Assessing the role of visual dysfunctions in the association between visual symptomatology and the use of digital devices / Evaluación del papel de las disfunciones visuales en la asociación entre la sintomatología visual y el uso de dispositivos digitales

Purpose: To evaluate the association between visual symptoms and use of digital devices considering the presence of visual dysfunctions. Methods: An optometric examination was conducted in a clinical sample of 346 patients to diagnose any type of visual anomaly. Visual symptoms were collected using the validated SQVD questionnaire. A threshold of 6 hours per day was used to quantify the effects of digital device usage and patients were divided into two groups: under and above of 35 years old. A multivariate logistic regression was employed to investigate the association between digital device use and symptoms, with visual dysfunctions considered as a confounding variable. Crude and the adjusted odds ratio (OR) were calculated for each variable. Results: 57.02 % of the subjects reported visual symptoms, and 65.02% exhibited some form of visual dysfunction. For patients under 35 years old, an association was found between having visual symptoms and digital device use (OR = 2.10, p = 0.01). However, after adjusting for visual dysfunctions, this association disappeared (OR = 1.44, p = 0.27) and the association was instead between symptoms and refractive dysfunction (OR = 6.52, p < 0.001), accommodative (OR = 10.47, p < 0.001), binocular (OR = 6.68, p < 0.001) and accommodative plus binocular dysfunctions (OR = 46.84, p < 0.001). Among patients over 35 years old, no association was found between symptoms and the use of digital devices (OR = 1.27, p = 0.49) but there was an association between symptoms and refractive dysfunction (OR = 3.54, p = 0.001). Conclusions: Visual symptoms are not dependent on the duration of digital device use but rather on the presence of any type of visual dysfunction: refractive, accommodative and/or binocular one, which should be diagnosed.(AU)

What does visual snow look like? Quantification by matching a simulation.

The primary symptom of visual snow syndrome (VSS) is the unremitting perception of small, flickering dots covering the visual field. VSS is a serious but poorly understood condition that can interfere with daily tasks. Several studies have provided qualitative data about the appearance of visual snow, but methods to quantify the symptom are lacking. Here, we developed a task in which participants with VSS adjusted parameters of simulated visual snow on a computer monitor until the simulation matched their internal visual snow. On each trial, participants (n = 31 with VSS) modified the size, density, update speed, and contrast of the simulation. Participants' settings were highly reliable across trials (intraclass correlation coefficients > 0.89), and they reported that the task was effective at stimulating their visual snow. On average, visual snow was very small (less than 2 arcmin in diameter), updated quickly (mean temporal frequency = 18.2 Hz), had low density (mean snow elements vs. background = 2.87%), and had low contrast (average root mean square contrast = 2.56%). Our task provided a quantitative assessment of visual snow percepts, which may help individuals with VSS communicate their experience to others, facilitate assessment of treatment efficacy, and further our understanding of the trajectory of symptoms, as well as the neural origins of VSS.

[Role of point-by-point light sensitivity in the assessment of glaucoma progression]. / Rol' potochechnoi svetochuvstvitel'nosti v otsenke progressirovaniya glaukomy.

PURPOSE: This study analyzes changes in light sensitivity in each test point of the visual field in patients with different stages of glaucoma. MATERIAL AND METHODS: The data of a prospective analytical case-control study were analyzed. All patients underwent assessment of retinal light sensitivity and its variability in 54 points corresponding to the 24-2 program. Mean light sensitivity values were calculated in each point. Intergroup analysis was performed to evaluate changes in light sensitivity in each point. RESULTS: The range of light sensitivity decrease in the early glaucoma group compared to the control group was from 1.5 to 3.6 dB. The range of light sensitivity decrease in the moderate glaucoma group compared to the control group was from 2.1 to 11.5 dB, and compared to the early glaucoma group - from -0.9 to 7.9 dB. The most frequent decrease in light sensitivity was detected in the nasal sector and along the horizontal line in the upper half of the visual field. This trend persisted within the central 10 degrees of the visual field. The range of light sensitivity decrease in the advanced glaucoma group compared to the control group was from 14.1 to 28.0 dB, and compared to the early glaucoma group - from 11.35 to 26.08 dB, compared to the moderate glaucoma group - from 9.1 to 23.5 dB. The most frequent and severe decrease in light sensitivity was detected in the paracentral zone in the lower half of the visual field. CONCLUSION: The study analyzed the trends in the development of glaucoma from the early to the advanced stage. The most frequent and severe defect in light sensitivity in cases of verified advanced glaucoma was found in the lower half of the visual field. Points No. 32, 33 and 40 can be indicated as the area of interest in assessing the progression of glaucoma, as they were found to have the most profound changes in light sensitivity as glaucoma progressed.

