Aging effects on upper and lower half visual fields by VECPs and automated static perimetry

We studied the aging effects on upper and lower half visual fields using pattern VECPs with half fields stimuli and automated static perimetry. The subjects, consisting of 56 normal volunteers ranging in age from 10 to 69 years old, were divided into three groups (10-29, 30-49, 50-69 years old). Their visual acuities were better than 1.0 and refractive errors were within +/- 2.0 diopters. Perimetry was performed with an automated perimeter (Octopus, program 61). An artificial pupil of 3 mm was used after cycloplegia with 1% tropicamide to eliminate senile miosis effects in recording of VECPs. Subjective light sensitivity decreased with age and there was a noticeable hiatus between the third and fourth decades. However the age-related decrease in sensitivity showed no difference between the upper and lower half fields. However VECPs results showed that with aging the P100 peak latency did not increase for lower half field stimuli, but increased for the upper half field stimuli, especially for smaller check sizes. These results suggested that there were different aging processes a in the upper and lower half fields and higher neural factors participated in the effects.     

Human flash visually evoked cortical potentials under different levels of halothane anesthesia

Flash visually evoked cortical potentials (FVECPs) were recorded in 13 surgical patients under different levels of halothane anesthesia, altering the rate of stimulus frequency from 0.5 Hz to 10 Hz. VECPs were obtained in the awake state under premedication with atropine sulphate, and at end-tidal halothane concentrations of 0.38%, 0.75%, 1.13% and 1.5%. The peak latency of P1 (the major positive component with a latency of about 100 msec) progressively increased from 116.7 +/- 3.3 msec (mean +/- SE) in the awake state to 124.3 +/- 6.3 msec, 136.5 +/- 5.2 msec, 151.5 +/- 5.2 msec and 166.3 +/- 8.7 msec with increasing halothane concentration. Significant reductions in P1 amplitude were observed to 2 Hz, 5 Hz and 10 Hz stimuli, whereas there were no significant changes in amplitude to 0.5 Hz and 1 Hz stimuli. P1 amplitude plotted against stimulus frequency had a maximum at 10 Hz in the awake state. This curve gradually and preferentially attenuated at higher frequencies as halothane concentration increased.     

Assessment of visual function before and after macular surgery by pattern visual evoked cortical potentials

PURPOSE: To investigate pre- and postoperative visual function in patients with macular hole and those with epiretinal macular membrane (ERM) by means of visual evoked cortical potential (VECP). MATERIAL AND METHODS: VECP was recorded from 15 eyes with macular hole and 9 eyes with ERM prior to and 3 months after surgical treatment. Check sizes of 30' for transient stimulation, and 7.5', 15', 30', 60' and 120' for steady-state stimulation were applied. RESULTS: In transient VECPs, the P 100 component was prolonged and attenuated in both diseases before surgery, and it remained unchanged after surgery. In the eyes with macular hole, the amplitudes of steady-state VECPs showed significant reduction in 15' and 30' check sizes before surgery, and recovered only in 15' check size after surgery. The preoperative spatial frequency curve of ERM was lowered in the whole frequency range measured. CONCLUSIONS: VECP reflected the area of macular hole and ERM. VECP changes after surgery were considered to depend on the degree of surgical invasion.     

Evaluation of color pattern VECP in deutan

Using an Equi-Energy-Color Pattern Generator, color vision experiments were performed on nine normal subjects, six cases of deuteranomalies, and six cases of deuteranopias with the use of Visually-evoked cortical potentials (VECPs). Checkerboard patterns, consisting of the pairing of any chosen one of three colors with its complementary color in terms of equal energy, were used. The pairing of a neutral color with its complementary color of protan, deutan and tritan were displayed on a color TV monitor. We measured the amplitude and latency of P100 component of VECPs. Cases of deuteranopia showed significantly smaller amplitude and longer latency of P100 component in protan and deutan responses than did normal subjects. Cases of deuteramomaly showed significantly smaller amplitude and longer latency of P100 component in only protan response compared to those of normal subjects. It was possible to objectively detect the deutan in color pattern VECPs.     

