Abstract
Purpose :
Electrically evoked response (EER) elicited by transcorneal electrical stimulation (TES) is an objective method to evaluate the visual pathway. We herein describe EERs in patients with inherited retinal disease (IRD) who shows severe photoreceptor dysfunction.
Methods :
EERs were recorded under the dark-adapted condition (after 20 minutes’ dark adaptation) using DTL stimulation, Oz-Pz potential recording at current intensities of 0.5 mA, 1 mA, 1.5 mA, and 2 mA. DTL electrodes for stimulations, with using 0.5 to 2.0mA. The two stimulus/recording grounds are FZ/LM. All tests were conducted with an Espion Profile electrophysiology system (Diagnosys LLC, MA, USA). The presence of EER responses for each component and each stimulus condition was evaluated by two investigators. A positive peak is defined as a peak measured relative to the preceding trough with an amplitude (> 0.8 μV). The sum of EER amplitudes (30-90 ms (P1), 90-150 ms (P2), and 150-210 ms (P3)) was calculated.
Results :
Fifty eyes of twenty-five patients with IRD including potentially therapeutic target were enrolled. The median age of disease onset/age at examination was, 21.0 (range, 0-52) years/51.0 (10-76) years, respectively. The median visual acuity was, 1.3 (-0.08-3.0)/ 1.3 (-0.08-3.0) in the logarithm of the minimum angle of resolution (LogMAR) unit in the right/left eye, respectively. The full-field ERG responses were undetectable. The presence of positive peaks for 0.5mA/1.0mA/1.5mA/2.0mA components was identified in 57.1%/70.8%/83.3%/87.5%, respectively. The median value of the sum of EER amplitudes was 2.45 (range, 0.54-10.5 µV).
Conclusions :
The presence of positive responses in EERs was frequently (>80%) identified in IRD patients. The sum of EER amplitudes can be a parameter to evaluate the visual pathway even when full-field ERGs are undetectable. These findings keep in EERs derived predominantly from retinal ganglion cells in IRD patients, which helps in assessing the objective function in patients with severe photoreceptor damage. Further studies such as comparing EER values with the other clinical parameters would be helpful to delineate the utilities and applications of EERs.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.