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.

Improving Understanding of Visual Snow by Quantifying its Appearance and Effect on Vision.

Purpose: Visual snow is the hallmark of the neurological condition visual snow syndrome (VSS) but the characteristics of the visual snow percept remain poorly defined. This study aimed to quantify its appearance, interobserver variability, and effect on measured visual performance and self-reported visual quality. Methods: Twenty-three participants with VSS estimated their visual snow dot size, separation, luminance, and flicker rate by matching to a simulation. To assess whether visual snow masks vision, we compared pattern discrimination thresholds for textures that were similar in spatial scale to visual snow as well as more coarse than visual snow, in participants with VSS, and with and without external noise simulating visual snow in 23 controls. Results: Mean and 95% confidence intervals for visual snow appearance were: size (6.0, 5.8-6.3 arcseconds), separation (2.0, 1.7-2.3 arcmin), luminance (72.4, 58.1-86.8 cd/m2), and flicker rate (25.8, 18.9-32.8 frames per image at 120 hertz [Hz]). Participants with finer dot spacing estimates also reported greater visibility of their visual snow (τb = -0.41, 95% confidence interval [CI] = -0.62 to -0.13, P = 0.01). In controls, adding simulated fine-scale visual snow to textures increased thresholds for fine but not coarse textures (F(1, 22) = 4.98, P = 0.036, ηp2 = 0.19). In VSS, thresholds for fine and coarse textures were similar (t(22) = 0.54, P = 0.60), suggesting that inherent visual snow does not act like external noise in controls. Conclusions: Our quantitative estimates of visual snow constrain its likely neural origins, may aid differential diagnosis, and inform future investigations of how it affects vision. Methods to quantify visual snow are needed for evaluation of potential treatments.

Enabling identification of component processes in perceptual learning with nonparametric hierarchical Bayesian modeling.

Perceptual learning is a multifaceted process, encompassing general learning, between-session forgetting or consolidation, and within-session fast relearning and deterioration. The learning curve constructed from threshold estimates in blocks or sessions, based on tens or hundreds of trials, may obscure component processes; high temporal resolution is necessary. We developed two nonparametric inference procedures: a Bayesian inference procedure (BIP) to estimate the posterior distribution of contrast threshold in each learning block for each learner independently and a hierarchical Bayesian model (HBM) that computes the joint posterior distribution of contrast threshold across all learning blocks at the population, subject, and test levels via the covariance of contrast thresholds across blocks. We applied the procedures to the data from two studies that investigated the interaction between feedback and training accuracy in Gabor orientation identification over 1920 trials across six sessions and estimated learning curve with block sizes L = 10, 20, 40, 80, 160, and 320 trials. The HBM generated significantly better fits to the data, smaller standard deviations, and more precise estimates, compared to the BIP across all block sizes. In addition, the HBM generated unbiased estimates, whereas the BIP only generated unbiased estimates with large block sizes but exhibited increased bias with small block sizes. With L = 10, 20, and 40, we were able to consistently identify general learning, between-session forgetting, and rapid relearning and adaptation within sessions. The nonparametric HBM provides a general framework for fine-grained assessment of the learning curve and enables identification of component processes in perceptual learning.

Phosphene and motor transcranial magnetic stimulation thresholds are correlated: A meta-analytic investigation.

Transcranial magnetic stimulation (TMS) is commonly delivered at an intensity defined by the resting motor threshold (rMT), which is thought to represent cortical excitability, even if the TMS target area falls outside of the motor cortex. This approach rests on the assumption that cortical excitability, as measured through the motor cortex, represents a 'global' measure of excitability. Another common approach to measure cortical excitability relies on the phosphene threshold (PT), measured through the visual cortex of the brain. However, it remains unclear whether either estimate can serve as a singular measure to infer cortical excitability across different brain regions. If PT and rMT can indeed be used to infer cortical excitability across brain regions, they should be correlated. To test this, we systematically identified previous studies that measured PT and rMT to calculate an overall correlation between the two estimates. Our results, based on 16 effect sizes from eight studies, indicated that PT and rMT are correlated (ρ = 0.4), and thus one measure could potentially serve as a measure to infer cortical excitability across brain regions. Three exploratory meta-analyses revealed that the strength of the correlation is affected by different methodologies, and that PT intensities are higher than rMT. Evidence for a PT-rMT correlation remained robust across all analyses. Further research is necessary for an in-depth understanding of how cortical excitability is reflected through TMS.

