Pattern Reversal Visual Evoked Potentials Research Articles

Motion onset VEPs can see through the blur

Motion-onset visual evoked potentials (MO VEPs) are robust to dioptric blur when low contrast and low spatial frequency patterns are used for stimulation. To reveal mechanisms of MO VEPs robustness, we studied whether the resistance to defocus persists even when using a high-contrast checkerboard using digital defocus in the emmetropic eyes of 13 subjects (males 20–60 years). We compared the dominant components of MO VEPs to pattern-reversal VEPs (PR VEP), which are sensitive to the blur. For stimulation, we used checkerboard patterns with 15´ and 60´ checks. To defocus the checkerboard, we rendered it with a second-order Zernike polynomial (Z20\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${Z}_{2}^{0}$$\\end{document}) with an equivalent defocus of 0, 2, or 4 D. For PR VEP, the checkerboards were reversed in terms of their contrast. To evoke MO VEP, the checkerboard of 60´ checks moved for 200 ms with a speed of 5 or 10 deg/s in the cardinal directions. The MO VEP did not change in peak time (P ≥ 0.0747) or interpeak amplitude (P > 0.0772) with digital blur. In contrast, for PR VEP, the results showed a decrease in interpeak amplitude (P ≤ 6.65ˑ10-4) and an increase in peak time (P ≤ 0.0385). Thus, we demonstrated that MO VEPs evoked by checkerboard, structure containing high spatial content, can be robust to defocus.

Study of Visual Evoked Potentials in Schoolchildren: A Promising Aid to Pediatric Ophthalmology.

Background Visual evoked potential (VEP) is a noninvasive investigation conducted to identify abnormalities in the visual system. It is especially suitable for young children who are unable to express visual symptoms or participate in conventional vision tests. This study was undertaken to examine the VEP among schoolchildren to assess the functionality of their optic pathway. Methodology This short-term observational study was performed in the Clinical Neurophysiology Unit of the Physiology Department of a rural medical college. The study population consisted of 60 schoolchildren aged 7-12. Both eyes were examined for transient pattern reversal VEP recordingsusing a Recorders & Medicare Systems Electromyography-Evoked Potential recorder (RMS EMG-EP MARK-II Pvt. Ltd., Chandigarh, India). Results VEPs were analyzed for latency and amplitude of the main components, namely P100, N70, and N155. The results showedmarkedly extended P100 latency in33.33%, i.e., eight outof 24 eyes of standard (std.) III children. Similar latency prolongation was obtained in 36.36% (eight out of 22)eyes of std. IV, 30% (six of 20 eyes) of std. V, 13.63% (three of 22 eyes) of std. VI, and 50% (eight of 16 eyes) in std. VII and VIIIchildren. A markedly reduced P100 amplitude was observedin two of 20 eyes (10%) of std. V, two of 16 eyes (12.5%) in std. VII and VIIIchildren, amounting to a P100amplitude abnormality in5%eyesin toto. The interocular differences in all VEP parameters amongthe subjects were statistically insignificant. Conclusion In schoolchildren in whom normal latencies and amplitudes were obtained, the presence of reproducible VEPs indicated the normal functionalstatus of their visual pathway. On the other hand,in those children where alteredVEP findings were found, it hinted towardcomplementary informationthat they may have underlying ocular disordersthat were yet to be diagnosed. Hence, this study provides insight into the assessment of visual system function, which is primarily difficult in young children.

Pattern-reversal visual evoked potentials in prosthetic vision and simulated visual reduction

ObjectiveTo quantitatively evaluate visual evoked potentials (VEPs) in prosthetic vision and simulated visual reduction.Methods and analysisFour blind patients implanted with the Argus II retinal prosthesis and seven sighted controls participated....

Visual evoked potentials in patients with congenital color vision deficiency.

