Observation of Conjunctiva-Associated Lymphoid Tissue With In Vivo Confocal Microscopy in Healthy Patients and Patients With Meibomian Gland Dysfunction

The purpose of this study was to assess the distribution and morphological variation of conjunctiva-associated lymphoid tissue (CALT) in healthy human subjects and patients with meibomian gland dysfunction (MGD) using laserscanningin vivo confocal microscopy. METHODS: A total of 34 healthy subjects and 32 patients with MGD were enrolled. All subjects underwent a conventional examination consisting of slitlamp biomicroscopy, tear film break-up time, and the Schirmer test. In vivo microscopy was applied to analyze the morphological changes in the diffuse lymphoid layer and lymphoid follicles in CALT. Conjunctival impression cytology (CIC) of samples of patients' palpebral conjunctiva and immunofluorescence staining of CD4 and CD8 antibodies were also performed to indicate the immune response status of CALT. RESULTS: In the MGD group, the density of diffuse lymphocytes (P < 0.001), follicles (P < 0.001), and perifollicular lymphocytes was higher (P < 0.001) and the central reflection of the follicles was stronger (P < 0.001) than in the control group, while there was no difference in the follicle area (P = 0.758). Besides, diffuse lymphocyte density was correlated with telangiectasia, and follicular center reflection intensity was correlated with plugging. CIC immunofluorescence staining showed a higher percentage of CD4(+) (P < 0.001) and CD8(+) (P < 0.001) cells in the MGD group than in the control group. CONCLUSIONS: Using laser scanning in vivo confocal microscopy and CIC immunofluorescence staining, we observed the activation of CALT in patients with MGD, and some CALT-related parameters correlated with the lid margin findings of patients with MGD.