[Thresholds and variability of retinal light sensitivity in each point of the examined visual field]. / Porogovye znacheniya i variabel'nost' svetochuvstvitel'nosti setchatki v kazhdoi tochke issleduemogo polya zreniya.

PURPOSE: This study assesses the light sensitivity and its variability in each point of the visual field in patients without glaucoma and with different stages of glaucoma. MATERIAL AND METHODS: The data of a prospective analytical case-control study involving 500 patients were analyzed. The initial examination of all patients was performed using basic ophthalmological methods, including static perimetry. Retinal light sensitivity and its variability were assessed in 54 points corresponding to the Humphrey 24-2 program. Mean deviation and pattern standard deviation of light sensitivity were calculated for each point. RESULTS: The lowest light sensitivity values in patients with moderate glaucoma were found in the periphery of the nasal sector, at point No. 27 - 14.4 dB, and at points No. 24-26 along the horizontal axis from the nasal side - from 17.7 to 22.7 dB. The maximum variability of light sensitivity was found in the nasal sector on both sides of the horizontal line - from 10.7 to 11.5 dB. The average light sensitivity above the horizontal axis in patients with advanced glaucoma was 10.8 dB, which is 2 dB higher than in the lower half of the visual field - 8.8 dB. The highest light sensitivity values were found at points No. 24 - 17.7 dB and No. 31 - 16.78 dB, the lowest - at point No. 32 - 4.5 dB. The average variability values of light sensitivity in the upper half of the visual field were 9.6 dB, which is 1 dB less than in the lower half of the visual field - 10.6 dB. CONCLUSION: According to our data, points No. 32 and No. 40 are of particular interest in the diagnostic plan. In these loci, the highest light sensitivity values were determined in early and moderate glaucoma. However, the values in these points decrease significantly in advanced glaucoma. It can be assumed that changes in light sensitivity in these loci at the early stages of glaucoma may be a predictor of glaucoma progression.

Subjective perception of visual field defects using random noise-moving images in patients with glaucoma: A comparison of computer graphics and analog noises.

PURPOSE: Random noise-moving images (noises) can make glaucoma patients with no subjective symptoms aware of visual field abnormalities. To explore this concept, we developed a noise using computer graphics (CG) and investigated the difference in the subjective perception of visual field abnormalities between CG and conventional analog noises. METHODS: We enrolled individuals with glaucoma (205 eyes), preperimetric glaucoma (PPG; 19 eyes), and normal eyes (35 eyes). For a CG noise, a series of still images was made by randomly selecting five monochromatic tones on 2-mm square dots, and these images were drawn at 60 frames per second (fps) to create a noise-moving image. The participants were asked to describe their perceived shadows on a paper. The results were categorized as follows based on the pattern deviation probability map of the Humphrey field analyzer (HFA): "agreement," "partial agreement," "disagreement," and "no response." The glaucoma stage was classified into four stages, from M1 to M4, based on the HFA's mean deviation. RESULT: The detection rates (agreement and partial agreement) were 80.5% and 65.4% for the CG and analog noises, respectively, with CG noise showing a significantly higher detection rate in all glaucoma eyes (P < 0.001). The detection rates tended to increase as the glaucoma stage progressed, and in Stage M3, these were 93.9% and 78.8% for the CG and analog noises, respectively. The PPG eyes did not exhibit subjective abnormalities for both noises. The specificity values were 97.1% and 100% for the CG and analog noises, respectively. CONCLUSION: The CG noise is more effective than the analog noise in evaluating the subjective perception of visual field abnormalities in patients with glaucoma.

