deviation; SE = spherical equivalent; UDVA = uncorrected distance visual acuity.
In only 1 case was HOA measurement impossible at baseline due to a small pupil diameter of 6 mm, and the number of eyes was 20.
The ALs of LASIK-treated eyes were reduced beyond the extent of corneal thinning. The preoperative AL was 26.41 ± 0.84 mm, but at 1 week postoperatively, it had significantly shortened to 26.28 ± 0.82 mm (P < 0.001). The average axial shortening compared with preoperative values was 0.13 ± 0.03 mm shorter at 1 week, 0.12 ± 0.03 mm at 1 month, and 0.12 ± 0.05 mm at 3 months postoperatively. These changes exceeded the average ablation depth, which was 0.09 ± 0.02 mm. In contrast, the corresponding corneal thickness changes measured by the IOL Master were 0.11 ± 0.03 mm at 1 week, 0.10 ± 0.03 mm at 1 month, and 0.10 ± 0.02 mm at 3 months. The reduction in AL was significantly greater than the reduction in corneal thickness at the postoperative time points (1 week, 1 month, and 3 months), with P values <0.05 (paired t-test) (Fig 2). There was no correlation between corneal thickness and AL either before or after surgery. In the LASIK-treated eyes, AL decreased to 26.29 ± 0.82 mm at 6 months postoperatively (P < 0.001), whereas in the SCL-wearing eyes, AL changed from 26.38 ± 0.76 mm preoperatively to 26.40 ± 0.76 mm at 6 months postoperatively (P = 0.14). One eye was not able to measure the AL at 1 month.
Figure 2.
Changes in AL shortening and corneal thickness thinning in LASIK-treated eyes. Axial length and corneal thickness were measured simultaneously using a noncontact optical biometer. For each postoperative time point, values were calculated as the difference from the corresponding preoperative measurements. AL = axial length; CCT = central corneal thickness.
No statistically significant difference was observed in the amount of axial elongation between the LASIK-treated eyes and the contralateral SCL-wearing eyes from 6 months to 2.5 years postoperatively (Fig 3). Furthermore, there was no significant interaction between treatment group and time point. At the 2-year time point, the least squares mean change in AL was 0.085 mm (95% confidence interval, 0.047–0.123) in the LASIK group and 0.061 mm (95% confidence interval, 0.023–0.099) in the SCL group.
Figure 3.
Longitudinal changes in axial length elongation in the LASIK and SCL groups. Axial length elongation at each time point was calculated by subtracting the baseline value at 6 months postoperatively from the measurement at each corresponding time point. SCL = soft contact lens.
From 6 months to 2.5 years postoperatively, UDVA and CDVA in LASIK-treated eyes were significantly better than those in SCL-wearing eyes (P < 0.001). However, no significant effects were observed for time points or for the interaction between time and refractive error correction method (LASIK vs. SCL). Spherical equivalent values showed no significant differences between LASIK and SCL eyes throughout the same postoperative period. Axial lengths in LASIK eyes were consistently shorter than those in SCL-wearing eyes from 6 months to 2.5 years postoperatively; however, similar to VA, no significant effects were found for time or for the interaction between time and correction method (Table 2).
Table 2.
Postoperative Refractive Characteristics
| Parameter | Timepoint | Operated Eye | Nonoperated Eye | P Value |
|---|---|---|---|---|
| UDVA∗ (logMAR) | 6 months | –0.19 | –0.11 | <0.01 |
| 12 months | –0.16 | –0.09 | <0.01 | |
| 18 months | –0.15 | –0.12 | 0.30 | |
| 24 months | –0.16 | –0.1 | <0.01 | |
| 30 months | –0.12 | –0.1 | 0.40 | |
| CDVA∗ (logMAR) | 6 months | –0.21 | –0.16 | <0.01 |
| 12 months | –0.21 | –0.16 | <0.01 | |
| 18 months | –0.21 | –0.18 | 0.06 | |
| 24 months | –0.2 | –0.16 | <0.05 | |
| 30 months | –0.2 | –0.17 | 0.16 | |
| SE∗ (D) | 6 months | –0.07 | –0.2 | 0.1 |
| 12 months | –0.11 | –0.23 | 0.14 | |
| 18 months | –0.2 | –0.24 | 0.55 | |
| 24 months | –0.18 | –0.27 | 0.27 | |
| 30 months | –0.25 | –0.17 | 0.3 | |
| Axial length (mm) | 6 months | 26.29 | 26.4 | <0.05 |
| 12 months | 26.31 | 26.42 | <0.05 | |
| 18 months | 26.33 | 26.43 | 0.05 | |
| 24 months | 26.34 | 26.44 | <0.05 | |
| 30 months | 26.38 | 26.47 | 0.1 |
CDVA = corrected distance visual acuity; D = diopters; logMAR = logarithm of the minimum angle of resolution; SE = spherical equivalent; UDVA = uncorrected distance visual acuity.