Congenital color vision deficiency (CCVD) is an eye disease characterized by abnormalities in the cone cells in the photoreceptor layer. Visual evoked potentials (VEPs) are electrophysiological tests that physiologically examine the optic nerve, other visual pathways, and the visual cortex. The aim of this research was to determine whether there are VEP abnormalities in CCVD patients. Patients with CCVD and healthy individuals were included in this prospective case-control study. Participants with eye disease or neurodegenerative disease were excluded from the study. Pattern reversal VEP (PVEP), flash VEP (FVEP), and optical coherence tomography were performed on all participants. Twenty healthy individuals (15 male) and 21 patients with CCVD (18 male) were included in the study. The mean ages of healthy individuals and patients with CCVD were 29.8 ± 9.6 and 31.1 ± 10.9years (p = 0.804). Retinal nerve fiber layer thickness and central macular thickness values did not differ between the two groups. In PVEP, Right P100, Left N75, P100, N135 values were delayed in CCVD patients compared to healthy individuals (p = 0.001, p = 0.032, p = 0.003, p = 0.032). At least one PVEP and FVEP abnormality was present in nine (42.9%) and six (28.6%) of the patients, respectively. PVEP or FVEP abnormalities were found in 13 (61.9%) of the patients. This study indicated that there may be PVEP and FVEP abnormalities in patients with CCVD.

Comparison of Visual Evoked Potential Latency and Amplitude Values According to Visual Acuity among Normal Adult Eyes in dr. Cipto Mangunkusumo Hospital

Visual Evoked Potential (VEP) is a diagnostic procedure to evaluate pathological conditions affecting the visual pathway with several protocols, including pattern onset/offset VEP, flash VEP, and pattern-reversal VEP (PRVEP), standardized by International Society For Clinical Electrophysiology In Vision (ISCEV). PRVEP, the most common protocol used in clinical practice, is not always directly proportional to visual acuity (VA). Clarity of the refractory media and gender are presumed to affect it; thus, using PRVEP reference value based on refractory status is not casually applicable when the VA does not resemble refractory status. This study aims to determine the changes in VEP latency and amplitude value according to various subjective VA, and to examine and analyze these latency and amplitude values within male and female subject groups. The research was conducted at the Department of Ophthalmology, dr. Cipto Mangunkusumo Hospital from August to October 2017. Latency and amplitude values were measured with PRVEP. Measurement was performed on normal VA and defocus-induced VA to 6/18, 6/30, and 6/60 values, using small and large-sized checkerboard stimuli. Prolonged latency and decreased amplitude were found in male and female subject groups, corresponding with decreasing VA levels. Using 18 min arc and 48 min arc-sized checkerboards gave the closest result to the reference value. The difference in VEP value according to subjects' gender was found in amplitude but not in latency.

Comparison of Visual Evoked Potential Latency and Amplitude Values According to Visual Acuity among Normal Adult Eyes in dr. Cipto Mangunkusumo Hospital

Visual Evoked Potential (VEP) is a diagnostic procedure to evaluate pathological conditions affecting the visual pathway with several protocols, including pattern onset/offset VEP, flash VEP, and pattern-reversal VEP (PRVEP), standardized by International Society For Clinical Electrophysiology In Vision (ISCEV). PRVEP, the most common protocol used in clinical practice, is not always directly proportional to visual acuity (VA). Clarity of the refractory media and gender are presumed to affect it; thus, using PRVEP reference value based on refractory status is not casually applicable when the VA does not resemble refractory status. This study aims to determine the changes in VEP latency and amplitude value according to various subjective VA, and to examine and analyze these latency and amplitude values within male and female subject groups. The research was conducted at the Department of Ophthalmology, dr. Cipto Mangunkusumo Hospital from August to October 2017. Latency and amplitude values were measured with PRVEP. Measurement was performed on normal VA and defocus-induced VA to 6/18, 6/30, and 6/60 values, using small and large-sized checkerboard stimuli. Prolonged latency and decreased amplitude were found in male and female subject groups, corresponding with decreasing VA levels. Using 18 min arc and 48 min arc-sized checkerboards gave the closest result to the reference value. The difference in VEP value according to subjects' gender was found in amplitude but not in latency.

