Abstract
Purpose:
To consider the effect of moderate intraocular pressure (IOP) perturbation on retinal oxygen saturation, blood flow and the pattern electroretinogram (PERG) in young, healthy participants.
Methods:
23 young (22-38 years), healthy participants had PERG, retinal oximetry and flowmetry images recorded before, during and after IOP elevation. Using a probe placed on the lower eyelid, IOP was increased to ~30 mmHg to lower ocular perfusion pressure (OPP) by ~30%. Steady-state PERG waveforms (8.3 Hz) were recorded bilaterally (200 sweeps) to return the second harmonic amplitude (16.7 reversals/sec). Peak oxygen saturation for arteries and veins of various diameters on oximetry (Oxymap retinal oximeter) was assessed by fitting Gaussian functions to frequency histograms of all pixels. Blood flow, volume and velocity (Heidelberg retinal flowmeter) were averaged within a 10x10 pixel window at the temporal retina.
Results:
OPP reduction remained stable between baseline and perturbation (F(2,66) = 1.42, p = 0.25). PERG amplitude was significantly reduced (F(2,44) = 24.24, p < 0.01) and phase significantly delayed (F(2,44) = 17.00, p < 0.01) during IOP perturbation. Contralateral eyes were unchanged. Arterial oxygen saturation remained the same (F(1.43,30.08) = 3.69, p = 0.05), whereas venous saturations reduced (F(1.39,29.15) = 38.64, p < 0.01). Blood flow was shown to change across the 3 conditions (F(2,36) = 5.37, p < 0.01). Poor correlation was found between OPP reduction and either PERG amplitude, PERG phase or venous oxygen saturation.
Conclusions:
PERG amplitude and retinal oxygen saturation are sensitive to an acute, moderate IOP perturbation in young participants.
Keywords: 509 electroretinography: clinical •
568 intraocular pressure •
635 oxygen