OBJECTIVES: To analyze the Nogo-P3 component of event-related potential (ERP) in the process of visual acuity processing, to provide electrophysiological evidence for objective evaluation of visual acuity. METHODS: Twenty-six subjects with no other ocular diseases except for ametropia were recruited, and all subjects had uncorrected visual acuity both eyes 1/10 (evaluated using Monoyer chart). Block letter E with different visual angles and directions were used as graphic stimuli. The Go/Nogo paradigm was used for ERP studies. The visual angle of Go stimulation angle was 1°15', Nogo stimuli were 1°15', 55', 24' and 15'. The visual acuity test was performed on each of the two naked eyes separately in all subjects, and the characteristics of the Nogo-P3 component were analyzed. RESULTS: The latency of Nogo-P3 showed no difference between the stimuli of 1°15' and 55', and between Nogo stimulation angle 24' and 15'. There was significant difference between Nogo stimulation angle 1°15' and 24', and between Nogo stimulation angle 1°15' and 15' (P<0.05). There was significant difference between Nogo stimulation angle 55' and 24', and between Nogo stimulation angle 55' and 15' (P<0.05). No significant differences were observed in the Nogo-P3 amplitude among Nogo stimulation. CONCLUSIONS In the Go/Nogo paradigm, Nogo-P3 can reflect the cognitive response of subjects to Nogo stimulation, which can be used for objective evaluation of visual acuity.
Electroencephalography ; Evoked Potentials/physiology* ; Humans ; Photic Stimulation ; Reaction Time/physiology* ; Refractive Errors ; Visual Acuity

An experimental investigation was conducted to explore visual reaction time and visual anticipation time between athletes and non-athletes. These visual perceptual skills form the base for cognitive processes required by the brain to respond instantaneously to a stimulus. A total of 228 adolescents, equally distributed between athletes and non-athletes, aged 13 to 16 years (mean age 14.69 ± 0.99 years) were examined. The visual reaction time and visual anticipation time were measured using a Lafayette Reaction Timer (Model 63035) and Bassin Anticipation Timer (Model 35575) respectively. The visual reaction time results revealed that athletes have faster reaction time scores as compared to non-athletes, whereas with visual anticipation time, athletes had fewer errors and a higher consistency compared to non-athletes. There was, however, no interaction between gender and sports participation noted for both these visual perceptual skills. These research findings indicate that gender was not an obstacle in sports participation, therefore not limiting the potential to excel in sports performance. Knowledge gained from these research findings will benefit the sports industry, specifically in athletic and sports training as well as provide a basis for the identification of an individual’s potential in their sports.
athletes ; non-athletes ; sports ; visual anticipation time ; visual reaction time

OBJECTIVE: Perspective-taking ability is an essential spatial faculty that is of much interest in both health and neuropsychiatric disorders. There is limited data on the neural correlates of perspective taking in the context of a realistic three-dimensional environment. We report the results of a pilot study exploring the same in eight healthy volunteers. METHODS: Subjects underwent two runs of an experiment in a 3 Tesla magnetic resonance imaging (MRI) involving alternate blocks of a first-person perspective based allocentric object location memory task (OLMT), a third-person perspective based egocentric visual perspective taking task (VPRT), and a table task (TT) that served as a control. Difference in blood oxygen level dependant response during task performance was analyzed using Statistical Parametric Mapping software, version 12. Activations were considered significant if they survived family-wise error correction at the cluster level using a height threshold of p<0.001, uncorrected at the voxel level. RESULTS: A significant difference in accuracy and reaction time based on task type was found. Subjects had significantly lower accuracy in VPRT compared to TT. Accuracy in the two active tasks was not significantly different. Subjects took significantly longer in the VPRT in comparison to TT. Reaction time in the two active tasks was not significantly different. Functional MRI revealed significantly higher activation in the bilateral visual cortex and left temporoparietal junction (TPJ) in VPRT compared to OLMT. CONCLUSION: The results underscore the importance of TPJ in egocentric manipulation in healthy controls in the context of reality-based spatial tasks.
Healthy Volunteers ; Magnetic Resonance Imaging* ; Memory ; Oxygen ; Pilot Projects ; Reaction Time ; Task Performance and Analysis ; Visual Cortex

