In vivo confocal microscopy of meibomian glands and palpebral conjunctiva in vernal keratoconjunctivitis

Purpose: To investigate the correlations between conjunctival inflammatory status and meibomian gland (MG) morphology in vernal keratoconjunctivitis (VKC) patients by using in vivo confocal microscopy (CM). Materials and Methods: Nineteen VKC patients (7 limbal, 7 tarsal, and 5 mixed forms) and 16 normal volunteers (controls) were enrolled. All subjects underwent CM scanning to obtain the images of upper palpebral conjunctiva and MGs. Inflammatory cell (IC) density in palpebral conjunctival epithelial and stromal layers, Langerhans cell (LC) density at lid margins and the stroma adjacent to the MG, and MG acinar unit density (MGAUD) were recorded. The longest and shortest diameters of MG acinar were measured. The Kruskal-Wallis test was used to compare the parameter differences whereas the Spearman's rank correlation analysis was applied to determine their correlations. Results: Among all groups, no significant statistical differences were found in epithelial and stromal IC densities, mean values of MG acinar unit densities, or longest and shortest diameters. Both LC parameters in the tarsal-mixed groups were significantly higher than those in the limbal and control groups. All LC densities of VKC patients showed a positive correlation with MGAUD and shortest diameter. Conclusions: In VKC patients, the conjunctival inflammatory status could be associated with the MG status. In vivo CM is a noninvasive, efficient tool in the assessment of MG status and ocular surface.