Limbal and bulbar hyperaemia in normal eyes.

Purpose: To investigate the appearance of limbal and bulbar hyperaemia in normal eyes, their relationship and the inter-observer agreement of clinical grading.
Methods: The right eyes of 120 healthy, non-contact lens-wearing subjects (m = 57, f = 63, median age = 45 years, range 18-77 years) were examined by two trained observers. Limbal and bulbar hyperaemia were scored using the Cornea and Contact Lens Research Unit (CCLRU) redness grading scales interpolated into 0.1 increments. Redness of four quadrants, and overall, were assessed, and quadrant-average redness was calculated. Inter-observer agreement was assessed at the start and end of the study (20 subjects each).
Results: For limbal redness, the overall (1.62 +/- 0.46) (mean units +/- S.D.) was not significantly different from the quadrant-average (1.61 +/- 0.40) score. For bulbar redness, the overall (2.02 +/- 0.49) was higher than the quadrant-average (1.82 +/- 0.39) score (p < 0.0001). Significant correlations were found between bulbar and limbal quadrants (Pearson: r > or = 0.43, p < 0.0001). Significant differences in redness were found between quadrants (p < 0.0001), with nasal and temporal redder than superior and inferior quadrants. Small effects of age and gender were found for limbal redness. The inter-observer 95% limits of agreement were similar at the start and end of the study. They were larger for overall (0.57) compared with quadrant-average (0.28) redness.
Conclusions: For similar populations, a limbal redness above 2.5 or a bulbar redness above 2.6 (quadrant-average) or 3.0 (overall) may be considered abnormal. Limbal and bulbar redness were correlated. Quadrant-average scores are recommended instead of overall scores, as inter-observer agreement was better.