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E.–N. Su, S.J. Cringle, D.–Y. Yu; Light Dependence of Sodium Fluorescein Induced Vasoconstriction on Retinal Microvessels . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2595.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine whether sodium fluorescein induced vasoconstriction in retinal arterioles and veins is dependent on light level. Methods: Segments of porcine retinal arterioles and veins were dissected, cannulated, and perfused, and their outer diameter monitored during intraluminal application of increasing doses (10–9– 10–3 %) of sodium fluorescein. A control injection (perfusate only) was performed prior to sodium fluorescein application and endothelin–1 (10–9 M) was used to assess the vasoactive response of the vessels after sodium fluorescein administration. The significance of any induced change in vessel diameter was assessed in relation to the initial vessel diameter. Experiments were performed under two microscope illumination levels, 350 or 4 lux. Results: At the higher light level (350 Lux) sodium fluorescein produced a significant dose dependent contraction in porcine retinal arterioles and veins with a threshold of 10–8 – 10–7 % sodium fluorescein. At the maximal dose tested (10–3 %) vessel diameter was reduced to ∼85% of the initial vessel diameter in retinal arterioles and veins. At the lower light level (4 Lux) the threshold for any vasoactive effect was increased and the maximal vasoconstrictive effect of sodium fluorescein was significantly reduced. Conclusions: Sodium fluorescein induced vasoconstrictive effects on the retinal vasculature of the pig are light dependent. Assuming a similar effect may be expected in human retinal vessels, reduced illumination level may limit any vasoconstrictive effects of sodium fluorescein when used in routine ophthalmic examinations.
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