Visual Evoked Potentials Results Research Articles

Optic nerve involvement in patients with Lyme neuroborreliosis: an electrophysiological study.

The aim of this neurophysiological study was to retrospectively analyze visual evoked potentials (VEPs) acquired during an examination for diagnosing optic nerve involvement in patients with Lyme neuroborreliosis (LNB). Attention was focused on LNB patients with peripheral facial palsy (PFP) and optic nerve involvement. A total of 241 Czech patients were classified as having probable/definite LNB (193/48); of these, 57 were younger than 40 years, with a median age of 26.3 years, and 184 were older than 40 years, with a median age of 58.8 years. All patients underwent pattern-reversal (PVEP) and motion-onset (MVEP) VEP examinations. Abnormal VEP results were observed in 150/241 patients and were noted more often in patients over 40 years (p = 0.008). Muscle/joint problems and paresthesia were observed to be significantly more common in patients older than 40 years (p = 0.002, p = 0.030), in contrast to headache and decreased visual acuity, which were seen more often in patients younger than 40 years (p = 0.001, p = 0.033). Peripheral facial palsy was diagnosed in 26/241 LNB patients. Among patients with PFP, VEP peak times above the laboratory limit was observed in 22 (84.6%) individuals. Monitoring of patients with PFP and pathological VEP showed that the adjustment of visual system function occurred in half of the patients in one to more years, in contrast to faster recovery from peripheral facial palsy within months in most patients. In LNB patients, VEP helps to increase sensitivity of an early diagnostic process.

Anatomo-functional state of the central retina in premature infants with intraventricular hemorrhage and retinopathy of prematurity

Assessment of the anatomo-functional state of the central retina in children with intraventricular hemorrhage (IVH) and retinopathy of prematurity (ROP) in the long-term period. We examined 51 patients (102 eyes) born 25-34 weeks' of gestation (birth weight 700-2290 g), aged 8.83±3.5 years, and 18 children (36 eyes) born prematurely aged 10.8±3.2 years. The children underwent standard ophthalmologic examination, optical coherence tomography (OCT) and visual evoked potentials (VEP). Retinal thickness (RT) and retinal volume (RV) in the fovea of premature infants with PH and/or IVH are significantly higher than in healthy full-term infants, which correlates with lower visual acuity (p<0.05). RT and RV in the fovea has an inverse proportional relationship with gestational age (GA), (p<0.05). According to the results of VEP, moderate organic changes in the conduction tract of the visual analyzer are noted in 45% of premature infants (p<0.05). The process of macula formation is affected by many perinatal and postnatal factors, namely: GA, birth weight, ROP, hypoxic-ischemic CNS diseases, and refractive disorders.

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.

Is the prolongation latency of visual evoked potentials a pathological sign in children with Down’s syndrome without ocular abnormalities? Case–control study of children with Down’s syndrome

ObjectiveTo evaluate retino-cortical function in children with Down’s syndrome (DS) and no evident ocular abnormalities beyond mild refractive error, by recording visual evoked potentials (VEP) in response to pattern-reversal stimuli...

The role of visual electrodiagnostics in management of children with neurofibromatosis type 1.

