PRK vs. LASIK in High Myopia: A Systematic Review and Meta-Analysis

1. INTRODUCTION

High myopia, defined as a refractive error of –6.00 diopters (D) or greater, is a major global public health concern due to its increasing prevalence and association with sight-threatening ocular complications such as retinal detachment, glaucoma, and myopic maculopathy [1, 2]. The worldwide prevalence of myopia has dramatically increased over the past few decades. As of 2020, approximately 30% of the global population was affected by myopia, and projections suggest that by 2050, nearly 50% of the global population will be myopic, with 10% of those developing high myopia, amounting to approximately 1 billion people [3]. Laser corneal refractive surgery has become a highly effective and predictable method for correcting myopia and reducing dependence on spectacles and contact lenses [4, 5]. PRK is considered a safe and effective option for vision correction. However, it has certain limitations, including delayed epithelial healing, postoperative pain, stromal haze, and the risk of corneal ectasia. [6-8]. With the introduction of LASIK, many surgeons prefer it as the primary choice due to its faster visual recovery and reduced discomfort in the early postoperative period. [9]. Nevertheless, PRK remains the preferred surgical option for patients with irregular corneal topography, thinner corneas, or those who do not qualify for LASIK [8].

Despite extensive evidence comparing PRK and LASIK in mild and moderate myopia, data in high myopia remain limited. The only prior systematic review addressing this topic found comparable long-term visual and refractive outcomes between the two procedures [10]. Previous systematic reviews comparing PRK and LASIK have largely evaluated mixed degrees of myopia and did not isolate high myopia (≥ –6.00 D) as a primary analytic population. The presents analysis incorporates newer studies reflecting the widespread adoption of femtosecond flap creation in LASIK, optimized excimer laser ablation profiles, and routine intraoperative mitomycin-C use in PRK. These technological advancements have significantly influenced refractive predictability, wound healing response, and complication profiles, particularly in highly myopic eyes. Given the distinct biomechanical and refractive challenges posed by high myopia compared with low to moderate myopia, a focused evaluation of this subgroup using more contemporary evidence is clinically warranted. To our knowledge, a dedicated meta-analysis specifically targeting high myopia in the modern surgical era has not been previously performed. This systematic review and meta-analysis, therefore, aimed to comprehensively compare the efficacy, safety, and long-term outcomes of PRK and LASIK in patients with high myopia to inform current surgical decision-making and patient selection.

2. METHODS AND MATERIALS

3. RESULTS

3.1. Study Selection

The study selection process is illustrated in Fig. (1). The initial search identified 385 records. After excluding 56 duplicates, 329 titles and abstracts underwent screening. Subsequently, 23 full-text articles were evaluated for eligibility, and 11 studies were ultimately included in the review. The baseline characteristics of these 11 studies are summarized in Table 1.

Table 1.

