Abstract
Purpose:
Bangerter foils have become an alternative treatment regimen for amblyopia penalization. We have previously found that while Bangerter foils can penalize the normal eye, they do so in a manner that is not graded. In this study, we investigated whether Bangerter foils promote binocular function within the amblyopic visual system.
Methods:
Suppression thresholds were measured for 17 amblyopes using our previously established “balance point” protocol combined with a Gabor direction discrimination task. We compared normal binocular viewing with viewing conditions where the fellow fixing eye was penalized with 0.8, 0.6, 0.4 and 0.2 strenght Bangerter foils. In addition, the effect of Bangerter filters on suppression thresholds for patients was compared to results from 10 control observers.
Results:
The 0.8, 0.6 and 0.4 labeled foils did not influence suppression in the amblyopic observers. The 0.2 Bangerter foil reduced suppression thresholds and a binocular balance point was obtained in 14 out of the 17 subjects.
Conclusions:
Bangerter foils do not gradually induce binocular facilitation. The 0.8 to 0.4 strength Bangerter foils did not predictably shift the binocular status of amblyopes. Only the most extreme foil tested, labeled 0.2, reduced suppression among the amblyopic subjects. Care should be taken when prescribing Bangerter foils in clinical practice.
Keywords: 417 amblyopia •
434 binocular vision/stereopsis