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S.A. Vaccari, T. Simpson, L. Jones, J. Flanagan, D. Fonn; The Assessment of Diurnal Variation of Bulbar Conjunctival Hyperemia, Temperature and Conjunctival Blood Flow Before and After Sleep . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2681.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To use novel objective methods to establish and measure the variation in bulbar conjunctival hyperemia, temperature and conjunctival blood flow 1) continuously; and 2) before and after sleep. Methods: Bulbar hyperemia was measured using a spectrophotometer and controlled illumination. Redness was quantified using CIE u’ chromaticity. Temperature was measured using an infrared (Tasco–Thi) thermometer. Measurements of conjunctival blood flow were obtained using a slightly modified Heidelberg Retinal Flowmeter (HRF). Statistical significance was assessed using repeated measures ANOVA. 1) Measurements were made every hour on the temporal bulbar conjunctiva of both eyes, beginning at 8:00am until 4:00pm. 2) Measurements were made every hour on the temporal bulbar conjunctiva of both eyes, beginning at 8pm until 11pm and again at 7am until 2pm. Results: 1) If shifted to correct for number of hours awake prior to the first measurement, there was a significant effect of time for redness, temperature and conjunctival blood flow, (F= 6.309, p= 0.000; F= 8.541, p= 0.000 and; F= 6.356, p= 0.000, respectively), with values decreasing during the early part of the cycle and increasing later on. 2) Redness, temperature and conjunctival blood flow were each significantly different over time, with no difference between eyes (F= 4.920, p= 0.000; F= 6.155, p= 0.000 and; F= 2.861, p= 0.001, respectively). From baseline at 4pm, redness and temperature increased slightly prior to sleep and conjunctival blood flow remained relatively constant. Upon waking, each was highest and then decreased to a minimum late in the morning, after which a steady increase occurred. Conclusions: Diurnal bulbar redness, temperature and conjunctival blood flow variation may be objectively quantified and all three are lowest during the middle of the day and maximal at the start of the day. This information should be considered when undertaking studies in which hyperemia, temperature and ocular surface blood flow are important outcome variables.
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