Purchase this article with an account.
Shresta Patangay, Zahra Derafshi, Jason C Park, Thasarat S Vajaranant, J Jason McAnany, John R Hetling; Pattern electroretinogram (pERG) responses evoked by a novel high-luminance three-dimensional stimulus source that targets the peripheral retina.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):463.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
There is evidence that glaucomatous damage first presents in the far-peripheral retina, beyond 40 degrees of visual angle. A functional test that specifically probes the peripheral retina may prove useful in early diagnosis and monitoring. Here we describe initial results from a novel pattern electroretinogram (pERG) stimulus source designed to evoke a response mediated by the far-peripheral retina (beyond 35 degrees).
A three-dimensional (3D) pattern stimulus source was created using a translucent hemispheric dome (radius = 30 cm) backlit by white LEDs in a checkerboard pattern. Checks (12 deg at 30 cm viewing distance) were arranged in four circumferential rows and 30 radial columns. The central field (70 degrees) was dark, with the checkerboard pattern extending from 70-170 degrees (full angles). Luminance of the “ON” checks had a standard deviation of 16% across the pattern. The ON luminance was varied from 65-1667 ph cd m(-2), yielding contrasts of >93% at all values. Pattern reversal rate was 4.6 rps.<br /> <br /> Peripheral pERG recording used a DTL corneal electrode referenced to a skin electrode on the ipsilateral temple; responses were filtered at 1-1000 Hz. Responses were recorded in several 5 second epochs, with rest periods between, yielding >115 reversals to be averaged per subject for SNR>30.
With ON-luminance of 65 ph cd m(-2), response waveforms were generally similar to those obtained from the central retina using a conventional pERG source (also performed in each subject, ON-luminnace = 81 ph cd m(-2)). Increasing the ON-luminance to 157, 834 and 1667 ph cd m(-2) resulted in response waveforms with three prominent positive peaks occurring at 20, 26 and 36 ms. Peak times (standard deviation = 2 ms for each peak) and overall waveform shape were very consistent for all normally-sighted subjects (n=3) across all three high-luminance patterns.
Evoking a pERG response from the far-peripheral retina is feasible with the 3D stimulus employed here. Use of high-output LEDs allows ON-check luminance well above that achievable with standard flat-panel displays. Recording from glaucomatous eyes, and pharmacological dissection of the peripheral pERG response in rat eyes, is in progress to elucidate the origin of the early positive peaks evoked by the high-luminance pattern.
This PDF is available to Subscribers Only