Abstract
Abstract: :
Purpose: To find the characteristics of the pattern reversal VER (visual evoked response) specific to macular and optic nerve diseases to help differentiating the two disorders. Methods: The steady state pattern VER (SS-PVER) recordings were recorded by the checker board pattern stimulus with five check sizes (160, 80, 40, 20 and 10 min of arc). The amplitude-check size function graphs (A-C graph) were drawn with the checkerboard sizes as the x-axis and amplitude of SS-VER as the y-axis. The A-C graphs of SS-PVER were compared in the patients with early optic neuritis (11 eyes), early stage glaucoma (6 eyes), macular edema (5 eyes), and idiopathic epiretinal membrane (ERM) (6 eyes). Of optic neuritis, 5 eyes had multiple sclerosis (MS). The macular edema after cataract surgery counted 3 eyes and the uveitis two. In each eye, the area under the curve (AUC) was measured. The ratio of AUC (AUC of 40 to 10 min of arc / 160 to 40 min of arc) was calculated new. Transient pattern VER was also recorded, and the major peak appearing 100 msec from the onset of stimulus (100-peak time) was evaluated. Results: In normal subjects, the A-C graph shows inverted U-shape with a peak at 40 or 20 min of arc. In all patients, the amplitude of the A-C graph was reduced. However, the degrees of suppression of each check size appeared to be different in each disease. The eyes with optic neuritis were attenuated uniformly and were peaking at 20 min of arc. The eyes with glaucoma and ERM peaked at 40 min of arc. In the eyes with ERM, the more severe it was, the more reduced the smaller check size. The eyes with macular edema were severely attenuated in 20 and 10 min of arc and were peaking at 80 min of arc. There was a significant difference between the rates of AUC of between optic nerve disease (optic neuritis and glaucoma) and macular disease (macular edema and ERM) (p=0.0043, unpaired t-test). Visual acuity did not differ significantly between the diseases (p≷0.05, unpaired t-test). In most patients, 100-peak time was prolonged. However, prolongation of the eyes with glaucoma was significantly less than eyes with other disease (p=0.028, unpaired t-test). Conclusion: This study demonstrates that the amplitude of SS-PVER is attenuated uniformly in optic nerve disease and keeps the peak at 40 or 20 min of arc. On the other hand, in macular disease, the amplitude of SS-PVER is mainly attenuated in smaller check size and shifts the peak of the amplitude-check size curve toward larger check size.
Keywords: 393 electrophysiology: clinical