Itoh Yoshiki, Maehara Seiya, Okada Keisuke, Izumisawa Yasuharu
Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Japan.
J Vet Med Sci. 2010 Nov;72(11):1449-53. doi: 10.1292/jvms.10-0073. Epub 2010 Jul 13.
The aim of this research was to evaluate the changes in the response of pattern-stimulated visual evoked potential (pVEP) with different pattern size, and demonstrate visual acuity from the minimum visual angle. pVEP was recorded from both eyes of six healthy beagles. Prior to pVEP recording, the dogs were sedated, and a traction fiber was used to prevent the eye from rolling down. The stimulator was set 30 cm from the subject's eye. Pattern reversal frequency of the stimulating monitor was 3 rev/sec, and pattern size was set at seven levels; 14-364 arc-min (1.2-31.4 mm). Amplitude of the P100 component was evaluated, and visual acuity was calculated from the minimum visual angle to obtain a pVEP response. A pVEP response (2.3-3.1 µV) was obtained from all subjects. The P100 component was detectable in 3 eyes with a check size of 14 arc-min and 7 eyes with 28 arc-min, and the component was undetectable with 14 arc-min in all subjects in which it was undetectable with 28 arc-min. From the minimum level to obtain the P100 component, the subjects' visual acuity was extrapolated as 0.54-2.14 cycles per degree. We demonstrated the change in P100 component with check size. However, our technique was inadequate to examine visual acuity because the subject's refractive index was ignored. We suggest that, with further study, pVEP with different check sizes would be applicable for canine visual acuity examination.
本研究的目的是评估不同图形大小下图形刺激视觉诱发电位（pVEP）反应的变化，并从最小视角来证明视力情况。对6只健康的比格犬的双眼进行pVEP记录。在进行pVEP记录之前，先对犬进行镇静，并使用牵引纤维防止眼睛向下转动。刺激器设置在距离受试动物眼睛30厘米处。刺激显示器的图形反转频率为3转/秒，图形大小设置为7个水平；14 - 364角分（1.2 - 31.4毫米）。评估P100成分的振幅，并从最小视角计算视力以获得pVEP反应。所有受试动物均获得了pVEP反应（2.3 - 3.1微伏）。在图形大小为14角分的情况下，3只眼睛可检测到P100成分；在图形大小为28角分的情况下，7只眼睛可检测到该成分，而在所有图形大小为28角分检测不到该成分的受试动物中，图形大小为14角分时该成分均检测不到。从获得P100成分的最小水平推断，受试动物的视力为0.54 - 2.14周/度。我们证明了P100成分随图形大小的变化。然而，由于忽略了受试动物的折射率，我们的技术不足以检测视力。我们建议，随着进一步研究，不同图形大小的pVEP将适用于犬的视力检查。
