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

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.