Visual evoked potentials were elicited by flash in 29 patients with a variety of cerebral lesions and in 10 normal controls. In 12 patients with focal brain lesions, no wave form could be recorded in one side. Of the remaining 23 sides, the average P1 latency showed no difference from that of the normal controls. In 17 patients with diffuse brain lesions no wave form could be elicited in 12 sides. Average P1 latency of remaining 22 sides showed statistlcally significant difference from that of normal controls. In this study it appears that delayed P1 latencies are associated with diffuse cerebral lesions rather than with localized lesions.
Brain ; Evoked Potentials, Visual* ; Humans

No abstract available.
Alcoholics* ; Evoked Potentials, Visual* ; Humans

OBJECTIVES: To explore the composition characteristic of event related potential （ERP） in different visual acuity levels, and to provide theoretical basis for the objective assessment of visual acuity. METHODS: Monocular stimulus was performed on 16 selected subjects. The subjects were required to look straight at the screen ahead and count the amount of stimuli from different directions. The pictures of optotype stimulus which corresponding to three different visual acuity levels were showed in the center of the screen. The ERP results were recorded separately. RESULTS: （1） The P₁ amplitudes of match stimuli recorded under the supra-threshold visual acuity level were higher than that of match stimuli recorded under the threshold and sub-threshold visual acuity levels. There was no significant difference between the P₁ amplitudes of match stimuli recorded under the threshold and sub-threshold visual acuity levels. The tendency of conflict stimuli was similar to that of match stimuli under three visual acuity levels. （2） In the 340-500 ms post-stimulus range, P₃₀₀ component was found under supra-threshold and threshold visual acuity levels; no P₃₀₀ component was found in corresponding time window under sub-threshold visual acuity. The differences of P₃₀₀ amplitudes among three visual acuity levels were statistically significant. The amplitudes from high to low were the supra-threshold, threshold and sub-threshold visual acuity levels. CONCLUSIONS ERP can be a potential new method for the objective assessment of visual acuity in forensic medicine.
Adult ; Evoked Potentials ; Evoked Potentials, Visual ; Humans ; Photic Stimulation ; Visual Acuity/physiology* ; Visual Perception

No abstract available.
Brain Mapping* ; Evoked Potentials, Visual* ; Schizophrenia*

PURPOSE: To obtain normal values of positive wave (b-wave) in the multifocal ERG in terms of age and sex of Koreans. METHODS: The multifocal ERGs by using RETIscan visual evoked response imaging system were tested for 80 eyes. 61 retinal locations were stimulated concurrently. We analyzed the average responses of 5 concentric rings. RESULTS: In the amplitudes of b-wave, ring 1, 84.1 5.4 nV/deg, was the largest of all the other rings and ring 5, 23.1+/-1.5 nV/deg, was the smallest of all the other rings (P<0.05). No statistically significant difference was observed in amplitude between sexs. The implicit time of b-wave was the longest in the ring 1, 40.8 1.6 ms, and shortest in the ring 4, 36.7+/-0.9 ms (P<0.05). CONCLUSIONS: The amplitude of b-wave was the largest in the fovea, and became smaller with eccentricity. The largest amplitude of b-wave was observed in the age of twenties. The amplitude of b-wave was decreased with age in the ring 3, 4, and 5. The interindividual variation of the amplitude of b-wave was greatest in the fovea. The implicit time of b-wave in the fovea was the longest, and that in the ring 4 was the shortest. It became longer from the ring 5, again.
Electroretinography* ; Evoked Potentials, Visual ; Reference Values* ; Retinaldehyde