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.

The Effect of Ethambutol Therapy in terms of Visual Evoked Potential, Color Vision Test, and Contrast Sensitivity Test at the Subclinical Level

Abstract
 Introduction & Objectives : Ethambutol is one of the first-line drugs in the treatment of tuberculosis and known to induce optic neuropathy. However, there are unknown protocols for detecting subclinical level of toxicity. The aim of this study was to assess the difference in amplitude and latency of visual evoked potential (VEP), color vision, and contrast sensitivity in tuberculosis patients before and after taking ethambutol for 1 and 2 months.
 Methods : This was a prospective observational cohort study of 38 eyes of 19 newly diagnosed patients with category-1 tuberculosis being treated with ethambutol. All patients were given ethambutol for 2 months at a dose of 15 - 20 mg/kg body weight/day. The participants underwent complete eye and visual function examination including pattern-reversal VEP, color vision with Farnsworth Munsell D-15 test, and contrast sensitivity with LEA Low Contrast Flip Chart before and after 1 and 2 months of treatment. Wilcoxon test was employed for data analysis.
 Results : During the study, no changes in visual acuity was observed. The results showed that the latencies of VEP after 1 month (p = 0.000) and 2 months (p = 0.000) of treatment were significantly delayed. There was a significant difference in contrast sensitivity after 2 months (p = 0.014) of treatment. However, no significant difference was found in color vision and amplitude of VEP.
 Conclusion : Latency of VEP and contrast sensitivity test could prove useful in detecting subclinical and hence very useful for monitoring patients under ethambutol therapy for ocular toxicity.

Relationship between pattern reversal visual evoked potential P100 wave latency and dysfunctional HDL in patients with multiple sclerosis subjected to an optic neuritis attack: A case-control study.

Optic neuritis frequently occurs during the clinical course of multiple sclerosis (MS). In this condition, demyelination of the optic nerve occurs, which electrophysiologically causes a delay in P100 wave latency. Sensitive cholesterol homeostasis is critical for the formation of the myelin sheath and for myelin to become functionally mature. High-density lipoprotein (HDL) becomes dysfunctional under oxidative stress and plays an important role in the pathogenesis of MS. In this study, HDL levels of MS patients suffering from optic neuritis were compared with those of healthy individuals, and the relationship between pattern reversal visual evoked potential (PRVEP) P100 wave latency and HDL levels in patients with optic neuritis attacks was analyzed. PRVEP studies were performed in patients with MS who had an episode of optic neuritis, and P100 wave latencies were measured. Peripheral blood samples were collected from healthy participants and patients. Lipid levels and myeloperoxidase (MPO) and paraoxonase (PON) activities were measured, and the MPO/PON ratio was then calculated. The lipid profiles and dysfunctional HDL levels in the healthy and patient groups were compared. Finally, the relationship between these parameters and the PRVEP-P100 wave latency was examined. Total cholesterol and low-density lipoprotein (LDL) levels were significantly higher in the patient group (P = .044; P = .038, respectively). There was no statistically significant difference in HDL levels between groups (P = .659). The distribution of MPO values was similar between groups (P = .452). PON values were significantly lower, whereas the MPO/PON ratios were significantly higher in the patient group than in the control group (P = .025; P = .028, respectively). A statistically significant positive correlation was found between the elevated MPO/PON ratio, representing dysfunctional HDL, and both the mean and maximum PRVEP-P100 wave latencies (P < .001, R = 0.690; P < .001, R = 0.815, respectively). A dysfunctional form of HDL may lead to poor deactivation of remyelination-limiting factors and may ultimately be associated with poor outcomes in optic neuritis.