Study	Study Design	Total Number of Patients (number of eyes)	Total Number of PRK Patients (number of eyes)	Total Number of LASIK Patients (number of eyes)	Age in Years (mean ± SD)	PRK Group Degree of Myopia (mean ± SD in diopters, preoperative)	LASIK Group Degree of Myopia (mean ± SD in diopters, preoperative)	PRK Group UDVA (mean ± SD, logMAR or Snellen)	LASIK Group UDVA (mean ± SD, logMAR or Snellen)
Zhang, Y et al. 2022 [16]	Prospective interventional study	32 patients, 64 eyes	32 eyes	32 eyes	18 years or older	−6.57 ± 2.01 D	−6.67 ± 1.99 D	1.07 ± 0.22 logMAR	1.08 ± 0.23 logMAR
Mounir et al. 2020 [14]	Prospective comparative interventional study	156 patients,156 eyes	72 eyes	84 eyes	PRK group: 29.76±5.01 LASIK group: 27.94±6.69	-8.86±1.81 D	-9.25±1.70 D	0.05±0.02	0.05±0.01
Jiafan Zhang et al. 2020 [17]	Prospective, non-randomized, cohort study	88 patients, 165 eyes	46 patients, 85 eyes	80 eyes of 42 patients	PRK group: 25.6 ± 6.1, LASIK group: 23.9 ± 5.5	−7.59 ± 0.84 D	−7.60 ± 1.21 D	1.22 ± 0.20 logMAR	1.25 ± 0.21 logMAR
Hashemi 2016 et al. [15]	Comparative nonrandomized clinical trial	30 patients, 60 eyes	30 eyes	30 eyes	PRK group: 27.14 ± 5.63 LASIK group: 28.60 ± 7.85	-8.54 ± 1.42 D	-8.19 ± 2.05 D	1.75 ± 0.16 logMAR	1.80 ± 0.15 logMAR
Ioannis M Aslanides, 2014 et al. [18]	Prospective interventional cohort with matched retrospective control groups	64 patients, 101 eyes	tPRK group: 27 patients (41 eyes) standard PRK group: 20 patients (29 eyes)	17 patients, 31 eyes	tPRK: 27 ± 6 PRK: 27 ± 6 LASIK: 31.3 ± 10	tPRK: -7.89 ± 1.24D PRK: -8.25 ± 1.72 D	-7.41 ± 1.35 D	N/A	N/A
Anders Ivarsen et al. 2009 [37]	Randomized clinical trial	46 patients, 46 eyes	20 patients, 20 eyes	25 patients, 25 eyes	PRK: 33± 8 LASIK:30± 7	-6.91 ± 0.57 D	-7.12 ± 0.57 D	N/A	N/A
Jorge L. Alió et al. 2009 [20]	Retrospective study	192 eyes	51 eyes	141 eyes	PRK: 33.96 ± 10.96 (20 to 66) LASIK: 32.44 ± 9.09	–12.44 ± 1.49 D	–12.81±1.64 D	N/A	N/A
Jorge L. Alió et al. 2010 [21]	Retrospective, control-matched study	65 patients, 68 eyes	33 patients, 34 eyes	32 patients, 34 eyes	PRK: 29.4 (6.8), LASIK 29.44 (6.8)	–8.42 ± 1.34 D	–8.30± 1.21 D	N/A	N/A
Hjortdal et al. 2005 [22]	Prospective randomized study	45 patients, 45 eyes	20 patients, 20 eyes	25 patients, 25 eyes	PRK (n=20) 33± 8, LASIK (n=25) 30± 7	–6.64 ± 0.55 D	-7.12 ± 0.57 D	N/A	N/A
Langrová et al. 2003 [23]	Comparative study	89 patients, 89 eyes	38 patients, 38 eyes	31 patients, 31 eyes	PRK: mean age of 25 (18± 48), LASIK: mean age of 24 years (19± 48)	–-8.0± 1.7 D	-9.2± 2.1 D	N/A	N/A
A. Helmy et al. 1996 [24]	Randomized clinical trial	59 patients, 80 eyes	40 eyes	40 eyes	Mean: 29	-7 D	-7.3 D	N/A	N/A

Abbreviations: SE = spherical equivalent; UDVA = uncorrected distance visual acuity; CDVA = corrected distance visual acuity; RCT = randomized controlled trial.

Quality assessment of the included studies is shown in Figs. (2 and 3). All non-randomized studies showed a moderate risk of bias, mainly due to confounding and deviations from interventions (Fig. 2). In contrast, RCTs showed a low risk of bias, with concerns noted in one study [14] regarding randomization and missing outcome data (Fig. 3).

Baseline SE was compared as shown in Fig. (4) across ten studies [14-23]. The pooled analysis revealed a comparable baseline SE between PRK and LASIK groups (MD, 0.17 D; 95% Cl, -0.07 to 0.42; P = 0.16), with no statistical or clinical significance.

Of the 11 studies, 4 studies reported SE at 1 month postoperatively, as shown in Fig. (5) [14, 16, 19, 22]. The initial analysis showed no statistically significant difference in refractive stability between PRK and LASIK (MD, 0.37 D; 95% CI, -0.26 to 0.99; P = 0.25). A sensitivity analysis excluding Hjortdal 2005, [22] markedly reduced heterogeneity from 94% to 56% and confirmed non-significance (MD, -0.04 D; 95% CI, -0.30 to 0.22; P = 0.77). The small numerical difference is not statistically or clinically meaningful.

