A Battery of Quantitative Binocular Vision Tests for Adults: Testing Protocols

Summary

Here we present a comprehensive battery of tasks to assess binocular vision. Tasks include peripheral stereoacuity and motion-in-depth, which are not assessed by current clinical tests. Incorporating these tasks will provide an in-depth assessment of an individual’s binocularity.

Abstract

Sensory fusion and stereopsis are two crucial components of binocular depth perception. Current clinical tests do not provide a quantitative measure of sensory fusion and assess limited aspects of stereopsis. More importantly, patients who show no binocular fusion in standard clinical tests can demonstrate binocular integration and perceive depth from binocular disparity and motion cues, suggesting that current tests are insufficient to examine all aspects of binocularity. A battery of eight tests is presented here to provide a comprehensive assessment of binocular vision. These tests are designed to refine and extend existing assessments by targeting different components of binocular processing. Specifically, letter ocular dominance and plaid motion integration provide quantitative measures of sensory fusion. Binocular integration in peripheral vision is evaluated using fine- and coarse-peripheral stereopsis tests, dynamic local stereopsis, and motion parallax. Motion-in-depth is assessed by dynamic local stereopsis, the Pulfrich task, and motion parallax. An additional da Vinci stereopsis test provides qualitative insight into binocular integration by measuring the occlusion difference between the two eyes. Exemplary results are shown from a participant with normal vision. Modifications to the current protocol can be made to accommodate specific needs and to support applications in broader populations.

Introduction

Binocular vision enables accurate depth perception through three hierarchical processes. The first step is simultaneous perception, in which the observer perceives information from both eyes. Subsequently, motor and sensory fusion occur when the two eyes are aligned and receive spatially correlated images. Stereopsis is the highest level of sensory fusion and relies on the processing of binocular disparity^1,2. A range of clinical tests is available to assess simultaneous perception and motor fusion, for example, synoptophores, fusional vergence using prisms, and Worth 4-Dot (W4D) tests³....

Protocol

This study protocol was approved by the University of Waterloo Office of Research Ethics (44843) and the McMaster Research Ethics Board (1733). All procedures were conducted in accordance with the principles outlined in the Declaration of Helsinki. Written informed consent was obtained prior to their participation. For specifications regarding the test stimulus, please refer to Supplementary File 1.

1. Prepare equipment setup

1. Set up the mirror stereoscope as shown in Figure 1.
2. Position the monitor at a viewing distance of 99.5 cm.
   ....

Results

Representative data were collected from a 20-year-old participant with normal vision (visual acuity 0.0 logMAR for each eye; stereoacuity 40 arcsec).

Letter ocular dominance
Results from two staircases and the method of constant stimuli (Figure 2C,D) indicate slightly stronger right-eye dominance for this participant.

Expected results: Each staircase should progressively approach its threshol.......

Discussion

This novel battery of tests was developed to assess multiple facets of binocular vision, ranging from simultaneous perception and fusion to distinct mechanisms underlying stereopsis. The entire protocol takes at least 85 minutes to complete, providing a comprehensive evaluation of depth perception. Tests may be administered individually or in combination, depending on research or clinical needs. The full test battery is best suited to research environments where longer testing durations are feasible. Nevertheless, subset.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Codes	N/A	https://git.uwaterloo.ca/hvnl/binocularbatterycodes_manuscript/-/tree/9f7ff9eb1705d50060ca46a8ac2d2d1848349368/	The codes used to generate the stimuli and run the protocol are available at the repository provided in the "Catalog Number" column.
Computer	Alienware, Dell Inc., Texas, USA	XPS 8930	Intel Core i7-9700 CPU, 64 GB RAM
Forehead and chin rest	N/A	N/A	Custom-built, used to maintain head position and viewing distance
Mirror stereoscope	N/A	N/A	Custom-built
Monitor	LG Electronics, Seoul, Korea	LG 27UP600-W	Resolution: 3840 × 2160 pixels, screen width: 59.5 cm, refresh rate: 60 Hz, response time: 5 ms; gray background luminance was set to 340 cd/m2
Mouse and keyboard	N/A	N/A	For experimenter use
Numeric pad	N/A	N/A	For participant use
Programming Environment	N/A	https://www.psychopy.org/	PsychoPy 2022.2.4 (on Python 3.6.6), running on Windows 10 (Microsoft Corporation, Redmond, WA, USA)
Response box	N/A	N/A	Custom-built, please see Schematics in Supplementary Documents for parts required