Value Of Visual Evoked Potentials Research Articles

Effects of Smoking on Pattern Visual Evoked Potentials

Aim: The aim of the study is to get a better understanding of the side effects of smoking by evaluating the effect of recently elevated smoking rate on Visual Evoked Potentials (VEP) and to determine whether it is necessary to use different normals when evaluating the VEP measurements of smoking patients. Material and Methods: The patients who have applied to our ophthalmology and neurology outpatient clinics during 2021-2022 are included to the study. Detailed ophthalmologic examination of the patients as well as their VEP test is completed followed by a dilated fundus examination assessment. The patients with normal results are included to the study. The smoking rate is calculated on pack/year basis. Pattern VEP (PVEP) recording is performed based on Keypoint (Dantec, Denmark) and International Society for Clinical Electrophysiology of Vision (ISCEV) criteria. Data obtained through the study are analyzed by SPSS 21.0 version software. Countable variables with normal distribution between two independent groups are analyzed with Independent Sample T test whereas variables without normal distribution are analyzed with Mann Whitney U test. Chi-square test is used for comparing categorical variables. Results: 71 patients were included to the study where 33 of them were placed in smoking group and 38 in non-smoking group (control group). Smoking group had a yearly cigarette package consumption of 5.20±8.93 (0.2-40). VEP latency and amplitude changes were compared and according to the obtained results; there was P100 latency prolongation in between left and right eye of the patients in the control group and smoking group but it did not have any statistical significance (p=0.910 and p=0.697 respectively). There was no statistically significant difference in either left nor right eye in terms of smoking and P100 and N70 latencies (p=0.707, p=0.838, p=0.717 and p=0.621 respectively). Similarly, there was no significant correlation between yearly package consumption and P100 and N70 latencies and amplitudes of left and right eyes (p=0.503, p=0.410, p=0.776 and p=0.940 respectively). Conclusion: No significant effect of smoking is found on VEP values thus leading us to believe that the same normal intervals can be used in the evaluation of VEP results of both smoking and non-smoking patients.

Prognostic Role of Visual Evoked Potentials in Non-Neuritic Eyes at Multiple Sclerosis Diagnosis

Introduction: This study aimed to assess the prognostic role of visual evoked potentials (VEPs) of the non-neuritic eye at the diagnosis of multiple sclerosis (MS). Patients and methods: We enrolled 181 MS patients (62% females, mean age at diagnosis: 38 years, standard deviation: 12) at the time of the first diagnostic work-up, including VEPs. We collected P100 latency and N75-P100 amplitude of non-neuritic eyes at diagnosis, and then we calculated the mean values in 127 patients with no history of optic neuritis (ON) or considered the unaffected eye in the remaining. At last follow-up (minimum: one year), disability was evaluated according to MS Severity Score or MSSS (median: 2.44, range: 0.18-9.63). Statistical analysis included Mann-Whitney descriptive analysis, Spearman correlation for independent samples, and linear regression for significant predictors of MSSS. Results: 38/181 patients had P100 latency >115 ms, and 63/181 showed N75-P100 amplitude < 5 microV in the unaffected eyes at MS diagnosis. At last follow-up, MSSS correlated with P100 latency (rho = 0.21, p = 0.004) and N75-P100 amplitude (rho = 0.19, p = 0.009) collected at diagnosis. P100 latency (not N75-P100 amplitude) resulted in a predictor for disability over time (MSSS) in the regression model (along with age at onset, MS course, and disease-modifying treatments). Conclusions: Our study showed a prognostic value of VEPs in clinically unaffected eyes at MS diagnosis to predict future disability, independently from a history of ON.