[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.

The speed of sight: Individual variation in critical flicker fusion thresholds.

The critical flicker fusion threshold is a psychophysical measure commonly used to quantify visual temporal resolution; the fastest rate at which a visual system can discriminate visual signals. Critical flicker fusion thresholds vary substantially among species, reflecting different ecological niches and demands. However, it is unclear how much variation exists in flicker fusion thresholds between healthy individuals of the same species, or how stable this attribute is over time within individuals. In this study, we assessed both inter- and intra-individual variation in critical flicker fusion thresholds in a cohort of healthy human participants within a specific age range, using two common psychophysical methods and three different measurements during each session. The resulting thresholds for each method were highly correlated. We found a between-participant maximum difference of roughly 30 Hz in flicker fusion thresholds and we estimated a 95% prediction interval of 21 Hz. We used random-effects models to compare between- and within-participant variance and found that approximately 80% of variance was due to between-individual differences, and about 10% of the variance originated from within-individual differences over three sessions. Within-individual thresholds did not differ significantly between the three sessions in males, but did in females (P<0.001 for two methods and P<0.05 for one method), indicating that critical flicker fusion thresholds may be more variable in females than in males.

Improving the robustness of the Sequentially Optimized Reconstruction Strategy (SORS) for visual field testing.

Perimetry, or visual field test, estimates differential light sensitivity thresholds across many locations in the visual field (e.g., 54 locations in the 24-2 grid). Recent developments have shown that an entire visual field may be relatively accurately reconstructed from measurements of a subset of these locations using a linear regression model. Here, we show that incorporating a dimensionality reduction layer can improve the robustness of this reconstruction. Specifically, we propose to use principal component analysis to transform the training dataset to a lower dimensional representation and then use this representation to reconstruct the visual field. We named our new reconstruction method the transformed-target principal component regression (TTPCR). When trained on a large dataset, our new method yielded results comparable with the original linear regression method, demonstrating that there is no underfitting associated with parameter reduction. However, when trained on a small dataset, our new method used on average 22% fewer trials to reach the same error. Our results suggest that dimensionality reduction techniques can improve the robustness of visual field testing reconstruction algorithms.

Detection of Threshold-Level Stimuli Modulated by Temporal Predictions of the Cerebellum.

The cerebellum has the reputation of being a primitive part of the brain that mostly is involved in motor coordination and motor control. Older lesion studies and more recent electrophysiological studies have, however, indicated that it is involved in temporal perception and temporal expectation building. An outstanding question is whether this temporal expectation building cerebellar activity has functional relevance. In this study, we collected magnetoencephalographic data from 30 healthy participants performing a detection task on at-threshold stimulation that was presented at the end of a sequence of temporally regular or irregular above-threshold stimulation. We found that behavioral detection rates depended on the degree of irregularity in the sequence preceding it. We also found cerebellar responses evoked by above-threshold and at-threshold stimulation. The evoked responses to at-threshold stimulation differed significantly, depending on whether it was preceded by a regular or an irregular sequence. Finally, we found that detection performance across participants correlated significantly with the differences in cerebellar evoked responses to the at-threshold stimulation, demonstrating the functional relevance of cerebellar activity in sensory expectation building. We furthermore found evidence of thalamic involvement, as indicated by responses in the beta band (14-30 Hz) and by significant modulations of cerebello-thalamic connectivity by the regularity of the sequence and the kind of stimulation terminating the sequence. These results provide evidence that the temporal expectation building mechanism of the cerebellum, what we and others have called an internal clock, shows functional relevance by regulating behavior and performance in sensory action that requires acting and integrating evidence over precise timescales.