Platelet aggregation and glaucoma

Scalp profiles of steady-state pattern visual evoked cortical potentials (VECPs) along the horizontal line at Pz (for upper field stimuli) and Oz (for lower field stimuli) were studied in 12 normal subjects by simultaneous five channel recordings from electrode positions 3 cm and 6 cm laterally on either side of, and at, Oz or Pz. Each electrode was referred to Fz or to the right earlobe. The amplitude and phase of the averaged VECPs (n = 20) were calculated by means of Fast Fourier Transform. With smaller check size the amplitude data verified that the scalp profile of the lower visual field peaked at the hemisphere contralateral to the quadrant stimulated. With larger check size the peak shifted to the ipsilateral hemisphere. With upper field quadrant stimulation, position of the reference electrode at Fz was found to be unsuitable since the VECP amplitude at the level of Pz was greatly reduced. Phase and apparent latency also varied with the field stimulated as well as with the position of electrodes.     

Comparative studies on pattern VECP between patients with ischemic optic neuropathy and optic neuritis

PURPOSE: To evaluate whether and how VECPs are useful in differentiating ION from ON. METHODS: We retrospectively studied 27 patients with non-arteritic ION and 69 patients with ON using pattern visually evoked cortical potentials (PVECPs) to 3 rev/sec stimulation (transient) and 12 rev/sec stimulation (steady-state). RESULTS: In patients with ION, non-recordable responses were found in 25% of those with transient VECP and in 74% of those with steady-state VECP. In ON patients, non-recordable responses were found in 34% of those with transient VECP and in 64% of those with steady-state VECP. The average peak latency of P100 component in those with ION was significantly shorter than in those with ON. The amplitude ratio (affected eye/fellow eye) of steady-state VECP was significantly higher in those with ION than in those with ON. The amplitude ratio of P100 showed no significant differences between groups. CONCLUSION: The P100 peak latency of transient VECPs and the amplitude of steady-state VECPs have the potential to differentiate between ION and ON.     

Assessment of central visual function after successful retinal detachment surgery by pattern visual evoked cortical potentials.

The pattern of visual recovery after successful surgery by pattern visual evoked cortical potentials (VECP), visual acuity, colour vision, and critical fusion frequency was investigated in 14 eyes with retinal detachment involving the macula. The temporal tuning characteristics in the evoked potentials were measured as based on the P100 amplitude and the frequency necessary for evoking 0 mu V amplitude, which was defined as an objective critical fusion frequency by extrapolating the curve. Significant improvement in visual acuity and colour vision was observed within 2 months postoperatively. A significantly increased P100 peak latency became shorter as the postoperative days increased. In general, a good correlation was noted between the P100 peak latency and subjectively measured visual acuity, colour vision, and critical fusion frequency. The objective critical fusion frequency measured by VECP recovered gradually during the 6 months after surgery. Functional recovery was not related to the length of time the macula was detached before surgery.     

Top-down知觉加工下的视觉传导特征

目的:研究Top-down知觉通路参与儿童视觉传导效率及其特征。方法:选取2020-01/06于我院门诊进行健康查体的儿童志愿者26名,采用儿童自我颜面部特征明显的照片作为Top-down知觉注视点图片,通过图形视觉诱发电位(PVEP)检查记录N75潜时、P100波峰时间、P100波幅及P100复极化时间。结果:不同视知觉加工路径对N75潜时无显著影响,而不同空间频率对N75潜时具有显著影响,高频空间刺激下N75潜时延长。视知觉加工路径与空间频率的交互作用对P100峰值时间呈现显著影响,Top-down条件下,高频空间刺激时P100波峰值出现时间显著缩短。不同视知觉加工路径和空间频率均对P100波幅影响显著,高频空间刺激下,Top-down知觉途径对P100波幅的影响显著。不同视知觉加工路径和空间频率均对P100波复极化时间影响显著,而加工路径与空间频率的交互作用影响不显著。结论:Top-down知觉途径参与下的儿童视觉过程视觉传导速度得到提高,视觉传导效率提高。     

Pattern ERG and VECP following optic neuritis in childhood

Pattern ERGs and pattern VECPs were recorded in 12 patients who had suffered from optic neuritis in childhood. When each individual's eyes were compared, the eye with the longer P100-latency in pattern VECP was found to have the smaller amplitude in pattern ERG. The latency differences correlated with the amplitude differences. These findings confirm that after optic neuritis the amplitude of pattern ERG is reduced.     

