Assessment of Short-Term Changes in Optic Nerve Head Hemodynamics in Hyperoxic Conditions with Laser Speckle Flowgraphy.
OBJECTIVE
To evaluate laser speckle flowgraphy (LSFG) measurements of the optic nerve head (ONH) blood flow (BF) response to hyperoxia.


METHODS
This prospective study included 30 eyes of 30 healthy volunteers (mean age: 28.5 ± 4.0, male:female = 13:17). The testing protocol had three phases: in the baseline phase, subjects breathed room air; in the hyperoxic phase, they breathed pure oxygen (6 L/min) for 15 min; and in the recovery phase, they were room air for 15 min. LSFG measurements of mean blur rate (MBR), which represents ONH BF, were taken every minute. The MBR ratio in the hyperoxic and recovery phases was calculated with reference to this baseline. Clinical parameters, including systemic blood pressure, pulse rate, and saturation of pulse-oximetry oxygen (SpO2), were measured every 5 min.


RESULTS
SpO2 increased significantly during hyperoxia (97.3 ± 1.1% to 99.3 ± 0.7%, p < 0.001). While clinical parameters were similar in hyperoxia and baseline, MBR decreased significantly after 2 min of hyperoxia (90.8 ± 12.6%, p = 0.02), stayed steady throughout hyperoxia (mean: 89.5 ± 10.8%, p range: <0.001-0.04) compared with baseline, and returned to baseline 1 min after recovery (93.7 ± 10.3%, p = 0.25). A linear regression using a third-order polynomial fitting curve analysis revealed that the time to reach minimum MBR was 7.78 min (adjusted R(2 )= 0.87).


CONCLUSIONS
LSFG could effectively assess ONH BF changes during hyperoxia.
a Department of Ophthalmology , Tohoku University Graduate School of Medicine , Miyagi , Japan .
Yukihiro
Y
Shiga
a Department of Ophthalmology , Tohoku University Graduate School of Medicine , Miyagi , Japan .
Marika
M
Sato
a Department of Ophthalmology , Tohoku University Graduate School of Medicine , Miyagi , Japan .
Kazuichi
K
Maruyama
b Comprehensive Education Center for Community Medicine, Tohoku University Graduate School of Medicine , Miyagi , Japan .
Shin
S
Takayama
a Department of Ophthalmology , Tohoku University Graduate School of Medicine , Miyagi , Japan .
Kazuko
K
Omodaka
a Department of Ophthalmology , Tohoku University Graduate School of Medicine , Miyagi , Japan .
Noriko
N
Himori
a Department of Ophthalmology , Tohoku University Graduate School of Medicine , Miyagi , Japan .|c Department of Retinal Disease Control , Tohoku University Graduate School of Medicine , Miyagi , Japan and.
Hiroshi
H
Kunikata
a Department of Ophthalmology , Tohoku University Graduate School of Medicine , Miyagi , Japan .|c Department of Retinal Disease Control , Tohoku University Graduate School of Medicine , Miyagi , Japan and.|d Department of Advanced Ophthalmic Medicine , Tohoku University Graduate School of Medicine , Miyagi , Japan.
Toru
T
Nakazawa
D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D018496:Hyperoxia / Q000503:physiopathology*; D007429:Intraocular Pressure; D017078:Laser-Doppler Flowmetry; D008297:Male; D009898:Optic Disk / Q000098:blood supply*; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000502:physiology*
D010100:Oxygen
Hyperoxia; laser speckle flowgraphy; ocular blood flow; optic nerve head; vasoreactivity