Comparison of grading schemes to quantitative assessments of nucleus-to-cytoplasmic ratios for human bulbar conjunctival cells collected by impression cytology

Abstract

Purpose. To quantitatively assess the measured nucleus-to-cytoplasm (N/C) ratios for sets of bulbar conjunctival cells categorised by a subjective grading scheme (0-3). Methods. Impression cytology samples were taken from the nasal bulbar conjunctiva of 37 individuals (aged 22 to 74 years) without any significant eye disease. The sheets of cells were generally stained with Giemsa, photographed and 35 mm slides prepared. The images were graded 0 to 3 according to the scheme of Nelson [Cornea 7, 71–81 (1988)] and approximately 35 contiguous cells from each image measured by planimetry from an overlay. Results. Analysis of 1097 cells revealed that the N/C ratios ranged from 1.395 to 0.056 and correlated well with the grading. The average N/C ratio (range for ± 1.96 SD) for each grade was 0.607 (0.983 to 0.531) for grade 0, 0.533 (0.759 to 0.333) for grade 1, 0.291 (0.427 to 0.155) for grade 2, and 0.154 (0.228 to 0.080) for grade 3. Conclusions. N/C ratios can be assessed from conjunctival impression cytology samples and appear to be sufficiently consistent to allow for a designated range of cell N/C ratios to be specified for each grade.