Democratizing Health Care in the Metaverse: How Video Games can Monitor Eye Conditions Using the Vision Performance Index: A Pilot Study.

Objective: In a world where digital media is deeply engrained into our everyday lives, there lies an opportunity to leverage interactions with technology for health and wellness. The Vision Performance Index (VPI) leverages natural human-technology interaction to evaluate visual function using visual, cognitive, and motor psychometric data over 5 domains: field of view, accuracy, multitracking, endurance, and detection. The purpose of this study was to describe a novel method of evaluating holistic visual function through video game-derived VPI score data in patients with specific ocular pathology. Design: Prospective comparative analysis. Participants: Patients with dry eye, glaucoma, cataract, diabetic retinopathy (DR), age-related macular degeneration, and healthy individuals. Methods: The Vizzario Inc software development kit was integrated into 2 video game applications, Balloon Pop and Picture Perfect, which allowed for generation of VPI scores. Study participants were instructed to play rounds of each video game, from which a VPI score was compiled. Main Outcome Measures: The primary outcome was VPI overall score in each comparison group. Vision Performance Index component, subcomponent scores, and psychophysical inputs were also compared. Results: Vision Performance Index scores were generated from 93 patients with macular degeneration (n = 10), cataract (n = 10), DR (n = 15), dry eye (n = 15), glaucoma (n = 16), and no ocular disease (n = 27). The VPI overall score was not significantly different across comparison groups. The VPI subcomponent "reaction accuracy" score was significantly greater in DR patients (106 ± 13.2) versus controls (96.9 ± 11.5), P = 0.0220. The VPI subcomponent "color detection" score was significantly lower in patients with DR (96.8 ± 2.5; p=0.0217) and glaucoma (98.5 ± 6.3; P = 0.0093) compared with controls (101 ± 11). Psychophysical measures were statistically significantly different from controls: proportion correct (lower in DR, age-related macular degeneration), contrast errors (higher in cataract, DR), and saturation errors (higher in dry eye). Conclusions: Vision Performance Index scores can be generated from interactions of an ocular disease population with video games. The VPI may offer utility in monitoring select ocular diseases through evaluation of subcomponent and psychophysical input scores; however, future larger-scale studies must evaluate the validity of this tool. Financial Disclosures: Proprietary or commercial disclosure may be found after the references.

Disambiguating serial effects of multiple timescales.

What has been previously experienced can systematically affect human perception in the present. We designed a novel psychophysical experiment to measure the perceptual effects of adapting to dynamically changing stimulus statistics. Observers are presented with a series of oriented Gabor patches and are asked occasionally to judge the orientation of highly ambiguous test patches. We developed a computational model to quantify the influence of past stimuli presentations on the observers' perception of test stimuli over multiple timescales and to show that this influence is distinguishable from simple response biases. The experimental results reveal that perception is attracted toward the very recent past and simultaneously repulsed from stimuli presented at short to medium timescales and attracted to presentations further in the past. All effects differ significantly both on their relative strength and their respective duration. Our model provides a structured way of quantifying serial effects in psychophysical experiments, and it could help experimenters in identifying such effects in their data and distinguish them from less interesting response biases.

Visual function, digital behavior and the vision performance index.

Historically, visual acuity has been the benchmark for visual function. It is used to measure therapeutic outcomes for vision-related services, products and interventions. Quantitative measurement of suboptimal visual acuity can potentially be corrected optically with proper refraction in some cases, but in many cases of reduced vision there is something else more serious that can potentially impact other aspects of visual function such as contrast sensitivity, color discrimination, peripheral field of view and higher-order visual processing. The measurement of visual acuity typically requires stimuli subject to some degree of standardization or calibration and has thus often been limited to clinical settings. However, we are spending increasing amounts of time interacting with devices that present high-resolution, full color images and video (hereafter, digital media) and can record our responses. Most of these devices can be used to measure visual acuity and other aspects of visual function, not just with targeted testing experiences but from typical device interactions. There is growing evidence that prolonged exposure to digital media can lead to various vision-related issues (eg, computer vision syndrome, dry eye, etc.). Our regular, daily interactions (digital behavior) can also be used to assess our visual function, passively and continuously. This allows us to expand vision health assessment beyond the clinic, to collect vision-related data in the whole range of settings for typical digital behavior from practically any population(s) of interest and to further explore just how our increasingly virtual interactions are affecting our vision. We present a tool that can be easily integrated into digital media to provide insights into our digital behavior.

The perceptual balance of color.

The cone contrasts carrying different dimensions of color vision vary greatly in magnitude, yet the perceived contrast of color and luminance in the world appears similar. We examined how this perceptual balance is adjusted by adaptation to the contrast in images. Observers set the level of L vs. M and S vs. LM contrast in 1/f noise images to match the perceived strength of a fixed level of luminance contrast. The perceptual balance of color in the images was roughly consistent with the range of contrast characteristic of natural images. Relative perceived contrast could be strongly biased by brief prior exposure to images with lower or higher levels of chromatic contrast. Similar adaptation effects were found for luminance contrast in images of natural scenes. For both, observers reliably chose the contrast balance that appeared correct, and these choices were rapidly recalibrated by adaptation. This recalibration of the norm for contrast could reflect both changes in sensitivity and shifts in criterion. Our results are consistent with the possibility that color mechanisms adjust the range of their responses to match the range of signals in the environment, and that contrast adaptation plays an important role in these adjustments.