PURPOSE: To report a case of cytomegalovirus (CMV) corneal endotheliitis following penetrating keratoplasty. CASE SUMMARY: A 45-year-old male with a history of re-penetrating keratoplasty due to corneal opacity and graft failure after previous penetrating keratoplasty of his right eye in April 2014, visited our clinic for intermittent injection of the right eye for several weeks (7 months postoperative). Corneal edema, diffuse keratic pigmentation and anterior chamber reaction with decreased endothelial cell density were observed in his right eye using the slit lamp examination. Seven months after keratoplasty, corneal graft rejection were determined but clinical findings showed features of CMV-related corneal endotheliitis. Under the impression of CMV corneal endotheliitis, diagnostic paracentesis was performed for CMV real time polymerase chain reaction (RT-PCR). Additionally, the patient was admitted for intravenous ganciclovir and topical ganciclovir therapy. The next day, the RT-PCR results confirmed CMV infection. After 2 weeks of intravenous ganciclovir treatment, the patient was discharged and prescribed oral ganciclovir for 1 month. A month later, the coin-shaped corneal lesion nearly disappeared. There was no evidence of complication or recurrence. CONCLUSIONS: CMV corneal endotheliitis typically presents with coin-shaped keratic pigmentation and can be confirmed with RT-PCR using aqueous humor collected from the anterior chamber. Due to the long period of systemic and topical steroid therapy, the risk of viral endotheliitis is relatively high in patients with a history of penetrating keratoplasty. Corneal graft rejection is similar to corneal endotheliitis in symptoms and clinical features such as ciliary injection, decreased visual acuity, corneal edema or anterior chamber reaction. In patients after penetrating keratoplasty, CMV RT-PCR should be considered if the clinical features suggest viral endotheliitis.
Anterior Chamber ; Aqueous Humor ; Corneal Edema ; Corneal Opacity ; Corneal Transplantation ; Cytomegalovirus* ; Endothelial Cells ; Ganciclovir ; Graft Rejection* ; Humans ; Keratoplasty, Penetrating ; Male ; Middle Aged ; Paracentesis ; Pigmentation ; Real-Time Polymerase Chain Reaction ; Recurrence ; Slit Lamp ; Transplants* ; Visual Acuity

OBJECTIVE: To study the variation of latency and amplitude of the event related potential (ERP) and its distribution in human scalp when the normal subjects were stimulated with different visual fields. METHODS: The ERP recorded in scalp with the stimulation of 10 degrees visual field and 60 degrees visual field respectively in 20 healthy volunteers with normal visual function. RESULTS: Two different visual field stimulation may evoke the different exogenous components P1 (70-125 ms), N1 (90-170 ms), P2 (140-220 ms) and endogenous components N2 (190-280 ms) and P3 (290-430 ms). The latencies of all the components evoked by 10 degrees visual field were shorter than that of the 60 degrees visual field while the amplitudes of N1 and N2 were lower and appeared over the extensive encephalic region; and the amplitudes of the P1, P2 and P3 were higher and appeared in occipitotemporal, prefrontal and occipital region, respectively. CONCLUSION Two different visual field stimulation may evoke all the ERP components with significant differences in the latency, amplitude and distribution. The differences may reflect the different visual information integration and processing in human brain during the different visual field stimulation.
Adult ; Brain/physiology* ; Electroencephalography/methods* ; Electrooculography ; Evoked Potentials, Visual/physiology* ; Female ; Humans ; Male ; Photic Stimulation ; Reaction Time/physiology* ; Reference Values ; Scalp/physiology* ; Visual Field Tests/methods* ; Visual Fields/physiology* ; Visual Perception/physiology* ; Young Adult

A 63-year-old man with a history of liver transplantation presented to our clinic complaining of visual disturbance. He had been receiving tacrolimus (FK 506) for 30 months (6 mg/day for 2 years and 3 mg/day for 6 months); he reported that the visual disturbance began while taking tacrolimus. A full ophthalmologic examination and electrophysiologic and imaging studies were performed. The best corrected visual acuity was 0.1 in both eyes. There were no abnormal finding in the anterior segment, pupillary reflexes were normal and, there was no swelling in either optic disc. Although the foveal reflex was slightly decreased, fluorescein angiography revealed non-specific signs, with the exception of a window defect. A multifocal electro-retinogram revealed decreased amplitude of the central ring. A Swedish interactive threshold algorithm-standard 10-2 visual field test revealed a central scotoma. These findings suggest that tacrolimus may result in maculopathy. Therefore, careful ophthalmologic examination is necessary in the patients taking tacrolimus.
Electroretinography ; Evoked Potentials, Visual ; Fundus Oculi ; Humans ; Immunosuppressive Agents/*adverse effects/therapeutic use ; Liver Transplantation ; Macula Lutea/*drug effects ; Male ; Middle Aged ; Postoperative Care ; Reaction Time ; Retinal Diseases/*chemically induced/diagnosis ; Scotoma/chemically induced/diagnosis ; Tacrolimus/*adverse effects/therapeutic use ; Tomography, Optical Coherence

