Abstract
Purpose :
Laser assisted in situ keratomileusis is a procedure for correcting refractive error through surgical reshaping of the cornea, which is thought to alter mechanical integrity. In this study, we assess changes in corneal stiffness due to LASIK using optical coherence elastography (OCE).
Methods :
We utilize three OCE techniques to interrogate the mechanical properties of ex vivo porcine corneas before and after LASIK. Six pairs of whole porcine eye globes were utilized for this study. Within each pair, one eye was kept as a control, while LASIK was performed on the fellow eye. OCE measurements were performed on each eye as intraocular pressure (IOP) was artificially maintained. Of the six pairs, three pairs were assessed using air coupled optical coherence elastography (ACUS-OCE), and the remaining three pairs were assessed using both compression OCE and heartbeat OCE (Hb-OCE).
Results :
Mean wave speed for untreated corneas were measured as 2.88 ± 0.04 m/s, 4.99 ± 0.18 m/s, and 6.18 ± 0.24 m/s at 10 mmHg, 20 mmHg, and 30 mmHg, respectively. Mean wave speeds for the LASIK-treated corneas were 2.73± 0.05 m/s, 4.34 ± 0.57 m/s, and 5.82 ± 0.97 m/s, respectively. Analysis of all samples showed a statistically significant increase in wave speed as a function of IOP for both tissue types by one way ANOVA. Hb-OCE and compression OCE did not show a statistically significant difference in strain between both techniques but did show a distinct difference in local strain between anterior and posterior segments of the cornea. Mean strain difference measured by Hb-OCE for the untreated and LASIK-treated corneas was 0.33 ± 0.44 mε and 1.09 ± 0.99 mε, respectively. The mean strain difference measured by compression OCE for the untreated and LASIK-treated corneas was 0.07 ± 0.04 mε and 0.16 ± 0.04 mε respectively.
Conclusions :
The results of this study suggest that LASIK may cause softening of the corneal tissue, and local changes to the tissue may have global impact over whole corneal stiffness. Future work will examine how corneal stiffness changes after LASIK in vivo.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.