Impacts of Mild and Moderate Acute Hypoxia on Visual Contrast Sensitivity

Introduction: Acute hypoxia could hamper the visual performance during the aviation. In the study, we aimed to investigate the effects of acute hypoxia on the contrast sensitivity (CS) and the color contrast sensitivity (CCS).Methos: 12 healthy volunteers (aged 20-22 years old) were selected for CS and CCS examination at altitude of 300m, 3000m and 4500m by applying the hypobaric cabin to simulate acute hypoxia (3000m in height = mild hypoxia; 4500m = moderate hypoxia). All data were collected after the heart rate and the blood oxygen saturation became stable, and were analyzed by the paired student’s t-test. Results: The CS at the spatial frequency of 1.5 Cpd was significantly increased at the altitude of 3000m (P<0.05), while CS at the higher spatial frequencies was not significantly affected. The CS of 1.5 and 3.0 Cpd was increased at the altitude of 4500m (P<0.05), while the CS of higher spatial frequency did not change significantly. With the increased degree of hypoxia, the overall CCS was increased with a statistical difference at 4500m (P<0.05). The CCS of the temporal superior and inferior quadrants were significantly affected (P<0.05), while those in other quadrants were significantly changed. Conclusions: Mild and moderate acute hypoxia could affect the CS in the low spatial frequency. With the increased degree of acute hypoxia, CCS deteriorates with the temporal quadrant more vulnerable to be affected.

Treatable metabolic and inflammatory abnormalities in Post COVID Syndrome (PCS) define the transcriptomic basis for persistent symptoms: Lessons from CIRS

Within three months of the onset of acute SARS-CoV-2 (COVID-19) infections, new and persistent symptoms were noted in survivors. While the world’s medical and research communities focus on saving lives following COVID-19 infection, a relentless march of new cases of Post-COVID Syndrome (PCS) continues to spread around the globe as a second COVID-related pandemic. Efforts to define the physiology of PCS, a multisystem, multi-symptom illness, continue without success, in part due to the markedly different case presentations. Using a transcriptomic assessment of persistently ill cases of PCS, we show the presence of (i) molecular hypometabolism (MHM) and proliferative physiology; (ii) elevated levels of ribosomal stress responses and a concomitant increase in gene activation of TGFBR; and (iii) common co-expression of CD14 and Toll Receptor 4, correlated to exposure of amplified microbial growth in a water-damaged environment, specifically Actinobacteria and endotoxin, respectively, compared to recovered PCS cases. Total symptom scores and visual contrast sensitivity (VCS) results showed statistically significant differences. The data reported here supports the concept that PCS occurs in patients with additional environmental exposures and enhanced TGF signaling. In a strikingly similar condition called Chronic Inflammatory Response Syndrome (CIRS), named in 2010, the transcriptomic abnormalities were identified to respond to treatment with FDA-cleared medications, with salutary benefits for affected cases. Though sparsely reported, PCS cases share proteomic findings with CIRS. While additional studies are indicated, a new approach to the treatment of PCS is suggested.

Usefulness of Itrace in Diagnosing Unclear Cases of the Deterioration in Visual Acuity. Congenital Lens Dysfunction as a New Disease Entity. Preliminary Reports.

The article analyses 22 cases of severe impairment of vision to far distances for no apparent reason. Visual impairment was observed regardless of patients’ age and type of eye defect diagnosed, with the majority of people suffering from myopia and accompanying astigmatism. The exclusion of causes related to the cornea and retina, optic nerve damage and the lack of visible pathologies of the lens in the physical examination did not allow for the determination of the cause of deterioration in visual acuity to far distances despite good vision to near distances. The results of examinations using iTrace indicated the lens as the cause of visual impairment despite the apparent lack of opacity and other pathologies within it. The results of examinations in the field of Higher Order Aberration, Opacity Map, Modulation Transfer Function™ and their graphical presentation using the Dysfunctional Lens Index™ module were analysed. Low values of visual contrast sensitivity and high values of higher order aberrations for the internal optics were observed, with the correct values for the cornea. The more pathological the results of the visual contrast sensitivity and higher order aberration, the lower the values of visual acuity to far distances. In most cases removing the dysfunctional lens and replacing it with an artificial lens allowed for a significant improvement in vision to far distances while maintaining proper vision to near distances. The procedure was performed on patients over 18 years of age. The medical history in the study group may indicate a congenital nature of the abnormal structure of the lens. Thus, it is necessary to consider verification of the diagnosis made in some patients, pointing to a new disease entity, i.e. congenital lens dysfunction.

Differential Eye Movements and Visual Contrast Acuity in National Collegiate Athletic Association Athletes

Though studies describe postconcussive changes in eye movements, there is a need for data describing baseline eye movements. The purpose of this study was to describe baseline eye movements and visual contrast acuity using the King-Devick (KD) Eye Tracking System and KD Visual Contrast Sensitivity Chart. Fewer total saccades were noted in soccer players than basketball players (soccer, 56.9 ± 14.3; basketball, 101.1 ± 41.3; p = .0005). No significant differences were noted for the number of saccades between sexes (males, 60.4 ± 20.3; females, 84.9 ± 41.8, p = .100) or in contrast acuity between all groups (p > .05). These results suggest the presence of sport-specific trends that may invalidate the comparison of postconcussion evaluation to generic baseline athlete eye movements.

Individual Differences in Multisensory Interactions: The Influence of Temporal Phase Coherence and Auditory Salience on Visual Contrast Sensitivity

While previous research has investigated key factors contributing to multisensory integration in isolation, relatively little is known regarding how these factors interact, especially when considering the enhancement of visual contrast sensitivity by a task-irrelevant sound. Here we explored how auditory stimulus properties, namely salience and temporal phase coherence in relation to the visual target, jointly affect the extent to which a sound can enhance visual contrast sensitivity. Visual contrast sensitivity was measured by a psychophysical task, where human adult participants reported the location of a visual Gabor pattern presented at various contrast levels. We expected the most enhanced contrast sensitivity, the lowest contrast threshold, when the visual stimulus was accompanied by a task-irrelevant sound, weak in auditory salience, modulated in-phase with the visual stimulus (strong temporal phase coherence). Our expectations were confirmed, but only if we accounted for individual differences in optimal auditory salience level to induce maximal multisensory enhancement effects. Our findings highlight the importance of interactions between temporal phase coherence and stimulus effectiveness in determining the strength of multisensory enhancement of visual contrast as well as highlighting the importance of accounting for individual differences.