Posters

Evaluation of blood flow autoregulation at optic nerve head and choroid under hyperoxia condition using laser speckle flowgraphy in healthy subjects.

Poster Details

First Author: E.Ra JAPAN

Co Author(s):    T. Iwase   K. Yamamoto   H. Terasaki                       

Abstract Details



Purpose:

To evaluate a blood flow autoregulation at optic nerve head (ONH) and choroid under hyperoxia condition using laser speckle flowgraphy (LSFG).

Setting:

Nagoya University Hospital

Methods:

This study comprised 15 healthy volunteers (mean age 31.2 ± 6.6). Fraction of inspired oxygen (FiO2) 40 % and then 80% was administered via a breathing mask for 10 min. The mean blur rate (MBR) of the ocular circulation at the ONH and the choroid in the subjects was assessed with LSFG (LSFG-NAVI®, softcare) before, during, and after oxygen breathing. Retinal artery vessel diameter, intraocular pressure (IOP), anterior chamber depth, axial length, retina-choroidal thickness measured by enhanced depth imaging optical coherence tomography, blood pressure and heart rate (HR) in the brachial artery were also recorded.

Results:

The mean MBR in the ONH was 47.7, 44.8, 40.6, and 47.7 before, during FiO2 40 %, FiO2 80 % and after oxygen breathing, respectively, and there was significant reduction during FiO2 80 % oxygen breathing compared to before oxygen breathing (paired t-test, P<0.001). Additionally, the retinal artery vessel diameter significantly decreased during FiO2 80 % oxygen breathing (paired t-test, P<0.001). On the other hand, the mean MBR in the choroid was 13.3, 12.5, 12.0, and 12.5 before, during FiO2 40 %, FiO2 80 % and after administration, respectively, and there was no significant difference (ANOVA, p>0.05). Also, there was no significant difference in the retinal and choroidal thickness, the anterior chamber depth, the axial length, the IOP, the HR, and systolic and diastolic blood pressure (ANOVA, p>0.05).

Conclusions:

The mean MBR at the ONH and the retinal artery vessel diameter significantly decreased during FiO2 80 % oxygen breathing, though the mean MBR at the choroid was no significant difference in all breathing conditions as well as other factors. Our results suggested that ONH had a blood flow autoregulation under hyperoxia condition, which was different from choroid.

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