Regulation of retinal blood flow in response to an experimental increase in intraocular pressure

Abstract

Purpose : There is evidence from several studies that retinal blood flow (RBF) is autoregulated in response to changes in ocular perfusion pressure (OPP). The present study set out to investigate RBF autoregulation during an experimental increase in intraocular pressure (IOP) using a custom-built Doppler optical coherence tomography (OCT) system.

Methods : Healthy male and female subjects were included in this open study. Retinal blood flow was measured at baseline using Doppler OCT. Thereafter, IOP was stepwise increased by a suction cup. Retinal blood flow was assessed at each step and systemic hemodynamics were evaluated every minute. After a resting period of 30 minutes, application of the suction cup was repeated and IOP was measured at each level of suction using applanation tonometry. OPP was calculated as OPP = 2/3 MAP-IOP.

Results : Fifteen healthy subjects aged between 23 and 32 years participated in the present study. Application of the suction cup induced a significant increase in IOP and a decrease in OPP (p < 0.01). During the stepwise increase in IOP, the decrease in RBF was less pronounced than the decrease in OPP (maximum decrease in OPP: -94.1 ± 8.8% , maximum decrease in RBF: -59.4 ± 20.8% from baseline, respectively).

Conclusions : Experimental increase in IOP induced a significant decrease in RBF. This decrease was less pronounced than the decrease in OPP, indicating some degree of retinal autoregulation. This is in line with previous studies using different techniques for assessment of retinal blood flow. Therefore, Doppler OCT seems to be a valuable technique for investigation of RBF autoregulation in humans.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Pressure-flow relationship during stepwise increase of IOP via suction cup. Error bars represent 95% CIs.