Lu Zhao . Yifan Zhou . Hongyu Duan . Yu Zhang . Baikai Ma . Tingting Yang . Jiawei Chen . Yueguo Chen . Hong Qi

Abstract

Introduction: Chronic ocular pain, particularly

prevalent in patients with dry eye disease and post-femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) surgery, presents with unclear clinical characteristics and an undefined pathogenesis. In this study, we aimed to compare clinical characteristics and tear neuropeptide concentrations in patients with dry eye disease (DED) with and without chronic ocular pain following FS-LASIK, and investigate correlations between ocular pain, clinical char- acteristics, and tear neuropeptide levels.

Methods: Thirty-eight post–FS-LASIK patients with DED were assigned to two groups: those with chronic ocular pain and those without chronic ocular pain. Dry eye, ocular pain, and mental health-related parameters were evalu- ated using specific questionnaires and tests. The morphology of corneal nerves and dendritic cells (DCs) was evaluated by in vivo confocal microscopy. Function of corneal innervation was evaluated by corneal sensitivity. Concen- trations of tear cytokines (interleukin [IL]-6, IL- 23, IL-17A, and interferon-c) and neuropeptides (a-melanocyte-stimulating hormone, neu- rotensin, b-endorphin, oxytocin, and substance P [SP]) were measured using the Luminex assay. Results: Most patients with chronic ocular pain experienced mild to moderate pain; the most common types included stimulated pain (pro- voked by wind and light), burning pain, and pressure sensation. More severe dry eye (P \ 0.001), anxiety symptoms (P = 0.026), lower Schirmer I test values (P = 0.035), lower corneal nerve density (P = 0.043), and more activated DCs (P = 0.041) were observed in patients with ocular pain. Tear concentrations of SP and oxytocin were significantly higher in patients with ocular pain (P = 0.001, P = 0.021, respectively). Furthermore, significant correla- tions were observed among ocular pain severity, SP, and anxiety levels.

Conclusions: Patients with DED after FS-LASIK who have chronic ocular pain show more severe ocular and psychological discomfort and higher tear levels of neuropeptides. Furthermore, ocu- lar pain severity is correlated with tear SP levels. Trial Registration: ClinicalTrials.gov identifier: NCT05600985.

Keywords: Dry eye; Ocular pain; Neuropeptides; Inflammatory cytokines; FS-LASIK

GKB-NON-2024-00433