UDVA, CDVA, and SE in the nonoperated eye were assessed with the subject wearing a soft contact lens.
Higher-order aberrations measured at a 4-mm pupil diameter from 6 months to 2.5 years postoperatively showed no significant differences between LASIK-treated and SCL-wearing eyes. In contrast, at a 6-mm pupil diameter, HOAs were significantly greater in the LASIK group compared with the SCL group. However, there were no significant effects of time point, nor any interaction between time and the refractive error correction method (LASIK or SCL) (Table 3). Contrast sensitivity, assessed under both natural and pharmacologically dilated pupils, did not differ significantly between the 2 groups.
Table 3.
Postoperative HOAs in 6 mm Characteristics
| Parameter | Timepoint | Operated Eye (μm) | Nonoperated Eye (μm) | P Value |
|---|---|---|---|---|
| Total HOA | 6 months | 0.57 | 0.45 | 0.19 |
| 12 months | 0.65 | 0.46 | 0.04 | |
| 24 months | 0.63 | 0.58 | 0.58 | |
| 30 months | 0.57 | 0.52 | 0.56 | |
| Coma-like aberration | 6 months | 0.37 | 0.33 | 0.34 |
| 12 months | 0.44 | 0.34 | 0.04 | |
| 24 months | 0.45 | 0.35 | 0.04 | |
| 30 months | 0.38 | 0.38 | 0.93 | |
| Spherical-like aberration | 6 months | 0.42 | 0.29 | 0.14 |
| 12 months | 0.46 | 0.28 | 0.04 | |
| 24 months | 0.42 | 0.41 | 0.91 | |
| 30 months | 0.40 | 0.33 | 0.41 | |
| Spherical aberration | 6 months | 0.35 | –0.05 | <0.01 |
| 12 months | 0.38 | –0.02 | <0.01 | |
| 24 months | 0.34 | 0.03 | <0.01 | |
| 30 months | 0.34 | –0.01 | <0.01 |
HOA = higher-order aberration.
In a questionnaire assessing visual preference between the LASIK-treated and SCL-wearing eyes, 48% of patients preferred the LASIK eye, 5% preferred the SCL eye, and 48% answered that they were the same at 6 months postoperatively. At 1 year postoperatively, 71% preferred the LASIK eye and 5% preferred the SCL eye. This trend continued with 70% versus 15% at 1.5 years, 67% versus 10% at 2 years, and 62% versus 10% at 2.5 years postoperatively (Fig 4). At the 1.5-year time point, 1 patient discontinued SCL use due to contact lens-related issues, resulting in data from 20 patients.
Figure 4.
Percentage of eye preference between LASIK-treated and SCL-wearing eyes at each time point. SCL = soft contact lens.
Complications observed during the follow-up period included dry eye in 1 LASIK-treated eye at 1 week postoperatively, diffuse lamellar keratitis in LASIK eyes at 1 week and 1 month postoperatively, and allergic conjunctivitis in a LASIK eye at 1 year. In the SCL group, 1 eye developed conjunctivitis at 1 year postoperatively.