To evaluate the role of visual electrodiagnostic testing in children with neurofibromatosis type 1 (NF1) despite improved accessibility to magnetic resonance imaging (MRI). The records from 39 children (78 eyes, 15 boys, 24 girls, average age at last visit of 11.5 ± 4.3years, average follow-up time of 7.8 ± 3.9years) with genetically confirmed NF1 were retrospectively analysed. They all underwent a thorough ophthalmological investigation, including age-appropriate visual acuity testing, anterior segment evaluation for Lisch nodules and a dilated fundus examination. If children were cooperative enough, colour vision was tested using the Hardy-Rand-Rittler test, visual fields were evaluated with Goldmann perimetry. All performed MRI of the brain and orbits as part of the standard of care protocol. Visual electrodiagnostics included electroretinography (ERG) and visual evoked potentials (VEP) using a standard protocol in older children, whereas with less cooperative children a modified protocol according to the Great Ormond Street Hospital (GOSH protocol) was used. The average visual acuity was 0.8 ± 0.3, colour vision was abnormal in 6%, perimetry in 8%, Lisch nodules were present in 62%, and the optic disc was pale in 66% of all eyes. Plexiform neurofibroma of the eyelid/orbit was present in 4%. Optic pathway glioma (OPG) was detected with MRI in 22 (57%) and in 6/22 treatment was indicated. Other intracranial NF1-related lesions were documented in 70% of children. VEP were abnormal in 16/39 of all children with NF1 (41%) comprising 14/22 (65%) of children with confirmed OPG and 2/17 (12%) of children without OPG. All full-field and pattern ERG responses were within normal limits. All individual VEP results are described and three cases from this cohort of children are presented in detail to illustrate the importance of VEP testing. In Case 1, VEP abnormality suggested subsequent MRI of the brain under general anaesthesia, which was otherwise contraindicated according to normal clinical findings and his young age. In Cases 2 and 3, VEP provided more precise functional information during the follow-up of OPG, while other psychophysical tests remained unchanged. Electrodiagnostics has multifactorial role and importance in children with NF1, either when visual pathway function is impaired in young children, even before MRI under general anaesthesia and other psychophysical tests can be performed, as well as for a more precise monitoring of the visual pathway function before potential treatment of OPG, or after it, to evaluate its success.

HEREDITARY NEUROPATHIES & ALS: P.107 Review of ophthalmologic findings following intrathecal gene transfer for giant axonal neuropathy

Giant Axonal Neuropathy (GAN) is an ultra-rare childhood onset neurodegenerative disorder of the peripheral and central nervous system. Recessive GAN mutations cause loss of function of gigaxonin, a cytoskeletal regulatory protein, leading to progressive sensorimotor and optic neuropathy, CNS involvement and respiratory failure. We report on the ophthalmologic findings of a single site, phase I, non-randomized, open label dose escalation gene transfer study for GAN (NCT02362438), a first-in-human intrathecal (IT) AAV9 mediated gene transfer. Data from 11 patients with GAN dosed at 3 dose levels; 3.5 × 1013 (1X), 1.2 × 1014 (3.3X), and 1.8 × 1014 (5X) with scAAV9-JeT-GAN with up to 3 years of follow up is analyzed. Ophthalmic evaluations include best-corrected visual acuity, color discrimination thresholds, fundus imaging, and measurement of retinal nerve fiber later (RNFL) thickness through optical coherence tomography. Photopic electroretinography including a photopic negative response and visual evoked potentials (VEP) were also recorded. GAN natural history study data is used for comparison of visual acuity and RNFL thickness as well as correlation of RNFL thickness with validated outcome measures of motor function. Cross sectional natural history analysis shows significant correlation between RNFL thickness and the MFM32 total score. Interim analysis reveals a trend towards stabilization and slowing of the expected decline in RNFL thickness and visual acuity compared to pre-trial lead in data and natural history. VEP results were variable with no consistent trends across natural history and clinical trial cohorts. The interim analysis of ophthalmologic assessments highlights several key aspects: 1) RNFL thickness, a structural assessment of optic nerve atrophy and axonal nerve degeneration at the level of the CNS is a biomarker strongly correlated to overall disease severity. In GAN patients, the decline in RNFL precedes change in visual acuity, and changes can be detected longitudinally. 2) The trend towards stabilization of RNFL thickness post gene transfer suggests that RNFL may be an objective and responsive biomarker of visual system involvement and overall nervous system degeneration in GAN. 3) Assessment of RNFL thickness post gene transfer may be used as an exploratory marker of feasibility of CNS transduction following IT gene transfer.

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

Transorbital ultrasonography in acute optic neuritis: Can it be a supportive diagnostic tool?