Влияние каротидной эндартерэктомии на функциональную активность зрительного анализатора у пациентов с хронической ишемической нейрооптикопатией, ассоциированной с гемодинамически значимым атеросклеротическим стенозом внутренней сонной артерии

Purpose. To assess the effect of carotid endarterectomy on the functional activity of the visual analyzer, based on the registration of visually evoked potentials in patients with chronic ischemic neuroopticopathy (CIN) associated with hemodynamically significant atherosclerotic stenosis of the internal carotid artery (ICA). Material and methods. The main group included patients with CIN (20 people, 20 eyes). Their age varied from 61 to 78 years (average 70 ± 4.5 years). Men – 13 people, women – 7. Of the specialized methods, the study of visual evoked potentials (VEP) was performed. Results. By the end of the follow-up (12 months), there was a decrease in the maximum corrected visual acuity below the preoperative values and an increase in the negative dynamics of the VEP values. There was an increase in the latency of the main peak by 13.2 % compared with the control and a decrease in amplitude by 34 % during stimulation with the pattern for both 30 and 60 minutes. Conclusion. Our studies have shown that further studies are required to develop an integrated approach to the treatment of CIN associated with hemodynamically significant atherosclerotic stenosis of the ICA. Keywords: visual evoked potentials, chronic ischemic neuroopticopathy, ocular ischemic syndrome, hemodynamically significant stenosis of the internal carotid artery.

Prediction of Post-operative Visual Deterioration Using Visual-Evoked Potential Latency in Extended Endoscopic Endonasal Resection of Craniopharyngiomas

Background: The current study aimed to investigate the predictive value of visual-evoked potential (VEP) latency for post-operative visual deterioration in patients undergoing craniopharyngioma resection via extended endoscopic endonasal approach (EEEA).Methods: Data from 90 patients who underwent craniopharyngioma resection via EEEA with intraoperative VEP monitoring were retrospectively reviewed. P100 latency was compared between patients with and without post-operative visual deterioration, and the threshold value of P100 latency for predicting post-operative visual deterioration was calculated by the receiver operating characteristic curve analysis. In addition, other potential prognostic factors regarding post-operative visual outcomes were also analyzed by multivariate analysis.Results: Patients with post-operative visual deterioration showed a significantly longer VEP latency than those without (p < 0.001). An extension over 8.61% in VEP latency was identified as a predictor of post-operative visual deterioration (p < 0.001). By contrast, longer preoperative visual impairment duration and larger tumor volume were not significant predictors for post-operative visual deterioration.Conclusions: The current study revealed that intraoperative VEP monitoring in EEEA is effective for predicting post-operative visual deterioration, and an extension over 8.61% in VEP latency can be used as a critical cut-off value to predict post-operative visual deterioration.

The predictive value of intraoperative visual evoked potential for visual outcome after extended endoscopic endonasal surgery for adult craniopharyngioma.

Due to the proximity of craniopharyngioma to the optic apparatus, one of the most common complications after surgery is visual deterioration. Intraoperative visual evoked potential (VEP), as a means of real-time visual function monitoring, has been integrated into transsphenoidal surgery for pituitary adenoma to predict postoperative visual outcome. Compared with pituitary tumor, craniopharyngioma often adheres to optic nerves, with increased risk of postoperative visual impairment. Furthermore, extended endoscopic endonasal surgery (EEES) can provide direct visualization of the surgical plane between the craniopharyngioma and the optic nerves, which contributes to analysis of the mechanism of real-time VEP changes during surgery. Therefore, VEP monitoring applied during EEES for craniopharyngioma may have more clinical value. However, only 9 patients who underwent EEES with VEP monitoring for craniopharyngioma have been sporadically reported to date. In this paper, the authors present the largest series to date analyzing the clinical value of VEP to predict postoperative visual outcome in adult patients with craniopharyngioma. Sixty-five adult patients who underwent EEES with intraoperative VEP monitoring for primary craniopharyngioma were retrospectively reviewed. The association between changes in VEP amplitude and postoperative visual outcome was determined. In addition, other potential prognostic factors with regard to postoperative visual outcomes were included in the analysis. Gross-total resection was achieved in 59 patients (90.8%). Reproducible and stable VEP was recorded in 128 of 130 eyes (98.5%). During surgery, VEP remained stable in 108 eyes, 10 (9.3%) of which had new visual acuity (VA) and/or visual field (VF) defects after surgery. Transient VEP decrease was recorded in 15 eyes, 4 (26.7%) of which had visual deterioration. Of the 5 eyes with permanent VEP decrease, 3 (60%) experienced postoperative visual impairment. Permanent VEP decrease (OR 19.868, p = 0.007) and tight adhesion (OR 6.104, p = 0.040) were independent adverse factors for postoperative VA deterioration. Tight adhesion (OR 7.150, p = 0.002) and larger tumor volume (OR 1.066, p = 0.001) were significant risk factors for postoperative VF defects. Intraoperative VEP monitoring can serve as a real-time warning to guide surgeons to avoid postoperative visual impairment. It effectively predicted VA changes in adult patients with craniopharyngioma after EEES. Tight adhesion and larger tumor volume were also strong predictors of postoperative visual impairment.

