Visual function, digital behavior and the vision performance index

Abstract

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.

Keywords: mobile applications; mobile gaming; software applications; technology; video games; vision assessment; vision education; visual acuity.

Figure 1

Examples of standardized eye charts. Notes: (A) Snellen test for acuity. Reproduced from Dahl J. A typical Snellen chart. Available from: https://commons.wikimedia.org/wiki/File:Snellen_chart.svg. Creative Commons license and disclaimer available from: http://creativecommons.org/licenses/by/4.0/legalcode. (B) LogMAR test for acuity. Reprinted from Vision Res, 90, Bailey IL, Lovie-Kitchin JE, Visual acuity testing. From the laboratory to the clinic. 2–9, Copyright (2013), with permission from Elsevier.

Figure 2

Illustration of a typical block letter E where each of five vertical segments subtends 1 minute of arc (totaling 5). Note: Note that the angles are not drawn to scale.

Figure 3

Distribution of VPI scores among a population, modeled as a normal distribution with a mean of 100 and an SD of 15. Note: Shaded areas show regions with an equal area of 20%: scores less than 87 (bottom 20%) are considered as abnormally low, while scores greater than 113 (top 20%) are considered as abnormally high. Abbreviation: VPI, vision performance index.

Figure 4

The five components of the VPI: FAMED and their subcomponents. Note: Each individual component is scored, providing additional detail on top of the main, or overall, VPI score. Abbreviations: VPI, vision performance index; FAMED, field of view, accuracy, multi-tracking, endurance and detection.

Figure 5

Example experiences used to gather baseline sample data. Notes: Left: Users must click or tap target balloons (those with stripes) and ignore distractor balloons (those without stripes); balloons vary randomly in size, color, transparency and speed (moving up). Middle: Users must click or tap target balloon containing the matching color and shape combination given at the top; one target is presented with varying number of distractors with random size, color and shape. Right: Users must use the slider to adjust the right image to match the left image; the parameter adjusted by the slider varies by trial among color (hue), saturation, brightness, (luminance) contrast, (Gaussian) blur and size. Each experience lasts 45 seconds, with a countdown timer (upper left corner) and rightward moving progress bar (grey line below experience title). Users may pause using the pause button (upper right corner).