LASIK may leave subtle but persistent changes in corneal nerves and immune cell behavior long after patients appear clinically recovered, according to a new Australian study that used advanced functional in vivo confocal microscopy (Fun-IVCM) to probe the post-surgical ocular surface in unprecedented detail.
Published in The Ocular Surface, the study compared 13 post-LASIK patients with 19 age-matched healthy controls, evaluating corneal nerve architecture, sensory responses, tear cytokines, and the morphodynamic behavior of immune cells up to two years after uncomplicated myopic LASIK.
The investigators found that although conventional ocular surface findings were largely similar between groups, post-LASIK corneas demonstrated marked subclinical differences in both nerve structure and immune surveillance. Central corneal nerve density and branching remained significantly reduced in LASIK-treated eyes, accompanied by impaired mechanical corneal sensitivity.
The study’s most novel findings emerged from dynamic immune cell imaging. Using time-lapse Fun-IVCM, researchers tracked epithelial T cells, dendritic cells (DCs), and stromal macrophages in both the corneal whorl and inferior cornea. Putative epithelial T cells in post-LASIK eyes moved significantly faster at the corneal whorl than those in healthy controls, suggesting heightened immune surveillance activity despite similar cell densities.
Meanwhile, dendritic cell behavior appeared regionally altered. DC density was lower in the inferior cornea of post-LASIK participants, but cells were larger, more circular, and morphologically distinct compared with controls. The authors note that increased dendritic cell size has previously been associated with immune activation in dry eye disease and ocular allergy, raising the possibility that LASIK induces a prolonged low-grade inflammatory state.
Supporting this hypothesis, tear analysis revealed significantly elevated interleukin-16 (IL-16) concentrations in post-LASIK participants. IL-16 is a pro-inflammatory cytokine involved in T-cell recruitment and neuroinflammatory signaling.
However, not all sensory pathways appeared equally affected. While mechanical sensitivity was reduced, responses to hyperosmolar saline stimuli were preserved, potentially suggesting relative sparing of osmosensory pathways after LASIK.
Despite these biological differences, many participants remained minimally symptomatic. About half of the LASIK cohort met TFOS DEWS II criteria for dry eye disease, but subgroup analyses showed no major differences in immune cell morphology or dynamics between symptomatic and asymptomatic post-LASIK patients.
Although the clinical significance of these persistent neuroimmune changes remains uncertain, the findings may have implications for understanding chronic post-LASIK dry eye, neuropathic ocular pain, and long-term corneal homeostasis.
The authors conclude that, given their findings, further studies are now warranted to elaborate on “the long-term functional significance of these differences in corneal nerve and immune cell features after LASIK.”
