Abstract
Purpose :
Meibomian gland dysfunction (MGD) produces alterations in the tear film (TF) lipid layer that causes excessive evaporation of tears from the ocular surface and subsequent increased osmolarity leading to dry eye disease. However, the molecular mechanism underlying TF evaporation has yet to be understood. This study aimed to investigate the association between (o-acyl)-omega-hydroxy fatty acids (OAHFAs) derived from TF and meibum and TF evaporation in a cohort of healthy and MGD subjects.
Methods :
Of 195 eligible subjects (18–84 years, 62.6% female), 178 and 170 subjects provided both TF optical coherence tomography (OCT) imaging and mass spectrometry data for tears (n = 178) and meibum (n = 170). The rate of TF thinning (μm/min) was measured in the right eye of each subject using an ultra-high-resolution, custom-built OCT. Tear and meibum samples from the right eye of each subject were infused into the SCIEX 5600 TripleTOF mass spectrometer in the negative ion mode. Intensities (m/z) of pre-identified OAHFAs were measured with Analyst 1.7TF and LipidView 1.3 (SCIEX) and normalized by internal standards, and then correlated with TF thinning rate using Spearman’s correlations.
Results :
Out of 76 OAHFAs detected in meibum samples, intensities of 28 OAHFAs had statistically significant negative correlations with TF thinning rate (all p < 0.05). These OAHFAs were: 18:2/16:2, 18:0/22:1, 18:0/23:0, 18:2/24:1, 18:1/24:1, 18:0/24:1, 18:0/24:0, 18:1/25:0, 18:1/26:1, 18:0/26:1, 18:1/28:1, 18:0/28:0, 18:0/28:1, 18:2/30:1, 18:1/30:1, 18:0/30:1, 18:0/31:2, 18:1/31:0, 18:2/32:2, 18:2/32:1, 18:1/32:1, 18:0/32:1, 18:1/33:0, 18:2/34:2, 18:2/34:1, 18:1/34:1, 18:2/36:1, 18:1/36:1. In contrast, there were statistically significant positive correlations between intensities of two meibum-derived OAHFAs (18:2/18:1, 16:1/28:3) and TF thinning rate (both p < 0.05). Of 78 OAHFAs detected in tear samples, intensities of six OAHFAs (18:0/24:0, 18:0/26:0, 18:2/27:2, 18:2/27:0, 18:2/28:2, and 18:2/29:2) were positively correlated with TF thinning rate, while one OAHFA (18:0/22:1) was negatively correlated (all p < 0.05).
Conclusions :
Several OAHFAs derived from the human tear film and meibum showed significant associations with alterations in TF thinning. These findings suggest that OAHFAs could be implicated in the mechanism underlying the stabilization and evaporation (or thinning) of TF in health and MGD.
This is a 2021 ARVO Annual Meeting abstract.