A comparison of visual electrophysiology measures in optic neuropathy

Aims/Purpose: Our aim is to explore the inter‐relationship of clinical PVEP and PERG measurements with each other and the optic nerve structure in children investigated for possible optic neuropathies.Methods: ISCEV Standard PVEPs and PERGs to 50′ check widths to large 30 and standard 15 degree fields were reviewed from children suspected to have optic neuropathy of various pathology. Amplitudes and peak times of PERG P50, N95, the N95:P50 amplitude ratio, the amplitude of the N95 from baseline and at 30 ms from the P50‐N95 slope were measured. Spectralis OCT RNFL sector measures and macular ganglion cell volumes were collated.Results: PERG, PVEP with OCT measurements were available for 42 patients, (83 eyes) aged 6‐17 yrs. Those with abnormal PVEPs (33 eyes) had the most severe macular RGC volume loss (mean 0.26 mm3 in 3.45 mm) with mean LogMAR VA 0.52 (range − 0.01 to 1.00). These patients had inherited optic neuropathies, optic neuritis associated with MOGAD and RMMS. In contrast, patients with papilledema, such as associated with IIH, or presenting with headache and reduced vision and full discs had normal PVEPs. Mean VA LogMAR 0.23 (range − 1.0 to 0.9), and mean macular RGC volume 0.45 mm3 in 3.45 mm circle. N95:P50 amplitude ratios ranged from 1.83 to 0.44 in 30 degree fields and 2.16 to 0.36 in 15 degree fields. The N95:P50 amplitude ratios, slope at 30 ms and N95 from baseline correlated with macular RGC volume, but the best PERG discriminator (AUC 0.83) in the large field was the N95 slope measured at 30 ms. RNFL values were confounded by disc oedema in many cases.Conclusions: Pattern reversal VEPs were abnormal in all patients with severe RGC volume loss. The PERG measures correlate with macular RGC volume. RNFL was confounded by disc oedema, but was helpful in highlighting temporal sector thinning in optic neuritis and inherited optic atrophy such as LHOA.

Poster Session II: Alternating orientation of the chromatic pattern VEP improves signal even in the absence of contrast adaptation.

The visual evoked potential (VEP) to chromatic pattern reversal is greatly reduced compared to VEPs to pattern onsets. Chromatic pattern onsets produce large and stereotypical waveforms that reliably differ from standard achromatic pattern reversal VEP waveforms used in clinical applications. Rapid contrast adaptation for sustained chromatic but not transient achromatic mechanisms has been suggested as one explanation for these observations. Here we first examined changes in the magnitude of response during recordings to reversing and onset grating patterns that preferentially modulate the L-M, S, and achromatic pathways. Given the evidence for both chromatic and achromatic orientation-selective mechanisms, we then hypothesized that contrast adaptation may be reduced by changing the orientation of the pattern for each reversal or onset. VEPs were recorded for 60 s with 2 onsets/reversals per second using both fixed and alternating (horizontal/vertical) orientations. FFT amplitudes for 6-second windows did not reveal evidence of adaptation for chromatic or achromatic onsets or reversal patterns over the 60-second recording period. Despite this, alternating pattern orientation increased the signal for all chromatic but not achromatic conditions. Although alternating the orientation for reversals increased the signal, the onset responses were still larger, even for non-alternating orientations. Mechanisms other than contrast adaptation must be invoked to explain the results.

Poster Session I: Comparison of tripolar and traditional electrodes: Waveform morphology.

The waveforms of visual evoked potentials (VEPs) recorded by tripolar electrodes are different from those recorded by traditional electrode arrays. Traditional arrays record potentials using both an active and a reference electrode. The location of this reference will affect the waveform amplitude and shape. Conversely, tripolar electrodes measure the surface Laplacian across three concentric rings housed within a single electrode surface. These differences may influence the morphology of evoked responses. We compared these two modalities by recording pattern-reversal VEPs to two sizes of checkerboard. Visual inspection of the VEPs suggest that the signals recorded by the tripolar system have attenuated higher frequencies and increased latency of the major waveform components. Root-mean-square comparison of the two signal types confirm attenuation at the higher frequencies in the tripolar recording. Additionally, there is a cumulative delay present within both the large and small check conditions, such that each subsequent component recorded by the tripolar electrodes is shifted increasingly later in time compared to the same components recoded by the traditional electrodes. Such latency shifts may be indicative of a difference in the physiological sources that are measured by the two EEG systems.

