Estimation of Strabismic Amblyopia by Non–Cartesian Concentric Gratings in Preverbal Children

Abstract

Abstract: : Purpose:To test the possibility of improving estimation of strabismic amblyopia in preverbal children by a newly designed preferential looking (PL) procedure. Methods: Thirty–three preverbal children (age 6–30 months) with endotropia (>10 prism diopters) were tested for monocular visual acuity using a PL device designed with concentric gratings which subtend 1.6º (smaller than typical size), in 1/3 octave steps, and with the classical Teller Acuity Cards (TAC). The results of the two previous tests were compared with those of fixation preference obtained in the same visit. In 15 of these children, Snellen visual acuity (Glasgow Acuity Cards) was obtained 1–3 years later (when they were verbal and after treating amblyopia and strabismus), and also compared with preverbal and simultaneous PL tests and fixation preference results. In 22 additional non–treated verbal strabismic children (age 39–48 months), Snellen visual acuity was compared with results of simultaneous PL tests and fixation preference. Results:Correlation of a fixation preference scale was significantly higher with interocular acuity difference (IAD) obtained by the concentric grating–PL procedure than by the TAC procedure in the preverbal group. Snellen IAD in the verbal group was also better correlated with IAD obtained by concentric grating–PL than by TAC in the same visit and in the preverbal visit, and even better with fixation preference testing. Conclusions: The concentric grating preferential looking procedure improves detection and estimation of amblyopia depth in strabismus, but it could still underestimate strabismic amblyopia.

Keywords: amblyopia • strabismus: diagnosis and detection • strabismus