Objective investigation of vision impairments using single trial pattern reversal visually evoked potentials

2013 ◽  
Vol 39 (5) ◽  
pp. 1549-1560 ◽  
Author(s):  
Vikneswaran Vijean ◽  
M. Hariharan ◽  
Sazali Yaacob ◽  
Mohd Nazri B. Sulaiman ◽  
A.H. Adom
Keyword(s):  
Evoked Potentials ◽  
Pattern Reversal ◽  
Visually Evoked Potentials ◽  
Single Trial ◽  
Objective Investigation

Gender-based normative values for pattern-reversal and flash visually evoked potentials under binocular and monocular stimulation in healthy adults

2017 ◽  
Vol 135 (1) ◽  
pp. 53-67 ◽  
Author(s):  
Patrícia de Freitas Dotto ◽  
Adriana Berezovsky ◽  
Paula Yuri Sacai ◽  
Daniel Martins Rocha ◽  
Solange Rios Salomão
Keyword(s):  
Evoked Potentials ◽  
Healthy Adults ◽  
Normative Values ◽  
Pattern Reversal ◽  
Visually Evoked Potentials ◽  
Monocular Stimulation ◽  
Gender Based

Visual function assessed by visually evoked potentials in adults with orbital and other primary intracranial tumors

2020 ◽  
pp. 112067212092564
Author(s):  
Patrícia de Freitas Dotto ◽  
Adriana Berezovsky ◽  
Paula Yuri Sacai ◽  
Daniel Martins Rocha ◽  
Arthur Gustavo Fernandes ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Evoked Potentials ◽  
Visual Function ◽  
Evoked Potential ◽  
Adult Patients ◽  
Low Grade ◽  
Pattern Reversal ◽  
Visually Evoked Potentials ◽  
Primary Tumors ◽  
Visually Evoked Potential

Purpose: The purpose of this study was to assess visual function by visually evoked potentials in adults with orbital and other primary brain tumors affecting the optic pathway. Methods: In this retrospective case–control series, patients with orbital (intraconal and extraconal) or midline/chiasmatic tumors were included. Visually evoked potentials using pattern-reversal visually evoked potential and flash visually evoked potential stimuli were performed according to the international standards. Outcome measures were visually evoked potential parameters of amplitude (µV) and peak times (ms) measured both for the P100 component (pattern-reversal visually evoked potentials) and the N2P2 complex (flash visually evoked potential). Individual results were also compared with gender-based normative values. Results: A group of 21 adult patients (17 females) and age- and sex-matched controls were evaluated. Tumor location was intraconal (6 meningiomas, 3 hemangiomas, 1 glioma), extraconal (6 meningiomas), and midline (3 pituitary adenomas, 2 hypothalamic/chiasmatic low-grade gliomas). Abnormal fundus (76%), abnormal pupillary reflexes (71%), reduced visual acuity (62%), strabismus (48%), and proptosis (38%) were present. Visually evoked potential abnormalities were found in at least one eye of all cases. Affected eyes had significantly reduced amplitudes and prolonged peak times for pattern-reversal visually evoked potentials ( p < .001) and significantly reduced amplitudes for flash visually evoked potential ( p < .001). In unilateral orbital tumors, abnormally prolonged pattern-reversal visually evoked potential peak times were also detected in some contralateral eyes ( n = 6/16). Conclusion: Visually evoked potential abnormalities were found in all adult patients with orbital and other intracranial primary tumors, even in eyes with normal exam and good visual acuity. Visually evoked potential can be used as a non-invasive ancillary test to characterize and monitor visual function in subjects with these neoplastic lesions.

scholarly journals High-frequency changes in single-trial visual evoked potentials for unattended stimuli in chronic schizophrenia

2021 ◽  
Author(s):  
Lech Kipinski ◽  
Andrzej Maciejowski ◽  
Krzysztof Malyszczak ◽  
Witold Pilecki
Keyword(s):  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Spectral Power ◽  
Chronic Schizophrenia ◽  
Gamma Oscillations ◽  
Pattern Reversal ◽  
Healthy Individuals ◽  
Single Trial ◽  
Time Frequency ◽  
Visual Evoked

Patients with schizophrenia reveal changes in information processing associated with external stimuli, which is reflected in the measurements of brain evoked potentials. We discuss actual knowledge on electro- (EEG) and magnetoencephalographic (MEG) changes in schizophrenia. The commonly used averaging technique entails the loss of information regarding the generation of evoked responses. We propose a methodology to describe single-trial (non-averaged) visual evoked potentials (VEP) using spectral and statistical analyses. We analysed EEG data registered in the O1-Cz and O2-Cz leads during unattended pattern-reversal stimulation, collected from a group of adult patients with chronic schizophrenia, and compared them to those of healthy individuals. Short-time single-trial VEP were transformed to the frequency domain using the FFT algorithm. Changes of the spectral power were visualized using spectrograms which were created by stacking single-trial spectra across all trials. Measures of the absolute and the relative spectral power were calculated and compared statistically. In schizophrenia, the energy density of VEP oscillations is shifted towards higher (gamma) frequencies, compared to healthy individuals. These differences are statistically significant in all analysed frequency bands for the relative power. This indicates distorted early processing of visual stimuli in schizophrenia. The presented observations complement the knowledge on gamma oscillations acquired from computationally more complex methods of time--frequency analysis.

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