Evaluation of ocular blood flow in response to induced systemic hyperoxia using a Laser Speckle Flowgraphylaser speckle flowgraphy in anesthetized pigs

Abstract

Purpose : Previous clinical studies have reported that systemic hyperoxia causes the decrease indecreased retinal blood flow (RBF) in humans, and impaired vascular reactivity to systemic hyperoxia in the retinal circulation has been implicated in the pathogenesis of diabetic retinopathy. Although it has reported that systemic hyperoxia cause the RBF in humans and cats, we investigated whether Laserif laser speckle flowgraphy（ (LSFG）may be capable to) can assess the hyperoxia-induced hemodynamic changes in the optic nerve head (ONH) circulation in normal anesthetized pigs.

Methods : We used six normal pigs in the current study. ChangesThe changes in ocular blood flow over time due to systemic hyperoxia, which is induced by the inhalation of 100% pure oxygen, were evaluated in anesthetized pigs. A special customized LSFG device for pig (LSFG-PIG)pigs was used forto measure the measurement of ocular blood flow, which was evaluated by based on the mean blur rate (MBR) on the ONH. Under general anesthesia with inhalation of isoflurane, we measured the blood flow that isas the baseline reference before loading, and continuously measured it for 5 minutes after the initiation of 100% pure oxygen.

Results : Before theinduction of systemic hyperoxia, the coefficient of variations (CV) for variation of five continuous measurement of the MBR on the ONH was 5.9±3.9% (mean ± standard deviation). After the inhalation of 100% oxygen, the MRB inof the ONH started to decrease and reached to the minimumminimal level of -27.5±11.8% (n=6, P=0.002) compared with the baseline at 5 minutes of systemic hyperoxia.

Conclusions : Our results indicateindicated that LSFG is ana reliable and appropriate method for non-invasive measurement of stable ocular blood flow in pigs. In addition, our results indicate and that systemic hyperoxia may be a useful index for evaluating the retinal vascular reactivity in both normal and diabetic pigs.

This is a 2020 ARVO Annual Meeting abstract.