Correlations between Tear Lymphocytotoxin-a (LT-α) Level and Disease Severity in Adult Keratoconus

Xiuxian Qin^1,2Shunrong Luo^1,2Xie Fang^1,2Xianwen Xiao^1,2Zhiwen Xie^1,2Xumin Shang^1,2juan yang^1,2XI LAN^1,2Huping Wu^1,2,3Zhirong Lin^1,2,3*

• ¹Eye Center, Xiamen University, Xiamen, Fujian Province, China
• ²Eye Institute, Xiamen University, Xiamen, Fujian Province, China
• ³Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, College of Medicine, Xiamen University, Xiamen, Fujian Province, China

To investigate the tear lymphocytotoxin-α (LT-α) levels in adult keratoconus patients and identify the correlations between LT-α and the disease severity of keratoconus. Methods: In this cross-sectional study, tear samples from 100 keratoconus patients (KC group) and 67 healthy controls (HC group) were collected. LT-α levels were tested immediately after collection using a commercially available Point-of-Care Test (POCT). Visual acuity, corneal tomography, Anterior Segment Optical Coherence Tomography (AS-OCT), tear film parameters, including non-invasive break-up time (NI-BUT), tear meniscus height (TMH), lipid layer thickness (LLT), and meibomian glands were also tested. Corneal topography values (K1, K2, Kmax, and astigmatism) were derived from the tomography data. Results: The tear LT-α levels in the HC group were significantly higher than in the KC group (P=0.038). The NIBUT, TMH, and LLT were significantly lower, while the meiboscore was higher in the KC group when compared to the HC group (P<0.001). In the KC group, patients were further divided into preclinical stage, initial stage, and complete stage groups. Significant differences in tear LT-α levels were found among the 3 subgroups. Within the KC group, LT-α levels were significantly correlated with various parameters, including thinnest corneal thickness, best-corrected visual acuity (BCVA) (LogMAR), K1, K2, Kmax, and astigmatism values. However, no significant correlation was observed between tear LT-α level and tear film parameters. Within the control group, no significant correlation was identified between the tear LT-αlevel and corneal topography or tear film parameters. Conclusion: Our data demonstrated the association between tear LT-α levels and disease severity of keratoconus, implying that immune-related factors might be involved in the pathogenesis and progression of keratoconus.