ISCEV standard pattern reversal VEP development: paediatric reference limits from 649 healthy subjects

PurposeTo establish the extent of agreement for ISCEV standard reference pattern reversal VEPs (prVEPs) acquired at three European centres, to determine any effect of sex, and to establish reference intervals from birth to adolescence.MethodsPrVEPs were recorded from healthy reference infants and children, aged 2 weeks to 16 years, from three centres using closely matched but non-identical protocols. Amplitudes and peak times were modelled with orthogonal quadratic and sigmoidal curves, respectively, and two-sided limits, 2.5th and 97.5th centiles, estimated using nonlinear quantile Bayesian regression. Data were compared by centre and by sex using median quantile confidence intervals. The ‘critical age’, i.e. age at which P100 peak time ceased to shorten, was calculated.ResultsData from the three centres were adequately comparable. Sex differences were not clinically meaningful. The pooled data showed rapid drops in P100 peak time which stabilised by 27 and by 34 weeks for large and small check widths, respectively. Post-critical-age reference limits were 87–115 ms and 96–131 ms for large and small check widths, respectively. Amplitudes varied markedly and reference limits for all ages were 5–57 μV and 3.5–56 μV for large and small check widths, respectively.ConclusionsPrVEP reference data could be combined despite some methodology differences within the tolerances of the ISCEV VEP Standard, supporting the clinical benefit of ISCEV Standards. Comparison with historical data is hampered by lack of minimum reporting guidelines. The reference data presented here could be validated or transformed for use elsewhere.

Exaggerated response to pattern reversal visual evoked potential among migraineurs

Objective Visual evoked potential recording has reported ambiguous results among migraineurs, thus the present study explored the association of check-size and reversal rates on the latency and amplitude of pattern reversal VEP among migraineurs. Method and material Monocular VEP responses for both eyes were recorded in 133 migraineurs and 111 controls. Checkerboard pattern with phase reversal frequency of 0.5, 1, 2 and 4 Hz and check-size of 16 × 16, 32 × 32, 64 × 64 and 128 × 128, i.e. spatial frequency of 0.475, 1.029, 2.056 and 4.112 cycle per degree (cpd) were used to record 100 responses each. Three-minutes gap was given after change of reversal frequency to a higher rate for next cycle of 4 check-size records. Result A linear increase in latencies was observed with decreasing check-size in both groups, but migraineurs had significantly higher latencies at a given reversal rate. Amplitudes A1 and A2 were higher among migraineurs and amplitude A2 showed an inverted ‘U’ shaped trend with maximum amplitude at 32 × 32 check size (1.029 cpd) in both groups, with an exaggerated response among migraineurs. Check-size 32 × 32 i.e. spatial frequency of 1.029 behaves differently than other larger or smaller check-sizes. Conclusion Variable VEP response for different visual stimuli may be due to differential activation of respective retinocortical pathways and cortical areas. The highest amplitude at modest check-size suggests a contributory role of foveal-parafoveal fibres in migraineurs. Exaggerated physiological response to visual stimuli may be responsible for higher amplitudes and prolonged latencies among migraineurs.

Objective detection of visual field defects with multifrequency VEPs.

To correlate multifrequency pattern reversal VEPs in quadrants (QmfrVEPs) with perimetric field losses for objective detection of visual field losses. QmfrVEP measurements were performed using four LED-based checkerboard stimulators to stimulate the four quadrants of the visual field. QmfrVEPs were measured monocularly in 5 normal subjects and in 5 glaucoma patients who showed losses in conventional Octopus perimetry. The pattern reversal frequency varied slightly between the stimulators: (11.92, 12.00, 12.08 and 12.16 reversals/sec). The responses to the different stimuli were identified by discrete Fourier analysis. VEPs were recorded using different electrode configurations, and the recording with the highest signal-to-noise ratio (SNR) was used for further analysis. QmfrVEP responses from the different quadrants can be reliably measured and separated using the 0.08 reversals/sec interstimulus reversal frequency differences. The signal-to-noise ratio in the four quadrants was significantly correlated with the equivalent visual field losses obtained with perimetry (Spearman rank correlation: P < 0.001). In the five glaucoma patients, the SNR was reduced in 15 out of the 16 quadrants with a perimetric defect, in comparison to the results in quadrants of healthy subjects. This confirms the sensitivity of the procedure. QmfrVEP responses can be measured reliably. This pilot study suggests that high SNR values exclude visual field defects and that focal defects can be identified in glaucoma patients. www. gov . NCT00494923.

