Abstract
Abstract: :
Purpose: To explore the possibility of developing isolated arterially perfused bovine eye as an in vitro model for studying retinal electrophysiology using multifocal electroretinography (mERG). Methods: Bovine eyes collected from the abattoir were cannulated through the ophthalmic artery and perfused with oxygenated Krebs' solution at 37 °C within 20 min of killing the animals. ERG was recorded using the VERIS 1.0 (Visual Evoked Response Imaging System), equipped with 61-hexagon stimulus pattern scaled with eccentricity. A Macintosh computer drove the mERG system and the stimulus was presented using Apple colour RGB monitor. Data were collected through an analog-to-digital converter board. Results: The mERG wave form of isolated arterially perfused bovine eye had the typical trough (negative wave, N1) and peak (positive wave, P1) similar to that of human mERG. The implicit times (peak latencies) for N1 and P1 were also similar to that in human, about 20 and 42 msec respectively. The average response amplitude (N1P1) was about 54 mV. The implicit times of N1 and P1 were maintained at their original values for more than 6 hours of the perfusion experiment. N1P1 amplitude was also well maintained for over 6 hours, indicating that the retina of perfused eye was functionally viable for at least 6 hours. Using neutral density filters, it was demonstrated that the mERG responses of the in vitro eye were affected proportionately by the stimulus intensity. The response amplitude was decreased with the decrease of stimulus intensity. Under 0 neutral density filters the response amplitude was about 54 nV which was diminished to about 26, 18 and 10 nV under filters of 0.4, 1.0 and 1.4 respectively. Partial covering of the cornea with opaque screen completely abolished the responses from the corresponding area of the retina. Conclusions: The retina of an enucleated eye can be kept alive by perfusing through the ophthalmic artery. Isolated arterially perfused bovine eye may be used as a useful experimental platform to study retinal electrophysiology using mERG. In vitro bovine eye may offer a cheap and easily obtainable alternative to primate model, particularly for screening and invasive studies.
Keywords: electroretinography: non-clinical • retina • animal model