Discussion
In the LASIK group, AL measurements were shorter than the corresponding corneal thickness changes up to 3 months postoperatively. There was no significant difference in AL elongation between 6 months and 2.5 years postoperatively between the LASIK-treated eyes and the SCL-wearing eyes. A greater proportion of patients subjectively reported better visual quality in the LASIK-treated eyes.
The present study confirmed that LASIK induces a shrinkage effect on the eyeball. In LASIK-treated eyes, the reduction in AL exceeded the corresponding corneal thickness changes, with the greatest decrease observed at 1 week postoperatively, greater than the expected maximum depth of excimer laser ablation. In contrast, eyes corrected with contact lenses exhibited no statistically significant change, showing a mean AL elongation of 0.016 mm at 6 months postoperatively. These findings support previous reports indicating that AL may decrease beyond theoretical expectations after LASIK surgery,28 possibly associated with choroidal thickening.29
No significant difference was observed in the amount of axial elongation at 6 months postoperatively between LASIK-treated eyes and SCL-wearing eyes. The mean axial elongation in LASIK-treated eyes was approximately 0.04 mm per year (0.085 mm over 2 years), which is lower than the previously reported rate of 0.065 mm per year in eyes with pathological myopia, defined as an SE of ≤ –6.0 D or an AL ≥26.5 mm.26 The average AL in this study was 26.41 ± 0.18 mm, which was slightly shorter than 26.5 mm and may account for the relatively low annual axial elongation observed. Although this 0.04 mm/year elongation was greater than the axial elongation reported in our previous study (0.01 mm/year),27 it was comparable to that found in prior contralateral eye comparison studies.30,31 Notably, a difference in axial elongation was observed between binocular LASIK-treated eyes (0.01 mm/year)27 and unilateral LASIK-treated eyes (0.04 mm/year),30,31 suggesting that axial elongation may be modulated by visual input from the contralateral eye. A recent study has also indicated that interocular differences in AL may represent a risk factor for further axial elongation.32 Future long-term, large-scale studies involving bilateral LASIK and SCL-wearing eyes are warranted to clarify the potential suppressive effect of LASIK on axial elongation.
Higher-order aberrations at a 6-mm pupil diameter were increased in LASIK-treated eyes; however, CDVA was better in the LASIK eyes. There were no significant differences between the LASIK and SCL-wearing eyes in terms of HOAs at 4 mm, CS under natural pupils, or CS under pharmacologically dilated pupils. Subjectively, many patients perceived the LASIK-treated eyes to provide better visual quality when comparing the 2 eyes. Notably, all patients who preferred the SCL-wearing eye, except 1 at 1.5 years postoperatively, had their dominant eye treated with SCL. These findings suggest that the increased HOAs at a 6-mm pupil diameter in modern LASIK-treated eyes have minimal impact on conscious visual perception and may exert only a latent influence. Previous studies33,34 have demonstrated that concentric focal shift designs in eyeglasses and SCLs can suppress axial elongation. Building on this concept, the selective increase in HOAs observed at a 6-mm analysis pupil diameter (but not at 4 mm) after LASIK may mimic the peripheral myopic focal shift effect, potentially contributing to the early axial shortening observed in this cohort.
No serious complications affecting visual function occurred in either eye throughout the study period, including during the surgical procedure. During the follow-up period, complications were observed in 4 LASIK-treated eyes and 1 SCL-wearing eye at isolated time points. Notably, no cases demonstrated recurrent symptoms or consistent findings across multiple follow-up periods.
Limitations of this study include that the statistical power was reduced because the final sample size was 2 subjects short of the planned number. And the lack of standardization in the SCLs used, which may limit the generalizability of the findings—particularly given that specific wavelengths of light have been reported to influence myopia progression35,36 and peripheral refraction varies depending on the type of SCL, which may have affected the progression of myopia.10 Furthermore, because axial elongation is partially related to overall body growth and may be influenced by interactions between both eyes, randomized controlled trials employing the same refractive correction method in both eyes would be more appropriate to yield definitive conclusions.