Patterned edge-illuminated display for clinical examination of visual evoked potentials using simultaneous magnetic resonance imaging

PurposeCommonly used technologies for visual pattern stimulation cannot operate in a magnetic resonance imaging room because they can interfere with the operation of the scanner and are vulnerable to its electromagnetic and magnetic fields. The aim of this single-center prospective observational study was to introduce a novel, structurally uncomplicated, easy-to-maintain, patterned edge-illuminated display (PEID) device for visual pattern-reversal stimulation, compare it with a commonly used cathode ray tube screen, and verify the equivalence of quantitative assays. Materials and methodsThe left and right eyes of 36 healthy participants with undilated pupils were examined on a commercial visual evoked potential (VEP) apparatus and on the PEID device, where pattern-reversal transient VEPs were elicited by checkerboard stimuli with large (0.89°; 0.86°–0.92°) and small (0.21°; 0.20°–0.23°) checks. ResultsThe PEID device demonstrated the required reliability and dynamic characteristics, as well as precise time-locking required for a VEP diagnosis. The results of Deming's correlation analysis showed that both the commercial cathode ray tube monitor and the PEID device produced identical VEP results within the context of experimental uncertainty. The standard deviation of Deming's regression may indicate the uncertainty of the VEPs measured in clinical practice. The Bland-Altman analysis of the mean showed no significant difference in the amplitude and peak time of VEPs measured on the PEID device compared to that of the commercial cathode ray tube monitor. ConclusionsThe presented PEID device meets all the required standards and can be easily installed in various types of commercial magnetic resonance imaging scanners.

Retinal structure and visual pathway function at school age in children born extremely preterm: a population-based study

BackgroundChildren born extremely preterm (gestational age < 28 weeks) show reduced visual function even without any cerebral or ophthalmological neonatal diagnosis. In this study, we aimed to assess the retinal structure with optical coherence tomography (OCT) and visual function with pattern-reversal visual evoked potentials (PR-VEPs) in a geographically defined population-based cohort of school-aged children born extremely preterm. Moreover, we aimed to explore the association between measures of retinal structure and visual pathway function in this cohort.MethodsAll children born extremely preterm from 2006–2011 (n = 65) in Central Norway were invited to participate. Thirty-six children (55%) with a median age of 13 years (range = 10–16) were examined with OCT, OCT-angiography (OCT-A), and PR-VEPs. The foveal avascular zone (FAZ) and circularity, central macular vascular density, and flow were measured on OCT-A images. Central retinal thickness, circumpapillary retinal nerve fibre layer (RNFL) and inner plexiform ganglion cell layer (IPGCL) thickness were measured on OCT images. The N70-P100 peak-to-peak amplitude and N70 and P100 latencies were assessed from PR-VEPs.ResultsParticipants displayed abnormal retinal structure and P100 latencies (≥ 2 SD) compared to reference populations. Moreover, there was a negative correlation between P100 latency in large checks and RNFL (r = -.54, p = .003) and IPGCL (r = -.41, p = .003) thickness. The FAZ was smaller (p = .003), macular vascular density (p = .006) and flow were higher (p = .004), and RNFL (p = .006) and IPGCL (p = .014) were thinner in participants with ROP (n = 7).ConclusionChildren born extremely preterm without preterm brain injury sequelae have signs of persistent immaturity of retinal vasculature and neuroretinal layers. Thinner neuroretinal layers are associated with delayed P100 latency, prompting further exploration of the visual pathway development in preterms.