Five studies evaluated SE at 6 months postoperatively, as shown in Fig. (6) [14, 15, 17, 19, 22]. The overall pooled estimate showed no significant difference (MD, -0.16 D; 95% CI, -0.39 to 0.07; P = 0.18), with moderate heterogeneity (I² = 68%). After excluding Zhang J 2020, [17] heterogeneity was eliminated (I² = 0%), and the statistical result became significant (MD, -0.29 D; 95% CI, -0.45 to –0.14; P = 0.0003), favoring PRK over LASIK.

Nine studies reported data about SE at 12 months postoperatively as shown in Fig. (7) [14, 16-23]. Analysis of these data indicated no statistically significant difference between PRK and LASIK (MD, -0.03 D; 95% CI, -0.19 to 0.13; P = 0.67), with moderate heterogeneity (I² = 69%). After excluding Alió 2009, [20] heterogeneity reduced to 50%, and the effect estimate remained non-significant (MD, 0.03 D; 95% CI, -0.09 to 0.16; P = 0.62).

UDVA logMAR at final follow-up was compared between PRK and LASIK across four studies, as shown in Fig. (8). The initial analysis showed no significant difference between the two groups (Mean Difference = 0.00; 95% CI: -0.03 to 0.03; P = 0.95), with substantial heterogeneity (I² = 65%). After excluding the Hashemi 2016 study, the analysis included three studies, and the results remained non-significant (Mean Difference = -0.02; 95% CI: -0.04 to 0.00; P = 0.10), with heterogeneity reduced to 25%, indicating improved consistency. Overall, these findings suggest that both PRK and LASIK provide comparable uncorrected distance visual acuity outcomes at final follow-up.

This figure compares PRK and LASIK in achieving a refractive outcome within ±0.50 diopters of the target, as shown in Fig. (9). The upper analysis, which includes all studies, shows no statistically significant difference between the two procedures (OR = 0.75, 95% CI: 0.36–1.54), and is marked by moderate heterogeneity (I² = 69%). In contrast, the lower analysis excluding the Zhang J 2020 study demonstrates a statistically significant advantage for LASIK (OR = 0.54, 95% CI: 0.31–0.94), with substantially reduced heterogeneity (I² = 33%). These findings indicate that LASIK is associated with more consistent and predictable refractive outcomes than PRK, with a greater proportion of eyes achieving close alignment with the intended correction.

The initial analysis of eight studies in Fig. (10) showed no statistically significant difference in achieving refractive outcomes within ±1.00 D between PRK and LASIK (OR = 0.72; 95% CI: 0.36–1.45; p = 0.36), with moderate heterogeneity (I² = 63%). After excluding Zhang J 2020 and Hjortdal 2008, the results became statistically significant in favor of LASIK (OR = 0.52; 95% CI: 0.29–0.92; p = 0.03), with heterogeneity reduced to 47%. These findings suggest that LASIK provides better refractive predictability than PRK when outlier studies are removed.

Data from six studies comparing the number of eyes achieving 20/20 vision or better following PRK versus LASIK are shown in Fig. (11). In the initial analysis, including all studies, no statistically significant difference is found between the two procedures (OR = 1.01, 95% CI: 0.48–2.15, p = 0.97), with moderate heterogeneity (I² = 48%). After excluding Zhang J 2020, the odds ratio shifts in favor of PRK (OR = 0.81), although the result remains statistically non-significant (95% CI: 0.41–1.61, p = 0.55), and heterogeneity is further reduced to a low level (I² = 30%). As the confidence intervals cross 1 in both analyses, no definitive advantage of PRK or LASIK can be concluded in achieving 20/20 or better vision, though the trend slightly favors PRK after excluding Zhang J 2020.