Why am I overwhelmed by bright lights? The behavioural mechanisms of post-stroke visual hypersensitivity.

After stroke, patients can experience visual hypersensitivity, an increase in their sensitivity for visual stimuli as compared to their state prior to the stroke. Candidate behavioural mechanisms for these subjective symptoms are atypical bottom-up sensory processing and impaired selective attention, but empirical evidence is currently lacking. In the current study, we aimed to investigate the relationship between post-stroke visual hypersensitivity and sensory thresholds, sensory processing speed, and selective attention using computational modelling of behavioural data. During a whole/partial report task, participants (51 stroke patients, 76 orthopedic patients, and 77 neurotypical adults) had to correctly identify a single target letter that was presented alone (for 17-100 ms) or along a distractor (for 83ms). Performance on this task was used to estimate the sensory threshold, sensory processing speed, and selective attention abilities of each participant. In the stroke population, both on a group and individual level, there was evidence for impaired selective attention and -to a lesser extent- lower sensory thresholds in patients with post-stroke visual hypersensitivity as compared to neurotypical adults, orthopedic patients, or stroke patients without post-stroke sensory hypersensitivity. These results provide a significant advancement in our comprehension of post-stroke visual hypersensitivity and can serve as a catalyst for further investigations into the underlying mechanisms of sensory hypersensitivity after other types of acquired brain injury as well as post-injury hypersensitivity for other sensory modalities.

Visual field asymmetries in visual word form identification.

Visual performance across the visual fields interacts with visual tasks and visual stimuli, and visual resolution decreases as a function of eccentricity, varying at isoeccentric locations. In this study, we investigated the extent of asymmetry and the rate of change in visual acuity threshold for visual word form (VWF) identification at horizontal and vertical azimuths across the fovea, and at eccentricities of 1°, 2°, 4°, 6° and 8° for 10%, 20%, 40%, and 80% contrast levels, to determine whether and how the eccentricities, meridians, and contrasts modulated the VWF identification acuity threshold. The stimuli were 16 traditional Chinese characters of similar legibility. Participants pressed a key to indicate the character presented, either monocularly or binocularly, at one of 21 randomly selected locations. A staircase procedure was used to determine the threshold, and a multiple linear regression model was used to fit the linear cortical magnification factor (CMF). We found that (1) the asymmetry was most pronounced on the vertical and superior azimuths, (2) the asymmetry between the right and left azimuths was not significant, (3) the CMF was significantly smaller on the vertical azimuth than on the horizontal azimuth, (4) the CMF was smaller on the superior vertical azimuth than on the inferior azimuth, and (5) monocular viewing and low contrast enhanced the CMF difference between azimuths. In conclusion, vertical and horizontal azimuths, location of eccentricity, contrast levels of word symbols, and monocular/binocular viewing have different effects on visual field asymmetry and cortical magnification factors.

A Bayesian observer model reveals a prior for natural daylights in hue perception.

Incorporating statistical characteristics of stimuli in perceptual processing can be highly beneficial for reliable estimation from noisy sensory measurements but may generate perceptual bias. According to Bayesian inference, perceptual biases arise from the integration of internal priors with noisy sensory inputs. In this study, we used a Bayesian observer model to derive biases and priors in hue perception based on discrimination data for hue ensembles with varying levels of chromatic noise. Our results showed that discrimination thresholds for isoluminant stimuli with hue defined by azimuth angle in cone-opponent color space exhibited a bimodal pattern, with lowest thresholds near a non-cardinal blue-yellow axis that aligns closely with the variation of natural daylights. Perceptual biases showed zero crossings around this axis, indicating repulsion away from yellow and attraction towards blue. These biases could be explained by the Bayesian observer model through a non-uniform prior with a preference for blue. Our findings suggest that visual processing takes advantage of knowledge of the distribution of colors in natural environments for hue perception.

Surround masking reveals binocular adding and differencing channels.

