Conventional tests of visual function include measures such as visual acuity, contrast sensitivity, perimetry, and color vision. However, standard clinical tests are typically designed to test those with normal or near-normal sensitivities. Such tests may be inappropriate where profound vision loss exists, as may be the case in retinal gene therapy if the therapy is nascent and/or the therapy is unable to fully restore the visual system. Here we provide step-by-step instructions for performing a battery of three computerized tests to quantify light detection, light localization, and motion detection, in eyes with profound vision loss. The tests use conventional computer hardware, do not require extensive calibration, and are relatively short to perform.

Visual acuity (VA) assessment traditionally relies on patient cooperation, which can be unreliable in pediatric cases, cognitive impairment, or suspected malingering. While the visual evoked potential (VEP) provides an objective alternative, it primarily reflects the integrity of the early visual pathways and may overestimate VA in conditions like amblyopia. This concise review explores the P300 event-related potential as a promising cognitively-driven tool for objective VA estimation. A literature search was conducted to identify studies utilizing the P300—a marker of high-level cognitive processing and conscious perception—for VA estimation. Additional literature was included to provide a broader context. Unlike the VEP, which depends on physical stimulus characteristics, the P300 is elicited during conscious stimulus categorization, typically using an oddball paradigm. Therefore, P300-based VA estimation can utilize standard clinical optotypes, such as Landolt Cs, allowing for a more direct comparison with gold-standard psychophysical testing. For instance, P300-based VA mirrors psychophysical deficits in amblyopia better than VEP-based methods. The P300 serves as a valuable objective complement to traditional visual electrophysiology, bridging the gap between physiological stimulus processing and conscious perception. While challenges such as recording duration still need to be resolved, the ability to use custom-tailored stimuli offers significant potential for forensic evaluations and complex clinical cases in ophthalmology.

Quanz et al. (Sci Rep 14:16797, 2024) reported that participants with nystagmus had higher objective visual evoked potential visual acuity estimates (VAVEP) by 0.12 logMAR relative compared to standard psychophysical VA (VAPsych_Stat). The cause of this modest, but significant VAVEP overestimation remains unclear. Here we investigated its association with the pattern-pulse stimulation mode applied for steady state VEP recording for VAVEP estimation. Specifically, we tested whether psychophysical visual acuity to pulsed optotypes (VAPsych_Pulsed) also exceeds standard optotype VAPsych_Stat. Twelve participants with nystagmus were included in this analysis. VAVEP was determined for pattern-pulse steady-state VEP stimulation (Quanz et al. in Sci Rep 14:16797, 2024) using EP2000, psychophysical VA was determined to stationary (VAPsych_Stat) and to pulsed (VAPsych_Pulsed) Landolt-C optotypes employing a modified version of the Freiburg Vision Test (FrACT). Pulsed stimulus timing was identical for VEP and VA (40 ms on and 93 ms off, i.e. at 7.5 Hz). In a separate measurement, fixation stability within the central 4° was determined using microperimetry (Nidek MP‐1), and the eye with the stronger fixation instability was selected for the analysis (12 eyes). LogMAR differences were assessed with a paired t-test and the correlation of fixation stability and VA differences (ΔVAPsych = VAPsych_Pulsed – VAPsych_Stat) was tested. VAPsych_Stat (0.43 ± 0.06 logMAR) and VAPsych_Pulsed (0.45 ± 0.06 logMAR, P = 0.15) did not differ from each other, but from VAVEP (0.26 ± 0.08 logMAR, P = 0.02 and P = 0.01, respectively). There was no correlation of ΔVAPsych with fixation instability (r2 = 0.002, P = 0.89). Pulsed stimulation appears not to be the reason for the VAVEP overestimation in nystagmus. Further research should address whether differences in the spatial stimulus properties might be of relevance, as VAPsych is tested with optotypes, VAVEP with extended patterns.

