Post-LASIK corneas show sub-clinical differences in sensory nerves and immune cell morphodynamics

PURPOSE: To compare corneal nerve architecture and sensory function, and the distribution and morphodynamic (morphologic and dynamic) features of epithelial and stromal immune cells, between healthy (control) and post-LASIK corneas. METHODS: Participants, comprising healthy (control) adults (n = 19) and age-similar individuals who had undergone myopic LASIK six to 24 months prior (n = 13), underwent ocular surface evaluations. Corneal sensitivity to mechanical (air) and hyper-osmotic (saline) stimuli were quantified. Corneal functional in vivo confocal microscopy (Fun-IVCM) imaging was performed; time-lapsed videos at ∼6.0 ± 2.0 min intervals, were used to quantify the density and morphodynamics of intraepithelial putative T cells and dendritic cells (DCs), and intrastromal macrophages. Corneal features, ocular surface findings and tear cytokines (analyzed using multiplex bead-based immunoassay) were compared between groups. RESULTS: Relative to controls, post-LASIK participants had lower central corneal epithelial nerve parameters, and attenuated sensitivity to mechanical, but not hyper-osmotic, stimuli. In the inferior cornea, putative DC density was lower and DC area was higher in post-LASIK corneas than controls (p < 0.05 for both comparisons). Putative T cell speed was higher in post-LASIK corneas at the whorl (p = 0.012), but similar in the inferior cornea. Clinical ocular surface findings, and corneal stromal macrophage features, were similar between groups. Post-LASIK participants had higher levels of tear interleukin-16 than controls (p = 0.0004). CONCLUSIONS: In post-LASIK corneas, sub-clinical differences in in vivo corneal nerve architecture and mechanosensitivity, and immune cell morphodynamics, were observed compared to healthy corneas. The long-term functional significance of these differences in corneal nerve and immune cell features after LASIK warrants further study.