Purpose:
To demonstrate age-related changes in the microenvironment of limbal stem cells (LSCs) and analyze the quantity and proliferative potential of the limbal basal epithelial cells (LBECs) by in vivo confocal microscopy.
Methods:
160 eyes of 160 healthy subjects were enrolled in this study after a routine slit-lamp examination. They were divided into four groups according to the age: A (0~19), B (20~39), C (40~59) and D(over 60). In vivo confocal microscopic examination was performed on the inferior limbus and the images were recorded. For each group, the positive rates of Vogt Palisades were analyzed to evaluate the microenvironment of LSCs. The average size of LBECs was measured to assess their proliferative potentials.
Results:
The rate of Vogt Palisades in group A,B,C,D were 97.5% (39/40), 95.0% (38/40) ,77.5% (31/40) ,40.0% (16/40) respectively, showing a significant decreasing tendency with age. Typical Vogt palisades were found in almost all subjects under 40, with a wavy epithelium-stromal boundary or alternant epithelium-stromal cords, a bright "purfle" of hyper-reflective basal epithelial cells, and a slender blood vessel along each stromal papillae (Fig A,B). In contrast, Vogt Palisades were not observed in nearly two thirds of subjects over 60, with thinner epithelium, flat epithelium-stromal boundary, and big vessels in the stroma. The hyper-reflective basal epithelial cells were replaced by relatively dark ones with invisible nuclei and clear borderline (Fig E,F). Moreover, eight subjects in group C and D manifested a transiting morphology named "atrophic Vogt Palisades", with a slight wavy epithelium-stromal boundary and decreasing reflection of basal cells (Fig C,D). The average size of LBECs in group A,B,C,D were (9.89±1.12) µm,(10.65±1.45) µm,(10.70±1.39) µm and (12.36±1.68)µm. Significant differences between groups were obvious except for that between groups B and C.
Conclusions:
The microenvironment of limbus degenerated with age. So did the qualities of LBECs, with average cell size enlargement and proliferative potential degeneration.
Keywords: microscopy: confocal/tunneling • cornea: clinical science • cornea: basic science