Visual and Refractive Outcomes of Corneal Refractive Surgery for Hyperopic and Mixed Astigmatism: A Systematic Review and Meta-Analysis.
TL;DR
Modern corneal refractive surgery provides substantial cylinder reduction, high predictability, and excellent safety in hyperopic and mixed astigmatism, supporting their use in appropriately selected patients.
Abstract
TOPIC To evaluate the visual and refractive outcomes of corneal refractive surgery (PRK, LASIK, and SMILE) for hyperopic and mixed astigmatism. The clinical question addressed was: in adults with hyperopic or mixed astigmatism, how effective and safe are modern corneal refractive procedures, without alternative surgical comparators, in reducing refractive cylinder and improving uncorrected distance visual acuity? CLINICAL RELEVANCE Hyperopic and mixed astigmatism are less predictable to correct than myopic errors due to biomechanical and ablation-profile complexity. Historically, these treatments showed higher regression and retreatment rates. With advances in excimer and femtosecond platforms, updated evidence is needed to inform clinical decision-making and patient counseling regarding expected efficacy, predictability, and safety.
Methods
A systematic review and meta-analysis were conducted following PRISMA 2020 and Cochrane guidelines. PubMed, Scopus, and Web of Science were searched from January 2010 to March 2025. Eligible studies included prospective, retrospective, or randomized human studies evaluating PRK, LASIK, or SMILE for hyperopic or mixed astigmatism. Case reports, small series (<10 eyes), intraocular procedures, and presbyopia treatments were excluded. Risk of bias was assessed using the NIH Quality Assessment Tool for Case Series Studies. Random-effects meta-analyses were performed, and heterogeneity was quantified with I2 statistics.
Results
Twenty-three studies (3,561 eyes) were included. Mean preoperative cylinder was 2.45 ± 1.23 D. Pooled residual astigmatism was 0.47 D (95% CI, 0.04-0.90) for hyperopic and 0.67 D (95% CI, 0.37-0.97) for mixed astigmatism. Approximately 66% (hyperopic) and 50% (mixed) achieved ≤ 0.50 D residual cylinder; 81% and 83%, respectively, were within ≤ 1.00 D. Uncorrected distance visual acuity (UDVA) of 20/20 or better was achieved in 60% (hyperopic) and 63% (mixed). Loss of ≥1 line of corrected distance visual acuity (CDVA) occurred in 6% (95% CI, 0.01-0.14) of hyperopic and 5% (95% CI, 0.03-0.15) of mixed eyes (pooled random-effects estimates). No significant differences were found between groups in comparative meta-analysis.
Conclusion
Modern corneal refractive surgery provides substantial cylinder reduction, high predictability, and excellent safety in hyperopic and mixed astigmatism. Although heterogeneity and predominantly non-randomized designs limit certainty, current laser technologies achieve clinically meaningful outcomes comparable between groups, supporting their use in appropriately selected patients.