A total of 5 studies reported the proportion of eyes achieving 20/40 or UDVA following PRK or LASIK, as shown in Fig. (12). The initial pooled analysis showed no statistically significant difference between the two procedures (OR = 0.64; 95% CI: 0.31–1.32; p = 0.23), with moderate heterogeneity (I² = 42%). After removing the outlier study by Zhang J 2020, the analysis demonstrated a statistically significant advantage for LASIK (OR = 0.52; 95% CI: 0.32–0.85; p = 0.009), with no evidence of heterogeneity (I² = 0%). These results indicate that LASIK is more likely to achieve 20/40 or better vision, with improved consistency across studies.

Secondary outcomes reported by each study and categorized by procedure (PRK vs. LASIK) are summarized in Table 2. The table demonstrates variability in the type and frequency of postoperative complications across both procedures. Corneal haze was more commonly associated with PRK, as evidenced by reports in 8 studies [14, 16, 18, 19, 20, 21, 23, 24], in contrast to LASIK, where only 2 studies documented its occurrence [16, 25]. Moreover, both procedures showed distinct adverse events. LASIK has more flap-related complications, as indicated by findings from 3 studies [14, 20, 22]. In contrast, PRK was characterized by complications such as delayed epithelial healing and haze formation. Corneal haze was reported more frequently after PRK in 8 studies; however, it is important to note that most of these studies did not use intraoperative MMC, which is now routinely applied to reduce haze risk [14, 15, 16, 18].

Table 2.

Study	Corneal Haze		Adverse Effects
	PRK	LASIK	PRK	LASIK
Zhang Y et al. 2022 [16]	-0.5 in 17 eyes -1.0 in 10 eyes	- 0.5 in 19 eyes -1.0 in 4 eyes	N/A	N/A
Mounir et al. 2020 [14]	2 eyes: -Grade 2: 1 eye -Grade 4: 1 eye	N/A	-Delayed epithelial healing in two eyes. -One eye suffered from toxic epitheliopathy.	-Two eyes with released suction ring and two eyes with microstriae which were corrected by re-floating the flap.
Jiafan Zhang et al. 2020 [17]	N/A	N/A	N/A	N/A
Hashemi et al. 2016 [15]	N/A	N/A	N/A	N/A
Ioannis M Aslanides et al. 2014 [18]	tPRK group: -3 months: 15 eyes -6 months: reduced to 9 eyes -12 months: 1 eye PRK group: -3 months: 6 eyes -6 months: 5 eyes -12 months: 0 eyes	N/A	N/A	N/A
Anders Ivarsen et al. 2009 [37]	1 eye	N/A	N/A	N/A
Jorge L. Alió et al. 2009 [20]	-Graded on a scale of 0 to 4 Grade 1: -18 eyes at 3 months -2 years: 18 eyes -10 years: 6 eyes	N/A	- 6 eyes lost 2 or more lines of CDVA. - 4 eyes lost lines due to CNVM formation. - 2 eyes lost lines due to the presence of haze.	- 7 eyes lost 2 or more lines of CDVA. - 2 eyes lost lines due to choroidal neovascular membrane formation. - 1 eye lost lines due to retinal detachment. - 4 eyes lost lines due to cataract formation.
Jorge L. Alió et al. 2010 [21]	At 10 years, one of 34 eyes had grade 0.5 haze	N/A	- Central island in 2 of 34 eyes; resolved spontaneously or corrected.	- Fine wrinkles (one of 34 eyes) confined to the flap and did not affect vision. - Corneal flap melt or necrosis (one of 34 eyes).
Hjortdal et al. 2005 [22]	N/A	N/A	-Peripheral flap edema and corneal epithelial thinning	-Peripheral flap edema and corneal epithelial thinning
Langrová et al. 2003 [23]	4 patients	N/A	N/A	N/A
A. Helmy et al. 1996 [24]	Mean haze: -1 month: 1.70 ± 0.56 -3 months: 1.70 ± 0.67 -6 months: 1.60 ± 1.07 -12 months: 1.20 ± 0.42	Mean haze: -1 month: 1.37 ± 0.74 -3 months: 0.75 ± 0.74 -6 months: 0.50 ± 0.53 -12 months: 0.25 ± 0.46	N/A	N/A

Abbreviations: MMC = Mitomycin-C; SE = spherical equivalent; CDVA Corrected distance visual acuity; CNVM = choroidal neovascular membrane.