Study on the variation of visual evoked potential and its diagnostic value in children with optic neuritis

Objective To investigate the characteristics and clinical value of visual evoked potentials(VEP) in children with optic neuritis. Methods The VEP of 33 children with optic neuritis were tested by NICOLET evoked potential instrument.The results were compared with those of cranial and/or orbital MRI and fundus examination, and the consistency with visual performance was analyzed.The correlation between visual sensitivity and VEP results was analyzed. Results Among 33 children with optic neuritis, the abnormal rate of VEP in 52 abnormal eyes was 88.5%; the abnormal rate of cranial and/or orbital MRI was 38.5%; the abnormal rate of fundus examination was 62.2%; the abnormal rate of VEP examination was significantly higher than that of cranial and/or orbital MRI and fundus examination (P<0.05); the consistency rate between VEP examination and visual acuity was 84.8%.The consistency rate between pattern reversal visual evoked potential (P-VEP) and visual acuity was 86.8%, and that between flash visual evoked potential (F-VEP) and visual acuity was 82.1%.With the increase of visual impairment, the percentage of P100 wave loss increased gradually.There was no correlation between visual acuity and the prolongation of P100 wave latency. Conclusion There are significant differences between VEP and fundus examination and MRI, the sensitivity of VEP is superior to both.P-VEP is more consistent with visual acuity than F-VEP.VEP has certain value in evaluating the degree of visual impairment in children with optic neuritis.It can not be used to evaluate the level of optic sensitivity when the latency of P100 wave is prolonging. Key words: Optic neuritis; Visual evoked potentials; Visual; Children

Visual evoked potentials follow-up in idiopathic intracranial hypertension.

Objectives:To demonstrate the importance of visual evoked potential (VEP) in determining the severity and prognosis of the disease and in monitoring the clinical course in patients with idiopathic intracranial hypertension (IIH).Methods:This is a prospective cross-sectional study conducted covering the period between March 2014 and January 2015. The study included 32 patients recently diagnosed with IIH and 30 healthy volunteers. The initial VEP values of the IIH patients were compared to the VEP values of the healthy control group. Furthermore, the initial VEP values of the IIH patients were compared with their VEP values after one month of treatment.Results:The mean age of the IIH patients was 37.8±12.02 years. Of the IIH patients, 27 (84%) were females and 5 (16%) were males. There was a statistically significant association of the initial VEP values with the visual field findings (p=0.011) and visual acuity (p=0.040). Moreover, a statistically significant difference was found between the control group and IIH patients in terms of right (p<0.001) and left P100 values (p<0.001). While 18 (56%) of the initial VEPs of IIH patients were pathological, 14 (44%) of the second VEPs were pathological, and this difference was not statistically significant (p=0.125).Conclusion:A relationship between the VEP P100 values and the severity of the disease was detected, while the importance of monitoring VEP values in the follow-up of IIH patients was not demonstrated.