Recent studies suggest that binocular adding S+ and differencing S- channels play an important role in binocular vision. To test for such a role in the context of binocular contrast detection and binocular summation, we employed a surround masking paradigm consisting of a central target disk surrounded by a mask annulus. All stimuli were horizontally oriented 0.5c/d sinusoidal gratings. Correlated stimuli were identical in interocular spatial phase while anticorrelated stimuli were opposite in interocular spatial phase. There were four target conditions: monocular left eye, monocular right eye, binocular correlated and binocular anticorrelated, and three surround mask conditions: no surround, binocularly correlated and binocularly anticorrelated. We observed consistent elevation of detection thresholds for monocular and binocular targets across the two binocular surround mask conditions. In addition, we found an interaction between the type of surround and the type of binocular target: both detection and summation were relatively enhanced by surround masks and targets with opposite interocular phase relationships and reduced by surround masks and targets with the same interocular phase relationships. The data were reasonably well accounted for by a model of binocular combination termed MAX (S+S-), in which the decision variable is the probability summation of modeled S+ and S- channel responses, with a free parameter determining the relative gains of the two channels. Our results support the existence of two channels involved in binocular combination, S+ and S-, whose relative gains are adjustable by surround context.

Intra-individual consistency of vestibular perceptual thresholds.

Vestibular perceptual thresholds quantify sensory noise associated with reliable perception of small self-motions. Previous studies have identified substantial variation between even healthy individuals' thresholds. However, it remains unclear if or how an individual's vestibular threshold varies over repeated measures across various time scales (repeated measurements on the same day, across days, weeks, or months). Here, we assessed yaw rotation and roll tilt thresholds in four individuals and compared this intra-individual variability to inter-individual variability of thresholds measured across a large age-matched cohort each measured only once. For analysis, we performed simulations of threshold measurements where there was no underlying variability (or it was manipulated) to compare to that observed empirically. We found remarkable consistency in vestibular thresholds within individuals, for both yaw rotation and roll tilt; this contrasts with substantial inter-individual differences. Thus, we conclude that vestibular perceptual thresholds are an innate characteristic, which validates pooling measures across sessions and potentially serves as a stable clinical diagnostic and/or biomarker.

Frequency dependence of human thresholds: both perceptual and vestibuloocular reflex thresholds.

Although perceptual thresholds have been widely studied, vestibuloocular reflex (VOR) thresholds have received less attention, so the relationship between VOR and perceptual thresholds remains unclear. We compared the frequency dependence of human VOR thresholds to human perceptual thresholds for yaw head rotation in both upright ("yaw rotation") and supine ("yaw tilt") positions, using the same human subjects and motion device. VOR thresholds were generally a little smaller than perceptual thresholds. We also found that horizontal VOR thresholds for both yaw rotation about an Earth-vertical axis and yaw tilt (yaw rotation about an Earth-horizontal axis) were relatively constant across four frequencies (0.2, 0.5, 1, and 2 Hz), with little difference between yaw rotation and yaw tilt VOR thresholds. For yaw tilt stimuli, perceptual thresholds were slightly lower at the lowest frequency and nearly constant at all other (higher) frequencies. However, for yaw rotation, perceptual thresholds increased significantly at the lowest frequency (0.2 Hz). We conclude 1) that VOR thresholds were relatively constant across frequency for both yaw rotation and yaw tilt, 2) that the known contributions of velocity storage to the VOR likely yielded these VOR thresholds that were similar for yaw rotation and yaw tilt for all frequencies tested, and 3) that the integration of otolith and horizontal canal signals during yaw tilt when supine contributes to stable perceptual thresholds, especially relative to the low-frequency perceptual thresholds recorded during yaw rotation.NEW & NOTEWORTHY We describe for the first time that human VOR thresholds differ from human forced-choice perceptual thresholds, with the difference especially evident at frequencies below 0.5 Hz. We also report that VOR thresholds are relatively constant across frequency for both yaw rotation and yaw tilt. These findings are consistent with the idea that high-pass filtering in cortical pathways impacts cognitive decision-making.

