Validation of Computer-Adaptive Contrast Sensitivity as a Tool to Assess Visual Impairment in Multiple Sclerosis Patients

BackgroundImpairment of visual function is one of the major symptoms of people with multiple sclerosis (pwMS). A multitude of disease effects including inflammation and neurodegeneration lead to structural impairment in the visual system. However, the gold standard of disability quantification, the expanded disability status scale (EDSS), relies on visual assessment charts. A more comprehensive assessment of visual function is the full contrast sensitivity function (CSF), but most tools are time consuming and not feasible in clinical routine. The quantitative CSF (qCSF) test is a computerized test to assess the full CSF. We have already shown a better correlation with visual quality of life (QoL) than for classical high and low contrast charts in multiple sclerosis (MS).ObjectiveTo study the precision, test duration, and repeatability of the qCSF in pwMS. In order to evaluate the discrimination ability, we compared the data of pwMS to healthy controls.MethodsWe recruited two independent cohorts of MS patients. Within the precision cohort (n = 54), we analyzed the benefit of running 50 instead of 25 qCSF trials. The repeatability cohort (n = 44) was assessed by high contrast vision charts and qCSF assessments twice and we computed repeatability metrics. For the discrimination ability we used the data from all pwMS without any previous optic neuritis and compared the area under the log CSF (AULCSF) to an age-matched healthy control data set.ResultsWe identified 25 trials of the qCSF algorithm as a sufficient amount for a precise estimate of the CSF. The median test duration for one eye was 185 s (range 129–373 s). The AULCSF had better test–retest repeatability (Mean Average Precision, MAP) than visual acuity measured by standard high contrast visual acuity charts or CSF acuity measured with the qCSF (0.18 vs. 0.11 and 0.17, respectively). Even better repeatability (MAP = 0.19) was demonstrated by a CSF-derived feature that was inspired by low-contrast acuity charts, i.e., the highest spatial frequency at 25% contrast. When compared to healthy controls, the MS patients showed reduced CSF (average AULCSF 1.21 vs. 1.42, p < 0.01).ConclusionHigh precision, usability, repeatability, and discrimination support the qCSF as a tool to assess contrast vision in pwMS.

Color and contrast vision in mouse models of aging and Alzheimer’s disease using a novel visual-stimuli four-arm maze

We introduce a novel visual-stimuli four-arm maze (ViS4M) equipped with spectrally- and intensity-controlled LED emitters and dynamic grayscale objects that relies on innate exploratory behavior to assess color and contrast vision in mice. Its application to detect visual impairments during normal aging and over the course of Alzheimer’s disease (AD) is evaluated in wild-type (WT) and transgenic APPSWE/PS1∆E9 murine models of AD (AD+) across an array of irradiance, chromaticity, and contrast conditions. Substantial color and contrast-mode alternation deficits appear in AD+ mice at an age when hippocampal-based memory and learning is still intact. Profiling of timespan, entries and transition patterns between the different arms uncovers variable AD-associated impairments in contrast sensitivity and color discrimination, reminiscent of tritanomalous defects documented in AD patients. Transition deficits are found in aged WT mice in the absence of alternation decline. Overall, ViS4M is a versatile, controlled device to measure color and contrast-related vision in aged and diseased mice.

3D-printed assistive pipetting system for gel electrophoresis for technicians with low acuity vision

In molecular biology laboratories, many tasks require fine motor control and high acuity vision. For example, lab technicians with visual impairment experience difficulty loading samples into the small wells of a horizontal agarose gel. We have developed a 3D-printable gel loading system which allows technicians with low-contrast vision to load gels correctly. It includes a casting tray, a bridge, and a modified comb. The system provides a high-contrast visual field to improve visibility, and the bridge allows pipette tips to be inserted at the correct location and only to the correct depth. The necessary computer files for printing this device are freely available to increase the accessibility of molecular biology laboratories to people with visual impairment.

Active Learning of Contrast Sensitivity to Assess Visual Function in Macula-Off Retinal Detachment

Purpose: This work characterizes the contrast sensitivity function (CSF) in patients with successful repair of macula-off rhegmatogenous retinal detachment (RD) using an adaptive computerized contrast testing device. Methods: CSF was prospectively measured in patients with macula-off RD following successful repair and age-matched controls at W.K. Kellogg Eye Center and Massachusetts Eye and Ear using Adaptive Sensory Technology’s Manifold Contrast Vision Meter. Outcome measures included average area under the CSF curve, contrast-sensitivity thresholds (1-18 cycles per degree), and best-corrected visual acuity (BCVA) in RD eyes, fellow eyes, and controls. A subanalysis was performed in eyes with BCVA of 20/30 or better. Results: Twenty-three macula-off RD eyes following repair, fellow healthy eyes, and 45 age-matched control eyes underwent CSF testing. Mean BCVA of the 23 RD eyes was 0.250 logMAR, which was, significantly reduced compared with fellow eyes 0.032 ( P < .001) and controls 0.026 ( P < .001). There was a statistically significant reduction in average area under the CSF curve in RD eyes compared with fellow eyes ( P < .0001) and age-matched controls ( z score –0.90, P < .0001) and CSF reduction across all spatial frequencies. In the 15 RD eyes with BCVA of 20/30 or better, the mean CSF was significantly reduced vs fellow eyes ( P = .02) and controls ( P = .045). Conclusions: CSF in macula-off RD eyes following repair was significantly reduced compared with fellow eyes and age-matched controls. CSF may be a promising visual function end point with applications in clinical practice and future clinical trials.

A Biomimetic Model of Adaptive Contrast Vision Enhancement from Mantis Shrimp

Mantis shrimp have complex visual sensors, and thus, they have both color vision and polarization vision, and are adept at using polarization information for visual tasks, such as finding prey. In addition, mantis shrimp, almost unique among animals, can perform three-axis eye movements, such as pitch, yaw, and roll. With this behavior, polarization contrast in their field of view can be adjusted in real time. Inspired by this, we propose a bionic model that can adaptively enhance contrast vision. In this model, a pixel array is used to simulate a compound eye array, and the angle of polarization (AoP) is used as an adjustment mechanism. The polarization information is pre-processed by adjusting the direction of the photosensitive axis point-to-point. Experiments were performed around scenes where the color of the target and the background were similar, or the visibility of the target was low. The influence of the pre-processing model on traditional feature components of polarized light was analyzed. The results show that the model can effectively improve the contrast between the object and the background in the AoP image, enhance the significance of the object, and have important research significance for applications, such as contrast-based object detection.