BackgroundBecause of limitations of conventional tools for diagnosing optic neuritis (ON), transorbital ultrasonography (TOUS) was introduced as a promising tool to evaluate the optic nerve. However, studies demonstrating its utility are scarce. ObjectiveTo assess the practical diagnostic value of TOUS in patients with ON along with other diagnostic tools such as visual evoked potential (VEP), MRI, and optical coherence tomography (OCT). MethodsSeventeen patients with first-attack unilateral acute ON were enrolled. Clinical characteristics, visual acuity, TOUS, MRI, VEP, and OCT results were evaluated. Bilateral optic nerves were scanned using TOUS to obtain axial images showing the optic nerve and the disc in the longitudinal plane. ResultsTOUS revealed thickening of the optic nerve sheath and optic nerve diameter with sheath on the affected side compared with the unaffected side (p = 0.002 and p = 0.003, respectively). Time since onset of initial symptoms was inversely correlated with optic nerve diameter (ρ = −0.517, p = 0.040) and retinal nerve fiber layer thickness (ρ = −0.831, p < 0.001). ConclusionTOUS could be a cost-effective tool for morphologically evaluating acute ON showing a significant thickening of the optic nerve and sheath, although only a limited retrobulbar area could be explored.

Visual evoked potential in multiple sclerosis and neuromyelitis optica spectrum disorder: A comparative study

Objectives The neuromyelitis optica spectrum disorder (NMOSD) was differentiated from relapsing-remitting multiple sclerosis (MS) by clinical, laboratory and physiopathological findings, including the presence of anti-aquaporin 4 (AQP4-Ab) antibody. Visual evoked potentials (VEP) are often used for the diagnosis of MS. However, the features of these VEP in the NMOSD have not been studied in detail. Our aim is to determine the epidemiological, clinical and especially neurophysiological (VEP) differences between MS and NMOSD. Methods Fourteen patients with NMOSD and 14 patients with RRMS were included in this study. The patients’ neurological symptoms and signs were examined and their VEP recorded. Results The mean age at onset of the patients with NMOSD was 43.21 years, which was older than that of the patients with RRMS (P = 0.017). The ratio of female patients with NMOSD was higher than that with RRMS (P = 0.012). The periods from onset to diagnosis were similar between the two groups. The prevalence of bilateral visual disturbance was higher in the NMOSD group (78.57%). Patients with RRMS presented a P100 latency and/or amplitude impairment in 6 asymptomatic eyes (21.42%). While in patients with NMOSD, there were 4 asymptomatic eyes that had all normal VEP. In VEP, 17.9% of NMOSD eyes presented no response and only 3.6% of MS eyes and the P100 amplitude impairment was predominant in NMOSD. Conclusion Sometimes, it remains critical to differentiate a MS from an NMOSD especially when the specific antibody is negative. VEP results can point to one of the two diseases even at an early stage.

Microstructure changes of occipital white matter are responsible for visual problems in the 3-4-year-old very low birth weight children.

Purpose:The main aim of the study was to evaluate which factors affect the long-time visual function in preterm children, whether it is prematurity or retinopathy of prematurity or perhaps disturbances in the visual pathway.Materials and Methods:Fifty-eight children with mean birth weight 1016 g (range 520–1500 g) were evaluated at mean age 48 months (range 42–54 months). All children underwent magnetic resonance imaging (MRI) studies, visual evoked potentials (VEPs), and the Developmental Test of Visual Perception (DTVP). The MRI evaluation included diffusion tensor imaging and fractional anisotropy (FA), and colored orientation maps were calculated for each subject. Based on the results of the VEP evaluation, children were divided into two groups: A-abnormal results of VEP (n = 16) and B-normal VEP results (comparison group, n = 42).Results:FA values of inferior left and right occipital white matter (OWM) were lower in the group of children with abnormal VEP compared to the comparison group (0.34 ± 0.06 vs. 0.38 ± 0.06; P = 0.047; 0.31 ± 0.04 vs. 0.36 ± 0.06; P = 0.007, respectively). Furthermore, there were correlations between the latency (r = −0.35; P = 0.01) and amplitude (r = 0.31; P = 0.02) and FA in OWM. Children with abnormal VEP had lower DTVP scores as compared with children with normal VEP results (88 ± 18 vs. 95 ± 16 points, P = 0.048). Finally, a multivariate logistic regression revealed that FA of the inferior OWM was the only independent risk factor for the abnormal VEP (P = 0.04).Conclusion:Visual perception, VEPs, and white matter microstructural abnormalities in very low birth weight children at the age of 3–4 are significantly correlated.

