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D. G. Hunter, S. E. Loudon, C. A. Rook, D. S. Nassif, N. V. Piskun; The Pediatric Vision Screener: Improvement of Binocularity Scores After Successful Treatment of Anisometropic Amblyopia. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2829. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The Pediatric Vision Screener (PVS) is a polarized binocular retinal birefringence scanner that detects binocular foveal fixation, generating a binocularity score (BIN; 0-100%). We have previously shown that a PVS BIN threshold of 60% detects strabismus with high accuracy in a 2.5 second series of 5 scans performed from a 40 cm distance. This study was undertaken to determine whether BIN changes after treatment of amblyopia and strabismus.
From June 2003 till December 2007, 202 children were scanned with the PVS at Children’s Hospital Boston. All children received a gold-standard orthoptic examination and were classified as amblyopic, at risk for amblyopia, or control. From May till December 2007 repeat testing was performed during follow-up appointments.
Twenty-two children received two sequential PVS measurements. Mean age was 5.0 years. Eight children had anisometropic amblyopia, 1 had treated anisometropic amblyopia, and 13 had strabismic or mixed amblyopia. Mean BIN at first measurement was 14% for the anisometropic amblyopes and 13% for the strabismic or mixed amblyopes. In the 4 patients with anisometropic amblyopia who were successfully treated for amblyopia, BIN improved to 100%. In the patient with treated anisometropic amblyopia, BIN remained 100%. In the 5 patients with constant strabismus who were successfully treated for amblyopia, BIN did not improve, except in one patient with intermittent strabismus who recovered stereopsis and improved to BIN 67%. BIN did not improve overall in the 12 patients who did not improve after amblyopia therapy.
Improvement in the BIN score is an indicator of successful amblyopia therapy in anisometropic amblyopes. The results are consistent with the hypothesis that patients with anisometropic amblyopia have a previously unrecognized microstrabismus. Furthermore, this microstrabismus appears to improve with successful amblyopia therapy. Strabismic amblyopes show no such change with treatment.
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