Functional differences between the extraordinary eyes of deep-sea hyperiid amphipods.

The ocean's midwater is a uniquely challenging yet predictable and simple visual environment. The need to see without being seen in this dim, open habitat has led to extraordinary visual adaptations. To understand these adaptations, we compared the morphological and functional differences between the eyes of three hyperiid amphipods-Hyperia galba, Streetsia challengeri and Phronima sedentaria. Combining micro-CT data with computational modelling, we mapped visual field topography and predicted detection distances for visual targets viewed in different directions through mesopelagic depths. Hyperia's eyes provide a wide visual field optimized for spatial vision over short distances, while Phronima's and Streetsia's eyes have the potential to achieve greater sensitivity and longer detection distances using spatial summation. These improvements come at the cost of smaller visual fields, but this loss is compensated for by a second pair of eyes in Phronima and by behaviour in Streetsia. The need to improve sensitivity while minimizing visible eye size to maintain crypsis has likely driven the evolution of hyperiid eye diversity. Our results provide an integrative look at how these elusive animals have adapted to the unique visual challenges of the mesopelagic.

Lateralized displays reveal the perceptual locus of the syllable transposition effect in Korean.

Studies of letter transposition effects in alphabetic scripts provide compelling evidence that letter position is encoded flexibly during reading, potentially during an early, perceptual stage of visual word recognition. Recent studies additionally suggest similar flexibility in the spatial encoding of syllabic information in the Korean Hangul script. With the present research, we conducted two experiments to investigate the locus of this syllabic transposition effect. In Experiment 1, lexical decisions for foveal stimulus presentations were less accurate and slower for four-syllable nonwords created by transposing two syllables in a base word as compared to control nonwords, replicating prior evidence for a transposed syllable effect in Korean word recognition. In Experiment 2, the same stimuli were presented to the right and left visual hemifields (i.e., RVF and LVF), which project both unilaterally and contralaterally to each participant's left and right cerebral hemisphere (i.e., LH and RH) respectively, using lateralized stimulus displays. Lexical decisions revealed a syllable transposition effect in the accuracy and latency of lexical decisions for both RVF and LVF presentations. However, response times for correct responses were longer in the LVF, and therefore the RH, as compared to the RVF/LH. As the LVF/RH appears to be selectively sensitive to the visual-perceptual attributes of words, the findings suggest that this syllable transposition effect partly finds its locus within a perceptual stage of processing. We discuss these findings in relation to current models of the spatial encoding of orthographic information during visual word recognition and accounts of visual word recognition in Korean.

[Preliminary clinical observation and analysis of structural changes of optic nerve head in glaucoma patients after visual training].

Objective: To investigate the effect of virtual reality visual training on remodeling optic nerve structures of glaucoma patients and analyze the influencing factors of visual training effect. Methods: A prospective non-randomized controlled trial was conducted. Glaucoma patients who presented to the Department of Ophthalmology, Beijing Shijitan Hospital between October 2021 and October 2022 were collected and divided into the training group or the control group according to their intentions. The training group accepted 3 months of visual training, while the control group did not. Optical coherence tomography was used to examine the disc edge area, cup volume, disc area, cup-to-disc ratio, and other parameters of the optic disc of both eyes of the patients at enrollment and after 3 months, and the changes of each parameter in the two groups were analyzed. Multivariate analysis was performed in the training group to investigate the effects of sex, age, visual field index, and mean defect on visual disc structure changes during visual training. Results: A total of 53 glaucoma patients (101 eyes) were included in the final analysis, among which the training group consisted of 27 cases (51 eyes), with 19 males and 8 females, and the age range was 48.0 (40.0, 61.0) years old. The control group comprised 26 cases (50 eyes), with 26 males and 11 females, and the age range was 54.0 (38.0, 63.0) years old. Compared with the control group, the deviation of cup volume was -0.006(-0.050, 0.015)mm3 (P<0.05), and the deviation of disc edge area was 0.00(-0.04, 0.05)mm2 (P<0. 05)in the visual training group after 3 months of visual training. The gender (OR=4.217, 95%CI=1.188-14.966) may be the influence factor of rim area. While,the mean defect (OR=1.526, 95%CI=0.245-9.491) was not that influential on rim area change. Conclusions: Visual training can increase the disc area and decrease the optic cup volume of the optic nerve in glaucoma patients. The rim area may be increased more easily after visual training in male glaucoma patients.

