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Luiz Barbosa Reis, Rafael Lani Louzada, Adalmir Morterá Dantas; Normative Study of The Full Field Electroretinogram in Cats: A Fast Dark-Adaptation Curve. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5755.
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© ARVO (1962-2015); The Authors (2016-present)
The aim of the present study is to standardize the normal values of each component of the signals that comprise the ERG of normal cats, in accordance with the ISCEV protocol currently recommended in clinical examinations, for its relevance as a diagnosis method to assess retinal function and detect lesions in their outer layers.
Ten healthy domestic cats (felis catus) were used for this study. The animals were treated in adherence to the ARVO guideline for the care and use of animals in visual research. The ERG was randomly recorded from one eye of the previously anesthesized cat, using a Nihon Kohden system, and according to the ISCEV protocol. We registered for each animal a series of light and dark-adapted ERGs. The cat is light-adapted to suppress rod activity and a response is recorded to single flash of bright light. After that, the cats were adapted for 5 minutes so as to record the scotopic ERG with both white and blue lights, as well as the isolation of the oscillatory potentials.
The mean amplitude of the b wave in photopic conditions with bright white flash is 180,0 μV, while in scotopic environment (animal adapted to darkness), also with white flash, we found a mean amplitude of 600,0 μV for the b wave, most of which was divided into two components (b1 and b2).The largest signal found with a dark adapted retina is consistent with the fact of the cat’s retina being a rod predominant retina. Using a blue flash, the signal recorded mostly do not express the dichotomized a and b wave found with white flash. As the blue filter isolate the rod electrical activity, this result points out a cone origin of the first a1 and b1 components of the negative (a) and positive (b) deflections of the full field ERG.
The cat ERG has a particular profile, with a fast dark-adapttion response. This normative study will allow the comparison of data recorded by different research groups, and enable a more complete use of the ERG as a tool for future studies on diagnosis and treatments of diseases affecting each retina layer in particular.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Figure 5 – The c wave of cats. Besides, for the c wave amplitude (pigment epithelium function), a positive and slower deflection that accurs after the positive b wave, we found a mean amplitude of 340 μV.
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