Dynamics of Changes in Visual Evoked Potentials Values with the Advance of Retinal Changes in Patients with Diabetes Mellitus

Dynamics of Changes in Visual Evoked Potentials Values with the Advance of Retinal Changes in Patients with Diabetes Mellitus

Preoperative visual evoked potential in the prediction of visual outcome after pituitary macroadenomas surgery.

The purpose of the present study is to investigate longitudinal changes in Visual evoked potential (VEP) parameters as an objective test after transsphenoidal surgery, its correlation with subjective tests and clinical value of VEP in the prediction of visual outcome. Fifty patients with pituitary macroadenoma who underwent surgical removal of the tumor recruited in this study. All the patients underwent ophthalmic examination, static automated perimetry (SAP), VEP and magnetic resonance imaging (MRI) preoperatively and 3months after surgery. Fifty patients with pituitary macroadenoma (size: 25.1 ± 9.9mm) were recruited in the study. Before surgery, the pattern of VEP showed a prolonged latency with reduced amplitude in eyes with abnormal visual acuity or abnormal visual field. The P100 wave latencies and amplitudes showed significant correlation with visual acuity and SAP scores. After surgery, visual acuity and visual field improvements were seen in 51% and 65.6% of eyes, respectively. Mean SAP and visual acuity scores increased significantly (p < 0.01), P100 wave latency declined and amplitude improved after surgery but not significantly. The mean age of patients, size of tumors and preoperative P100 wave latency were significantly lower in eyes with visual field and acuity improvement. VEP is a helpful quantitative and objective complementary test to visual acuity and SAP exams for assessing pre-operative visual abnormalities and post-operative visual outcome in patients with pituitary macroadenoma.

Functional Changes of Retinal Ganglion Cells and Visual Pathways in Patients with Chronic Leber’s Hereditary Optic Neuropathy during One Year of Follow-up

To assess changes of retinal ganglion cells (RGCs) and visual pathways' function in patients with Leber's hereditary optic neuropathy (LHON) during 12 months of follow-up of the chronic phase. Retrospective case series. Twenty-two patients with LHON (mean age, 36.3±9.3 years) in the "chronic phase" of the disease, providing 42 eyes (LHON group) with different pathogenic mitochondrial DNA mutations (group 11778: 21 eyes; group 3460: 4 eyes; group 14484: 13 eyes; and group 14568: 4 eyes) were enrolled. Twenty-five age-similar healthy participants, providing 25 eyes, served as controls. Pattern electroretinogram (PERG) and visual evoked potentials (VEP), in response to 60' and 15' checks visual stimuli, were recorded at baseline in all subjects and after 6 and 12 months of follow-up in patients with LHON. At baseline, in all LHON eyes for each PERG and VEP parameter (amplitude and implicit time), the 95% confidence limit (CL) of test-retest variability was calculated. The PERG and VEP mean values observed in LHON eyes were compared (1-way analysis of variance [ANOVA]) with those of controls. During the follow-up, the PERG and VEP differences observed with respect to baseline were evaluated by ANOVA. Changes of individual and mean absolute values of 60' and 15' PERG amplitude and VEP amplitude and implicit time at each time point compared with baseline values in the LHON group. At baseline, mean values of PERG and VEP parameters detected in the LHON group were significantly (P < 0.01) different with respect to control values. In the LHON group, at 6 and 12 months of follow-up, the majority of eyes showed unmodified (within 95% CL) PERG and VEP values, and mean absolute values of these measures were not significantly (P > 0.01) different from baseline values. In our untreated patients with chronic LHON, with different specific pathogenic mutations, RGCs and visual pathways function were not significantly modified during 12 months of follow-up. This should be considered in the disease natural history when attempts for treatments are proposed in chronic LHON.

