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CL Prokopich, JG Flanagan; Ocular Response to Centrally Mediated Cold Stress in Vasospasm . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3410.
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Purpose: To investigate the capillary blood flow of the superficial retina (SR), superficial optic nerve head (SN) and deep optic nerve (DN) in response to cooling of the forehead in subjects with vasospastic symptoms. Methods: The sample consisted of 10 women with vasospastic symptoms (31.8 ±7.9 years) and 10 age and sex matched controls. Perfusion maps (10º x 2.5º) of the optic nerve and juxtapapillary retina were obtained from one eye of each subject using the Heidelberg Retinal Flowmeter (HRF). Focus was set at the level of the nerve fibre layer for the superficial retina and superficial optic nerve measurements, and was focussed -0.50D deeper for the deep optic nerve measurements. Twenty perfusion maps were measured alternately for each focus setting at a forehead temperature of 34°C, then following a centrally mediated cold stress test by decreasing the temperature of the forehead to 5°C. Digital skin perfusion was simultaneously recorded from the middle finger of the subject’s right hand. Results: The group means (all subjects) for the baseline blood flow were: SR 280.7, SN 456.7 and DN 365.9(arbitrary units). The vasospastic group showed an approximately equal decrease in capillary blood flow for all test locations (-7.9% DN; -7.8% SN; -6.2% SR) in response to centrally mediated cold stress. All 10 subjects in this group demonstrated a significant response (p<0.05). The control group showed an increase in capillary blood flow for the optic nerve locations (3.4% DN; 8.4% SN), but a large decrease in flow at the superficial retina (-15.4% SR: 6 of 10, p<0.05). Relative to controls, the vasospastic group demonstrated a reduction in blood flow in the DN (-11.3%) and the SN (-16.2%). The reduction in flow was less than that of the controls (9.2%) in the SR. Conclusion: There was a marked difference in the ocular response to a centrally mediated cold stress test between subjects with vasospastic symptoms and normal controls, as measured by the capillary blood flow at the optic nerve and retina. Such differences would suggest an abnormal ocular autoregulatory response in subjects with vasospastic symptoms.
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