Morphometry of the corneal endothelium in glassblowers compared to non-glassblowers

Acute exposure to high levels of IR radiation (IRR) can damage the endothelial cell layer of the human cornea, but the impact of chronic lower-dose exposure has not been assessed objectively. The corneal endothelium of 10 individuals who had occupational exposure to IRR as glassblowers (average 16 years) was examined by photo-slitlamp biomicroscopy, the endothelial mosaic assessed by morphometry, and compared to 10 non-glassblowers (controls). The analyses reveal the glassblowers to have higher than expected endothelial cell density (ECD, average 3371+/-304 cells/mm(2) compared to a control value of 3072+/-198 cells/mm(2)), a higher variance in cell area, and a lower percentage of the most-prevalent cell type, i.e. the six-sided cells (average 52.0+/-12.2%, compared to controls of 64.1+/-6.6%). Analyses of the sizes of different cell types (four-, five-, six-sided, etc.) indicate that the cells in both groups are proportionately larger as the number of sides increases, but that this area-side relationship is different in the glassblowers, who had both smaller and larger cells compared to controls. Two other cases had even higher cell density values (>5000 cells/mm(2)) and <50% six-sided cells. Occupational exposure to a mixture of IRR, perhaps some UVR as well as thermal convection effects, can apparently result in morphological changes in the human corneal endothelium. These may be the result of IRR-stimulated cell division.