Binocular fixation pattern.

The binocular fixation pattern (BFP) is a convenient clinical test that may be used to diagnose strabismic amblyopia in children who are too young to cooperate with conventional testing of visual acuity. A retrospective analysis of amblyopic and nonamblyopic patients with esotropia and exotropia demonstrates the effectiveness of the BFP in detecting strabismic amblyopia in children under 4 years of age. Amblyopic patients with either esotropia or exotropia reliably demonstrate strong grades of preference. Nonamblyopic patients with esotropia or exotropia usually demonstrate weak grades of fixation preference, with the important exception that most patients with small angles of esotropia have strong fixation preference even in the absence of amblyopia.