Correlation Study Between Abnormal Morphology of Meibomian Glands and Meibum in Patients With Dry Eye Disease Under in vivo Confocal Microscopy

Objective: To observe differences in meibomian gland morphology among patients with meibomian gland dysfunction (MGD) with liquid meibum, with solid meibum, and a non-MGD group by laser scanning in vivo confocal microscopy (IVCM), and then analyze the correlation between meibomian gland abnormalities and dry eye disease. Methods: Twenty-one patients with MGD (42 eyes) with liquid meibum, 21 patients with MGD (38 eyes) with solid meibum, and 24 non-MGD patients (39 eyes) were enrolled in the study. IVCM examination and Schirmer II test were performed, and non-invasive tear-film breakup time (NIBUT) was measured. Results: Data obtained from all the patients were normally distributed; therefore, one-way analysis of variance was performed. The meibomian gland opening diameter and gland opening area of the patients with MGD were greater than those of the non-MGD patients, and values of the liquid meibum group were greater than those of the solid meibum group (F = 17.96, p < 0.001; F = 8.84, p < 0.001, respectively). Due to changes in meibomian gland opening diameter and dilation of meibomian gland acini, the acinar longest diameter and unit area of the patients with MGD were also greater than those of the non-MGD patients, and the values of the solid meibum group were greater than those of the liquid meibum group (F = 36.52, p < 0.001; F = 27.81, p < 0.001, respectively). In the aspect of acinar shortest diameter, there was no difference among the three groups (F = 0.24, P > 0.05). Highest inflammatory cell density was observed in the solid meibum group, followed by the liquid meibum group, and the non-MGD group (F = 111.54, p < 0.001). Similarly, the results of the Schirmer II test and NIBUT showed that the condition of the patients with MGD in the solid meibum group was worst, followed by that of the liquid meibum group and the non-MGD group (F = 99.57, p < 0.001; F = 11.87, p < 0.001, respectively). Conclusions: The different meibum in the patients with MGD is accompanied by different meibomian gland morphologies. Compared with the patients with liquid meibum, those with solid meibum have more obvious dilatation of meibomian glands under confocal microscopy and in these patients, the density of inflammatory cells among glands is higher, and the quality of tears is worse.