In conclusion, LASIK demonstrates a transient AL shortening effect; however, long-term studies employing the same refractive correction in both eyes are necessary to determine whether LASIK sustainably suppresses axial elongation. Although HOAs measured at a 6 mm pupil diameter increased in post-LASIK eyes, this did not negatively impact patients' subjective visual preferences. Future research should explore the potential relationship between increased HOAs and AL changes to further understand their role in myopia control.
Declaration of Generative AI and AI-Assisted Technologies in the Writing Process
During the preparation of this manuscript, the authors utilized ChatGPT (OpenAI) to aid in refining the language and improving the overall clarity and coherence of the text. Following its use, the authors thoroughly reviewed and revised the content as necessary and accept full responsibility for the final version of the manuscript.
Data Availability
The data sets generated and analyzed during the current study are available from the corresponding author on reasonable request.
Manuscript no. XOPS-D-25-00385.
Footnotes
Disclosure(s):
All authors have completed and submitted the ICMJE disclosures form.
The authors have no proprietary or commercial interest in any materials discussed in this article.
HUMAN SUBJECTS: Human subjects were included in this study. This study was a single-center, within-person, randomized, prospective clinical trial. It was approved by the Clinical Research Review Board of Kyoto Prefectural University of Medicine, Kyoto, Japan (ERB-C825-2), and registered with the Japan Registry of Clinical Trials (JRCT: https://jrct.mhlw.go.jp/) under Registration No. jRCTs052180173. The study adhered to the principles of the Declaration of Helsinki, and informed consent was obtained from all participants.
No animal subjects were included in this study.
Author Contributions:
Conception and design: Hieda, Yamamura, Wakimasu, Nakamura, Kinoshita
Data collection: Hieda, Yamamura, Wakimasu, Nakamura
Analysis and interpretation: Hieda, Yamamura, Tanaka
Obtained funding: N/A
Overall responsibility: Hieda
References
- 1.Modjtahedi B.S., Abbott R.L., Fong D.S., et al. Reducing the global burden of myopia by delaying the onset of myopia and reducing myopic progression in children: the academy's task force on myopia. Ophthalmology. 2021;128:816–826. doi: 10.1016/j.ophtha.2020.10.040. [DOI] [PubMed] [Google Scholar]
- 2.Itoi M., Hieda O., Kusada N., et al. Progression of myopic maculopathy: a systematic review and meta-analysis. Eye Contact Lens. 2023;49:83–87. doi: 10.1097/ICL.0000000000000948. [DOI] [PubMed] [Google Scholar]
- 3.Bullimore M.A., Ritchey E.R., Shah S., et al. The risks and benefits of myopia control. Ophthalmology. 2021;128:1561–1579. doi: 10.1016/j.ophtha.2021.04.032. [DOI] [PubMed] [Google Scholar]
- 4.Brennan N.A., Cheng X., Bullimore M.A. Adult myopia progression. Invest Ophthalmol Vis Sci. 2024;65:49. doi: 10.1167/iovs.65.13.49. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Lee S.S., Lingham G., Wang C.A., et al. Changes in refractive error during young adulthood: the effects of longitudinal screen time, ocular sun exposure, and genetic predisposition. Invest Ophthalmol Vis Sci. 2023;64:28. doi: 10.1167/iovs.64.14.28. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Smith E.L., 3rd, Ramamirtham R., Qiao-Grider Y., et al. Effects of foveal ablation on emmetropization and form-deprivation myopia. Invest Ophthalmol Vis Sci. 2007;48:3914–3922. doi: 10.1167/iovs.06-1264. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Sankaridurg P., Holden B., Smith E., 3rd, et al. Decrease in rate of myopia progression with a contact lens designed to reduce relative peripheral hyperopia: one-year results. Invest Ophthalmol Vis Sci. 2011;52:9362–9367. doi: 10.1167/iovs.11-7260. [DOI] [PubMed] [Google Scholar]