Visual evoked potentials after hematopoietic allogeneic stem cell transplantation in childhood

ObjectiveTo study visual pathway pathology detected by visual evoked potentials (VEPs) in patients treated with hematopoietic stem cell transplantation (HSCT) in childhood and to determine the impact of adverse ocular findings, somatic diseases, and conditioning regimens on the VEP results. MethodsOphthalmological assessments including pattern VEPs were performed in 47 of 79 patients at a median age of 15years (range 3–21years) in median 6years (1–17years) after HSCT. Somatic data were extracted from medical records. ResultsEight patients of 47 (17%) demonstrated pathological VEPs with prolonged latencies bilaterally (n=3) or unilaterally (n=5) at their latest VEP test at an age of 12–18years. A subnormal visual acuity was present in 8/11 eyes with pathological VEPs: one eye had cataract, six eyes had cataract surgery where of two had developed secondary cataracts. One eye had residual retinopathy of prematurity. Pathological VEPs were associated with decreased visual acuity (p=0.00019) but not linked to gender, malignant diagnosis or conditioning. ConclusionVEP recordings showed an association with decreased visual acuity but no relationship with irradiation or chemotherapy in the present study. SignificanceVEP recordings might be of clinical value for children with an unexplained subnormal visual acuity undergoing HSCT.

O69. Visual evoked potential as neurophysiological evaluation of patients with severe PE and visual disturbances

Introduction Visual symptoms are present in about 25% of women with pre-eclampsia (PE). The origin of these visual disturbances is localized in either the neurological or ophthalmic pathway. The exact causative factors of these disturbances have not been elucidated yet. Cerebral edema may affect the visual cortex, which can even lead to cortical blindness. The occipital cortex seems to be more susceptible for preeclampsia related breakthrough of the cerebral autoregulation. Because the vertebrobasilar system is less innervated with sympathetic nerves, this part of the brain is less capable to regulate cerebral blood flow with rising blood pressure. Objectives The objective of the study was to describe the neurophysiological changes by means of visual evoked potentials (VEPs) in patients with PE. A VEP measures the functional integrity of the visual pathway from retina to the occipital cortex of the brain. Our hypothesis is that women with PE have a longer VEP latency and lower amplitude compared to normotensive pregnant women. Methods From October 2005 till July 2008 a prospective study was performed. Normotensive pregnant women were recruited at the outpatient clinic from a gestational age of 12 weeks. They underwent clinical and neurophysiological measurements at 5 different time points: at a gestational age of 12–14 weeks, 26–28 weeks, 32–34 weeks, 36–40 weeks and 6–8 weeks postpartum. Women PE were recruited at the moment of diagnosis and investigated during pregnancy and 6-8 weeks postpartum. The visual evoked potentials were measured using a checkerboard pattern (Viking 4 device). Results VEP measurements of 29 normotensive controls, 15 mild PE and 34 severe PE were performed. The absolute values of the mean latency and amplitude were not significantly different between the groups. When compared to normative values of a group of women in the age of 20–59 year in the normotensive controls a higher proportion of women in the severe PE group had a latency time >107 (left eye: controls 31.0%, mild PE 41.7%, severe PE 52.9%, p = 0.215; right eye: controls 10.3% , mild PE 26.7%, severe PE 38.2%, p = 0.041). Conclusion This study showed that a higher percentage of women with PE had a longer latency. We are now studying the association between the VEP results and the cerebral blood flow measured with transcranial Doppler in these women.