No abstract available.
Evoked Potentials, Visual* ; Humans ; Infant, Newborn*

The pattern reversal visual evoked potential(PRVEP) and flash electroretinogram(flash ERG) were performed in 22 patients with optic atrophy. Patients with ophthalmologic problems other than optic atrophy or with systemic disorders were excluded from the analysis The results are as follows: 1. In the 41 eyes of patients with optic atrophy, 39 of them showed abnormal PRVEP, in which all the eyes had no consistent waveform except in one patient 2 eyes with delayed P1 latency. 2. 13 eyes were abnormal in both PRVEP and flash ERG but no eye was abnomnal in flash ERG only 3, Regarding the flash ERG examination, 13 eyes were abnomlal. Of these, there was a period of 1 to 2 years for 1 eye's disease, a period of 2 to 5 years for another eye' disease and after 5 years 11 eyes were diseased. Therefore, it showed that the longer the duration of disease lasted, the more flash ERG abnormalities developed. 4. The abnormalities of PRVEP haxe no significant relationship with the duration of the disease.
Evoked Potentials, Visual* ; Humans ; Optic Atrophy*

OBJECTIVES: To study the effect of different attentional conditions on the event-related potential （ERP） components generated by the visual information stimuli related to visual acuity, and provide a theoretical reference for clinical forensic visual objective evaluation. METHODS: With visual acuity optotypes as normal form of visual information stimuli, 15 volunteers as study subjects were supposed to account the visual acuity optotypes under the attentional condition of visual stimuli. Furthermore, the subjects were required to listen to the storytelling carefully under the non-attentional condition of visual stimuli, and after the examination, they needed to answer the story-related questions. All the EEG results of two different attentional conditions from the subjects were recorded by 32 channel ERP system. RESULTS: Under two attentional conditions, P₁ and P₃₀₀ components were evoked by the visual acuity optotypes on supra-threshold and threshold visual acuity levels, while only P₁ component were evoked by the visual acuity optotypes on sub-threshold levels. In the ERP waveforms evoked by the visual acuity optotypes on supra-threshold, P₁ and P₃₀₀ amplitudes under attentional condition were larger than that under non-attentional condition. CONCLUSIONS Attentional conditions can influence the detection of visual acuity. P₃₀₀ component can be used to distinguish the visual acuity levels with supra-threshold and sub-threshold under non-attentional condition.
Attention/physiology* ; Electroencephalography ; Evoked Potentials ; Evoked Potentials, Visual ; Humans ; Visual Acuity

The amplitude and latency of visual evoked potentials to pattern-reversal half-field stimulation were measured in 20 normal right-handed subjects to determine whether the individual contribution of right and left cerebral hemispheres is different as related to the generation of pattern-evoked potentials. The amplitude and latency of P1 from a lateral occipital electrode ipsilateral to the halffield stimulation were significantly greater with right half-field wtimulation. The amplitude and latency difference between both sides probably reflects asymmetries of human striate cortex.
Cerebrum ; Electrodes ; Evoked Potentials, Visual* ; Humans ; Visual Cortex

PURPOSE: To evaluate the change in multifocal visual evoked potential (mfVEP) in unilateral anisometropic amblyopia before and after occlusion treatment. METHODS: The mfVEP was performed using RETIscan(R) (Roland,Brandenburg, Germany) for patients with unilateral anisometropic amblyopia before and after occlusion treatment. Amplitude and latency values of mfVEP were analyzed according to the field divided by 6 rings or 4 sectors. RESULTS: The each amplitude of values of all 6 rings were not significantly different before treatment (p = 0.077) in amblyopic eyes. However, the value of ring 1 (p = 0.00) was significantly higher than the value of other rings after treatment. In fellow eyes, the values of ring 1 was consistently significantly higher than the value of other rings before (p = 0.014) and after (p = 0.049) occlusion treatment. Additionally, the amplitudes of ring 1 (p = 0.005) and ring 3 (p = 0.007) were significantly increased in amblyopic eyes after occlusion treatment. In fellow eyes, the values of all rings did not change significantly. The analysis of amplitudes with 4 sectors revealed no significant result. The analysis of latencies with 6 rings and 4 sectors revealed no significant result. CONCLUSIONS: The change in amplitude on the central field (ring 1) in amblyopic eyes can be a useful objective monitoring method observing the improvement progress in visual acuity.
Amblyopia ; Evoked Potentials, Visual ; Eye ; Humans ; Visual Acuity