- 8.Kang P., Fan Y., Oh K., et al. Effect of single vision soft contact lenses on peripheral refraction. Optom Vis Sci. 2012;89:1014–1021. doi: 10.1097/OPX.0b013e31825da339. [DOI] [PubMed] [Google Scholar]
- 9.Lam C.S.Y., Tang W.C., Tse D.Y., et al. Defocus incorporated multiple segments (DIMS) spectacle lenses slow myopia progression: a 2-year randomised clinical trial. Br J Ophthalmol. 2020;104:363–368. doi: 10.1136/bjophthalmol-2018-313739. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Mutti D.O., Sinnott L.T., Berntsen D.A., et al. The effect of multifocal soft contact lens wear on axial and peripheral eye elongation in the BLINK study. Invest Ophthalmol Vis Sci. 2022;63:17. doi: 10.1167/iovs.63.10.17. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Queirós A., González-Méijome J.M., Jorge J., et al. Peripheral refraction in myopic patients after orthokeratology. Optom Vis Sci. 2010;87:323–329. doi: 10.1097/OPX.0b013e3181d951f7. [DOI] [PubMed] [Google Scholar]
- 12.Jonas J.B., Ang M., Cho P., et al. IMI prevention of myopia and its progression. Invest Ophthalmol Vis Sci. 2021;62:6. doi: 10.1167/iovs.62.5.6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Solomon K.D., Fernandez de Castro L.E., Sandoval H.P., et al. LASIK world literature review: quality of life and patient satisfaction. Ophthalmology. 2009;116:691–701. doi: 10.1016/j.ophtha.2008.12.037. [DOI] [PubMed] [Google Scholar]
- 14.Kim T.-I., Alió del Barrio J.L., Wilkins M., et al. Refractive surgery. Lancet. 2019;393:2085–2098. doi: 10.1016/S0140-6736(18)33209-4. [DOI] [PubMed] [Google Scholar]
- 15.Sandoval H.P., Donnenfeld E.D., Kohnen T., et al. Modern laser in situ keratomileusis outcomes. J Cataract Refract Surg. 2016;42:1224–1234. doi: 10.1016/j.jcrs.2016.07.012. [DOI] [PubMed] [Google Scholar]
- 16.Oshika T., Miyata K., Tokunaga T., et al. Higher order wavefront aberrations of cornea and magnitude of refractive correction in laser in situ keratomileusis. Ophthalmology. 2002;109:1154–1158. doi: 10.1016/s0161-6420(02)01028-x. [DOI] [PubMed] [Google Scholar]
- 17.Xia L.K., Ma J., Liu H.N., et al. Three-year results of small incision lenticule extraction and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis for correction of high myopia and myopic astigmatism. Int J Ophthalmol. 2018;11:470–477. doi: 10.18240/ijo.2018.03.18. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Queirós A., Villa-Collar C., Jorge J., et al. Peripheral refraction in myopic eyes after LASIK surgery. Optom Vis Sci. 2012;89:977–983. doi: 10.1097/OPX.0b013e31825ddf54. [DOI] [PubMed] [Google Scholar]
- 19.Nangia V., Jonas J.B., Sinha A., et al. Central corneal thickness and its association with ocular and general parameters in Indians: the central India eye and medical study. Ophthalmology. 2010;117:705–710. doi: 10.1016/j.ophtha.2009.09.003. [DOI] [PubMed] [Google Scholar]
- 20.Yin G., Wang Y.X., Zheng Z.Y., et al. Ocular axial length and its associations in Chinese: the Beijing eye study. PLoS One. 2012;7 doi: 10.1371/journal.pone.0043172. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Schallhorn S., Brown M., Venter J., et al. Early clinical outcomes of wavefront-guided myopic LASIK treatments using a new-generation hartmann-shack aberrometer. J Refract Surg. 2014;30:14–21. doi: 10.3928/1081597X-20131029-02. [DOI] [PubMed] [Google Scholar]
- 22.Farjo A.A., Sugar A., Schallhorn S.C., et al. Femtosecond lasers for LASIK flap creation: a report by the American academy of ophthalmology. Ophthalmology. 2013;120:e5–e20. doi: 10.1016/j.ophtha.2012.08.013. [DOI] [PubMed] [Google Scholar]
