Abstract
Abstract: :
Purpose: To examine the diurnal variation in bulbar hyperemia that occurs over an 8 hour period, using a novel objective photometric method. Methods: Objective measurements of bulbar hyperemia were obtained using a Spectra Scan PR650© spectrophotometer and controlled illumination. Hyperemia was quantified using CIEu’ chromaticity units. Measurements were made every hour on the temporal bulbar conjunctiva of both eyes, beginning at 8:00am for a period of 8 hours. Statistical significance was assessed using a repeated measures ANOVA method. Results: From baseline values, hyperemia values decreased maximally at approximately mid–day, after which a steady increase in hyperemia occurred. A return to baseline values occurred approximately eight hours from the start of the measurement time. These variations in hyperemia over time were statistically significant (F=3.30, p=0.008). Conclusions: This pilot study demonstrates that diurnal bulbar hyperemia variation may be objectively quantified using chromaticity and indicates that hyperemia is minimal during the middle of the day. This information should be considered when undertaking studies in which hyperemia is an important outcome variable.