Contrast adaptation reveals increased organizational complexity of chromatic processing in the visual evoked potential.

Results from psychophysics and single-unit recordings suggest that color vision comprises multiple stages of processing. Postreceptoral channels appear to consist of both a stage of broadly tuned opponent channels that compare cone signals and a subsequent stage, which includes cells tuned to many different directions in color space. The chromatic visual evoked potential (crVEP) has demonstrated chromatic processing selective for cardinal axes of color space. However, crVEP evidence for higher-order color mechanisms is lacking. The present study aimed to assess the contribution of lower- and higher-order color mechanisms to the crVEP by using chromatic contrast adaptation. The results reveal the presence of mechanisms tuned to intermediate directions in color space in addition to those tuned to the fundamental cardinal axes.

Tests of a functional account of the Abney effect.

The Abney effect refers to changes in the hue of lights as they are desaturated. Normally the purity is varied by desaturating with a fixed spectrum. Mizokami et al. [J. Vis.6, 996 (2006)] instead varied purity by using Gaussian spectra and increasing their bandwidth. Under these conditions the hues of lights at short and medium wavelengths tended to remain constant and thus were tied to a fixed property of the stimulus such as the spectral peak, possibly reflecting a compensation for the spectral filtering effects of the eye. Here we test this account more completely by comparing constant hue loci across a wide range of wavelengths and between the fovea and periphery. Purity was varied by adding either a fixed spectrum or by varying the spectral bandwidth, using an Agile Light Source capable of generating arbitrary spectra. For both types of spectra, hue loci were approximated by the Gaussian model at short and medium wavelengths, though the model failed to predict the precise form of the hue changes or the differences between the fovea and periphery. Our results suggest that a Gaussian model provides a useful heuristic for predicting constant hue loci and the form of the Abney effect at short and medium wavelengths and may approximate the inferences underlying the representation of hue in the visual system.

Uniform color spaces and natural image statistics.

Many aspects of visual coding have been successfully predicted by starting from the statistics of natural scenes and then asking how the stimulus could be efficiently represented. We started from the representation of color characterized by uniform color spaces, and then asked what type of color environment they implied. These spaces are designed to represent equal perceptual differences in color discrimination or appearance by equal distances in the space. The relative sensitivity to different axes within the space might therefore reflect the gamut of colors in natural scenes. To examine this, we projected perceptually uniform distributions within the Munsell, CIE L(*)u(*)v(*) or CIE L(*)a(*)b(*) spaces into cone-opponent space. All were elongated along a bluish-yellowish axis reflecting covarying signals along the L-M and S-(L+M) cardinal axes, a pattern typical (though not identical) to many natural environments. In turn, color distributions from environments were more uniform when projected into the CIE L(*)a(*)b(*) perceptual space than when represented in a normalized cone-opponent space. These analyses suggest the bluish-yellowish bias in environmental colors might be an important factor shaping chromatic sensitivity, and also suggest that perceptually uniform color metrics could be derived from natural scene statistics and potentially tailored to specific environments.

Adaptation and visual salience.

We examined how the salience of color is affected by adaptation to different color distributions. Observers searched for a color target on a dense background of distractors varying along different directions in color space. Prior adaptation to the backgrounds enhanced search on the same background while adaptation to orthogonal background directions slowed detection. Advantages of adaptation were seen for both contrast adaptation (to different color axes) and chromatic adaptation (to different mean chromaticities). Control experiments, including analyses of eye movements during the search, suggest that these aftereffects are unlikely to reflect simple learning or changes in search strategies on familiar backgrounds, and instead result from how adaptation alters the relative salience of the target and background colors. Comparable effects were observed along different axes in the chromatic plane or for axes defined by different combinations of luminance and chromatic contrast, consistent with visual search and adaptation mediated by multiple color mechanisms. Similar effects also occurred for color distributions characteristic of natural environments with strongly selective color gamuts. Our results are consistent with the hypothesis that adaptation may play an important functional role in highlighting the salience of novel stimuli by discounting ambient properties of the visual environment.

Simulations of adaptation and color appearance in observers with varying spectral sensitivity.

A model of adaptation and visual coding was used to simulate how color appearance might vary among individuals that differ only in their sensitivity to wavelength. Color responses to images were calculated for cone receptors with spectral sensitivities specific to the individual, and in postreceptoral mechanisms tuned to different combinations of the cones. Adaptation was assumed to normalize sensitivity within each cone and postreceptoral channel so that the average response to an ensemble of scenes equaled the mean response in channels defined for the reference observer. Image colors were then rendered from the adapted channels' outputs. The transformed images provide an illustration of the variations in color appearance that could be attributed to differences in spectral sensitivity in otherwise identical observers adapted to identical worlds, and examples of these predictions are shown for both normal variation (e.g. in lens and macular pigment) and color deficiencies (anomalous trichromacy). The simulations highlight the role that known processes of adaptation may play in compensating color appearance for variations in sensitivity both within and across observers, and provide a novel tool for visualizing the perceptual consequences of any variation in visual sensitivity including changes associated with development or disease.