Effect of refractive error on visual evoked potentials with pattern stimulation in dogs

Area of Science:

• Veterinary Ophthalmology
• Neuroscience
• Visual Electrophysiology

Background:

• Refractive errors are common in animals and can affect visual function.
• Visual evoked potentials (VEP) are a non-invasive method to assess the integrity of the visual pathway.

Purpose of the Study:

• To investigate the influence of varying refractive errors on pattern-stimulated canine visual evoked potentials (P-VEP).

Main Methods:

• Six beagle dogs underwent refractive error correction using contact lenses, ranging from -4 to +2 diopters.
• Pattern-VEP was recorded at each refractive state, with stimuli presented at 50.3 arc-min size and 50 cm distance.
• The P100 implicit time was analyzed in relation to refractive power.

Main Results:

• The P100 component peaked around 100 ms when the refractive error was -2 diopters (optimal focus).
• Significant delays (prolongation) in P100 implicit time were observed at refractive errors of -4, -3, 0, and +1 diopters compared to -2 diopters.
• These findings demonstrate a clear correlation between refractive error and VEP latency.

Conclusions:

• Canine refractive error demonstrably affects the P100 implicit time in pattern-VEP recordings.
• Refractive correction is crucial for accurate electrophysiological assessment of visual function in dogs.
• This study highlights the importance of considering refractive status in canine visual electrophysiology research.