Outcomes Of Laser-Assisted In Situ Keratomileusis In Hyperopic Patients With Very Thick Corneas: A Retrospective Cohort Study

To evaluate the safety, efficacy, and refractive outcomes of laser-assisted in situ keratomileusis (LASIK) in hyperopic patients with very thick corneas (greater than 600 microns) compared to those with normal corneal thickness (between 500 and 600 microns). Although concerns exist regarding performing LASIK on patients with very thick corneas, this study investigates whether these individuals achieve comparable results in uncorrected and corrected distance visual acuity, refractive stability, safety, retreatment rates and postoperative ectasia.

A retrospective analysis of LASIK procedures performed at Care-Vision Laser Centers, a high-volume refractive surgery clinic in Tel Aviv, Israel, between January 2010 and June 2024.

A total of 1475 eyes from patients 16 - 40 years of age with hyperopia up to 12.0 diopters were included. Eyes were divided into two groups based on corneal thickness: the normal corneal thickness group, (1421 eyes) with corneal thickness of 500 - 600 microns, and the very thick cornea group, consisting of 54 eyes with corneal thickness >600 microns. Preoperative, intraoperative, and postoperative parameters were analyzed, including uncorrected and corrected distance visual acuity, refraction, corneal curvature, optical zone, maximum ablation depth, percent of corneal tissue ablated, residual stromal bed thickness, and retreatment and ectasia rates. Statistical adjustments were made to account for potential confounding variables.

The normal and thick cornea groups had similar demographics. Preoperatively, the thick cornea group had significantly greater corneal thickness (614.5 ± 11.3 vs 542.8 ± 24.6 µm, p < 0.0001) and more hyperopic refractive error (SEQ: 2.375 ± 2.240 vs 0.697 ± 2.136 D, p < 0.0001). Intraoperatively, residual stromal bed was greater (446.6 ± 26.9 vs 385.2 ± 30.3 µm, p = 0.7441), and percent of tissue ablated was lower (27.3 ± 4.0% vs 29.1 ± 3.9%, p < 0.0001). Postoperatively, there was a trend toward lower UDVA, CDVA, safety, and efficacy in the thick cornea group, though differences were not statistically significant (p > 0.05). Retreatment occurred in 1.3% of normal cornea cases but none in the thick cornea group. No ectasia was observed.

LASIK in hyperopic patients with thick corneas appears safe and effective, though trends toward lower safety and efficacy indices suggest potential differences in outcomes compared to normal thickness corneas. The absence of retreatments in the thick cornea group limits conclusions regarding enhancement rates. Similarly, no cases of ectasia were observed, precluding assessment of its risk. These findings highlight the need for further research to determine whether thick corneas influence LASIK outcomes in hyperopic patients.