Racial Differences in Diagnostic Accuracy of Retinal Nerve Fiber Layer Thickness in Primary Open-Angle Glaucoma.

Purpose: To evaluate the diagnostic accuracy of retinal nerve fiber layer thickness (RNFLT) by spectral-domain optical coherence tomography (OCT) in primary open-angle glaucoma (POAG) in eyes of African (AD) and European descent (ED). Design: Comparative diagnostic accuracy analysis by race. Participants: 379 healthy eyes (125 AD and 254 ED) and 442 glaucomatous eyes (226 AD and 216 ED) from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. Methods: Spectralis (Heidelberg Engineering GmbH) and Cirrus (Carl Zeiss Meditec) OCT scans were taken within one year from each other. Main Outcome Measures: Diagnostic accuracy of RNFLT measurements. Results: Diagnostic accuracy for Spectralis-RNFLT was significantly lower in eyes of AD compared to those of ED (area under the receiver operating curve [AUROC]: 0.85 and 0.91, respectively, P=0.04). Results for Cirrus-RNFLT were similar but did not reach statistical significance (AUROC: 0.86 and 0.90 in AD and ED, respectively, P =0.33). Adjustments for age, central corneal thickness, axial length, disc area, visual field mean deviation, and intraocular pressure yielded similar results. Conclusions: OCT-RNFLT has lower diagnostic accuracy in eyes of AD compared to those of ED. This finding was generally robust across two OCT instruments and remained after adjustment for many potential confounders. Further studies are needed to explore the potential sources of this difference.

The resolution of face perception varies systematically across the visual field.

Visual abilities tend to vary predictably across the visual field-for simple low-level stimuli, visibility is better along the horizontal vs. vertical meridian and in the lower vs. upper visual field. In contrast, face perception abilities have been reported to show either distinct or entirely idiosyncratic patterns of variation in peripheral vision, suggesting a dissociation between the spatial properties of low- and higher-level vision. To assess this link more clearly, we extended methods used in low-level vision to develop an acuity test for face perception, measuring the smallest size at which facial gender can be reliably judged in peripheral vision. In 3 experiments, we show the characteristic inversion effect, with better acuity for upright faces than inverted, demonstrating the engagement of high-level face-selective processes in peripheral vision. We also observe a clear advantage for gender acuity on the horizontal vs. vertical meridian and a smaller-but-consistent lower- vs. upper-field advantage. These visual field variations match those of low-level vision, indicating that higher-level face processing abilities either inherit or actively maintain the characteristic patterns of spatial selectivity found in early vision. The commonality of these spatial variations throughout the visual hierarchy means that the location of faces in our visual field systematically influences our perception of them.

Multimodal Structural and Functional Characterization of Retinal Vasculopathy with Cerebral Leukoencephalopathy.