Performance on a contour integration task as a function of contour shape in schizophrenia and controls.

Contour Integration (CI) is the ability to integrate elemental features into objects and is a basic visual process essential for object perception and recognition, and for functioning in visual environments. It is now well documented that people with schizophrenia (SZ), in addition to having cognitive impairments, also have several visual perceptual deficits, including in CI. Here, we retrospectively characterize the performance of both SZ and neurotypical individuals (NT) on a series of contour shapes, made up of Gabor elements, that varied in terms of closure and curvature. Participants in both groups performed a CI training task that included 7 different families of shapes (Lines, Ellipse, Blobs, Squiggles, Spiral, Circle and Letters) for up to 40 sessions. Two parameters were manipulated in the training task: Orientation Jitter (OJ, i.e., orientation deviations of individual Gabor elements from ideal for each shape) and Inducer Number (IN, i.e., number of Gabor elements defining the shape). Results show that both OJ and IN thresholds significantly differed between the groups, with higher (OJ) and lower (IN) thresholds observed in the controls. Furthermore, we found significant effects as a function of the contour shapes, with differences between groups emerging with contours that were considered more complex, e.g., due to having a higher degree of curvature (Blobs, Spiral, Letters). These data can inform future work that aims to characterize visual integration impairments in schizophrenia.

Effect of the rs2821557 Polymorphism of the Human Kv1.3 Gene on Olfactory Function and BMI in Different Age Groups.

The sense of smell plays an important role in influencing the eating habits of individuals and consequently, their body weight, and its impairment has been associated with modified eating behaviors and malnutrition problems. The inter-individual variability of olfactory function depends on several factors, including genetic and physiological ones. In this study, we evaluated the role of the Kv1.3 channel genotype and age, as well as their mutual relationships, on the olfactory function and BMI of individuals divided into young, adult and elderly groups. We assessed olfactory performance in 112 healthy individuals (young n = 39, adult n = 36, elderly n = 37) based on their TDI olfactory score obtained through the Sniffin' Sticks test and their BMI. Participants were genotyped for the rs2821557 polymorphism of the human gene encoding Kv1.3 channels, the minor C allele of which was associated with a decreased sense of smell and higher BMIs compared to the major T allele. The results show that TT homozygous subjects obtained higher TDI olfactory scores and showed lower BMIs than CC homozygous subjects, in all age groups considered. Furthermore, the positive effect of the T allele on olfactory function and BMI decreased with increasing age. The contribution of the genetic factor is less evident with advancing age, while the importance of the age factor is compensated for by genetics. These results show that genetic and physiological factors such as age act to balance each other.

Factors influencing olfactory function in an adult general population sample: the CHRIS study.

The sense of smell allows for the assessment of the chemical composition of volatiles in our environment. Different factors are associated with reduced olfactory function, including age, sex, as well as health and lifestyle conditions. However, most studies that aimed at identifying the variables that drive olfactory function in the population suffered from methodological weaknesses in study designs and participant selection, such as the inclusion of convenience sample or only of certain age groups, or recruitment biases. We aimed to overcome these issues by investigating the Cooperative Health Research in South Tyrol (CHRIS) cohort, a population-based cohort, by using a validated odor identification test. Specifically, we hypothesized that a series of medical, demographic and lifestyle variables is associated with odor identification abilities. In addition, our goal was to provide clinicians and researchers with normative values for the Sniffin' Sticks identification set, after exclusion of individuals with impaired nasal patency. We included 6,944 participants without acute nasal obstruction and assessed several biological, social, and medical parameters. A basic model determined that age, sex, years of education, and smoking status together explained roughly 13% of the total variance in the data. We further observed that variables related to medical (positive screening for cognitive impairment and for Parkinson's disease, history of skull fracture, stage 2 hypertension) and lifestyle (alcohol abstinence) conditions had a negative effect on odor identification scores. Finally, we provide clinicians with normative values for both versions of the Sniffin' Sticks odor identification test, i.e. with 16 items and with 12 items.

