Variations in human corneal endothelial cell morphology and permeability to fluorescein with age

Fluorophotometry with topically applied fluorescein and endothelial cell photography were performed on 80 normal subjects (age 5–79 yr). Variations in endothelial cell morphology and function, flow of aqueous humor, and intraocular pressure were recorded. The mean endothelial cell size was 332·3 ± 46·3 μm 2. A 28% increase in endothelial cell size was measured over the eight decades ( r = 0·53, P < 0·001). The coefficient of variation of cell size also increased with age ( r = 0·41, P < 0·001). The percentage of hexagonal endothelial cells decreased by 14% ( r = −0·48, P < 0·001), while the percentage of pentagonal and heptagonal cells increased by 50% ( r = 0·44, P < 0·001) and 40% ( r = 0·33, P < 0·002), respectively, with age. The mean endothelial permeability to fluorescein was 4·03 ± 0·63 × 10 −4 cm min −1. A 23% increase in endothelial permeability with age was observed ( r = 0·44, P < 0·001). No change in central corneal thickness or endothelial pump rate was found. Flow of aqueous humor remained stable with age, despite a 25% increase in intraocular pressure ( r = 0·50, P < 0·001). Polarization of fluorescence of fluorescein in the corneal stroma decreased with age ( r = −0·46, P < 0·001). We conclude that with age the human corneal endothelium becomes morphologically less regular and may become more permeable to fluorescein.