Comparison of Visual Evoked Potentials in Patients Undergoing Peritoneal Dialysis and Hemodialysis and its Association with Blood Biochemical Profile

Purpose: Cranial nerve is one of optic nerves to be influenced by uremia. The symptoms can be diagnosed by Visual Evoked Potential (VEP) tests. The present study was designed to evaluate the effect of peritoneal dialysis and hemodialysis upon VEP results and assess the association of VEP results with the results of blood biochemical tests and dialysis duration. Methods: VEP was assessed in 30 patients undergoing peritoneal dialysis, 29 patients undergoing hemodialysis and 40 healthy controls. Moreover, blood biochemical tests involving urea, ceartinine, potassium, cholesterol, triglyceride, hemoglobin, hematocrit, albumin, parathormon (PTH) were carried out in all subjects. Results: In comparison with the control group, there were exclusively significant prolonged N140 and P100 latencies in hemodialysis and peritoneal dialysis group; notwithstanding nonsignificant P100 amplitude and N75 latency. Durations of renal failure and dialysis were not associated with VEP parameters. Of the blood biochemical parameters, P100 latency in the right eyes and N140 latency in the left eyes were exclusively associated with serum potassium. Conclusion: The present study suggests that optic pathway can be affected by chronic renal failure; even so, there would be no marked difference in optic pathway involvement between patients undergoing hemodialysis and peritoneal dialysis. This may indicate the equal effects of hemodialysis and peritoneal dialysis upon subclinical damages of optic pathway.

Longitudinal study of perception of structured optic flow and random visual motion in infants using high-density EEG.

Electroencephalogram (EEG) was used in infants at 3-4 months and 11-12 months to longitudinally study brain electrical activity as the infants were exposed to structured forwards and reversed optic flow, and non-structured random visual motion. Analyses of visual evoked potential (VEP) and temporal spectral evolution (TSE, time-dependent amplitude changes) were performed on EEG data recorded with a 128-channel sensor array. VEP results showed infants to significantly differentiate between the radial motion conditions, but only at 11-12 months where they showed shortest latency for forwards optic flow and longest latency for random visual motion. When the TSE results of the motion conditions were compared with those of a static non-flow dot pattern, infants at 3-4 and 11-12 months both showed significant differences in induced activity. A decrease in amplitudes at 5-7 Hz was observed as desynchronized theta-band activity at both 3-4 and 11-12 months, while an increase in amplitudes at 9-13 Hz was observed as synchronized alpha-band activity only at 11-12 months. It was concluded that brain electrical activities related to visual motion perception change during the first year of life, and these changes can be observed both in the VEP and induced activities of EEG. With adequate neurobiological development and locomotor experience infants around 1 year of age rely, more so than when they were younger, on structured optic flow and show a more adult-like specialization for motion where faster oscillating cell assemblies have fewer but more specialized neurons, resulting in improved visual motion perception.

Multifocal and pattern-reversal visual evoked potentials vs. automated perimetry frequency-doubling technology matrix in optic neuritis

Background:To compare the usefulness of the traditional pattern-reversal Visual Evoked Potentials (VEP) with multifocal VEP (mfVEP) and Frequency-Doubling Technology (FDT) perimetry in the evaluation of the ocular abnormalities induced by acute or subacute optic neuritis (ON).Materials and Methods:The test results of 24 ON patients were compared with those obtained in 40 normal control subjects. MfVEP recordings were obtained by using an Optoelectronic Stimulator that extracts topographic VEP using a pseudorandom m-sequence stimulus. Receiver operator characteristic (ROC) curves were calculated to determine the sensitivity and specificity of abnormal values.Results:The frequency of the abnormal ocular findings differed in the ON patients according to the used technique. Reduced visual sensitivity was demonstrated in 12 eyes (54.5%) using FDT perimetry; 17 eyes (77.2%) showed decreased amplitude and/or an increase in the implicit time of the P1 wave in mfVEP and 20 eyes (90.9%) showed an abnormal decrease in the amplitude and/or an increase in the latency of the P100 peak at VEP examination. The areas under the ROC curves ranged from 0.743 to 0.935, with VEP having the largest areas. The VEP and mfVEP amplitudes and latencies yielded the greatest sensitivity and specificity.Conclusions:The mfVEP and the FDT perimetry can be used for the evaluation and monitoring of visual impairment in patients with ON. The most sensitive and practical diagnostic tool in patients with ON is, however, the traditional VEP. The mfVEP can be utilized in those cases with doubtful or negative VEP results.

