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Olga Kraszewska, Brian Cichocki, Quentin Davis; Adapting the RETeval ERG device into a veterinary tool.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5754.
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© ARVO (1962-2015); The Authors (2016-present)
The RETeval is a portable ERG/VEP device that is used to assess visual function in humans. In this report, we adapt the RETeval device to be a veterinary tool helpful in assessing retinal function before performing cataract surgery. Adding assessment of the retinal function to the standard funduscopic exam helps in determining whether the surgery will substantially contribute to the sight improvement.
The parameters of ERG testing in dog differ from human ISCEV standards. A custom protocol was developed for the RETeval device to allow for rod and cone function assessment. Platinum subdermal needle electrodes (reference and ground) and an ERG-Jet corneal electrode (active) were used to make an electrical connection to the animal. These initial ERG results were obtained from 5 un-sedated dogs.
The breeds tested have been Maltese, 15 y/o, spayed female (A), Dachshund, 13 y/o, neutered male ( B), Pomeranian, 7 y/o, male ( C), Amstaff, 3 y/o, neutered male (D) and Poodle, 0.5 y/o un-neutered male (E). Dog A had hypermature cataracts OU, ERG was performed to determine candidacy for phaco in OS alone (OD had secondary glaucoma, severe anterior segment abnormalities secondary to chronic uncontrolled phacolytic uveitis). Flat retinal response resulted in failure as a surgical candidate. Dog B had a complete cataract OS and unremarkable OD. ERG was performed to determine candidacy for phaco. Severely blunted ERG waveforms and abnormal amplitude resulted in failure as a surgical candidate. Chronic inflammation in OS is suspected, as OD is funduscopically normal. Doc C had funduscopically normal OD with early immature cataract and late immature cataract in OS. ERG was performed to verify retinal function prior to phaco. Photopic and scotopic recordings were as expected. The complete set of readings were obtained from OS, since that was the retina that could not be visualized. Cataract surgery was performed and dog C is doing very well since. The owners of dogs D and E have elected to have ERGs performed to help starting data collection for a normative database.
The RETeval device can be adapted for use in a busy veterinary practice to assess visual function. The hand-held nature of the device made it easy to bring the apparatus to the dog to accommodate different sized breeds. The outcome of ERG results was pivotal in deciding about performing cataract surgery in dogs.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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