Visual information is fundamental to how we appreciate our environment and interact with others. The visual evoked potential (VEP) is among those evoked potentials that are the bioelectric signals generated in the striate and extrastriate cortex when the retina is stimulated with light which can be recorded from the scalp electrodes. In the current paper, we provide an overview of the various modalities, techniques, and methodologies which have been employed for visual evoked potentials over the years. In the first part of the paper, we cast a cursory glance on the historical aspect of evoked potentials. Then the growing clinical significance and advantages of VEPs in clinical disorders have been briefly described, followed by the discussion on the earlier and currently available methods for VEPs based on the studies in the past and recent times. Next, we mention the standards and protocols laid down by the authorized agencies. We then summarize the recently developed techniques for VEP. In the concluding section, we lay down prospective research directives related to fundamental and applied aspects of VEPs as well as offering perspectives for further research to stimulate inquiry into the role of visual evoked potentials in visual processing impairment related disorders.

Background: Primary amenorrhea is one of the most common disorders seen as gynecological problems in adolescent girls. It refers to the participants who did not attain menarche by the age of 11–15 years. Chromosome abnormalities contribute as one of the etiological factors in patients with primary amenorrhea. Aims: The aim of this study was to evaluate the frequency of chromosomal abnormalities and to investigate the abnormal karyotypes in patients referred with the symptom of primary amenorrhea for better management and counseling. Setting and Design: One hundred and seventy-four cases of primary amenorrhea were referred from the obstetrics and gynecology department to our cytogenetic laboratory for chromosomal analysis. G-banded chromosomes were karyotyped, and chromosomal analysis of all patients was done. Results: Out of 174 patients, we observed 23 (13.22%) participants with abnormal karyotype. In 23 cases of chromosomal abnormalities, 10 cases were sex reversal female (46,XY) and Turner karyotype (45,X) in 6 females. Other numerical and structural abnormalities were also seen such as 47,XXX; 45,X/47,XXX; 45,X/46, X,dic(X); 46,XX, inv (9); 45,X/46,X,i(Xq); 46,X,mar(X); and 45,X/46,XY in the primary amenorrhea cases. Conclusion: This study definitely attests the importance of chromosomal analysis in the etiologic diagnosis of primary amenorrhea patients. Karyotyping will help to counsel and manage the cases of primary amenorrhea in a better way. This study reveals the frequencies and different types of chromosomal abnormalities found in primary amenorrhea individuals and that might help to make the national database on primary amenorrhea in relation to chromosomal aberrations.

Purpose:The aim of this study was to find whether the visual evoked potential (VEP) latencies and amplitude are altered with different visual angles in healthy adult volunteers or not and to determine the visual angle which is the optimum and most appropriate among a wide range of check sizes for the reliable interpretation of pattern reversal VEPs (PRVEPs).Materials and Methods:The present study was conducted on 40 healthy volunteers. The subjects were divided into two groups. One group consisted of 20 individuals (nine males and 11 females) in the age range of 25-57 years and they were exposed to checks subtending a visual angle of 90, 120, and 180 minutes of arc. Another group comprised of 20 individuals (10 males and 10 females) in the age range of 36-60 years and they were subjected to checks subtending a visual angle of 15, 30, and 120 minutes of arc. The stimulus configuration comprised of the transient pattern reversal method in which a black and white checker board is generated (full field) on a VEP Monitor by an Evoked Potential Recorder (RMS EMG. EPMARK II). The statistical analysis was done by One Way Analysis of Variance (ANOVA) using EPI INFO 6.Results:In Group I, the maximum (max.) P100 latency of 98.8 ± 4.7 and the max. P100 amplitude of 10.05 ± 3.1 μV was obtained with checks of 90 minutes. In Group II, the max. P100 latency of 105.19 ± 4.75 msec as well as the max. P100 amplitude of 8.23 ± 3.30 μV was obtained with 15 minutes. The min. P100 latency in both the groups was obtained with checks of 120 minutes while the min. P100 amplitude was obtained with 180 minutes. A statistically significant difference was derived between means of P100 latency for 15 and 30 minutes with reference to its value for 120 minutes and between the mean value of P100 amplitude for 120 minutes and that of 90 and 180 minutes.Conclusion:Altering the size of stimulus (visual angle) has an effect on the PRVEP parameters. Our study found that the 120 is the appropriate (and optimal) check size that can be used for accurate interpretation of PRVEPs. This will help in better assessment of the optic nerve function and integrity of anterior visual pathways.

Visual evoked potentials is an important visual electrophysiological tool which has been used for the evaluation of visual field defects in primary open-angle glaucoma and is an appropriate objective measure of optic nerve function. Significant correlations between the magnitude of the VEP parameters and MD of Humphrey static perimetry suggest that the impaired visual cortical responses observed in glaucoma patients can be revealed by both electrophysiological and psychophysical methods. In addition, the severity of global glaucomatous damage evidenced by reduction in MD could depend on the delay in neural conduction from retina to the visual cortex as revealed by the significant correlation between VEP latencies and MD which also supports the validity of the VEP testing in progression of glaucoma.

Context:Cerebral palsy (CP) is a heterogeneous group of permanent, non-progressive motor disorders of movement and posture caused by chronic brain injuries. It is the most common cause of physical disability in childhood; spastic cerebral palsy being the most prevalent of its various forms. There is scanty information about the neurophysiologic investigations in children diagnosed as having spastic CP.Aims:The aim of the study was to investigate the relationship between abnormal VEP and BAEP findings with different clinical parameters in children with spastic cerebral palsy.Materials and Methods:Fifteen children with spastic CP in the age range 4 months to 10 years participated in this study. Evaluation of VEPs, brainstem evoked potentials (BAEPs) were performed in all study patients as well as 35 healthy children as controls. The study was conducted after obtaining ethics committee approval and informed consent of parents.Statistical Analysis Used:Significance of difference in the mean values of different parameters in different groups was assessed by Student’s “t” test and the P value <0.05 was considered to be significant. All the values were expressed as mean ± 1 Std. Deviation.Results:A significant difference was found in the VEP latencies and amplitude between the subjects with CP and controls. Striking BAEP abnormalities in CP patients include prolongation of absolute latency of wave V, interpeak latencies of III-V and lowered I-V ratio. Abnormal VEPs and BAEPs in children with bilateral spastic cerebral palsy demonstrated a correlation with the presence of moderate to severe developmental delay.Conclusions:The differences in VEPs and BAEPs were determined between CP children and healthy children. The abnormalities found are probably linked to the neurological deficits present in cases of cerebral palsy.