Ex Vivo Assessment of Excimer Laser-Assisted Lenticule Customization

To introduce and assess the reproducibility of a method for ex vivo assessment of excimer laser-modified stromal lenticules derived from keratorefractive lenticule extraction (KLEx) procedures, using a calibration sphere and anterior segment imaging.

Four myopic lenticules (small incision lenticule extraction [SMILE]) from patients and four hyperopic lenticules (SMILE and corneal lenticule extraction for advanced refractive correction [CLEAR]) from pig eyes were created and subjected to partial phototherapeutic keratectomy (PTK) using a masking technique. Lenticule thickness and curvature were assessed pre- and post-ablation using anterior-segment optical coherence tomography and topography while mounted on a calibration sphere. A controlled dehydration protocol was applied. Ablated and non-ablated regions were compared for intralenticular differences in curvature and thickness.

Reproducibility of keratometry measurements across six lenticules showed coefficients of variation (CVs) of 0.10% to 5.24% (mean = 1.78%). When higher variability lenticules were considered separately, the remaining lenticules demonstrated lower variability (average CV = 0.67%; reproducibility coefficient [CR] = 0.57). Following excimer ablation, the average thickness in ablated regions was 50.63 ± 18.72 µm compared with 82.88 ± 21.12 µm in non-ablated regions (P = 0.00015), accompanied by an apparent localized flattening of 9.88 ± 4.58 D (P = 0.00049). When analyzed by subgroup, the mean keratometric difference was 7.25 ± 2.22 D in myopic lenticules and 12.50 ± 5.07 D in hyperopic lenticules. Post-PTK topography demonstrated asymmetric regional curvature changes in all lenticules. Glycerol application improved imaging acquisition.

This study introduces a non-implantation-based method for evaluating the morphological effects of excimer laser ablation on stromal lenticules, enabling direct assessment of customized reshaping strategies supporting stromal keratophakia applications, particularly for keratoconus. Interpretation is limited by the exploratory sample size; further refinement and larger studies are warranted.

This ex vivo model provides a method for imaging excimer laser reshaping of lenticules and reduces reliance on lenticule implantation solely for imaging and assessment during early-phase customization studies.