  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.