Aims/Purpose: Cross‐sectional study to compare testability and performance of the Freiburg Visual Acuity Test (FrACT) and LEA Symbols Test (LEA) and to determine test–retest variability of visual acuities (VAs) achieved with the FrACT in preschool children. Methods: Monocular VA of both eyes was measured in 136 preschool children (268 eyes) aged 3.0 to 6.8 years – once with the LEA and twice with a 4‐orientation Landolt C version of the FrACT. The monocular FrACT runs were preceded by a binocular run for explanatory purposes. The test order alternated between subjects. Optotypes were presented either on a computer monitor (FrACT) or on cards (Lighthouse Single Symbol Book; LEA) at a distance of 3 m. Results: The overall testability of children was 70.1% for FrACT (188 of 268 eyes) and 90.3% for LEA (242 of 268 eyes). Testability depended markedly on age, with children aged <4 years at 23.0% (FrACT), 73.0% (LEA); ≥ 4 years: 88.1% (FrACT), 96.9% (LEA). The mean VA difference between FrACT and LEA was 0.11 LogMAR, with LEA reporting better acuity. The difference depended on age, with children aged <4 years exhibiting greater VA differences (0.27 LogMAR) while differences were smaller in children aged ≥4 years (0.09 LogMAR); in an additional adult control group the VA values of LEA and FrACT were even closer with 0.02 LogMAR mean difference. The 95% limits of agreement of test–retest‐variability of VAs in the FrACT were ± 0.29 LogMAR with a bias of 0.017 LogMAR (better acuity for the first test run). Conclusions: The FrACT, as an examiner‐independent tool using international reference Landolt C optotypes, can be reliably used to assess VA in preschool children aged 4 years and older. We confirm that the LEA Symbols Test reports better acuity than tests based on Landolt rings.

AbstractThis study investigated gaze behavior during visuo-cognitive-motor tasks with a change of movement direction in glaucoma patients and healthy controls. Nineteen glaucoma patients (10 females, 9 males) and 30 healthy sighted controls (17 females, 13 males) participated in this cross-sectional study. Participants performed two visuo-cognitive-motor tasks with a change of movement direction: (i) the “Speed-Court-Test” that involved stepping on different sensors in response to a visual sign displayed on either a large or small screen (165″ and 55″, respectively); (ii) the “Trail-Walking-Test” that required walking to 15 cones labeled with numbers (1–8) or letters (A-G) in an alternately ascending order. During these tasks, the time needed for completing each task was determined and the gaze behavior (e.g., saccade duration, fixation duration) was recorded via eye tracking. Data were analyzed with repeated measures analyses of covariance (ANCOVA; GROUP × SCREEN) and one-way ANCOVA. No differences between groups were found for the time needed to complete the tasks. However, during the “Trail-Walking-Test”, the fixation duration was longer for glaucoma patients than for controls (p = 0.016, $${\upeta }_{\text{p}}^{2}$$ η p 2 = 0.131). Furthermore, during the “Speed-Court-Test”, there was a screen size effect. Irrespective of group, saccade amplitudes were lower (p < 0.001, $${\upeta }_{\text{p}}^{2}$$ η p 2 = 0.242) and fixation durations were higher (p = 0.021, $${\upeta }_{\text{p}}^{2}$$ η p 2 = 0.125) for the small screen. Fixation durations were longer in glaucoma patients during the cognitively demanding “Trail-Walking-Test”, which might indicate a strategy to compensate for their visual impairment.

The pattern electroretinogram (PERG) is a localized retinal response evoked by a contrast-reversing pattern, usually a black and white checkerboard, which provides information about macular and retinal ganglion cell function. This document, from the International Society for Clinical Electrophysiology of Vision (ISCEV; www.iscev.org ) presents an updated and revised Standard for clinical PERG testing. This replaces the 2013 and all earlier versions. Minimum protocols for basic PERG stimuli, recording methods and reporting are specified, to promote consistency of methods for diagnosis and monitoring purposes, while responding to evolving clinical practices and technology. The main changes in the updated ISCEV Standard for clinical PERG include expanded guidance about large stimulus fields, stimulus parameters for simultaneous PERG and pattern visual evoked potential recording, baseline drift correction, and use of consistent ambient room lighting. These changes aim to provide a clinically relevant document about current practice which will facilitate good quality recordings and inter-laboratory comparisons.