OBJECTIVE: To describe and quantify the structural and functional consequences of retinal vasculopathy with cerebral leukoencephalopathy (RVCL) on the neurosensory retina. DESIGN: Cross sectional descriptive study from December 2021 to December 2022. PARTICIPANTS: Retinal vasculopathy with cerebral leukoencephalopathy patients (n = 9, 18 eyes) recruited from the RVCL Research Center at Washington University in St. Louis. METHODS: Retinal vasculopathy with cerebral leukoencephalopathy patients underwent comprehensive ophthalmological evaluation including OCT, OCT angiography (OCTA), ultrawidefield fundus imaging, retinal autofluorescence, dark adaptation, electroretinography (ERG), Goldmann kinetic perimetry, and fluorescein angiography (FA). MAIN OUTCOME MEASURES: Comprehensive characterization from various modalities including best-corrected visual acuity, central subfield thickness (µm) from OCT, foveal avascular zone (mm2) from OCTA, dark adaptation rod intercept (seconds), cone response in ERG, and presence or absence of vascular abnormalities, leakage, neovascularization, and nonperfusion on FA. RESULTS: A total of 18 eyes from 9 individuals were included in this study. The best-corrected visual acuity ranged from 20/15 to 20/70. The mean central subfield thickness from OCT was 275.8 µm (range, 217-488 µm). The mean foveal avascular zone (FAZ) from OCTA was 0.65 (range, 0.18-1.76) mm2. On dark adaptometry, the mean time was 5.02 (range, 2.9-6.5) minutes, and 1 individual had impaired dark adaptation. Electroretinography demonstrated mild cone response impairment in 4 eyes. On FA, there was evidence of macular and peripheral capillary nonperfusion in 16 of 18 eyes and notable areas of vascular leakage and retinal edema in 5 of the 18 eyes. CONCLUSIONS: This study illustrates the phenotypic spectrum of disease and may be clinically valuable for aiding diagnosis, monitoring disease progression, and further elucidating the pathophysiology of RVCL to aid in the development of therapies. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

[INTERVENTIONAL GLAUCOMA - A SHIFT IN THE TREATMENT PARADIGM].

INTRODUCTION: Glaucoma is a progressive optic neuropathy and is the leading cause of preventable irreversible blindness worldwide. Glaucoma causes progressive visual field loss and can have significant implications on the patient's quality of life. Lowering intraocular pressure (IOP) is the only treatment proven to prevent vision loss from glaucoma. It is achieved using medication, laser treatment and surgery. The treatment paradigm of glaucoma has been one whereby surgical intervention has been left for advanced cases due to a variety of reasons, mainly concerning safety and long term success. The past two decades have seen a paradigm shift towards earlier IOP lowering interventions using a wide array of different technologies in the laser and surgical spaces. This review aims to understand the background to this paradigm shift, its necessity, and its potential impact on the vision and life of glaucoma patients.

Evaluation of optical coherence tomography findings in patients with multiple sclerosis and glaucoma.

PURPOSE: Glaucoma and multiple sclerosis (MS) can cause optic disc pathology and, in this way, affect optical coherence tomography (OCT) data. In this context, the objective of this study is to investigate the changes in the mean, quadrant, and sector data measured by OCT in glaucoma and MS patients. METHODS: The sample of this prospective cohort study consisted of 42 MS patients (84 eyes), 34 Primary open-angle glaucomas patients (67 eyes), and 24 healthy control subjects (48 eyes). The MS group was divided into two groups according to the presence of a history of optic neuritis. Accordingly, those with a history of optic neuritis were included in the MS ON group, and those without a history of optic neuritis were included in the MS NON group. The differences between these groups in the mean, quadrant, and sector data related to the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) were evaluated. RESULTS: Superior nasal (SN), superior temporal (ST), inferior nasal (IN), and superior quadrant (SUP) values were significantly lower in the glaucoma group than in the MS group (p < 0.05). The mean superior GCC (GCC SUP) value was significantly lower in the MS ON group than in the glaucoma group (p < 0.05). On the other hand, SN, ST, inferior temporal (IT), IN, average RNFL (AVE RNFL), semi-average superior RNFL (SUP AVE RNFL), semi-average inferior RNFL (INF AVE RNFL), SUP, and inferior quadrant RNFL (INF) values were significantly lower in the glaucoma group than in the MS NON group (p < 0.05). CONCLUSION: RNFL and GCC parameters get thinner in MS and glaucoma patients. While the inferior and superior RNFL quadrants are more frequently affected in glaucoma patients, the affected quadrants vary according to the presence of a history of optic neuritis in MS patients. It is noteworthy that the GCC superior quadrant was thin in MS ON patients. The findings of this study indicate that OCT data may be valuable in the differential diagnosis of glaucoma and MS.