Evidence of an increased neuronal activation-to-resting glucose uptake ratio in the visual cortex of migraine patients: a study comparing 18FDG-PET and visual evoked potentials

BackgroundMigraine attacks might be triggered by a disruption of cerebral homeostasis. During the interictal period migraine patients are characterized by abnormal sensory information processing, but this functional abnormality may not be sufficient to disrupt the physiological equilibrium of the cortex unless it is accompanied by additional pathological mechanisms, like a reduction in energetic reserves. The aim of this study was to compare resting cerebral glucose uptake (using positron emission tomography (18fluorodeoxyglucose-PET)), and visual cortex activation (using visual evoked potentials (VEP)), between episodic migraine without aura patients in the interictal period and healthy volunteers.MethodsTwenty episodic migraine without aura patients and twenty healthy volunteers were studied. 18FDG-PET and VEP recordings were performed on separate days. The overall glucose uptake in the visual cortex-to-VEP response ratio was calculated and compared between the groups. Additionally, PET scan comparisons adding area under the VEP curve as a covariate were performed. For case-wise analysis, eigenvalues from a specific region exhibiting significantly different FDG-PET signal in the visual cortex were extracted. Standardized glucose uptake values from this region and VEP values from each subject were then coupled and compared between the groups.ResultsThe mean area under the curve of VEP was greater in migraine patients compared to healthy controls. In the same line, patients had an increased neuronal activation-to-resting glucose uptake ratio in the visual cortex. Statistical parametric mapping analysis revealed that cortical FDG-PET signal in relation to VEP area under the curve was significantly reduced in migraineurs in a cluster extending throughout the left visual cortex, from Brodmann’s areas 19 and 18 to area 7. Within this region, case-wise analyses showed that a visual neuronal activation exceeding glucose uptake was present in 90% of migraine patients, but in only 15% of healthy volunteers.ConclusionThis study identifies an area of increased neuronal activation-to-resting glucose uptake ratio in the visual cortex of migraine patients between attacks. Such observation supports the concept that an activity-induced rupture of cerebral metabolic homeostasis may be a cornerstone of migraine pathophysiology.This article has been selected as the winner of the 2018 Enrico Greppi Award. The Enrico Greppi Award is made to an unpublished paper dealing with clinical, epidemiological, genetic, pathophysiological or therapeutic aspects of headache. Italian Society for the Study of Headaches (SISC) sponsors this award, and the award is supported through an educational grant from Teva Neuroscience. This article did not undergo the standard peer review process for The Journal of Headache and Pain. The members of the 2018 Enrico Greppi Award Selection Committee were: Francesco Pierelli, Paolo Martelletti, Lyn Griffiths, Simona Sacco, Andreas Straube and Cenk Ayata.

Pattern visual evoked potentials and their relation to the peripapillary and retrobulbar blood flow in glaucoma

To examine the relationship between the development of bioelectric response of retinal cell elements to pattern stimulus and the ocular blood flow. Electrophysiological studies, including pattern-reversal visual evoked potentials (VEP) with large 1 degree (1°) and small 0.25° checks, Color Doppler imaging (CDI) of the retrobulbar vessels, and OCT Angiography in the area of the optic disc and peripapillary retina were performed in 48 patients with initial primary open-angle glaucoma (POAG), 47 patients with advanced POAG, and 42 control subjects. Authors also studied the correlations between VEP values and the parameters used in CDI and OCT-A examination. The most noticeable differences between the study groups were the amplitudes of P100 pattern VEP values for small and large patterns and the OCT-A parameters: Whole-image Disc Vessel Density (widVD), Peripapillary Vessel Density (pVD), Peripapillary Vessel Density Inferior Temporalis (pVD IT). In initial glaucoma, a strong correlation was observed between the amplitude of P100 pattern VEP 1° and pVD IT (r=0.75; p<0.0001); the blood flow rates in ophthalmic artery, central retinal artery, central retinal vein and short posterior ciliary arteries were below normal, while the blood flow in these vessels had statistically reliable correlation with the amplitude of P100 pattern VEP (p<0.05). No correlation was found in patients with advanced stages of glaucoma. Pattern VEP is an informative method of glaucoma diagnostics which accuracy can be enhanced by combining it with OCT-A blood flow examination.

