Alternative Flicker Glass: A New Anti-Suppression Approach to the Treatment of Anisometropic Amblyopia

Abstract

Introduction: Amblyopia always presents with monocular and binocular dysfunction. In this study, we aim to investigate the efficacy of alternative occlusion using liquid crystal glasses versus continuous occlusion therapy using traditional patches for treating amblyopia.

Methods: Eligible subjects with anisometropic amblyopia were randomized into 2 groups: alternative flicker glass (AFG) or patching group. In the AFG group, subjects were instructed to wear the flicker glasses for 1 h a day. The AFG is a lightweight spectacle frame with liquid crystal lenses that provide direct square-wave alternating occlusion, which were preprogrammed at a temporal frequency of 7 Hz. In the patching group, the patients were prescribed to wear traditional patches for 2 h a day. The best-corrected visual acuity (BCVA), contrast sensitivity function (CSF), and stereoacuity were measured at the baseline and 3 and 12 weeks.

Results: In this pilot study, a total of 40 children were recruited, with 20 in the AFG group. Mean BCVA improved by 0.17 ± 0.14 logMAR (95% CI = 0.10-0.23) in the AFG group and 0.18 ± 0.18 logMAR (95% CI = 0.09-0.26) in the patching group from baseline to 12 weeks. The improvement in BCVA in both groups was significant (both p < 0.01), while there was no significant difference between the groups (p = 0.82). The CSF of both low and high spatial frequencies exhibited significant improvement at 12 weeks in the AFG group (p < 0.01, respectively) and just had a significant improvement at low spatial frequency in the patching group (p < 0.01). The stereoacuity significantly improved by 504.00 ± 848.00 (95% CI = 107.12 to 900.88) arc seconds in the AFG group (p < 0.05), while it was 263.50 ± 639.55 (95% CI = -35.82 to 562.82) arc seconds in the patching group (p > 0.05).

Conclusion: Alternative flicker glass was effective in improving both monocular and binocular function, which was most likely achieved by reducing suppression and promoting binocular fusion. This therapy exhibited promise as an alternative method for amblyopia treatment.

Keywords: Alternative flicker glass; Anisometropic amblyopia; Contrast sensitivity; Stereoacuity.

Fig. 1

The best-corrected visual acuity at baseline and each follow-up visit. Boxes indicate the mean value; whiskers represent the 95% confidence interval; *p < 0.05 compared with the baseline visual acuity in the AFG group; ^#p < 0.05 compared with the baseline in the patching group.

Fig. 2

The contrast sensitivity of the 3, 6, 12, and 18 cycles per degree spatial frequencies at baseline and each follow-up visit. a The patching group. b The AFG group. Boxes indicate the mean value.

Fig. 3

The improvement in contrast sensitivity function after 12-week treatment. Boxes indicate the quarter values (from one-fourth to three-fourths); whiskers represent the maximum and minimum value; the hyphen in the box indicates the median value; the cross in the box indicates the mean value. *p < 0.05 compared with the improvement in contrast sensitivity function in the patching group.

Fig. 4

Stereoacuity at baseline and each follow-up visit. Boxes indicate the mean value; whiskers represent the 95% confidence interval; *p < 0.05 compared with the baseline stereoacuity in the AFG group.