4. DISCUSSION

In this systematic review and meta-analysis, we compared the safety and efficacy of PRK and LASIK specifically in eyes with high myopia. While both procedures demonstrated acceptable visual and refractive outcomes, LASIK showed superior refractive predictability within ±0.50 D and ±1.00 D in sensitivity analyses with reduced heterogeneity. These findings suggest that, in appropriately selected high myopic eyes, LASIK may offer more consistent refractive accuracy, whereas PRK remains a viable alternative in cases where corneal thickness or topography preclude flap-based surgery. Importantly, differences between procedures were more apparent after accounting for influential studies, highlighting the impact of study design and patient selection on pooled outcomes.

The findings of this meta-analysis should be interpreted in the context of prior systematic reviews. Shortt et al. (2006) and the subsequent Cochrane update by Shortt et al. (2013) compared PRK and LASIK across a broad spectrum of myopia and concluded that LASIK offered faster visual recovery, with largely comparable long-term visual and refractive outcomes [10, 26]. However, those reviews primarily included studies conducted before widespread adoption of modern excimer platforms, femtosecond flap creation, routine MMC use in PRK, and contemporary ablation algorithms. In addition to isolating high myopia as the primary analytic population, this study contributes several additional findings not previously emphasized in earlier meta-analyses. These include a focused evaluation of refractive predictability within ±0.50 D and ±1.00 D in high myopic eyes, sensitivity analyses demonstrating the influence of specific outlier studies on heterogeneity, and an assessment of medium-term refractive stability at 6 months following exclusion of influential data. These analyses provide a more granular understanding of refractive outcomes in high myopia than previously reported.

Although newer refractive techniques such as small incision lenticule extraction (SMILE) have become increasingly popular for myopic correction, the clinical decision between surface ablation and lamellar procedures remains highly relevant, particularly in patients with high myopia or reduced corneal thickness. SMILE is generally limited by the lack of cyclotorsion control and is not suitable for cases requiring customized ablation profiles or topography-guided treatments [19, 27]. In contrast, PRK and LASIK remain the primary options for patients with thin or irregular corneas, previous ocular surgery, or borderline residual stromal bed thickness. Despite abundant comparative data on PRK and LASIK in low-to-moderate myopia, studies focused exclusively on high myopia are scarce. The present meta-analysis, therefore, provides an updated synthesis of modern refractive outcomes, incorporating recent evidence on the use of intraoperative MMC to mitigate haze and improve visual predictability, thereby refining understanding of safety and efficacy in contemporary high myopia correction.

The analysis revealed no statistically significant difference between the two procedures in preoperative SE or SE at 1 month. These findings align with previous meta-analyses [10, 26]. At the 6-month postoperative mark, our meta-analysis revealed no significant difference in SE between PRK and LASIK initially; however, after excluding Zhang J. 2020, a statistically significant difference emerged in favor of PRK (MD: –0.29 D; 95% CI: –0.45 to –0.14; P = 0.0003). This suggests a potential advantage of PRK in refractive stability in the medium term. Curcă et al. also demonstrated significantly better SE outcomes at 6 months for PRK compared to LASIK, supporting this finding [28]. This difference reflects variations in corneal wound healing and biomechanical responses between surface ablation and flap-based procedures. In highly myopic eyes, deeper stromal ablation may predispose LASIK-treated corneas to early refractive regression, whereas PRK, particularly with modern ablation profiles and adjunctive usage of MMC, may allow more uniform stromal remodeling and improved refractive stability over time [6, 8]. Likewise, Mounir et al. reported stable SE outcomes over 12 months in both t-PRK and Femto-LASIK for high myopia, with no significant difference between groups at 6 months (p > 0.05), though their reported mean SE values at this point also numerically favored PRK (−1.08 ± 0.92 D vs. −0.74 ± 0.48 D) [14]. These findings reinforce our observation that PRK may yield more stable refractive outcomes at 6 months in patients with high myopia. By 12 months, the outcomes between the two groups converged again, with no significant difference observed in SE. A previous randomized clinical trial in low myopia patients has shown no significant difference in SE between PRK and LASIK at 12 months postoperatively [29]. While these findings were observed in patients with milder refractive errors, our analysis suggests this trend extends to high myopia populations as well. Moreover, a 12-month PRK series found that high myopic corrections maintained mean spherical equivalent near emmetropia and ≥20/20 UDVA in the majority of eyes, with efficacy and safety indices similar to those observed with lower myopia [30, 31]. This suggests that modern PRK provides excellent efficacy and safety across a wide myopic spectrum. Longer-term cohorts and predictive factor analyses further indicate that PRK maintains good stability over at least 2 years, and that higher myopia can still achieve efficacy indices close to those of low myopia when patient selection and surgical planning are carefully optimized [32].

