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Takeshi Iwase, Eimei Ra, Kentaro Yamamoto, Kenichi Kawano, Takeshi Hatano, Shuta Kitagawa, Yuki Tamai, Yuta Okumura, Hiroko Terasaki; Determination of autoregulation of blood flow on optic nerve head and choroid of healthy eyes under hyperoxic conditions by laser speckle flowgraphy. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4332.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether the blood flow on the optic nerve head (ONH) and choroid is autoregulated under hyperoxic conditions by laser speckle flowgraphy (LSFG).
Fifteen healthy volunteers with a mean age of 31.2±6.6 years were studied. The effect of the fraction of inspired oxygen (FiO2) of 21% (room air), 40%, and 80% on the blood flow was measured. The different FiO2 levels were administered by a breathing mask for 10 min. The mean blur rate (MBR) of the blood flow at the ONH and the choroid was determined by LSFG (LSFG-NAVI®, Softcare) before, during, and after the oxygen breathing. The retinal artery diameter, intraocular pressure (IOP), anterior chamber depth, axial length, retinochoroidal thickness measured by enhanced depth imaging optical coherence tomography, blood pressure, and heart rate (HR) in the brachial artery were also recorded.
The mean MBR in the ONH was 47.7 before (21%), 44.8 with 40% FiO2, 40.6 with 80% FiO2, and 47.7 after returning to 21% FiO2 breathing. There was a significant reduction in the MBR during 80% FiO2 breathing compared to that during breathing room air (paired t test, P<0.001). Additionally, the retinal artery diameter was significantly decreased during FiO2 80% oxygen breathing (paired t test, P<0.001). On the other hand, the mean MBR of the choroid was 13.3 before, 12.5 with 40% FiO2, 12.0 with 80% FiO2, and 12.5 with return to room air. None of these differences was significant (ANOVA, P>0.05). In addition, there were no significant differences in the retinochoroidal thickness, the anterior chamber depth, the axial length, the IOP, the heart rate, and systolic and diastolic blood pressure (ANOVA, P>0.05).
These results indicate that the blood flow on the ONH is autoregulated under hyperoxic conditions which is different from that of the choroid.
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