A comparative study of the usefulness of color vision, photostress recovery time, and visual evoked potential tests in early detection of ocular toxicity from hydroxychloroquine

Ocular toxicity from hydroxychloroquine (HCQ) is rare, but its potential permanence and severity makes it imperative to employ measures and screening protocols to minimize its occurrence. This study was performed to assess the usefulness of color vision, photo stress recovery time (PSRT), and visual evoked potentials (VEP) in early detection of ocular toxicity of HCQ, in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). 86 patients were included in the study and divided into three groups: (1) with history of HCQ use: interventional 1 (Int.1) without fundoscopic changes and Int.2 with fundoscopic changes; and (2) without history of HCQ use, as control. Visual field, color vision, PSRT and VEP results were recorded for all patients and the effect of age, disease duration, treatment duration and cumulative dose of HCQ on each test was assessed in each group. There was a significant relationship among PSRT and age, treatment duration, cumulative dose of HCQ and disease duration (P<0.001 for all). Color vision was normal in all the cases. P100 amplitude was not different between the three groups (P=0.846), but P100 latency was significantly different (P=0.025) and for Int.2 it was greater than the others. The percentage of abnormal visual fields for Int.2 was more than Int.1 and control groups (P=0.002 and P=0.005 respectively), but Int.1 and control groups were not significantly different (P>0.50). In the early stages of maculopathy, P100 latencies of VEP and PSRT are useful predictors of HCQ ocular toxicity. In patients without ocular symptoms and fundoscopic changes, the P100 latency of VEP predicts more precisely than the others.

The role of visual evoked potential and electroretinography in the preoperative assessment of osteo‐keratoprosthesis or osteo‐odonto‐keratoprosthesis surgery

To determine the value of electroretinography (ERG) and visual evoked potential (VEP) in predicting visual outcome in patients undergoing osteo-keratoprosthesis (OKP) or osteo-odonto-keratoprosthesis (OOKP) surgery. We performed a retrospective cohort study of 143 eyes in 101 patients who underwent OKP or OOKP surgery. The subjects underwent ERG, VEP testing or both up to 6 months prior to surgery. The ERG and VEP results were classified into four categories based on wave amplitude, latency and configuration. The main outcome was the maximum best-corrected visual acuity (maxBCVA) reached at any time postoperatively. One hundred thirty-four cases had undergone preoperative ERG, 82 VEP and 73 both examinations. The sensitivities of ERG and VEP to detect maxBCVA≥0.05 were 68.5% and 87%, respectively, while the specificity was 63.2% for ERG and 47.4% for VEP. The maxBCVA was significantly better in patients with normal ERG (p=0.033) and those with normal VEP (p=0.048), once having defined appropriate normal and abnormal cut-off levels. When comparing fellow eyes in patients who underwent surgery in both eyes, maxBCVA was better in the eyes that had better VEP results (p=0.013). Eyes demonstrating normal ERG or VEP achieved better visual outcome than those with abnormal results. In addition, VEP proved instrumental in determining the eye with the best prognosis when comparing both eyes of a given patient.