Abstract In order to determine the effect of nystagmus on objective visual acuity (VA) estimates, we compared subjective (VApsych) and objective (VEP, VAVEP) VA estimates in participants with nystagmus. For this purpose, 20 participants with nystagmus (NY) caused by idiopathic infantile nystagmus, albinism, achiasma or acquired nystagmus were recruited in this study. Estimates of BCVA (best corrected visual acuity) were determined psychophysically (VApsych; FrACT, Freiburg visual acuity test) and electrophysiologically (VAVEP; EP2000) according to ISCEV (International Society of Clinical Electrophysiology of Vision) guidelines. For each participant the eye with the stronger fixation instability [Nidek microperimeter (MP-1), Nidek Instruments] was included for further analysis. VApsych vs VAVEP were compared via paired t-tests and the correlation of the difference between VApsych and VAVEP (∆VA) vs the degree of fixation instability was tested with Pearson correlation (r). We found VAVEP to be better than VApsych [by 0.12 Logarithm of the Minimum Angle of Resolution (logMAR); mean ± standard error (SE) of VAVEP vs VApsych: 0.176 ± 0.06 vs. 0.299 ± 0.06, P = 0.017] and ∆VA to be correlated linearly with the degree of fixation instability (r2 = 0.21,p = 0.048). In conclusion, on average we report a small VA overestimation, around 1 line, for VAVEP compared to VApsych in NY. This overestimation depended on the magnitude of the fixation instability. As a rule of thumb, a reduction of the fixation probability in the central 4° from 100 to 50% leads on average to a VAVEP overestimation of around 0.25 logMAR, i.e. 2.5 lines.

AbstractPrevious pattern electroretinogram studies indicate reduced retinal contrast gain in patients with a major depressive disorder (MDD) which may contribute to alterations in visual perception. In line, psychophysical investigations reported elevated contrast thresholds in MDD. This study aims to gain insights into higher-level processing of visual information in MDD by evaluating contrast suppression. We examined contrast suppression of 21 MDD patients and 23 healthy controls (HC) using four different stimulus conditions (spatial frequencies 6.3 and 12.6 cpd at 30% and 60% background contrast) in a psychophysical test. Participants were instructed to adjust perceived contrasts between two vertical target patches, embedded in a horizontally or vertically oriented grid background. With finer stimulus gratings, MDD patients exhibited less contrast suppression compared to HC, particularly when the stimulus contrast was high (p = 0.006; MDD vs. HC = − 45%). Contrast suppression in the HC group was significantly reduced for the coarse compared to the fine grating, while contrast suppression scores in MDD did not change with the spatial properties of the stimulus. The reduced contrast suppression in patients with MDD supports the hypothesis of altered dopaminergic neurotransmission and could be attributed to alterations in the retinal receptive fields or in dysfunctional adaptation mechanisms in depression.

Purpose:The purpose of this study was to determine and compare binocularsummation (BiS) of conventional visual acuity (cVA) versus hyperacuity (hVA) forphotopic and scotopic luminance conditions as a potential biomarker to assess theoutcome of interventions on binocular function. Methods: Sixteen young adults (age range [years] = 21-31; 8 women; cVA logMAR < 0.0) participated in this study. The Freiburg Visual Acuity Test (FrACT) was used for VA testing and retested on another day. Both cVA and hVA were determined for dark grey optotypes on light grey background. Participants underwent 40 minutes of dark adaptation prior to scotopic VA testing. Binocular and monocular VA testing was performed. The eye with better VA over the 2 days of testing was selected, the BiS was quantified (binocular VA - better monocular VA) and repeated measures ANOVAs were performed. Results: Binocular VA exceeded monocular VA for all luminance conditions, VA-types, and sessions. We report BiS estimates for photopic and scotopic cVA and hVA, (logMAR BiS +/- SEM [decimal BiS]): photopic = -0.01 +/- 0.01 [1.03] and -0.06 +/- 0.03 [1.15]; and scotopic = -0.05 +/- 0.01 [1.12] and -0.11 +/- 0.04 [1.28], respectively). Improvement for binocular vision estimates ranged from 0.01 to 0.11 logMAR. A repeated-measures ANOVA (RM ANOVA) did not reveal significant effects of LUMINANCE or VA TYPE on BiS, albeit a trend for strongest BiS for scotopic hVA (15% vs. 28%, photopic versus scotopic, respectively) and weakest for photopic cVA (3% vs. 12%, photopic versus scotopic conditions, respectively). Conclusions: Our results indicate that BiS of VA is relevant to scotopic and photopic hVA and cVA. It appears therefore a plausible candidate biomarker to assess the outcome of retinal therapies restoring rod or cone function on binocular vision.

