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T. Okuno, T. Hirose; Spatial Tuning Loss in the Pattern Reversal Visual Evoked Response (PVER) Peak Time in Optic Neuritis . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4115.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate how the peak times of the pattern reversal visual evoked response (PVER) change with pattern stimulus of different checkerboard sizes in optic neuritis and normal controls. Methods: The steady state pattern VER (SS-PVER) recordings were obtained with five checkerboard sizes (160, 80, 40, 20 and 10 min of arc) and the transient pattern PVER (Tr-PVER) were obtained with 40 min of arc. The peak times of SS-PVER were decided as the closest peak time of P100 time of Tr-PVER. The peak time-checkerboard size function graphs (P-C graphs) were drawn by plotting the peak time of SS-PVER taken as an ordinate against the checkerboard sizes taken as abscissa. The P-C graphs were compared in the patients of optic neuritis (19 eyes) and normal controls (22 eyes). The peak time of the SS-PVER against those of the Tr-PVER (peak time ratio) was calculated. The peak time ratio was drawn against checkerboard size. Comparison was made between those of optic neuritis and those of normal controls. Results: The mean peak times of Tr-PVER were 100.3 msec in normal and 128.8 msec in optic neuritis. The mean peak times of SS-PVER in normal controls were 106.5 msec for 160 min of arc, 104.6 for 80, 104.4 for 40, 108.3 for 20, and 118.8 for 10. Corresponding value for optic neuritis were 134.6 for 160, 129.8 for 80, 131.5 for 40, 133.5 for 20, and 136.1 for 10. In normal subjects, the peak times were prolonged in smaller checkerboard sizes, especially in 10 min of arc (p<0.0001, vs. all other checkerboard sizes, unpaired t-test). However, the peak times did not show significant difference among checkerboard sizes in optic neuritis, although peak times were longer than normal controls. The peak time ratios were significantly different between optic neuritis and normal controls (p=0.0005, two way ANOVA). Conclusions: The spatial tuning of amplitude of PVER against checkerboard sizes is known in normal individuals. The present study demonstrates that this spatial tuning exists in peak time also and that this spatial tuning of the peak time is lost in optic neuritis.
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