The effect of Bangerter filters on optotype acuity, Vernier acuity, and contrast sensitivity.
OBJECTIVE
Bangerter filters are designed to cause progressive degradation of distance optotype acuity to predicted levels (density label indicating expected decimal acuity) and are used to treat amblyopia and diplopia. Few authors have reported data regarding induced acuity deficits. We investigated the effect of Bangerter filters on distance and near optotype acuity, vernier acuity, and contrast sensitivity.


METHODS
Fifteen subjects with best-corrected optotype acuity of at least 20/25 in each eye were blurred sequentially in one eye with 7 Bangerter filters (densities <0.1, 0.1, 0.2, 0.3, 0.4, 0.8, and 1.0). At each filter level, distance and near optotype acuity (LogMAR), vernier acuity, and contrast sensitivity were assessed. Mean log acuities were compared using generalized estimating equation methods.


RESULTS
The 1.0, 0.8, and 0.4 filters degraded distance optotype acuity to a similar degree (mean 0.22, 0.23, and 0.28 logMAR). Subsequent filters progressively degraded acuity: 0.44, 0.57, 0.93, and 1.69 logMAR. Near optotype acuity was reduced in a similar pattern. Vernier acuity was minimally degraded by 1.0, 0.8, and 0.4 filters (18, 19, and 20 arcsec), followed by progressive degradation with subsequent filters (31, 35, 113, and 387 arcsec). Contrast sensitivity was minimally reduced with filters 1.0 through 0.2 and then precipitously degraded with 0.1 and <0.1 filters.


CONCLUSIONS
The 1.0, 0.8, and 0.4 filters cause similar, minimal degradation of distance and near optotype and vernier acuity, whereas subsequent filters cause progressive degradation. Contrast sensitivity is not markedly reduced until the 0.1 filter. These results have important implications for the use of Bangerter filters therapeutically.
Odell
Naomi V
NV
Mayo Medical School, Rochester, Minnesota 55905, USA.
Leske
David A
DA
Hatt
Sarah R
SR
Adams
Wendy E
WE
Holmes
Jonathan M
JM
D000328:Adult; D015350:Contrast Sensitivity; D004215:Distance Perception / Q000502:physiology; D005260:Female; D005374:Filtration / Q000295:instrumentation*; D006801:Humans; D008297:Male; D010469:Perceptual Distortion / Q000502:physiology*; D014787:Vision Tests / Q000295:instrumentation*; D014792:Visual Acuity; D055815:Young Adult