OBJECTIVE: To explore pattern reversal visual evoked potential (PRVEP) P100 components in the patients with different visual acuity and the correlation of P100 components with visual acuity using different visual simulation angles. METHODS: PRVEPs were recorded at Oz point in the patients (100 eyes) with different visual acuity including 0.2, 0.4, 0.6, 0.8 and 1.0 and induced by pattern reversal visual simulation with the different spatial frequencies(check sizes: 8 degrees-7.5'). The latency and amplitude of components P100 were analyzed and statistical analysis was performed using SPSS 13.0 software. RESULTS: The latency and amplitude of P100 wave showed a curvilinear relationship with check sizes. With check size 10 simulation in 0.2 visual acuity group, the P100 latency reached to the minimum and the P100 amplitude showed peak value. Other groups displayed the best value with check size 30'. The P100 latency and amplitude showed a linear correlation with visual acuity. With the increase of visual acuity, the P100 wave latency decreased and the amplitude increased gradually. Regression models between visual acuity and the Pic wave latency and amplitude were also established. CONCLUSION The regression functions can be an objective and accurate method to evaluate the visual acuity based on the better simulation angles using PRVEP examination.
Adult ; Evoked Potentials, Visual/physiology* ; Female ; Forensic Medicine/methods* ; Humans ; Male ; Myopia/physiopathology* ; Pattern Recognition, Visual/physiology* ; Photic Stimulation ; Reaction Time/physiology* ; Reference Values ; Regression Analysis ; Visual Acuity

OBJECTIVE: To explore the influence of visual attention in visual evoked potential (VEP) examination. METHODS: The pattern visual evoked potential (PVEP) and flash visual evoked potential (FVEP) were used to examine 110 normal subjects whose visual acuity or corrected visual acuity is in the range of 4.8-5.2, and age between 20 to 30 years old. In PVEP inspection, subjects were asked to watch with three ways, to stare at the central screen (at the same time count silently the number of alternating of black and white squares to improve the subjects' attention), to stare at the central screen at the same time thinking other things, to look sideways (the left eye stared at the left bottom corner of the screen or the right eye stared at the right one). In FVEP inspection, subjects were checked with eyes open and closed respectively. The latency and amplitude of P100 wave were recorded. The data were statistically analyzed by SPSS 13.0 software. RESULTS In PVEP inspection, the latency and amplitude of P100 wave were statistically different among three watching ways. In FVEP inspection, latency and amplitude of P100 wave were statistically different between eyes open and closed group. CONCLUSION Although the visual evoked potential test is an objective electrophysiological visual function test, it is susceptible to the influence of various subjective factors such as visual attention. It should arise the attention of forensic experts.
Adult ; Attention ; Cooperative Behavior ; Electroencephalography ; Electrophysiology ; Evoked Potentials, Visual/physiology* ; Female ; Forensic Medicine/methods* ; Humans ; Male ; Pattern Recognition, Visual ; Photic Stimulation ; Reaction Time ; Visual Acuity/physiology* ; Visual Fields/physiology* ; Young Adult

OBJECTIVETo investigate the spatiotemporal pattern of event-related potentials (ERPs) induced by emotional Stroop task.

METHODSThe ERPs of 19 channels were recorded from 13 healthy subjects while performing emotional Stroop task by pressing the buttons representing the colors in which the words denoting different emotions were displayed. A repeated-measures factorial design was adopted with three levels (word valence: positive, neutral and negative). The result of ERP analysis was presented in the form of statistical parametric mapping (SPM) of F value.

RESULTSNo significant difference was found in either reaction time or accuracy. The SPM of ERPs suggested significant emotional valence effects in the occipital region (200-220 ms), the left and central frontal regions (270-300 ms), and the bilateral temporal and parietal cortex (560-580 and 620-630 ms, respectively).

CONCLUSIONProcessing of task-irrelevant emotional valence information involves the dynamic operation of extensive brain regions. The ERPs are more sensitive than the behavioral indices in emotional evaluation.

Adult ; Attention ; physiology ; Brain ; physiology ; Brain Mapping ; Color ; Emotions ; physiology ; Evoked Potentials ; physiology ; Female ; Humans ; Male ; Neuropsychological Tests ; Pattern Recognition, Visual ; Psychomotor Performance ; physiology ; Reaction Time ; Semantics ; Young Adult

OBJECTIVE: To investigate whether the dual route model is applicable to Korean word reading in acquired dyslexia after stroke. METHOD: Sixty-two year old patient with dyslexia after left inferior temporal and occipital lobe infarct was evaluated according to the lexical processing. After evaluation of general cognitive and language function, visual perception, semantic, and lexical stages were assessed. RESULTS: Visual perception was appropriate, and semantic categorization and picture-word matching tasks were 80.6% and 78.6% correct, respectively. Lexical decision task showed no significant differences within word classes, except shorter reaction time in reading words of Korean origin than those of chinese origin (p <0.05). The patient was able to read only 39.8% of tested words, and he could not read all the non-words. Reading of high frequency word was superior (65.4%) to that of low frequency words (10.9%) and semantic errors were not remarkable (p <0.05). CONCLUSION: The patient showed characteristics of recovery from deep to phonologic dyslexia with impairment of grapheme to phoneme conversion (GPC) route. These findings support that dual route model is applicable to Korean word reading.
Asian Continental Ancestry Group ; Dyslexia ; Dyslexia, Acquired ; Humans ; Language Disorders ; Occipital Lobe ; Reaction Time ; Semantics ; Stroke* ; Visual Perception