Associations of long-term fluctuation in blood pressure and ocular perfusion pressure with visual field progression in normal-tension glaucoma.

BACKGROUD: The aim of this study was to investigate the associations between fluctuation in blood pressure (BP), ocular perfusion pressure (OPP) and visual field (VF) progression in normal-tension glaucoma (NTG). METHODS: This prospective, longitudinal study included 44 patients with NTG. Only newly diagnosed NTG patients who had not been treated with a glaucoma medication were included. Patients were examined every year for 7 years. Intraocular pressure (IOP), heart rate (HR), systolic BP (SBP), diastolic BP (DBP), ocular perfusion pressure (OPP), and diastolic ocular perfusion pressure (DOPP) were measured at the same time. Ophthalmic examinations, including perimetry, were performed also. Initial VF were compared with follow-up data after 7 years. RESULTS: After 7 years of follow-up, 9 of the 44 patients showed VF progression. The standard deviation (SD) of SBP and OPP were significantly associated with VF progression (P = 0.007, < 0.001, respectively). Multiple regression analysis showed that VF progression was significantly associated with SD of OPP (odds ratio, OR = 2.012, 95% CI = 1.016-3.985; P = 0.045). CONCLUSIONS: Fluctuation in OPP was associated with VF progression in patients with NTG.

ASSOCIATION OF MACULAR STRUCTURE WITH MICROPERIMETRY SENSITIVITY FOLLOWING VITRECTOMY FOR PROLIFERATE DIABETIC RETINOPATHY.

PURPOSE: To evaluate macular sensitivity using microperimetry in patients with proliferate diabetic retinopathy following vitrectomy and to investigate the relationship between the sensitivity and foveal microstructures with optical coherence tomography/angiography. METHODS: Eighty-four eyes of 84 patients with proliferative diabetic retinopathy, who were indicated for vitrectomy, had no intraocular surgery history 3 months preoperatively, and were able to ensure fundus examination after the vitrectomy, were included. A logMAR best-corrected visual acuity, macular sensitivity of microperimetry, macular retinal thickness, and macular vessel perfusion using optical coherence tomography/angiography were examined at 1 week, 1 month, and 3 months postoperatively. RESULTS: The logMAR best-corrected visual acuity and mean macular sensitivity of patients with proliferative diabetic retinopathy improved postoperatively (P < 0.05). There was a significant correlation between best-corrected visual acuity and mean sensitivity (P < 0.05). Postoperative mean macular sensitivity was significantly correlated with outer retinal thickness in the 0 to 6 mm macular area (P < 0.05) and also significantly correlated with deep capillary plexus perfusion (P < 0.05). Fixation stability and mean macular sensitivity did not show any correlation with glycated hemoglobin, triglyceride, serum total cholesterol, carbamide, and creatinine and duration of diabetes mellitus (P > 0.05). CONCLUSION: Postoperative mean macular sensitivity was significantly correlated with outer retinal thickness and deep capillary plexus perfusion for patients with proliferative diabetic retinopathy. The authors found that the visual performance of patients can be evaluated by the outer retinal thickness and deep capillary plexus perfusion, so optical coherence tomography/angiography examination can be an important prognostic factor for visual performance in patients.Clinical Trial Registration: This trial is registered with the Chinese Clinical Trial Registry (http://www.chictr.org.cn; Registration No.: ChiCTR2100043399).

Contrast Discrimination and Global Form Perception in Primary Open-Angle Glaucoma and Primary Angle-Closure Glaucoma.