A feasibility study for objective evaluation of visual acuity based on pattern-reversal visual evoked potentials and other related visual parameters with machine learning algorithm

BackgroundTo develop machine learning models for objectively evaluating visual acuity (VA) based on pattern-reversal visual evoked potentials (PRVEPs) and other related visual parameters.MethodsTwenty-four volunteers were recruited and forty-eight eyes were divided into four groups of 1.0, 0.8, 0.6, and 0.4 (decimal vision). The relationship between VA, peak time, or amplitude of P100 recorded at 5.7°, 2.6°, 1°, 34′, 15′, and 7′ check sizes were analyzed using repeated-measures analysis of variance. Correlations between VA and P100, contrast sensitivity (CS), refractive error, wavefront aberrations, and visual field were analyzed by rank correlation. Based on meaningful P100 peak time, P100 amplitude, and other related visual parameters, four machine learning algorithms and an ensemble classification algorithm were used to construct objective assessment models for VA. Receiver operating characteristic (ROC) curves were used to compare the efficacy of different models by repeated sampling comparisons and ten-fold cross-validation.ResultsThe main effects of P100 peak time and amplitude between different VA and check sizes were statistically significant (all P < 0.05). Except amplitude at 2.6° and 5.7°, VA was negatively correlated with peak time and positively correlated with amplitude. The peak time initially shortened with increasing check size and gradually lengthened after the minimum value was reached at 1°. At the 1° check size, there were statistically significant differences when comparing the peak times between the vision groups with each other (all P < 0.05), and the amplitudes of the vision reduction groups were significantly lower than that of the 1.0 vision group (all P < 0.01). The correlations between peak time, amplitude, and visual acuity were all highest at 1° (rs = − 0.740, 0.438). VA positively correlated with CS and spherical equivalent (all P < 0.001). There was a negative correlation between VA and coma aberrations (P < 0.05). For different binarization classifications of VA, the classifier models with the best assessment efficacy all had the mean area under the ROC curves (AUC) above 0.95 for 500 replicate samples and above 0.84 for ten-fold cross-validation.ConclusionsMachine learning models established by meaning visual parameters related to visual acuity can assist in the objective evaluation of VA.

The integrity of psychophysical visual function in non-immunocompromised PLHIV (NIPLHIV) without retinitis on antiretroviral therapy (ART).

The present study investigated the integrity of contrast sensitivity (CS), colour vision, and pattern evoked vision potentials (VEP) in non-immunocompromised people living with HIV (NIPLHIV) without retinitis. All participants were visually asymptomatic and no history of ocular disorders, with CD4 counts above 350 cells/mm3, low viral loads and on ART. Thirty NIPLHIV and 30 age-matched HIV negative control groups underwent F100 hue colour assessment, Pelli-Robson contrast sensitivity assessment and pattern-reversal VEP. The median F100 total error scores for NIPLHIV and controls was 33 (IQR: 28;41) and 28 (IQR: 26;48.50) respectively, this was statistically different (p= 0.020). The median P100 amplitude for NIPLHIV was 5.75 µV (IQR: 4.4;8.85) and 4.05 µV (IQR: 3.2;5.8) for controls, this was statistically different (p=0.045). The mean LogCS score 1.83±0.14 and the median P100 peak latency was 105.45 msec (IQR: 102.98;108.98) for NIPLHIV. Higher CD4+ counts were significantly associated with having higher F100 total error scores (OR=0.995; p=0.018), lower P100 amplitudes (OR=1.007; p=0.010) and higher P100 latencies (OR=0.994; p=0.011). Contrast sensitivity function, colour vision, and VEP were uncompromised in NIPLHIV. Associations between CD4 counts with F100 total error scores and P100 latency may aid in the surveillance of vision of NIPLHIV.

In childhood, a different electrode placement improves the recording of pattern reversal visual evoked potentials.

In childhood, a different electrode placement improves the recording of pattern reversal visual evoked potentials.