scholarly journals The effects of checkerboard pattern check size on the VECP

1975 ◽  
Vol 6 (3) ◽  
pp. 306-308 ◽  
Author(s):  
John B. Siegfried
Keyword(s):  
Checkerboard Pattern ◽  
Check Size

scholarly journals Pattern reversal visual evoked potentials in adults: variability with age

2017 ◽  
Vol 40 (6) ◽  
pp. 252 ◽  
Author(s):  
Raja Sawaya ◽  
Helen Sawaya ◽  
Gilbert Youssef
Keyword(s):  
Linear Trend ◽  
Age Groups ◽  
Normal Subjects ◽  
Pattern Reversal ◽  
Checkerboard Pattern ◽  
Check Size ◽  
Band Pass ◽  
The Difference ◽  
And Gender ◽  
Visual Evoked

Purpose: Pattern reversal visual evoked potential (PRVEP) is an electrophysiological test for evaluating the visual pathway. This study measured the changes in the latencies and amplitudes of the PRVEP with age and gender in normal subjects. Methods: Healthy participants (n=81; 162 total eyes), between the ages of 20 and 92 years were recruited for the study. Stimulation was performed monocularly with a high-contrast (>50%) black-white checkerboard pattern with a check size of 30° at a reversal rate of 2 Hz, a band-pass of 1-100 Hz, a sweep of 250 msec and an average of 150 stimulations in a dark room. Mean and standard deviations for three latencies (N75, P100 and N145) and the amplitude (N75-P100) for each decade were measured. Results: There was a linear trend by age for all three latencies, indicating that the higher age groups had longer latencies. The latencies decreased in the 5th decade before increasing in the higher age groups. The amplitude of N75-P100 decreased with age. The P100 latencies were longer in males than females in all age groups and the difference increased with increasing age.

The Unlearnable Checkerboard Pattern

2019 ◽  
Vol 1 (2) ◽  
pp. 78-80
Author(s):  
Eric Holloway
Keyword(s):  
Machine Learning ◽  
Learning Algorithms ◽  
Machine Learning Algorithms ◽  
Checkerboard Pattern ◽  
Simple Task

Detecting some patterns is a simple task for humans, but nearly impossible for current machine learning algorithms.  Here, the "checkerboard" pattern is examined, where human prediction nears 100% and machine prediction drops significantly below 50%.

Visual Evoked potential signal processing and analysis for normal and galucomic eyes

2015 ◽  
Vol 8 (2) ◽  
pp. 2106-2121
Author(s):  
Hamed Ibrahem Abdelkader ◽  
Mona Abdelkader ◽  
Mohammed Kabeel ◽  
Malak Alya
Keyword(s):  
Evoked Potentials ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Optic Tract ◽  
Pattern Reversal ◽  
Blue Color ◽  
Check Size ◽  
Retinal Stimulation ◽  
Normal Individuals ◽  
Visual Evoked

Visual evoked potentials (VEPS) are obtained from optic tract by recording the evoked potentials generated by retinal stimulation. The flash VEP (FVEP) is used less frequently than pattern reversal VEP (PRVEP) because; it shows great variation in both latency and amplitude. The present study was undertaken to evaluate the effect of change of wavelength of flash and change of check size on the parameters of visual evoked potential (amplitude and latency) in normal individuals and glaucoma patients. The group of healthy subjects in the age of 20-45 years while the group of glaucoma subjects where  in the age of 25-50 years.  The two groups were exposed to flash VEP with white light and blue color and they also were exposed to checks subtending a visual angles of 15, 30,60 and 120 minutes of arc. The measured data were statistically analyzed and summarized by histograms. The interindividual and intraindividual in latencies and amplitudes for FVEP were assessed using  the coefficient of variation (COV). In conclusion, monochromatic flash VEP was preferred than white as there were minimal inter and intra individual variation of latencies and amplitudes. The most preferred check size in PRVEP was 120' for  the two groups.  

Effects of light scatter, defocusing, mean luminosity, contrast, and central scotoma on the PVER amplitude-check size function curve

2009 ◽  
Vol 71 (5) ◽  
pp. 606-615 ◽  
Author(s):  
Osamu Katsumi ◽  
Hitomi Tetsuka ◽  
Soichi Tetsuka ◽  
Young Hoon-Ohn ◽  
Tatsuo Hirose
Keyword(s):  
Light Scatter ◽  
Central Scotoma ◽  
Check Size ◽  
Size Function

FEATURE DETECTION AND CORRESPONDENCE FOR CAMERA CALIBRATION

2008 ◽  
Vol 05 (01) ◽  
pp. 41-50 ◽  
Author(s):  
ZHIGANG ZHENG ◽  
ZHENGJUN ZHA ◽  
LONG HAN ◽  
ZENGFU WANG
Keyword(s):  
Camera Calibration ◽  
Feature Detection ◽  
Checkerboard Pattern ◽  
Geometrical Constraint ◽  
Precise Position ◽  
3D Space ◽  
Corner Points ◽  
Calibration Pattern ◽  
Fully Automatic ◽  
Automatic Camera Calibration

This paper addresses the problem of highly accurate, highly speedy, more reliable and fully automatic camera calibration. Our objective is to construct a reliable and fully automatic system to supply a more robust and highly accurate calibration scheme. A checkerboard pattern is used as calibration pattern. After the corner points on image are detected, an improved Delaunay triangulation based algorithm is used to make correspondences between corner points on image and corner points on checkerboard in 3D space. In order to determine precise position of the actual corner points, a geometrical constraint based global curve fitting algorithm has been developed. The experimental results show that the geometrical constraint based method can improve remarkably the performance of the feature detection and camera calibration.

scholarly journals Pattern ERG as a predictor in ocular hypertensive

2016 ◽  
Vol 15 (2) ◽  
Author(s):  
Paaraj Dave ◽  
Jitendra Jethani
Keyword(s):  
Amplitude Ratio ◽  
Corneal Thickness ◽  
Visual Fields ◽  
Cross Sectional Study ◽  
Control Group ◽  
Study Group ◽  
Pattern Erg ◽  
Check Size ◽  
Cross Sectional ◽  
The Mean

Purpose: To report the repeatability of Pattern Electrotretinogram (PERG) and its findings in ocular hypertension (OHT) and normal eyes.Methods: A cross-sectional study where PERG responses were compared between the study group comprising of 80 eyes of 80 patients with intraocular pressure (IOP)>21 mmHg and the control group with 80 eyes of 80 normal individuals (IOP≤21mmHg). The optic disc and the visual fields were normal with a visual acuity of ≥ 0.8 in both groups. PERG was recorded twice for each individual in the control group by a single operator on 2 consecutive days to assess the repeatability.Results: The mean age in the study and control groups was 50.05±10.03 and 54.8±7.66 years(p=0.44) respectively. The mean IOP was 26.55±3.9 mmHg for the study group as opposed to 14.45±2.9 mmHg for the controls (p<0.001). The central corneal thickness and the cup-disc ratio was similar between the groups (p>.05). The P50-N95 amplitude (p=0.01) and the P50 latency (p<0.001) was statistically significantly different between both the groups. The intra-class correlation coefficient (ICC) showed poor agreement for all parameters except for N35-P50 0.8 to 16 degree check size amplitude ratio (PERG ratio).Conclusion:  Increase in P50 latency emerges as a new candidate for early glaucoma indicator in addition to reduction in P50-N95 amplitude. PERG parameters suffer from high test-retest variability. Deterioration in PERG recordings should be interpreted with caution. The variability is lesser for the PERG ratio which maybe more meaningful while monitoring for change over time.

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