On the Variability in Goblet Cell Density in Human Bulbar Conjunctival Samples Collected by Impression Cytology with Millicell-CM Biopore Membrane Units.

Purpose: To assess whether or not the numbers of goblet cells were different across regions of a conjunctival impression cytology (CIC) specimen.
Methods: CIC specimens were obtained from the exposed nasal bulbar conjunctiva from 22 healthy young Caucasian adults, stained with Giemsa and evaluated at a final magnification of 200× (medium power fields). Up to 14 different non-overlapping microscope fields, depending on whether or not a field was without goblet cells, were randomly selected.
Results: A microscope field could contain between 0 and 145 goblet cells. If only fields that included goblet cells were analyzed, the mean goblet cell counts (22 specimens, 10 fields/specimen) ranged from 37.8 to 44.8/field (equivalent to 259-313 goblet cells/mm ² ). When 3, 5 or 10 fields were used to calculate average goblet cell counts for each specimen, the standard deviation values were between 15.8/field and 21.7/field, with the lower values obtained if 10 fields were used. The resultant averaged inter-sample variability, as the coefficient of variation (COV), ranged from 40.0% to 57.5%, while the averaged intra-sample variability in counts ranged from 52.1% to 73.9%. If fields without goblet cells were also used, the resultant mean goblet cell count (from 10 fields/specimen) was statistically lower at 33.1/field (232 goblet cells/mm ² ).
Conclusions: These analyses confirm various subjective comments made by early CIC investigators; the distribution of goblet cells across a CIC filter may be highly variable.