An observational study of olfactory functions in total laryngectomees.

OBJECTIVE: To evaluate the olfactory acuity and quality of life in patients who have undergone total laryngectomy. The study also aims to identify any specific patient-related risk factors linked to worse olfactory outcomes. METHODS: This is a prospective cross-sectional study conducted at the University Malaya Medical Centre. A total of 30 patients who have undergone total laryngectomy were assessed objectively using the Sniffin' Sticks test and compared against normal age-matched Malaysians. Subsequently, they also filled out the modified Questionnaire on Olfactory Disorders. Correlations of patient demographics, disease and treatment variables against olfactory outcomes were conducted. RESULTS: All subjects suffered olfactory impairment, with 66.7% of them being anosmic after total laryngectomy. The Sniffin' Sticks test demonstrated a statistically significant difference between laryngectomees and the normal age-matched Malaysian population in all three subtests for odor threshold, discrimination and identification. 37% of patients developed olfactory adaptive methods, which resulted in higher olfactory scores and a better quality of life. There were no patient demographics, disease or treatment variables associated with a poorer olfactory outcome identified. CONCLUSION: Olfactory impairment should not be overlooked among patients after total laryngectomy. Although as many as a third of patients developed some sort of olfactory adaptive behavior, early rehabilitation should be integrated into the multidisciplinary rehabilitation program after total laryngectomy.

Olfactory threshold as a biomarker of long-term relapse activity in multiple sclerosis.

BACKGROUND: Olfactory threshold (OT) is a marker of short-term inflammatory activity in multiple sclerosis (MS). OBJECTIVE: To investigate whether OT predicts long-term MS clinical disease course. METHODS: This was a 6-year prospective longitudinal study on MS patients at the MS clinic Innsbruck. Clinical visits assessing the occurrence of relapses, Expanded Disability Status Scale (EDSS) scores, and disease-modifying treatment (DMT), were conducted biannually. OT testing was performed at baseline (BL), year 1 (Y1), year 2 (Y2) and year 6 (Y6), using the threshold subscore of the "Sniffin' Sticks" test. Cognitive function was assessed by the Symbol Digit Modalities Test. RESULTS: Of 139 MS patients, 92 were eligible for Y6 follow-up. 68% experienced relapses, 53% EDSS worsening, 29% progression independent of relapse activity (PIRA) and 41% cognitive deterioration. OT scores were lower at BL, Y1 and Y2 in patients requiring DMT escalation. In multivariable analysis, higher OT scores at BL, Y1, Y2 and Y6 were associated with lower risk of relapse (hazard ratio, HR: 0.65-0.92) and EDSS worsening (HR: 0.86-0.89), while no associations were found for PIRA and cognitive deterioration. CONCLUSIONS: OT is a potential surrogate marker for long-term inflammatory disease activity and DMT failure in MS.

Effect of wearing masks on odor detection and recognition.

BACKGROUND: The effect of wearing masks on olfaction remains unclear. OBJECTIVES: This study aimed to clarify the differences between the effects of no masks, surgical masks, and N95 respirator masks by conducting both identification and threshold olfaction tests. METHODS: Young, healthy volunteers aged ≥ 18 years and < 30 years without awareness of apparent olfactory disorder were included. All participants filled out a questionnaire on olfaction and completed an acuity smell identification test (Open Essence test) and an olfactory threshold test (T&T olfactometry) while wearing no masks, surgical masks, or N95 respirator masks. RESULTS: In the Open Essence tests, the no-mask group score was significantly higher than those of the surgical- and N95-mask groups. Using T&T olfactometry, the median-detection threshold of the no-mask group was significantly lower than that of the surgical-mask group, and the surgical-mask group threshold was significantly lower than that of the N95-mask group. Similar patterns were observed for the median-recognition threshold. CONCLUSIONS: Wearing masks, especially an N95 mask, reduces the ability to detect and identify odors. This disadvantage should be considered by professionals such as healthcare workers, who require proper olfaction to perform appropriate tasks.