Purpose: This study explored early (contrast discrimination) and intermediate (global form perception) visual processing in primary subtypes of glaucoma: primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). We aimed to understand early and intermediate visual processing in POAG and PACG, matched for similar visual field defect severity. Methods: Early visual processing was measured using a contrast discrimination task described by Porkorny and Smith (1997), and intermediate processing using a global form perception task using glass pattern coherence thresholds. Thresholds were determined centrally and at a single midperipheral location (12.5°) in a quadrant without visual field defects. Controls were tested in corresponding quadrants to individuals with glaucoma. Results: Sixty participants (20 POAG, 20 PACG, and 20 age-matched controls), aged 50 to 77 years, were included. Visual field defects were matched between POAG and PACG, with mean deviation values of -6.53 ± 4.46 (range: -1.5 to -16.85) dB and -6.2 ± 4.24 (range: -1.37 to -16.42) dB, respectively. Two-Way ANOVA revealed significant differences in thresholds between the glaucoma groups and the control group for both contrast discrimination and global form perception tasks, with higher thresholds in the glaucoma groups. Post hoc analyses showed no significant contrast discrimination difference between POAG and PACG, but POAG had significantly higher thresholds than PACG for form perception. Conclusions: In form perception, POAG showed slightly worse performance than PACG, suggesting that individuals with POAG may experience more severe functional damage than PACG of similar visual field severity.

Training-induced changes in population receptive field properties in visual cortex: Impact of eccentric vision training on population receptive field properties and the crowding effect.

This study aimed to investigate the impact of eccentric-vision training on population receptive field (pRF) estimates to provide insights into brain plasticity processes driven by practice. Fifteen participants underwent functional magnetic resonance imaging (fMRI) measurements before and after behavioral training on a visual crowding task, where the relative orientation of the opening (gap position: up/down, left/right) in a Landolt C optotype had to be discriminated in the presence of flanking ring stimuli. Drifting checkerboard bar stimuli were used for pRF size estimation in multiple regions of interest (ROIs): dorsal-V1 (dV1), dorsal-V2 (dV2), ventral-V1 (vV1), and ventral-V2 (vV2), including the visual cortex region corresponding to the trained retinal location. pRF estimates in V1 and V2 were obtained along eccentricities from 0.5° to 9°. Statistical analyses revealed a significant decrease of the crowding anisotropy index (p = 0.009) after training, indicating improvement on crowding task performance following training. Notably, pRF sizes at and near the trained location decreased significantly (p = 0.005). Dorsal and ventral V2 exhibited significant pRF size reductions, especially at eccentricities where the training stimuli were presented (p < 0.001). In contrast, no significant changes in pRF estimates were found in either vV1 (p = 0.181) or dV1 (p = 0.055) voxels. These findings suggest that practice on a crowding task can lead to a reduction of pRF sizes in trained visual cortex, particularly in V2, highlighting the plasticity and adaptability of the adult visual system induced by prolonged training.

Effects of post-saccadic oscillations on visual processing times.

Saccadic eye movements enable us to search for the target of interest in a crowded scene or, in the case of goal-directed saccades, to simply bring the image of the peripheral target to the very centre of the fovea. This mechanism extends the use of the superior image processing performance of the fovea over a large visual field. We know that visual information is processed quickly at the end of each saccade but estimates of the times involved remain controversial. This study aims to investigate the processing of visual information during post fixation oscillations of the eyeball. A new psychophysical test measures the combined eye movement response latencies, including fixation duration and visual processing times. When the test is used in conjunction with an eye tracker, each component that makes up the 'integrated saccade latency' time, from the onset of the peripheral stimulus to the correct interpretation of the information carried by the stimulus, can be measured and the discrete components delineated. The results show that the time required to process and encode the stimulus attribute of interest at the end of a saccade is longer than the time needed to carry out the same task in the absence of an eye movement. We propose two principal hypotheses, each of which can account for this finding. 1. The known inhibition of afferent retinal signals during fast eye movements extends beyond the end point of the saccade. 2. The extended visual processing times measured when saccades are involved are caused by the transient loss of spatial resolution due to eyeball instability during post-saccadic oscillations. The latter can best be described as retinal image smear with greater loss of spatial resolution expected for stimuli of low luminance contrast.

Measuring Visual Fields in Children With Glaucoma Using a Portable Tablet.