Can somatosensory and visual evoked potentials predict neurological outcome during targeted temperature management in post cardiac arrest patients?

PurposesIn cardiac arrest patients treated with targeted temperature management (TTM), it is not certain if somatosensory evoked potentials (SEPs) and visual evoked potentials (VEPs) can predict neurological outcomes during TTM. The aim of this study was to investigate the prognostic value of SEPs and VEPs during TTM and after rewarming. MethodsThis retrospective cohort study included comatose patients resuscitated from cardiac arrest and treated with TTM between March 2007 and July 2015. SEPs and VEPs were recorded during TTM and after rewarming in these patients. Neurological outcome was assessed at discharge by the Cerebral Performance Category (CPC) Scale. ResultsIn total, 115 patients were included. A total of 175 SEPs and 150 VEPs were performed. Five SEPs during treated with TTM and nine SEPs after rewarming were excluded from outcome prediction by SEPs due to an indeterminable N20 response because of technical error. Using 80 SEPs and 85 VEPs during treated with TTM, absent SEPs yielded a sensitivity of 58% and a specificity of 100% for poor outcome (CPC 3–5), and absent VEPs predicted poor neurological outcome with a sensitivity of 44% and a specificity of 96%. The AUC of combination of SEPs and VEPs was superior to either test alone (0.788 for absent SEPs and 0.713 for absent VEPs compared with 0.838 for the combination). After rewarming, absent SEPs and absent VEPs predicted poor neurological outcome with a specificity of 100%. When SEPs and VEPs were combined, VEPs slightly increased the prognostic accuracy of SEPs alone. Although one patient with absent VEP during treated with TTM had a good neurological outcome, none of the patients with good neurological outcome had an absent VEP after rewarming. ConclusionAbsent SEPs could predict poor neurological outcome during TTM as well as after rewarming. Absent VEPs may predict poor neurological outcome in both periods and VEPs may provide additional prognostic value in outcome prediction.

Neural Correlates of Expert Visuomotor Performance in Badminton Players.

Elite/skilled athletes participating in sports that require the initiation of targeted movements in response to visual cues under critical time pressure typically outperform nonathletes in a visuomotor reaction task. However, the exact physiological mechanisms of this advantage remain unclear. Therefore, this study aimed to determine the neurophysiological processes contributing to superior visuomotor performance in athletes using visual evoked potential (VEP). Central and peripheral determinants of visuomotor reaction time were investigated in 15 skilled badminton players and 28 age-matched nonathletic controls. To determine the speed of visual signal perception in the cortex, chromatic and achromatic pattern reversal stimuli were presented, and VEP values were recorded with a 64-channel EEG system. Further, a simple visuomotor reaction task was performed to investigate the transformation of the visual into a motor signal in the brain as well as the timing of muscular activation. Amplitude and latency of VEP (N75, P100, and N145) revealed that the athletes did not significantly differ from the nonathletes. However, visuomotor reaction time was significantly reduced in the athletes compared with nonathletes (athletes = 234.9 ms, nonathletes = 260.3 ms, P = 0.015). This was accompanied by an earlier activation of the premotor and supplementary motor areas (athletes = 163.9 ms, nonathletes = 199.1 ms, P = 0.015) as well as an earlier EMG onset (athletes = 167.5 ms, nonathletes = 206.5 ms, P < 0.001). The latency of premotor and supplementary motor area activation was correlated with EMG onset (r = 0.41) and visuomotor reaction time (r = 0.43). The results of this study indicate that superior visuomotor performance in athletes originates from faster visuomotor transformation in the premotor and supplementary motor cortical regions rather than from earlier perception of visual signals in the visual cortex.

