Eletrofisiologia ocular em felinos domésticos : eletrorretinografia de campo total e potencial visual evocado por flash de luz

Abstract

The aim of this study was to standardize the total short-field electroretinogram(ERGpc), flicker and light-evoked potential (PVE-F) in awake cats, as well as to correlate healthy patient PVE-F waves with those with symptoms of feline cognitive dysfunction syndrome (CKD). We selected 17 male and female animals of different ages and submitted to two moments of evaluation (M1 and M2). Clinical and ophthalmic evaluation was performed in M1, as well was collected a blood sampling for hemogram, blood glucose, renal and hepatic profiles, and commercial test of FiV and FeLV. In M2 moment, ERGpc, flicker and PVE-F were performed in one eye at a time. The Nihon Kohdem system, Neuropack 2 MEB-7102A / k, was used with the signal scanned by the DATAQ® DI-158U through a three-channel RS232 cable and attached to an Acer Aspire 4732Z-4620 notebook. The first test was the PVE-F where the electrodes were arranged in the following sequence: the ground (Fpz) was placed in the frontonasal joint, the cranial (O2) into the external sargital crest and the reference (Cz) in the middle distance between them. At the end of PVE-F, ERGpc was recorded by instillation of two tropicamide-based eye drops, with a 5 minute interval each other. The patient was then kept in the dark room for 20 minutes adaptation, when the photopic phase was performed. After this period, the electrodes were placed in two monopolar positions, one being 0.5 cm from the temporal commissure (reference) and the other at the caudal part of the cervical region ground, were used Neuroline subdermal 12x0.40mm subcutaneous electrodes of the Ambu® model . For placement of active monopolar corneal electrode ERG-jet model, a drop of proximetacaine eye drops followed by 1% methylcellulose was instilled. Regarding the standardization of ERG, there was no statistically significant differences it was noticed that there was no statistical significance between the age groups. As for PVE-F, there were four positive and negative points (N1, P1, N2, P2, N3, P3, N4 and P4). In G1b, the absence of P2, N3 and P3 waves formation was remarkable for both eyes (5/7 patients). In the group with SDC signals it was observed that the greatest implicit time was in P2 for both eyes (OD 28.95 and OE 30.6). Amplitude reduction reached statistical significance. Conclude that ERG in a short protocol, photopically and the flicker can be performed without the use of anesthesia or sedation in any age group and that the PVE-F once recognized or discarded the affections with Syndrome-like symptomatology of cognitive dysfunction (CKD) it may be a useful diagnostic tool.