Age-related changes of human conjunctiva on in vivo confocal microscopy

Aims To analyse age-related changes of human conjunctiva by in vivo laser scanning confocal microscopy (LSCM). Methods 80 healthy subjects were enrolled and divided into four groups according to age: A (0-19 years), B (20-39 years), C (40-59 years) and D (over 60 years). In vivo LSCM was performed on the subjects' bulbar conjunctivas, and the images were recorded. The morphology and densities of conjunctival epithelial cells, goblet cells (GCs), dendritic cells (DCs) and the positive rate of conjunctival microcysts were analysed. The diameters of subepithelial fibres in each group were measured as well. Results The morphology and the densities of both conjunctival epithelial cells and GCs showed no significant age-related differences. The positive rates of conjunctival microcysts were 30% (6/20), 50% (10/20), 60% (12/20) and 75% (15/20) in each group, showing a substantial increase with age (p=0.035). The densities of DCs decreased significantly with ageing (p=0.033). The diameters of subepithelial fibres reduced with age significantly also (p=0.000). Conclusions The age-related changes of conjunctivas included decreasing densities of DCs as well as the degeneration of subepithelial structures. Even though no significant changes in GCs densities could be seen in the different age groups, the increasing rates of conjunctival microcysts indicated that the cellular function of GCs declined while ageing.