12. Sensitivity and predictive value of OCT and VEP in multiple sclerosis

Aim of the study was to evaluate the role of optical coherence tomography (OCT) and visual evoked potentials (VEPs) in patients with multiple sclerosis (MS), on 121 consecutive subjects with MS. Of 242 eyes, 166 had no previous history of optic neuritis (ON), 22 had a single recent ON episode (<3 months); 54 had chronic ON (at least 1 episode >3 months before). All patients underwent assessment of EDSS, OCT retinal nerve fiber layer (RNFL) thickness and VEP (checkerboard, size 15′); 77 subjects underwent a second EDSS (EDSS2) evaluation after a mean time of 2 ± 0.69) years (median EDSS 2, range 0–7). In eyes with recent ON, the sensitivity of OCT was 38.9% with a higher sensitivity of VEP (77.3%; McNemar p < 0.02). In eyes with chronic ON, no significant difference was found between OCT (68.5%) and VEP (81.5%) sensitivity. In asymptomatic eyes, VEPs had a higher sensitivity (31.7%) vs OCT (19.9%; p = 0.005); VEP/OCT combined detected abnormalities in 39.2%. In follow up evaluation, OCT alterations were associated with development of disability after 2 years (p = 0.013). VEP alterations did not predict future disability development neither in patients with previous ON nor in those without. The present findings confirm a higher sensitivity of VEPs in the subacute phases of optic neuritis (less than 3 months) and in asymptomatic eyes. In eyes without previous optic neuritis, early asymptomatic OCT abnormalities are associated with short-term worsening of disability. Further longitudinal studies are needed to confirm our findings.

Neural coding of image structure and contrast polarity of Cartesian, hyperbolic, and polar gratings in the primary and secondary visual cortex of the tree shrew.

We comprehensively characterize spiking and visual evoked potential (VEP) activity in tree shrew V1 and V2 using Cartesian, hyperbolic, and polar gratings. Neural selectivity to structure of Cartesian gratings was higher than other grating classes in both visual areas. From V1 to V2, structure selectivity of spiking activity increased, whereas corresponding VEP values tended to decrease, suggesting that single-neuron coding of Cartesian grating attributes improved while the cortical columnar organization of these neurons became less precise from V1 to V2. We observed that neurons in V2 generally exhibited similar selectivity for polar and Cartesian gratings, suggesting that structure of polar-like stimuli might be encoded as early as in V2. This hypothesis is supported by the preference shift from V1 to V2 toward polar gratings of higher spatial frequency, consistent with the notion that V2 neurons encode visual scene borders and contours. Neural sensitivity to modulations of polarity of hyperbolic gratings was highest among all grating classes and closely related to the visual receptive field (RF) organization of ON- and OFF-dominated subregions. We show that spatial RF reconstructions depend strongly on grating class, suggesting that intracortical contributions to RF structure are strongest for Cartesian and polar gratings. Hyperbolic gratings tend to recruit least cortical elaboration such that the RF maps are similar to those generated by sparse noise, which most closely approximate feedforward inputs. Our findings complement previous literature in primates, rodents, and carnivores and highlight novel aspects of shape representation and coding occurring in mammalian early visual cortex.

Treatment with citicoline eye drops enhances retinal function and neural conduction along the visual pathways in open angle glaucoma.

To evaluate the retinal function and the neural conduction along the visual pathways after treatment with citicoline eye drops in patients with open angle glaucoma (OAG). Fifty-six OAG patients (mean age 52.4 ± 4.72 years, IOP <18 mmHg with beta-blocker monotherapy only) were enrolled. Of these, 47 eyes completed the study: 24 OAG eyes were treated with topical citicoline (OMK1®, Omikron Italia, 3 drops/day) (GC eyes) over a 4-month period (month 4) followed by a 2-month period of citicoline wash-out (month 6), and another 23 OAG eyes were only treated with beta-blocker monotherapy (GP eyes). In GC and GP eyes, pattern electroretinogram (PERG) and visual evoked potentials (VEP) were assessed at baseline and at months 4 and 6 in both groups. At baseline, similar (ANOVA, p > 0.01) PERG and VEP values in GC and GP eyes were observed. After treatment with topical citicoline, a significant (p < 0.01) increase of PERG P50-N95 and VEP N75-P100 amplitudes, and a significant (p < 0.01) shortening of VEP P100 implicit times were found. In GC eyes, the shortening of VEP P100 implicit times was correlated significantly (p < 0.01) with the increase of PERG P50-N95 amplitudes. After a 2-month period of topical Citicoline wash-out, PERG and VEP values were similar (p > 0.01) to baseline ones. GP eyes showed not significant changes of PERG and VEP values during the entire follow-up. Topical treatment with citicoline in OAG eyes induces an enhancement of the retinal bioelectrical responses (increase of PERG amplitude) with a consequent improvement of the bioelectrical activity of the visual cortex (shortening and increase of VEP implicit time and amplitude, respectively).

