Comparison of degradation of stereoacuity with reduced visual input
Reviewed by Fiona Rowe

The aim of this study was to investigate the differing extents to which stereo thresholds obtained with Frisby, TNO, Lang Stereopad and ASTEROID stereo tests are affected by changes in visual input in adults. Bangerter foils (0.2 and 0.4) were used over the right eye to simulate reduction in visual acuity of 0.4 and 0.7logMAR, in 51 participants (17 male, 34 female). Mean age was 25 ±8.35 years. Stereoacuity degradation versus monocular blur showed a weak correlation for the 0.2 foil: Frisby r=0.268, TNO r=0.192, Land r=-0.218 and ASTEROID r=0.069. For the 0.2 vs. 0.4 foil, correlations were Frisby r=0.2, TNO r=0.02, Land r=-0.11 and ASTEROID r=0.18. None of the correlations were significant. Various stereo tests degraded by differing amounts: Frisby showed least median change and ASTEROID was most sensitive to change. The authors conclude that test selection should be consistent across appointments and follow-up visits to facilitate detection of subtle changes in stereoacuity. Stereo tests are not interchangeable.

Variation in the degradation of stereoacuity via monocular blur across multiple stereotests. 
Davies J, O’Connor A, Mehta J. 
STRABISMUS
2025;33(3):151–7.