Follow-up studies of optic neuritis with lymphocytic adenohypophysitis

BACKGROUND: We report a 38-year-old female suffering from bilateral optic neuritis with lymphocytic adenohypophysitis. CASE: The initial symptom of the 38-year-old-female was diabetes insipidus. Magnetic resonance imaging showed swollen pituitary stalk and disappearance of the T1 shortening of the neurohypophysis. Immunological tests showed that the serum anterior pituitary antibody was positive. These findings suggested lymphocystic adenohypophysitis. Bilateral optic neuritis also occurred and the pattern visual evoked cortical potential (VECP) demonstrated increased P100 peak latency and reduction of amplitude. After steroid pulse therapy, the visual acuity and field improved and the pattern VECP became normal. Temporal hemianopia was not noted. CONCLUSION: A direct infiltration of the inflammatory change in the pituitary gland or some autoimmune problem was considered as a cause of the optic neuritis. In contrast to the VECPs of multiple sclerosis patients, the prolonged peak latency of pattern VECPs of this case were shortened in accordance with the recovery of visual acuity.     

Electroretinograms and pattern visually evoked cortical potentials in central areolar choroidal dystrophy

We describe three patients with central areolar choroidal dystrophy whose electroretinograms (ERGs) and pattern visually evoked cortical potentials (VECPs) confirmed their macular dysfunction. Visual fields measured by Goldmann perimetry showed central relative scotomata corresponding to a dystrophic lesion. Dark adaptation curves were slightly abnormal either in the first curve or in the second curve, depending on the visual acuity. Color vision was disturbed irregularly. Fluorescein angiography revealed a loss of the choriocapillaries, and a hyperfluorescent border outlined the dystrophic lesion.Single-flash dark-adapted ERGs and scotopic ERGs were almost normal, while photopic and flicker ERGs showed slightly attenuated amplitudes. Conversely, VECPs to pattern reversal stimulation were greatly affected for both transient and steady-state stimuli.We conclude that, in central areolar choroidal dystrophy, pattern VECPs can provide more information on macular dysfunction than does the ERG.     

Temporal frequency characteristics of retinitis pigmentosa obtained by pattern visual evoked cortical potential to checkerboard stimuli

We examined temporal frequency curves by pattern visual evoked potential in 28 eyes suffering from retinitis pigmentosa (RP). The peak latency of the P100 component was 110.3 ± 3.0 msec (S.E.), which was not significantly different from the 110.2 0.8 msec (S.E.) obtained from 60 normal controls. The P100 amplitudes of whole reversal frequencies, however, were decreased in patients with RP (p < 0.05), especially at lower frequencies. We thought this phenomenon was useful for determining central visual function in patients with RP.     

Visual evoked potentials in children cured with sodium-calcium versenate because of high blood lead level--the prospective study

PURPOSE: To find out if blood lead level (Pb-B) changes have influence on visual evoked potentials. MATERIAL AND METHODS: 18 children (36 eyes) treated with CaNa2EDTA because of chronic environmental lead poisoning were examined two times: first at age 2-15.5 (mean 8) years and second 4 years later. For pattern VEP LKC equipment, UTAS E-2000 program and stimulations of 13', 26', 52', 105' were used. P100 amplitude and latency were calculated. RESULTS: Pb-B was decreased from 150-486 (mean 262) microg/l to 42-248 (mean 103) microg/l. After 4 years, P100 latency was significantly delayed in children with Pb-B above 100 microg/l at second examination. In children with Pb-B below 100 microg/l no significant differences between two consecutive examinations were observed. There were no significant differences in P100 amplitude. CONCLUSIONS: Delayed P100 latency of PVEP in children is permanent but non-progressive if Pb-B is lower than 100 microg/l.     

