We present a procedure for full-field ERG recording in rabbits, based on the human ERG standards published by the International Society for Clinical Electrophysiology of Vision (ISCEV). Following initial pilot experiments, six animals aged 3 months and 11 animals between 1 and 2 years were investigated. All animals displayed well detectable and reproducible separate cone and rod responses under appropriate stimulus conditions. The b-wave was smaller in young animals than in old, but there were no similar differences in the b-wave implicit times. The animals had to be lightly sedated, which was shown to have no adverse effects on the recordings. Standard deviations of normalized adult rabbit recordings were comparable to human recordings. The measurements were less precise in young animals. We suggest that our procedure is well suited for further scientific studies in this animal model.
"A standardized full-field ERG was recorded 7 days before surgery and 41 days post-operatively on the right eye using a Nicolet Viking analysis system (Nicolet Biomedical Instruments, Madison, WI) as previously described . During examination the rabbits were sedated with Hypnorm (0.2 mg ml À1 fentanyl and 10 mg ml À1 fluanisone), 0.1 ml kg À1 intra-muscularly, and the pupils were dilated with Cyclogyl (1% cyclopentolate hydrochloride) to a pupil diameter of 8–9 mm. "
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to employ an experimental protocol for in vivo evaluation of sols of 5 wt.% poly(ethylene glycol) (PEG) in phosphate-buffered saline as artificial vitreous substitutes. A 20 gauge pars plana vitrectomy and posterior vitreous detachment were performed in the right eye of eight pigmented rabbits. Approximately 1 ml of the viscoelastic PEG sols was then injected into the vitreous space of six eyes. PEG with an average molecular weight of 300,000 and 400,000 g mol(-1) was used in two and four eyes, respectively. Two eyes received balanced salt solution and served as controls. Full-field electroretinography was carried out and intra-ocular pressure (IOP, palpation) measured pre- and post-operatively at regular intervals up to 41 days. The rabbits were killed and the eyes examined by retinal photography, gross macroscopic examination and histology. The viscoelastic sols were successfully injected and remained translucent throughout the post-operative period, with some inferior formation of precipitates. None of the eyes displayed IOP elevation post-operatively, but in three of the PEG sol injected eyes transient hypotony was noted. One eye sustained retinal detachment during surgery and another two in the post-operative period. ERG recordings confirmed preservation of retinal function in three out of four eyes injected with 400,000 g mol(-1) PEG. Histological examination revealed up-regulation of glial acidic fibrillary protein in Müller cells in PEG sol injected eyes, but normal overall morphology in eyes with attached retinas. The viscosity of the sol was not retained throughout the post-operative period, indicating the demand for polymer cross-linking to increase residence time. The results provide promising preliminary results on the use of PEG hydrogels as a vitreous substitute.
[Show abstract][Hide abstract] ABSTRACT: In people, retinal detachment often leads to a significant loss in cone-based vision. Most of the animal models commonly used for studying the consequences of retinal detachment have rod-dominated retinas. The purpose of this investigation was to evaluate the possibility that the ground squirrel, a rodent with a heavily cone-dominated retina, might provide a useful model for studying cone function in retinal detachment. Corneal ERGs were recorded from ground squirrels for large-field temporal modulations presented on a computer-controlled color monitor. Modulations were chosen to selectively stimulate either of the two classes of cone found in the ground squirrel retina. Under these test conditions, large and reliable cone ERGs could be readily recorded. In animals in which the retina had been surgically detached, the loss of cone signal was directly related to the number of cones in the detachment zone relative to the total cone population and that relationship did not differ for short-wavelength sensitive (S) and middle-wavelength sensitive (M) cones. Surgical reattachment produced a progressive recovery of cone-based signals. The ground squirrel seems likely to provide a useful animal model for studying the dynamics of cone function in retinal detachment and subsequent events.
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