Three Dimensional Stimulus Source for Pattern Electroretinography in Mid- and Far-peripheral Retina

The pattern electroretinogram (pERG) response reflects, in part, ganglion cell function. However, probing retinal ganglion cell (RGC) function in the mid- and far peripheral retina is difficult with conventional flat-panel pERG stimulus sources. A pattern stimulus source is presented for probing the peripheral retina. Peripheral pERG (ppERG) responses were evaluated versus luminance, reversal rate, and field subtended, and were compared with conventional pERG in healthy eyes.

Eleven normally-sighted subjects were recruited. A hemispherical surface was used to present a reversing checkerboard pattern to the peripheral retina, from approximately 35° to 85° of visual field, in all directions. Responses to stimuli presented to peripheral field sectors (superior, nasal, inferior, temporal) were also recorded. Conventional pERG responses were recorded on the same day. Amplitudes and implicit times of waveform peaks were evaluated.

Robust pERG responses from peripheral retina resemble conventional pERG responses but with shorter implicit times and reduced positive component. Responses to high-luminance patterns include high-frequency components resembling flash ERG oscillatory potentials. Negative response component amplitudes increased with increasing pattern luminance, and decreased with increasing reversal rate.

Peripheral-field pERG responses are robust and repeatable; the unique response properties reflect differences between central and peripheral retina. Field-sector response ratios can be used to probe for sectoral dysfunction associated with disease.

The ppERG approach provides direct measurement of proximal retinal function beyond the fields probed by conventional perimetry and pERG, providing access to a relatively under studied part of the retina relevant to early stage glaucoma.