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K.J. Wallace, M.L. Archibald, T.L. LeVatte, B.C. Chauhan, R.P. LeBlanc, M.T. Nicolela; Effects of oral nimodipine on retinal microcirculation, visual function and plasma levels of endothelin–1 following a cooling provocation test: A double–masked, placebo controlled cross–over design study. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4440.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the effects of a single oral dose of nimodipine (a calcium channel blocker with central activity) or placebo on retinal microcirculation, standard automated perimetry (SAP) and plasma levels of endothelin–1 (ET–1) in a cohort of patients previously shown to have a large increase in plasma ET–1 following a cold provocation test. Methods: 10 open–angle glaucoma patients were randomized to receive a single dose of either nimodipine (60 mg) or placebo, two hours prior to the study visit. Baseline pre–cooling measurements consisted of SAP examination (24–2 SITA program of the Humphrey Field Analyzer), scanning laser Doppler flowmetry (SLDF) of the peripapillary retina (Heidelberg Retina Flowmeter) and pulsatile ocular blood flow (POBF) measurements. After 30 minutes of a cold provocative test, administered via a head–vest cooling garment containing coolant fluid, the same tests were repeated. Blood was collected before and after cooling and plasma ET–1 was determined by immunoassay. Blood pressure, pulse, finger flow measurements and skin temperature were monitored during the experiment. SAP, SLDF and POBF tests were repeated one week later in a recovery visit. After one month, patients were crossed–over to the other treatment arm and the procedures as described above were repeated. A group comparison of pre–cooling measurements and the effect of cooling in each group were analysed. Results: No significant differences were observed following nimodipine or placebo between baseline pre–cooling visual field indices (MD and PSD), SLDF measurements, POBF values, plasma ET–1, blood pressure and pulse (p > 0.5). After cold provocation test, no significant changes were observed in SLDF and POBF measurements, visual field indices or plasma ET–1, either in the nimodipine or placebo arms (p > 0.2). The average percentage increase in plasma ET–1 after cooling was 12 and 18% following nimodipine or placebo respectively (p = 0.7). Conclusions: Following a single dose of nimodipine, no significant changes were observed in retinal microcirculation, POBF, visual field function or plasma ET–1 levels, either at baseline or following a cold provocation test.
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