- 23.Murakami Y., Manche E.E. Prospective, randomized comparison of self-reported postoperative dry eye and visual fluctuation in LASIK and photorefractive keratectomy. Ophthalmology. 2012;119:2220–2224. doi: 10.1016/j.ophtha.2012.06.013. [DOI] [PubMed] [Google Scholar]
- 24.He S., Luo Y., Chen P., et al. Prospective, randomized, contralateral eye comparison of functional optical zone, and visual quality after SMILE and FS-LASIK for high myopia. Transl Vis Sci Technol. 2022;11:13. doi: 10.1167/tvst.11.2.13. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Brennan N.A., Toubouti Y.M., Cheng X., Bullimore M.A. Efficacy in myopia control. Prog Retin Eye Res. 2021;83 doi: 10.1016/j.preteyeres.2020.100923. [DOI] [PubMed] [Google Scholar]
- 26.Saka N., Moriyama M., Shimada N., et al. Changes of axial length measured by IOL master during 2 years in eyes of adults with pathologic myopia. Graefes Arch Clin Exp Ophthalmol. 2013;251:495–499. doi: 10.1007/s00417-012-2066-9. [DOI] [PubMed] [Google Scholar]
- 27.Sasaki M., Hieda O., Wakimasu K., et al. Myopia progression over a 4-year period after laser-assisted refractive surgery in patients in their 20s and 30s. Jpn J Ophthalmol. 2020;64:450–454. doi: 10.1007/s10384-020-00751-2. [DOI] [PubMed] [Google Scholar]
- 28.Tay E., Li X., Gimbel H.V., Kaye G. Assessment of axial length before and after myopic LASIK with the IOLMaster. J Refract Surg. 2013;29:838–841. doi: 10.3928/1081597X-20130924-01. [DOI] [PubMed] [Google Scholar]
- 29.Li S.M., Kang M.T., Wu S.S., et al. Efficacy, safety and acceptability of orthokeratology on slowing axial elongation in myopic children by meta-analysis. Curr Eye Res. 2016;41:600–608. doi: 10.3109/02713683.2015.1050743. [DOI] [PubMed] [Google Scholar]
- 30.Weng C., Xia F., Xu D., et al. Axial length growth difference between eyes after monocular laser refractive surgery: eight patients who underwent myopic laser ablation for both eyes at intervals of several years. BMC Ophthalmol. 2022;22:20. doi: 10.1186/s12886-022-02243-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Chen X., Guo L., Han T., et al. Contralateral eye comparison of the long-term visual quality and stability between implantable collamer lens and laser refractive surgery for myopia. Acta Ophthalmol. 2019;97:e471–e478. doi: 10.1111/aos.13846. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Kong K., Jiang J., Wang P., et al. Progression patterns and risk factors of axial elongation in young adults with nonpathologic high myopia: three-year large longitudinal cohort Follow-Up. Am J Ophthalmol. 2024;267:293–303. doi: 10.1016/j.ajo.2024.08.006. [DOI] [PubMed] [Google Scholar]
- 33.Ruiz-Pomeda A., Perez-Sanchez B., Valls I., et al. MiSight assessment study Spain (MASS). A 2-year randomized clinical trial. Graefes Arch Clin Exp Ophthalmol. 2018;256:1011–1021. doi: 10.1007/s00417-018-3906-z. [DOI] [PubMed] [Google Scholar]
- 34.Bao J., Huang Y., Li X., et al. Spectacle lenses with aspherical lenslets for myopia control vs single-vision spectacle lenses: a randomized clinical trial. JAMA Ophthalmol. 2022;140:472–478. doi: 10.1001/jamaophthalmol.2022.0401. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Torii H., Kurihara T., Seko Y., et al. Violet light exposure can be a preventive strategy against myopia progression. EBioMedicine. 2017;15:210–219. doi: 10.1016/j.ebiom.2016.12.007. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 36.Jiang Y., Zhu Z., Tan X., et al. Effect of repeated low-level red-light therapy for myopia control in children: a multicenter randomized controlled trial. Ophthalmology. 2022;129:509–519. doi: 10.1016/j.ophtha.2021.11.023. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data sets generated and analyzed during the current study are available from the corresponding author on reasonable request.