Purpose: To compare perimetric outcomes of an iPad perimetry app (Melbourne Rapid Fields [MRF]) with those of the Humphrey Field Analyser (HFA) testing children with glaucoma. Methods: Sixteen children diagnosed and treated for glaucoma were recruited to evaluate their perimetric performance over two visits. At each visit, they undertook visual field assessment using the MRF application as well as the HFA. The HFA test was part of their usual clinical work up and a clinical assistant judged which test format (24-2 SITA standard or SITA fast) might be suited to the testing of that child. The primary outcome measure was the association and repeatability of mean deviation (MD) for the MRF and HFA tests, by way of regression, intraclass correlation coefficient and Bland-Altman analysis. Secondary measures were comparisons of pattern deviation indices, test times as well as an indication of participant test preference. Summary data show means ± standard deviation. Results: The age for our cohort was 7 to 15 years of age (mean, 10.0 ± 2.4 years of age). The MRF MD was in close concordance to HFA MD with an intraclass correlation coefficient of 0.91 (95% confidence interval, 0.82-0.95). Bland-Altman analysis found little bias (-0.6 dB) and a 95% coefficient of repeatability of 2.1 dB in eyes having a normal HFA MD. In eyes with glaucomatous visual field defects the 95% coefficient of repeatability at retest was much larger for both the MRF (10.5 dB) as well as for the HFA (10.0 dB). Average MRF test times (5.6 ± 1.2 minutes) were similar to SITA Fast (5.4 ± 1.9 minutes) with both being significantly faster than SITA standard (8.6 ± 1.4 minutes; P < 0.001). All children chose testing with the MRF as their preference. Conclusions: MRF correlated strongly with HFA and was preferred by the children over the HFA. MRF is suitable for perimetric evaluation of children with glaucoma. Translational Relevance: This study finds that an iPad based visual field test can be used with children having glaucoma to yield outcomes similar to SITA-fast. Children indicate a preference for such testing.

Retinal Nerve Fiber Layer Damage Assessment in Glaucomatous Eyes Using Retinal Retardance Measured by Polarization-Sensitive Optical Coherence Tomography.

Purpose: To assess the diagnostic performance and structure-function association of retinal retardance (RR), a customized metric measured by a prototype polarization-sensitive optical coherence tomography (PS-OCT), across various stages of glaucoma. Methods: This cross-sectional pilot study analyzed 170 eyes from 49 healthy individuals and 68 patients with glaucoma. The patients underwent PS-OCT imaging and conventional spectral-domain optical coherence tomography (SD-OCT), as well as visual field (VF) tests. Parameters including RR and retinal nerve fiber layer thickness (RNFLT) were extracted from identical circumpapillary regions of the fundus. Glaucomatous eyes were categorized into early, moderate, or severe stages based on VF mean deviation (MD). The diagnostic performance of RR and RNFLT in discriminating glaucoma from controls was assessed using receiver operating characteristic (ROC) curves. Correlations among VF-MD, RR, and RNFLT were evaluated and compared within different groups of disease severity. Results: The diagnostic performance of both RR and RNFLT was comparable for glaucoma detection (RR AUC = 0.98, RNFLT AUC = 0.97; P = 0.553). RR showed better structure-function association with VF-MD than RNFLT (RR VF-MD = 0.68, RNFLT VF-MD = 0.58; z = 1.99; P = 0.047) in glaucoma cases, especially in severe glaucoma, where the correlation between VF-MD and RR (r = 0.73) was significantly stronger than with RNFLT (r = 0.43, z = 1.96, P = 0.050). In eyes with early and moderate glaucoma, the structure-function association was similar when using RNFLT and RR. Conclusions: RR and RNFLT have similar performance in glaucoma diagnosis. However, in patients with glaucoma especially severe glaucoma, RR showed a stronger correlation with VF test results. Further research is needed to validate RR as an indicator for severe glaucoma evaluation and to explore the benefits of using PS-OCT in clinical practice. Translational Relevance: We demonstrated that PS-OCT has the potential to evaluate the status of RNFL structural damage in eyes with severe glaucoma, which is currently challenging in clinics.