An interactive framework for the evaluation and detection of stereoacuity threshold under ambient lighting

TL;DR

This study introduces a Bayesian-based interactive framework for continuous stereoacuity evaluation under different ambient lighting conditions, demonstrating its reliability and importance in clinical assessments of stereo-deficits.

Contribution

The paper presents a novel, quick, and reliable framework combining psychophysical methods and adaptive gamma calibration to assess stereoacuity under ambient lighting.

Findings

Stereoacuity thresholds vary significantly with lighting in IDS and IA patients.

The framework shows high reliability (>0.9) and correlates well with clinical tests.

Ambient lighting impacts stereoacuity measurement accuracy without AGC.

Abstract

Objective: Our study aims to provide a novel framework for the continuous evaluation of stereoacuity under ambient lighting conditions using Bayesian inference. Methods: We applied a combination of psychophysical and expected entropy minimization procedures for the computation of a continuous stereoacuity threshold. Subsequently, we evaluated the effect of ambient lighting during stereoacuity testing (ST) by adopting a bisection-matching based adaptive gamma calibration (AGC). Participants ($N=187$) including visually healthy controls ($N=51$), patients with Intermittent Divergent Squint (IDS; $N=45$), and controls with induced anisometropia (IA; $N=91$) performed ST with and without AGC under two lighting conditions: completely dark (20 cd/m$^2$) and normally lit (130 cd/m$^2$) rooms. Results: Our framework demonstrated "excellent" reliability ($> 0.9$) and a positive correlation with TNO (a clinical stereo test), regardless of whether AGC was conducted. However, when AGC is not performed, significant differences (Friedman $X_{r}^{2} = 28.015$; $p<0.00001$; Bland-Altman bias: 30 arc-sec) were found in stereoacuity thresholds between dark and light conditions for participants with IDS and IA. Controls are unaffected by AGC and yield a similar stereoacuity threshold under both lighting conditions. Conclusion: Our study proves that stereoacuity threshold is significantly deviated particularly in participants with IDS or IA stereo-deficits if ambient lighting is not taken into consideration. Moreover, our framework provides a quick (approximately 5-10 minutes) assessment of stereoacuity threshold and can be performed within 30 ST and 15 AGC trials. Significance: Our test is useful in planning treatments and monitoring prognosis for patients with stereo-deficits by accurately assessing stereovision.