In our meta-analysis, no statistically significant difference was found between PRK and LASIK in achieving a UDVA of 20/20 or better, before or after sensitivity analysis. After excluding Zhang J. (2020), heterogeneity decreased from 48% to 30%, further supporting the reliability of comparable outcomes between the two procedures. These findings are consistent with previous reports, such as the Cochrane review by Shortt et al., which found no difference in achieving 20/20 vision between PRK and LASIK in myopic patients, though most included studies involved low-to-moderate myopia [26]. When evaluating the more inclusive threshold of 20/40 or better, our analysis demonstrated a statistically significant advantage for LASIK (OR = 0.52; 95% CI: 0.32–0.85; P = 0.009), indicating that LASIK-treated eyes were more likely to achieve functional uncorrected distance vision in the high myopia subgroup. This finding was robust, with no heterogeneity among studies (I² = 0%). Supporting this, El Danasoury et al. reported faster visual recovery and earlier achievement of functional vision following LASIK, especially in patients with higher refractive errors [29]. While PRK and LASIK may provide similar final high-acuity outcomes, LASIK may offer earlier functional gains in UDVA in highly myopic eyes.

The findings of this study showed no significant difference in final UDVA (logMAR) between PRK and LASIK, as also demonstrated in several comparative studies. Miraftab et al. reported that at 12 months postoperatively, PRK achieved a mean UDVA of 0.05 ± 0.13 logMAR, while Femto-LASIK achieved 0.02 ± 0.06, indicating highly similar uncorrected visual acuity outcomes in high myopia [33]. Similarly, Curcă et al. observed no clinically relevant difference in postoperative UDVA logMAR at final follow-up between PRK and LASIK-treated eyes [28]. Although LASIK has historically been associated with faster early visual recovery, our analysis and supporting evidence indicate that both techniques offer equivalent uncorrected distance visual acuity in the long term.

The pooled analysis indicated that LASIK demonstrated superior predictability in achieving a postoperative SE within ±1.00 D, particularly after excluding high-risk studies such as Zhang J 2020 and Hjortdal 2005, where the odds significantly favored LASIK (OR = 0.52; 95% CI: 0.29–0.94; p = 0.03). This observation agrees with the Cochrane systematic review by Shortt et al., which found that in eyes with moderate to high myopia, LASIK had a higher likelihood of achieving within ±1.00 D compared to PRK, although the difference did not always reach statistical significance (OR 0.58; 95% CI: 0.31–1.06) [26]. Similarly, Mounir et al. reported a higher proportion of eyes within ±1.00 D at 12 months following Femto-LASIK (85.71%) compared to t-PRK (71.43%) in high myopic patients [14]. For the stricter ±0.50 D target, the evidence was less consistent. The Cochrane review revealed no significant difference between LASIK and PRK in achieving ±0.50 D accuracy across all degrees of myopia (OR = 0.94; 95% CI: 0.42–2.11), with substantial heterogeneity noted (I² = 53.9%) [26]. The cohort analyzed by Kaushik et al. demonstrated superior refractive predictability with LASIK-based modalities compared to PRK. Specifically, the proportion of eyes achieving a post-operative spherical equivalent within ±0.50 D of the intended target was significantly higher following Contoura LASIK (97%) and wavefront-optimized LASIK (95%) than after PRK (90%). Furthermore, patients in both LASIK subcohorts experienced accelerated visual recovery [34]. These findings support the interpretation that while both procedures provide acceptable refractive accuracy, LASIK may offer a slight advantage in predictability.