Background Intraocular pressure (IOP) monitoring in glaucoma management is evolving with novel devices. We investigated the reproducibility of 24 hour profiles on two consecutive days and after 30 days of self-measurements via telemetric IOP monitoring. Methods Seven primary patients with open-angle glaucoma previously implanted with a telemetric IOP sensor in one eye underwent automatic measurements throughout 24 hours on two consecutive days ('day 1' and 'day 2'). Patients wore an antenna adjacent to the study eye connected to a reader device to record IOP every 5 min. Also, self-measurements in six of seven patients were collected for a period of 30 days. Analysis included calculation of hourly averages to correlate time-pairs of day 1 versus day 2 and the self-measurements vers day 2. Results The number of IOP measurements per patient ranged between 151 and 268 on day 1, 175 and 268 on day 2 and 19 and 1236 during 30 days of self-measurements. IOP time-pairs of automatic measurements on day 1 and day 2 were significantly correlated at the group level (R=0.83, p<0.001) and in four individual patients (1, 2, 6 and 7). IOP time-pairs of self-measurements and day 2 were significantly correlated at the group level (R=0.4, p<0.001) and in four individual patients (2, 5, 6 and 7). Conclusions Twenty-four hour automatic measurements of IOP are correlated on consecutive days and, though to a lesser degree, with self-measurements. Therefore a virtual 24-hour IOP curve might be constructed from self-measurements. Both options provide an alternative to frequent in-office IOP measurements.

PURPOSE . Our primary aim was to compare adult full -field ERG (ffERG) responses in albinism, idiopathic infantile nystagmus (IIN), and controls. A secondary aim was to investigate the effect of within -subject changes in nystagmus eye movements on ffERG responses. METHODS . Dilated Ganzfeld flash ffERG responses were recorded using DTL electrodes under conditions of dark (standard and dim flash) and light adaptation in 68 participants with albinism, 43 with IIN, and 24 controls. For the primary aim, the effect of group and age on ffERG responses was investigated. For the secondary aim, null region characteristics were determined using eye movements recorded prior to ffERG recordings. ffERG responses were recorded near and away from the null regions of 18 participants also measuring the success rate of recordings. RESULTS . For the primary aim, age -adjusted photopic a- and b -wave amplitudes were consistently smaller in IIN compared with controls ( P < 0.0001), with responses in both groups decreasing with age. In contrast, photopic a -wave amplitudes increased with age in albinism ( P = 0.0035). For the secondary aim, more intense nystagmus significantly reduced the success rate of measurable responses. Within -subject changes in nystagmus intensity generated small, borderline significant differences in photopic b -wave peak times and a -and b -wave amplitudes under scotopic conditions with standard flash. CONCLUSIONS . Age -adjusted photopic ffERG responses are significantly reduced in IIN adding to the growing body of evidence of retinal abnormalities in IIN. Differences between photopic responses in albinism and controls depend on age. Success at obtaining ffERG responses could be improved by recording responses at the null region.

