scholarly journals Pattern and Sweep Visual Evoked Potential in the Objective Determination of Visual Acuity

2018 ◽  
Author(s):  
Mualla Hamurcu

Abstract Background: To investigate the effects of pattern visual evoked potential (pVEP) and sweep visual evoked potential (sVEP) on the accurate visual acuity (VA) measurement in adults. Methods: Medical files of 282 eyes of 141 patients who underwent VA measurement in our electrophysiology laboratory and did not undergo simulation were retrospectively analyzed. The VA was measured using the Snellen chart. Only those with a VA of higher than 1/10 on the Snellen chart were included in the study. The VA was assessed and reported by the pVEP (VA-pVEP) and sVEP test (VA-sVEP). The correlation analysis was performed using the Pearson correlation analysis. Results: Of 141 patients, 92 were males and 49 were females with a mean age of 37.7±18.4 years. There was a strong positive correlation between the VA values obtained from both eyes by pVEP (VA-pVEP) (r=0.858, p<0.001). There was a weak positive correlation (r=0.267, p<0.001) between the VA measured by the Snellen chart and the VA measured by the sVEP (VA-sVEP). A weak positive correlation was found for the VA-pVEP and VA-sVEP (r=0.313, p<0.001). Conclusions: For the measurement of the degree of the VA, it seems reasonable to use pVEP initially, while sVEP should be used in cases with short attention span and those who are non-cooperative and in infants.

Wave generated into visual cortex of brain, when subject focused his/her attention on visual stimulus flickers at certain frequency. The main challenge with SSVEP Based Brain computer interface (BCI) System is to detect the stimulus frequency from recorded brain signal. Canonical Correlation analysis (CCA) is one of the most popular methods to recognize the frequency of Steady state visual evoked potential (SSVEP). This paper focuses on the study of CCA algorithm to recognize the SSVEP signal frequency. For experiment purpose, a single channel data with flickering frequency in the range of (6Hz-10Hz) is used. The performance of the BCI System is measured in terms of detection accuracy and Information transmission rate (ITR). The maximum accuracy is obtained as 83.90% and ITR is 15.35 at stimulus frequency of 8.2Hz


2007 ◽  
Vol 53 (4) ◽  
pp. 615-621
Author(s):  
HIROSHI YOSHIGI ◽  
YOSHIMITSU KOHMURA ◽  
MINORU TANAKA ◽  
ATSUSHI MIZOTA

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