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Updated: Oct 11, 2026
The Measurement and Treatment of Suppression in Amblyopia
Published on: December 14, 2012
Chromatic-filter light therapy versus part-time occlusion for unilateral amblyopia: a quasi-experimental longitudinal
Shakila Abbas1, Humaima Saeed1, Memoona Arshad1
1The University of Faisalabad, Department of Optometry, Faisalabad, Pakistan.
Purpose:
To compare wavelength-specific chromatic-filter light therapy using amber-red, yellow, or orange filters with conventional patching for unilateral amblyopia and to evaluate longitudinal changes in best-corrected visual acuity (BCVA), contrast sensitivity, and stereopsis.
Methods:
This assessor-masked, quasi-experimental study included 88 participants aged 5-15 years with unilateral anisometropic or strabismic amblyopia after refractive adaptation. Forty-six participants received chromatic light therapy and 42 received part-time patching. The chromatic group included amber-red (n = 16), yellow (n = 15), and orange (n = 15) subgroups. Outcomes were assessed at 4 weeks, 3 months, 5 months, 7 months, and 2 months after treatment cessation. Baseline-adjusted linear mixed-effects models were fitted using restricted maximum likelihood and an autoregressive AR(1) covariance structure. Fixed effects included follow-up visit, treatment group, the visit-by-treatment interaction, and the corresponding baseline outcome.
Results:
BCVA improved over time in both groups. Adjusted BCVA changed from 0.458 to 0.261 logMAR with patching and from 0.446 to 0.246 logMAR with chromatic filters between 4 weeks and 7 months; the treatment-by-time interaction was not significant (p = .585). Treatment-by-time interactions were significant for contrast sensitivity and log10 stereopsis (both p < .001). From 3 months onward, the chromatic-filter group had higher adjusted contrast-sensitivity scores and lower, therefore better, stereopsis thresholds than the patching group. Within the chromatic-filter group, no filter-by-time interaction was detected for BCVA (p = .152), contrast sensitivity (p = .312), or stereopsis (p = .089). Most gains were maintained after treatment cessation.
Conclusion:
All chromatic filters improved visual function, with benefits generally maintained after cessation. Yellow demonstrated an advantage over Orange for BCVA. Compared with patching, chromatic light therapy produced comparable BCVA improvement and superior contrast-sensitivity and stereopsis outcomes, supporting its potential as a non-invasive and patient-friendly treatment option for amblyopia.