Corneal haze was reported in 8 studies; however, most reports originated from studies that did not routinely use intraoperative MMC. Seven of the eleven included studies did not report MMC use, whereas four studies used MMC and generally reported lower rates of clinically significant haze. MMC is now widely applied in contemporary PRK to inhibit keratocyte proliferation and reduce haze formation. In contrast, LASIK is distinguished by flap-related complications, as indicated by findings from 3 studies [14, 20, 22]. While rare, such issues can affect vision quality and may necessitate additional surgical management [35, 36, 37]. Proper surgical technique and adherence to postoperative care are crucial in minimizing these risks [20, 22].

This meta-analysis provides valuable insights into the outcomes of PRK versus LASIK in patients with high myopia. While both procedures offer comparable visual acuity at final follow-up, LASIK demonstrates superior refractive predictability and accuracy. Therefore, LASIK is preferred in cases where precise refractive outcomes and faster visual recovery are desired. However, the distinct complications must be considered. LASIK is more often associated with flap-related complications, whereas PRK is linked to delayed epithelial healing and corneal haze. In clinical practice, the choice of procedure should be tailored to the patient's characteristics, preferences, and lifestyle.

This systematic review and meta-analysis have several limitations that should be acknowledged. First, heterogeneity within the PRK and LASIK groups, including variations in surface ablation techniques (conventional PRK, transepithelial PRK, and advanced surface laser ablation), flap creation methods (femtosecond versus microkeratome LASIK), and the inconsistent use of Mitomycin C, may have influenced pooled outcomes and could not be fully explored through formal subgroup analyses because of limited reporting and sample size. Second, although several included studies were non-randomized and demonstrated moderate risk of bias, restricting inclusion exclusively to randomized controlled trials would have substantially limited the available evidence specific to high myopia. Given the relative scarcity of RCTs focusing solely on ≥ –6.00 D, the inclusion of well-conducted observational studies was necessary to provide a comprehensive assessment of this subgroup. Importantly, sensitivity analyses excluding higher risk and influential studies reduced heterogeneity and did not materially alter the direction or magnitude of the pooled outcomes, supporting the robustness of the conclusions despite methodological variability. Finally, publication bias could not be formally assessed using funnel plots due to the limited number of studies per outcome, and the findings should therefore be interpreted with appropriate caution. There are several key strengths to this study. A comprehensive risk of bias assessment was conducted to ensure transparency in evaluating the reliability of the included studies. The review focused on clinically relevant outcomes, including UDVA, refractive predictability, and postoperative complications, making the findings directly applicable to clinical decision-making. Furthermore, the systematic use of sensitivity analyses to address heterogeneity and assess the influence of outlier studies enhances the reliability of the conclusions.

Future myopic refractive research should prioritize large-scale, prospective, randomized controlled trials with extended follow-up durations. This prolonged tracking is vital for evaluating long-term refractive stability alongside the true incidence of late-stage complications, including corneal ectasia, regression, and chronic dry eye syndrome.

CONCLUSION

This systematic review and meta-analysis found that both PRK and LASIK are effective and safe options for correcting high myopia, yielding comparable long-term visual acuity and spherical equivalent outcomes. However, LASIK demonstrated superior refractive predictability, with a significantly higher proportion of eyes achieving ±0.50 D and ±1.00 D of the target refraction, as well as better odds of reaching 20/40 vision or better. PRK, while effective, was more frequently associated with postoperative haze and healing-related complications, suggesting that individualized procedure selection remains essential based on corneal profile and patient-specific risk factors.

Future studies should prioritize large-scale, prospective randomized controlled trials with extended follow-up beyond 12 months to assess long-term refractive stability and late-onset complications such as ectasia or regression. More consistent reporting of complications and standardized outcome measures across studies is needed to improve data comparability. Investigating newer surface ablation techniques (e.g., transepithelial PRK) and their performance in high myopia could further inform surgical decision-making.

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