1089 Visual Evoked Potentials in Term and Preterm Infants

Background and AimsEvoked potentials are a useful non-invasive method for the assessment of neurological status in term and preterm infants at risk for perinatal CNS damage. The present study intended...

B12 Vitamini Eksikliğinde Görsel Uyandırılmış Potansiyeller: Ön Çalışma Sonuçları

Objective: Aim of this study was to investigate the possible relationship between serum vitamin B12 levels and P100 latency and amplitudes with visual evoked potentials (VEP) in patients with B12 vitamin deficiency without optic neuritis (ON). Material and Methods: Patients who presented to the outpatient neurology clinic of Canakkale Onsekiz Mart University Research Hospital underwent initial evaluation. Among those, complete blood count, full biochemistry (blood glucose, liver and kidney function tests, electrolites) and thyroid function tests were performed to the patients with serum B12 vitamin levels l200 pg/dl and without optic neuritis who accepted to participate. Electrophysiological evaluations included VEP. Data were organized in SPSS 15.0 programme and statistical analysis were performed in this programme. Non-parametric correlation test and Spierman's rho tests were used for statistical analysis. Results: Patients enrolled the study consisted of 13 (68.4%) men and 6 (31.6%) women. Mean age was 52.68p15.10 years (range=19-75 years). Mean vitamin B12 levels were160.41p44.59 pg/ml (range=78-230 pg/ml). There was no statistically significant correlation between serum vitamin B12 levels and P100 latency and amplitudes (pg0.05). Conclusion: Our results reveals that there is no correlation between the VEP values and the severity of vitamin B12 deficiency in the absence of ON in patients with vitamin B12 deficiency. Study still continues, but results of the preliminary study are shared in order to discuss the value of VEP in patients with vitamin B12 deficiency without ON. Key words: Vitamin B12 Deficiency; Optic Nerve; Visual Evoked Potentials.

Predictive value of visual evoked potentials, relative afferent pupillary defect, and orbital fractures in patients with traumatic optic neuropathy

Background:The purpose of this study was to determine the predictive value of flash visual-evoked potentials (VEP), relative afferent pupillary defect, and presence of orbital fractures in patients with traumatic optic neuropathy.Methods:A prospective study was conducted in 15 patients with indirect traumatic optic neuropathy. All patients underwent a thorough ophthalmic examination. Initial visual acuity, final visual acuity, and relative afferent pupillary defect were determined, and visual acuity was converted into logMAR units. We performed flash VEP and an orbital computed tomography scan in all patients.Results:There was a good correlation between relative afferent pupillary defect and final visual acuity (r = −0.83), and better initial visual acuity could predict better final visual acuity (r = 0.92). According to findings from flash VEP parameters, there was a relationship between final visual acuity and amplitude ratio of the wave (r = 0.59) and latency ratio of the wave (r = −0.61). Neither primary visual acuity nor final visual acuity was related to the presence of orbital fractures in the orbital CT scan.Conclusion:Patients with traumatic optic neuropathy often present with severe vision loss. Flash VEP, poor initial visual acuity, and higher grade of relative afferent pupillary defect could predict final visual acuity in these patients. Presence of orbital fracture was not a predictive factor for primary visual acuity or final visual acuity.