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Clinical Examination in Neuro-Ophthalmology
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Selvakumar Ambika, Krishnakumar Padmalakshmi
Optokinetic nystagmus drum is beneficial in assessing the vision in infants (Figure 1.4). It elicits jerk nystagmus with a slow phase following the target and a corrective jerk in the opposite direction. The degree of visual acuity can be assessed based on the size of target. The preferential looking test and visual-evoked potential (VEP) is also used to estimate visual acuity in infants. For older children, HOTV charts and Illiterate E test or pictorial charts can be used.2,3
Eye Gaze Collaboration with Brain–Computer Interfaces
Published in Chang S. Nam, Anton Nijholt, Fabien Lotte, Brain–Computer Interfaces Handbook, 2018
Gaye Lightbody, Chris P. Brennan, Paul J. McCullagh, Leo Galway
The visual evoked potential (VEP) can be detected in the EEG in response to external visual stimuli. The stimuli can be pattern reversal (e.g., a checkerboard on computer screen), flashing icons on a computer screen, or externally modulated flashing lights, usually LEDs (Zhu et al. 2010). The VEP component is prominent in the visual region of the occipital cortex (Regan 1988). If the visual stimulus is presented at a rate greater than 6 Hz, an oscillatory response is evoked. This response is termed steady-state visual evoked potential (SSVEP). If users pay attention to one or more stimuli that oscillate between 6 and 50 Hz, corresponding frequencies may be measured over visual areas of the brain. Users can thus communicate by focusing on one stimulus while ignoring others. Different frequencies elicit different SSVEP activity across different subjects (Gao et al. 2003; Kelly et al. 2005) Allison et al. (2008) showed that SSVEP sufficient for BCI control may be elicited by selective attention to one of two overlapping stimuli. Thus, some SSVEP-based BCI approaches may not depend on gaze control and could function in severely disabled users (Allison et al. 2010; Pfurtscheller et al. 2010b; Volosyak et al. 2011).
Giga-Ohm High-Impedance FET Input Amplifiers for Dry Electrode Biosensor Circuits and Systems
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
Gaetano Gargiulo, Paolo Bifulco, Rafael A. Calvo, Maria Romano, Mariano Ruffo, Richard Shephard, Mario Cesarelli, Craig Jin, Alistair McEwan, André van Schaik
The serial comparison experiment involved recording a visual-evoked response. The visual-evoked potential is a transient response elicited by specific visual stimuli. It is used in combination with continuous EEG recordings to document the integrity of neural pathways and does not require a motor response. An example of such elicited responses is the FVEP. Despite the fact that FVEPs are very variable, they are often used in general medical practice to assess the eyes to cortex pathway integrity [48,49]. In this experiment, we compare the test EEG system configured with dry electrodes with a reference system referred to as the g.BSamp system which used standard brass golden cup electrodes. The g.BSamp system is in use at the biomedical lab at the University of Naples. Once again, as previously mentioned, both systems were first tested using a signal generator. Also, as previously mentioned, the EEG signals recorded with both systems were filtered using a software band-pass filter, 0.05–100 Hz (50th-order FIR) and an additional 50th-order IIR notch filter at 50 Hz was applied.
A Story of Discovery and Change: What We Learned from Studying Nystagmus in Infancy and Childhood
Published in Journal of Binocular Vision and Ocular Motility, 2022
Special testing of the visual system is an important part of the evaluation of a patient with nystagmus since over 70% have other associated visual system abnormalities and more than 50% have an associated systemic condition.4,12,13 The ultimate diagnosis of nystagmus type is dependent on the use of eye movement recordings (EMR) in the same way as arrythmias of the heart are diagnostically dependent on electrocardiographic technology. In addition, all patients should undergo formal color vision testing, electroretinography (ERG), optical coherence tomography (OCT), and fundus photography. We now routinely perform contrast sensitivity testing (CSF) and targeted genetic testing of suspected optic nerve, retinal and syndromic conditions. In those patients with low vision, optic nerve, or cerebral disorders, visual evoked potential testing (VEP) is also performed. We rarely perform central nervous system imaging (MRI or CT Scan).
Transverse myelitis associated with primary biliary cirrhosis: clinical, laboratory, and neuroradiological features
Published in International Journal of Neuroscience, 2022
Mangsuo Zhao, Mingjie Zhang, Shimei Zhou, Bingxin Shi, Yan Wei, Fangjie Huang, Jing Wang, Jingfeng Huang, Liyan Qiao
On laboratory workup, the results of routine blood tests, urine test, stool analysis, and measurements of liver, renal, and thyroid functions, homocysteine, folic acid, and vitamin B12 levels, and the erythrocyte sedimentation rate (ESR) were all within the normal limits. Anti-nuclear (ANA), anti-double-stranded DNA, anti-extractable nuclear antigen, and anti-neutrophil cytoplasmic antibodies were not found in the serum. The results of routine and biochemical tests of the cerebrospinal fluid (CSF) were normal. Oligoclonal bands (OB) were positive. Anti-AQP4 IgG was not detected in serum or CSF. Serum and CSF were negative for the following antibodies: anti-N-methyl-d-aspartic acid receptor, anti-contactin-associated protein-like 2, anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor 1 and 2, anti-leucine-rich glioma-inactivated 1, anti-gamma-aminobutyric acid B receptor, and anti-dipeptidyl-peptidase-like protein 6 for autoimmune encephalitis. As biomarkers of paraneoplastic syndromes, Hu (anti-neuronal nuclear antibody 1), Yo (Purkinje cell autoantibody, PCA1), Ri (anti-neuronal nuclear antibody 2), Ma2, CV2/CRMP5, and amphiphysin were not detected in serum or CSF. Magnetic resonance imaging (MRI) studies of the brain and spinal cord were performed. Abnormal enhancement of the spinal cord was observed at T8–T9, suggestive of incomplete TM (Figure 1). Brain MRI showed no obvious abnormalities. Visual evoked potential and brainstem auditory evoked potential were within the respective normal ranges. The P40 wave of the somatosensory evoked potential disappeared bilaterally.
Expanding the phenotype of mucopolysaccharidosis type II retinopathy
Published in Ophthalmic Genetics, 2021
Tanya Kowalski, Jonathan B Ruddle, Gerard de Jong, Heather G Mack
His best corrected visual acuity with high hypermetropic correction (+9.00 dioptres right and left) was 20/25.5 in both eyes. Intraocular pressures were within normal range. His anterior segments demonstrated clear corneas, deep angles and clear crystalline lenses. His fundus showed crowded optic discs with CDR of 0.1 bilaterally but no disc swelling or pallor (Figure 3(a,b)). The retinal examination was otherwise clinically normal. OCT imaging showed epiretinal membrane, thickening of the ELM and mild foveal hypoplasia in both eyes (Figure 3(c,d)). Automated visual field testing (Humphrey, Zeiss, Germany) was normal bilaterally. Full field ERG was reduced in amplitude with normal latency, in all test conditions (Figure 2). Visual evoked potential testing was normal bilaterally. VEP was also normal bilaterally (data not shown).