Sub‐clinical atrophy of the retinal nerve fibre layer in multiple sclerosis

This study aimed to evaluate the presence of abnormalities in the retinal nerve fibre layer (RNFL) in multiple sclerosis (MS) patients with normal ophthalmic examination, and to compare the ability of optical coherence tomography (OCT) and scanning laser polarimetry (GDx) to detect axonal loss. Patients with MS and disease-free controls were invited to enrol in the study from 1 February 2007 to 30 June 2008. Ophthalmic examination, including evaluation of visual acuity (VA) and visual field (VF), showed normal results in all subjects. Retinal nerve fibre layer properties were measured by means of OCT and GDx. Visual evoked potentials (VEPs) were also recorded. Forty eyes of 40 MS patients and 20 eyes of age- and sex-matched controls were included in the study. Despite normal VA and VF results, significant differences between the two groups were observed in VF mean deviation (MD), most of the RNFL measurements provided by OCT and GDx, and VEP P100 latency and amplitude. There was a significant correlation between OCT and GDx parameters, and between these parameters and VEP results. Nineteen MS eyes (35.7%) showed RNFL abnormalities detected either by OCT or GDx. Sub-clinical ganglion cell loss can be detected in MS patients with normal visual function. Both OCT and GDx are useful complementary tools with which to identify this damage.

The Effects of Optic Disc Drusen on the Latency of the Pattern-Reversal Checkerboard and Multifocal Visual Evoked Potentials

To determine the effect of optic disc drusen on the latency of the pattern-reversal checkerboard visual evoked potentials (VEPs) and multifocal (mf)VEPs and to better understand the pathophysiology of the condition. Eighteen eyes with optic disc drusen (10 patients) and 38 control eyes (19 subjects) underwent VEP, mfVEP, and visual field testing. Only one eye of each individual, the one with the more affected visual field, was used in the analyses. The VEPs were recorded with a 15' and 60' reversing checkerboard pattern, and the mfVEPs were elicited by a 60-sector dartboard display. Unlike the VEP results, the mfVEP revealed a significant increase in the average monocular latency of the optic disc drusen group compared with that of the control group. The average mfVEP relative latency for the optic disc drusen group (4.1 ms) was greater than that (0.8 ms) in the control group. For monocular and interocular analyses, the average percentage of points delayed in the drusen group was significantly greater than that in the control group. Optic disc drusen produced significant latency delays on the mfVEP test but not on the VEP test, presumably due to the mfVEP's ability to detect the effects of local changes. The results are consistent with the hypothesis that local mechanical compression by optic disc drusen leads to abnormal retinal ganglion cell activity.

Psychophysiological characteristics of patients with alcohol epileptic syndrome

The relationship between ongoing occipital alpha rhythm (8–12 Hz) and the generation of visual evoked potentials (VEPs) has been discussed controversially. While the “evoked theory” sees no interaction between VEP generation and the alpha rhythm, the “oscillatory theory” (also known as “phase-reset theory”) postulates VEP generation to be based on alpha rhythm phase resetting. Previous experimental results are contradictory, rendering a straightforward interpretation difficult. Our approach was to theoretically model the implications of the evoked and oscillatory theory also incorporating stimulus-induced alpha-rhythm desynchronization. As a result, the model based on the oscillatory theory predicts alpha-band dependent VEP amplitudes but constant phase locking. The model based on the evoked theory predicts unaffected VEP amplitudes but alpha-band dependent phase locking. Subsequently, we analyzed experimental data in which VEPs were assessed in an “eyes open” and “eyes closed” condition in 17 subjects. For early components of the VEP, findings are in agreement with the evoked theory, i.e. VEP amplitudes remain unaffected and phase locking decreases during periods of high alpha activity. Late VEP component amplitudes (> 175 ms), however, are dependent on pre-stimulus alpha amplitudes. This interaction is contradictory to the oscillatory theory since this VEP amplitude difference is not paralleled by a corresponding difference in alpha-band amplitude in the affected time window. In summary, by using a model-based approach we identified early VEPs to be compatible with the evoked theory, while results of late VEPs support a modulatory but not causative role – the latter implied by the oscillatory theory – of alpha activity for EP generation.