Purpose:To determine the testability, performance, and test-retest variability (TRV) of visual acuity (VA) assessment using the Freiburg Visual Acuity Test (FrACT) compared to the LEA Symbols Test (LEA) in preschool children. Methods:In 134 preschool children aged 3.0 to 6.8 years, monocular VA of each eye was measured twice with a four-orientation Landolt C version of the FrACT and once with the LEA. FrACT runs were preceded by a binocular run for explanatory purposes. Test order alternated between subjects. Optotypes were presented on a computer monitor (FrACT) or on cards (LEA) at a distance of 3 m. Results:Overall, 68% completed the FrACT (91/134 children) and 88% completed the LEA (118/134 children). Testability depended on age: FrACT, 19% (<4 years) and 87% (≥4 years); LEA, 70% (<4 years) and 95% (≥4 years). Mean ± SD VA difference between tests was 0.11 ± 0.19 logarithm of the minimum angle of resolution [logMAR], with LEA reporting better acuity. The difference depended on age (0.27 ± 0.23 logMAR [<4 years], 0.09 ± 0.18 logMAR [≥4 years], P < 0.001) and on test sequence (higher age dependence of FrACT VAs for LEA first, P < 0.001). The 95% limits of agreement for the FrACT TRV were ±0.298 logMAR. Conclusions:The examiner-independent FrACT, using international reference Landolt C optotypes, can be used to assess VA in preschool children aged ≥4 years, with reliability comparable to other pediatric VA tests. Translational Relevance:Use of the automated FrACT for VA assessment in preschool children may benefit objectivity and validity as it is a computerized test and employs the international reference Landolt C optotype.

AbstractThe Rapid Campimetry (RC), a kinetic visual field test proved to reliably detect visual field defects within the central 10° degrees, the most crucial part for visual acuity and quality of life, affected even at very early stages of glaucoma, within a short measurement epoch, ~ 1 min. This study aims to further investigate RC correspondence with standard tests in glaucoma, namely standard automated perimetry (SAP) and optical coherence tomography (OCT) within 10° of visual field (VF). For this purpose, we included 41 participants, [21 glaucoma (GLA, mean age: 65.9 ± 12.4; 12 preperimetric eyes and 11 with VF defects) and 20 healthy controls (HC; mean age: 65.0 ± 10.3); 20 eyes]. At first, we compared the rate of detection/exclusion of VF defects in RC vs. SAP. Then, for those with VF defects (11 eyes), we investigated the 68-pointwise correspondence of 10 − 2 layout of RC and SAP. For functional and structural (SF) correspondence, pointwise correspondence of RC, SAP vs. OCTmacula [ macular ganglion cell thickness (GCL)] was also performed. Further, we compared sector-based correspondence of RC, SAP vs. OCTmacula accounting for GCL displacement at the fovea as well as sector-based correspondence with OCTdisc [peripapillary retinal nerve fiber layer thickness (pRNFL)]. Agreement estimates were reported along with Cohen Kappa ($$\:\kappa\:$$) statistic. For overall performance, RC and SAP showed 100% agreement ($$\:\kappa\:=1$$) for the exclusion of VF defects (HC and preperimetric GLA) and for detection of VF defects [11 eyes of 9 GLA, ($$\:\kappa\:=1)$$]. Further, RC outperformed SAP in detection of arcuate scotomas, 7 vs. 5, respectively. Pointwise correspondence of VF defects (11 eyes), RC-SAP agreement reached 90% accuracy ($$\:\kappa\:=0.77,\:substantial\:agreement$$). For SF correspondence, RC [SAP] showed 62% [69%] pointwise agreement with OCTmacula, ($$\:\kappa\:=0.10\:\left[0.33\right]$$). For macular sector-based correspondence, SF correspondence improved and reached 83% [83%] agreement, ($$\:\kappa\:=0.57\:\left[0.57\right]$$). For OCTdisc sector-based analysis, SF correspondence was highest, 100% [100%] agreement, ($$\:\kappa\:=1\:\left[1\right]$$). Rapid Campimetry gave reproducible results in comparison to SAP and OCT with high potential as a screening VF method given its short testing duration, ~ 1 min in screening mode, and compatibility with telemedicine technologies upon future optimization and automation.