Asymmetries of optokinetic nystagmus in amblyopia: the effect of selected retinal stimulation

Open loop optokinetic eye movements were measured in response to monocular nasalward and temporalward visual field movement presented at four selected retinal sites in 6 strabismic amblyopes and 4 normal observers. Stimulus sites included the central retina (10 X 10 deg), a large field (40 X 32 deg), a large peripheral field with the center (10 X 10 deg) blocked out and a hemiretinal field (15 X 32 deg) excluding the fovea. We found directional preferences of OKN in amblyopia to nasalward stimulus movement for the foveal and concentric peripheral stimuli. The results of peripheral hemiretinal optokinetic stimulation of amblyopic subjects revealed a deficient OKN slow phase response from the temporal hemiretina, particularly for temporalward stimulus movement. There was no marked asymmetry of OKN in the normal group for the concentric stimuli. A normal preference was found for nasalward and temporalward stimulus field movement imaged on the nasal and temporal hemiretinae respectively. These results are interpreted in terms of a model of cortical and subcortical pathways for OKN derived from comparative studies of cat and monkey.     

光学诱导散光对视觉信号传导及皮层反应的影响

目的研究光学诱导不同程度散光产生的视觉信号对皮层反应时间及强度的影响;研究散光是否可导致视觉信号传导时程异常,观察视觉信号传导时间及视皮层反应强度与散光程度的量化关系。方法完全随机设计研究。对视力或矫正视力正常的被检者眼前依次放置0～5D度数正柱镜片诱导不同程度散光。每一实验镜片条件下行单眼图形视觉诱发电位（PVEP）检查。记录P100振幅和潜伏期。数据采用单因素方差分析、配对t检验和Pearson相关性检验。结果当采用较低空间频率的刺激时（60＇棋盘格刺激）,P100潜伏期随散光程度的增加变化不显著,无相关性,单因素方差分析示差异无统计学意义（F=0．290,P〉0．05）,P100振幅随散光程度的增加而逐渐降低（F=3．947,P〈0．01;r=-0．470,P〈0．01）;当采用较高空间频率刺激时（15’棋盘格刺激）,P100潜伏期随散光程度的增加而延长（F=10．850,P〈0．01;r=0．647,P〈0．01）,P100振幅亦随散光程度增加而逐渐降低（F=14．280．P〈0．01;r=-0．699,P〈0．01）。结论成像于视网膜上的物像引起视觉中枢反应的时间和强度与视网膜物像的清晰度和空间频率密切相关,高空间频率的清晰物像引起视觉环路上的神经元发生反应较早较强：低空间频率的物像在清晰度下降时虽有皮层神经元反应强度的下降,但反应时间无明显延长。     

左旋多巴对弱视眼视诱发电位影响的研究

目的:探讨左旋多巴治疗弱视的效果。方法:正常眼和弱视眼服用单次剂量左旋多巴前后进行图形视诱发电位(pattem visual evoked poten-tial,PVEP)检测。结果:正常眼服药后中空间频率PVEP的N_1P_1振幅和高空间频率PVEP的P_1N_2振幅增大,弱视眼服药后低空间频率PVEP的N_1波潜伏期和中空间频率PVEP的P_1波潜伏期缩短。结论:左旋多巴可改善弱视眼的视功能,可作为弱视的一种新的治疗方法。眼科学报1997;13:182—185。     

Spatial-temporal interactions in the steady-state pattern electroretinogram

It is currently assumed that steady-state pattern electroretinograms can be obtained only at high rates of pattern reversal. However, steady-state responses can also be obtained at very low temporal frequencies (less than 1 Hz), provided that the reversal is sinusoidal. In five healthy volunteers, we studied the frequency characteristics of the pattern-reversal electroretinogram in response to sinusoidal gratings of 0.4 and 4 c/deg, reversed sinusoidally in contrast at frequencies ranging from 1 to 27 Hz. Steady-state responses dominated by the second harmonic component were obtained at all temporal frequencies tested; the amplitude of the second harmonic changed with stimulus temporal frequency. In the low-temporal-frequency range, stimuli of high spatial frequency appear to elicit larger contribution of generators with sustained or tonic characteristics compared with stimuli of low spatial frequency.     

