Gil Ben-Shlomo1, Caryn Plummer, Kathleen Barrie, Dennis Brooks. 1. Veterinary Clinical Sciences, Iowa State University Department of Small and Large Animal Clinical Sciences, University of Florida, Gainesville, FL, USA. gil.benshlomo@yahoo.com
Abstract
OBJECTIVE: The goal of this work is to study the dark adaptation curve of the normal horse electroretinogram (ERG). PROCEDURES: The electroretinographic responses were recorded from six healthy female ponies using a contact lens electrode and a mini-Ganzfeld electroretinographic unit. The horses were sedated intravenously with detomidine, an auriculopalpebral nerve block was then performed, and the pupil was fully dilated. The ERG was recorded in response to a low intensity light stimulus (30 mcd.s/m(2) ) that was given at times (T) T = 5, 10, 15, 20, 25, 30, 40, 50, and 60 min of dark adaptation. Off-line analysis of the ERG was then performed. RESULTS: Mean b-wave amplitude of the full-field ERG increased continuously from 5 to 25 min of dark adaptation. The b-wave amplitude peaked at T = 25, however, there was no statistical significance between T = 20 and T = 25. The b-wave amplitude then remained elevated with no significant changes until the end of the study at T = 60 (P > 0.49). The b-wave implicit time increased continuously between T = 5 and T = 20, then gradually decreased until T = 60. No distinct a-wave was observed during the testing time. CONCLUSIONS: Evaluation of horse rod function or combined rod/cone function by means of full-field ERG should be performed after a minimum 20 min of dark adaptation.
OBJECTIVE: The goal of this work is to study the dark adaptation curve of the normal horse electroretinogram (ERG). PROCEDURES: The electroretinographic responses were recorded from six healthy female ponies using a contact lens electrode and a mini-Ganzfeld electroretinographic unit. The horses were sedated intravenously with detomidine, an auriculopalpebral nerve block was then performed, and the pupil was fully dilated. The ERG was recorded in response to a low intensity light stimulus (30 mcd.s/m(2) ) that was given at times (T) T = 5, 10, 15, 20, 25, 30, 40, 50, and 60 min of dark adaptation. Off-line analysis of the ERG was then performed. RESULTS: Mean b-wave amplitude of the full-field ERG increased continuously from 5 to 25 min of dark adaptation. The b-wave amplitude peaked at T = 25, however, there was no statistical significance between T = 20 and T = 25. The b-wave amplitude then remained elevated with no significant changes until the end of the study at T = 60 (P > 0.49). The b-wave implicit time increased continuously between T = 5 and T = 20, then gradually decreased until T = 60. No distinct a-wave was observed during the testing time. CONCLUSIONS: Evaluation of horse rod function or combined rod/cone function by means of full-field ERG should be performed after a minimum 20 min of dark adaptation.
Authors: Eline Vercruysse; Carolina Naranjo; Aurélie Sauvage; Maxime Vandersmissen; Magda Grauwels; Sébastien Monclin Journal: Open Vet J Date: 2021-11-19