Visual acuity is a psychophysical threshold that we want to determine as precisely and efficiently as possible. The Freiburg Vision Test FrACT employs the automated Bayesian “Best PEST” algorithm for this purpose: the next optotype size is always selected to be at threshold based on the information acquired so far, thereby maximizing information gain. We assessed the test–retest Limits of Agreement (LoA, Bland Altman 1986) across 6 to 48 trials in 2 × 78 runs involving 26 participants; visual acuity (in part artificially reduced) ranged from 1.22 to -0.59 LogMAR. LoA exhibited a steep decline from ± 0.46 LogMAR at six trials to ± 0.17 at 18 trials; with more trials, LoA showed less change, reaching ± 0.12 LogMAR at 48 trials. LoA did not significantly change over the wide acuity range assessed here. These findings suggest that 18 trials represent an efficient balance between precision and burden on the participant and examiner. This observation holds for the eight response alternatives used in this study (8 Landolt C orientations) and is anticipated to apply to the ten Sloan letters as well. With only four choices (e.g., tumbling E), more trials will be necessary. What is known What is new

L-cone opsin expression by gene therapy is a promising treatment for blue cone monochromacy (BCM) caused by congenital lack of long- and middle-wavelength-sensitive (L/M) cone function. Eight patients with BCM and confirmed pathogenic variants at the OPN1LW/OPN1MW gene cluster participated. Optical coherence tomography (OCT), chromatic perimetry, chromatic microperimetry, chromatic visual acuity (VA), and chromaticity thresholds were performed with unmodified commercial equipment and/or methods available in the public domain. Adaptive optics scanning laser ophthalmoscope (AOSLO) imaging was performed in a subset of patients. Outer retinal changes were detectable by OCT with an age-related effect on the foveal disease stage. Rod and short-wavelength-sensitive (S) cone functions were relatively retained by perimetry, although likely impacted by age-related increases in the pre-retinal absorption of short-wavelength lights. The central macula showed a large loss of red sensitivity on dark-adapted microperimetry. Chromatic VAs with high-contrast red gratings on a blue background were not detectable. Color vision was severely deficient. AOSLO imaging showed reduced total cone density with majority of the population being non-waveguiding. This study developed and evaluated specialized outcomes that will be needed for the determination of efficacy and safety in human clinical trials. Dark-adapted microperimetry with a red stimulus sampling the central macula would be a key endpoint to evaluate the light sensitivity improvements. VA changes specific to L-opsin can be measured with red gratings on a bright blue background and should also be considered as outcome measures in future interventional trials.

Purpose:Temporal-to-nasal macular ganglion cell layer thickness ratios are reduced in albinism. We explored similar ratios in a large twin cohort to investigate ranges in healthy adults, correlations with age, and heritability. Methods:More than 1000 twin pairs from TwinsUK underwent macular optical coherence tomography (OCT) scans. Automated segmentation yielded thicknesses for the combined ganglion cell and inner plexiform layer (GCIPL) in Early Treatment of Diabetic Retinopathy Study subfields. Participants with diseases likely to affect these layers or segmentation accuracy were excluded. Inner and outer ratios were defined as the ratio of temporal-to-nasal GCIPL thickness for inner and outer subfields respectively. Corresponding ratios were obtained from a smaller cohort undergoing OCTs with a different device (three-dimensional (3D)-OCT, Topcon, Japan). Results:Scans from 2300 twins (1150 pairs) were included (mean [SD] age, 53.9 (16.5) years). Mean (SD) inner and outer ratios were 0.89 (0.09) and 0.84 (0.11), correlating negatively with age (coefficients, -0.17 and -0.21, respectively). In males (150 pairs) ratios were higher and did not correlate significantly with age. Intrapair correlation coefficients were higher in monozygotic than dizygotic pairs; age-adjusted heritability estimates were 0.20 and 0.23 for inner and outer ratios, respectively. For the second cohort (n = 166), mean (SD) ratios were 0.93 (0.08) and 0.91 (0.09), significantly greater than for the larger cohort. Conclusions:Our study gives reference values for temporal-to-nasal macular GCIPL subfield ratios. Weak negative correlations with age emerged. Genetic factors may contribute to ∼20% to 23% of the variance in healthy individuals. The ratios differ according to the OCT platform used.

