Assessment of goblet cell size and density in relation to epithelial cell (multi)layering on conjunctival impression cytology samples

Purpose To assess goblet cell size and numbers in relation to the extent of multilayering of conjunctival impression cytology (CIC) samples as a basis for reducing variability in image selection for goblet cell density (GCD) estimates. Methods CIC was undertaken immediately postmortem off the superior bulbar conjunctiva of healthy young adult rabbits onto Millicell-CM Biopore filter units. After fixation with buffered glutaraldehyde and Giemsa staining, two × 200 images were selected from each sample representative of either slight multilayering or substantial multilayering, projected at × 1000, an overlay of the outlines of the goblet cells was made, and their dimensions and areas were measured. Results From measures of 4918 goblet cells, the average value (+/− SD) for the longest dimension was 17.7 ± 6.4 μm and 14.6 ± 5.3 μm for the shortest dimension. The GCD values ranged from 210 to 2069/mm 2 , with a mean of 1074 ± 601/mm 2 , but was lower for slightly multilayered images (at 537 ± 239 cells/mm ) compared with multilayered regions (at 1612 ± 601 cells/mm 2 ; p < 0.001). The measured areas ranged from 72 to 491 μm 2 , with average values from any particular image ranging from 110 to 370 μm 2 , which were inversely correlated with the estimated GCD (Spearman’s rho = − 0.722, p < 0.05). Conclusions Larger goblet cells but in fewer numbers were predictably found across the filter surface where there were fewer layers of cells and vice versa. This difference could be considered in selection of images for counts of goblet cells from CIC specimens.