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M. Furushima, K. Nakatsuka, C.S. Matsumoto, T. Eto; The Blood Pressure Differential Between Central Retinal Artery and Choroidal Circulation in Monkeys . Invest. Ophthalmol. Vis. Sci. 2003;44(13):5015.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The circulation of choroid and retina is influenced by systemic blood pressure (BP) and intraocular pressure (IOP). We determined the pressure of the choroidal circulation (CC) and central retinal artery (CRA) by an imaging hemodynamic study with controlled IOP . Methods: Five Japanese monkeys (Macaca fuscata, mean weight: 5.2 ±0.7 kg) were used in accordance with the ARVO statement for the Use of Animals in Ophthalmic and Vision Research. Animals underwent vitrectomy in one eye under anestesia. During the procedure, IOP and BP (femoral artery) were measured using a pressure transducer. IOP was controlled by changing vitreous perfusion pressure. The hemodynamic study was performed by the Intraoperative Fluorescein Fundus Angiography System [Furushima et al., Folia Ophthalmol Jpn 53(12),2002], under the assumption that systolic CC and CRA pressure should equate IOP when pulsation flow appeared on vessels. Results: Systolic and diastolic BP was stable at 101.8 ±12.5/62.5 ±12.6 mmHg. CC and CRA blood flow were completely interrupted at IOP equal to or exceeding systolic BP. CC pulsation flow appeared as choroidal lobular background luminescence at IOP measuring 91.5 ±9.1 mmHg, but CRA blood flow did not appear while under these IOP conditions. CRA pulsation flow appeared on the optic disc at IOP measuring 81.8 ±10.9 mmHg. There was individual variability of the systemic blood pressure. However, a consistent and significant difference in pressure was identified between systolic BP and CC (10.2 ±3.3 mmHg, p<0.01) and between systolic CC and CRA (9.8 ±1.9 mmHg, p<0.005). This hemodynamic method provides measures of systolic CC and CRA pressure. The tension exerted by IOP on blood vessels of the choroid and retina should be similar, since both are confined in the same compartment covered by the rigid scleral wall. These results showed that the CC pressure was always higher than CRA pressure. Conclusions: Anatomical studies show the different transscleral pathways between CC(ciliary artery) and CRA. Our physiological findings suggest the presence of vascular resistance reducing pressure in the central retinal artery as it passes through the lamina cribrosa.
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