The electroretinogram (ERG), a non-invasive electrophysiological tool used in ophthalmology, is increasingly applied to investigate neural correlates of depression. The present study aimed to reconsider previous findings in major depressive disorder (MDD) reporting (1) a diminished contrast sensitivity and (2) a reduced patten ERG (PERG) amplitude ratio, and additionally, to assess (3) the photopic negative response (PhNR) from the flash ERG (fERG), with the RETeval® device, a more practical option for clinical routine use. We examined 30 patients with a MDD and 42 healthy controls (HC), assessing individual contrast sensitivity thresholds with an optotype-based contrast test. Moreover, we compared the PERG ratio, an established method for early glaucoma detection, between both groups. The handheld ERG device was used to measure amplitudes and peak times of the fERG components including a-wave, b-wave and PhNR in both MDD patients and HCs. MDD patients exhibited diminished contrast sensitivity together with a reduced PERG ratio, compared to HC. With the handheld ERG device, we found reduced a-wave amplitudes in MDD, whereas no significant differences were observed in the fERG b-wave or PhNR between patients and controls. The reduced contrast sensitivity and PERG ratio in MDD patients supports the hypothesis that depression is associated with altered visual processing. The findings underscore the PERG's potential as a possible objective marker for depression. The reduced a-wave amplitude recorded with the RETeval® system in MDD patients might open new avenues for using handheld ERG devices as simplified approaches for advancing depression research compared to the PERG.

BackgroundElectroretinograms (ERG) are usually recorded with non-invasive corneal electrodes, requiring direct contact with the ocular surface. However, corneal electrode application is not tolerated by some individuals. The advent of handheld ERG devices has facilitated the use of skin electrodes for ERG measurements. Skin electrodes do not require corneal contact and thus enhance patient comfort, simplify the attachment process, and reduce preparation time, which is particularly beneficial for clinical psychiatric research. Nevertheless, due to the different attachment methods, ERG amplitudes recorded with skin compared to corneal electrodes are considerably smaller. However, comparative data on ERGs recorded with skin vs. corneal electrodes in psychiatric populations are currently lacking.Materials and methodsWe recorded flash electroretinograms of 57 healthy controls (HC) and 30 patients with a major depressive disorder (MDD) using both sensor strip skin and corneal electrodes with the handheld RETeval® device.ResultsThe significant reduction in both the amplitude and peak time of the a-wave in MDD when using sensor strip skin electrodes could not be replicated with corneal electrodes. Comparing both electrode types in HC revealed a fair correlation between sensor strip and corneal electrodes for a- and b-wave amplitudes and a moderate correlation for a- and b-wave peak times.ConclusionIn addition to being better tolerated, sensor strip skin electrodes appear to be more effective than corneal electrodes in detecting ERG alterations in patients with MDD when using the RETeval® device, making them a promising alternative to traditional corneal electrodes.

Navigation is essential for moving between locations in our daily lives. We investigated the relationship between visual impairment in glaucoma and path-integration-based navigation. Fourteen glaucoma and 15 controls underwent ophthalmological examination (including visual acuity (logMAR), visual field sensitivity (MD: mean deviation from matched reference cohort), and peripapillary retinal nerve fiber layer (pRNFL)). Both groups navigated physically in virtual reality (VR) environments during daylight and dawn conditions. Briefly, the participants traversed a path marked by three targets, subsequently pointing back to the path’s origin. Outcome measures included (i) travel-time, (ii) pointing-time, and (iii) Euclidian-distance error between indicated and starting position. Robust linear regression was conducted between visual function outcomes of the better eye and VR outcome measures. Glaucoma patients showed increase in travel-time (by 8.2 ± 1.7 s; p = 0.002) and in pointing-time (by 5.3 ± 1.6 s; p = 0.016). Predictors were MD for all outcome measures (p < 0.01) and pRNFL for travel-time (p < 0.01). The results suggest that the effect of glaucoma on the elapsed time depends on disease progression, i.e. people with stronger visual impairment need more time. This uncertainty during everyday navigation tasks may adversely affect their quality of life.