Spatial frequency tuned covariance channels for red-green and luminance-modulated gratings: psychophysical data from human adults

Both chromatic and luminance-modulated stimuli are served by multiple spatial-frequency-tuned channels. This experiment investigated the independence versus interdependence of spatial frequency channels that serve the detection of red-green chromatic versus yellow-black luminance-modulated stimuli at low spatial frequencies. Contrast thresholds for both chromatic and luminance-modulated gratings were measured within 12 individual subjects using a repeated-measures design. Spatial frequencies ranged from 0.27 to 2.16 c/deg. A covariance structure analysis of individual differences was applied to the data. We computed statistical sources of individual variability, used them to define covariance channels, and determined the number and frequency tuning of these channels. For luminance-modulated gratings, two covariance channels were found, including one above and one below 1 c/deg [cf. Peterzell, & Teller (1996). Individual differences in contrast sensitivity functions: the coarsest spatial pattern analyzer. Vision Research, 36, 3077-3085]. For chromatic gratings, correlations between thresholds for most spatial frequencies were uniformly high, yielding a single covariance channel covering all but the highest spatial frequency tested. A combined analysis of both data sets recovered the same three covariance channels, and showed that detection thresholds for low-frequency red-green chromatic and luminance-modulated stimuli are served by separate, statistically independent processes.     

Binocular interactions in visual evoked cortical potentials with two light-emitting-diodes

Binocular interaction for a central field was studied with transient scalp visual evoked cortical potentials (VECPs) using two light-emitting-diodes. VECPs were obtained for binocular and monocular visions with dominant and non-dominant eyes, and arithmetical sums of monocular VECPs with dominant and non-dominant eyes were calculated. Amplitude and latency of remarkable initial three peaks were tested with the multivariate analysis of variance. Significant differences were noted among the four VECPs. Pairwise comparisons showed that (1) the amplitude of the first peak for the binocular VECPs was larger than that for the monocular VECPs but smaller than that for the sum-VECPs; the latency of the first peaks for the binocular VECPs were earlier than that for the monocular VECPs with the non-dominant eye; (2) the amplitude of the first negative peak for the sum-VECPs was larger than that for the binocular VECPs, and the peak latency for the sum-VECPs showed later than that for the binocular VECPs; (3) the amplitude of the second positive peak for the binocular VECPs and monocular VECPs with the dominant eye was larger than that with the non-dominant eye, but smaller for the binocular VECPS than that for the sum-VECPs; the latency for the binocular VECPs showed earlier than that for the monocular VECPs with the dominant eye and for the sum-VECPs. Binocular suppression was noted in amplitude for the three peaks and binocular facilitation was noted in latency for the latter two peaks. This revised version was published online in July 2006 with corrections to the Cover Date.     

Visual evoked potentials in children with high blood lead level

PURPOSE: The aim of this study is to find the relationship between lead level in blood (Pb-B) and visual evoked potentials (VEP) in children, environmentally exposed to lead. MATERIAL AND METHODS: 32 children (64 eyes) with no clinical signs of lead poisoning were examined. Corrected visual acuity was 5/5 in all eyes. Age of the children was 2-15.5 years (mean 8), Pb-B ranged from 150 to 486 (mean 262) microg/l. For pattern VEP LKC equipment, UTAS E-2000 program and stimulations of 13', 26', 52', 105' were used. P100 amplitude and latency were calculated. RESULTS: P100 latency was significantly delayed in children at the age of seven, with Pb-B above 150 microg/l. The latencies were more delayed in children with higher than in lower Pb-B, but the relation was not linear. P100 amplitudes did not differ significantly from the control group. In some children VEP had abnormal morphology, double P100 peak or P100 without sharp, but extended peak. CONCLUSION: Delayed P100 PVEP latency occurred in children with blood lead level higher than 150 microg/l, after at least 7 years of environmental exposure. Changes in VEP are similar to those which are caused by demyelinization and are found in multiple sclerosis.