Refraction as a basis for screening children for squint and amblyopia

Abstract

+2.00 to +2.75 dioptres of spherical hypermetropia in the more emmetropic of a pair of eyes is significantly associated with esotropia (P<0.001) and the presence of amblyopia (P<0.01). Anisometropia is not significantly associated with esotropia (P=0.31) unless there is spherical hypermetropia of + 2.00 dioptres or more in the more emmetropic eye (P<0.001). Hypermetropic anisometropia of +1.00 DS or +1.00 D. Cyl. is associated with the presence of amblyopia (P<0.001). In the absence of esotropia there is also a significant association between the amount of anisometropia and the initial depth of amblyopia (P<0.01). The additional presence of esotropia increases the depth of amblyopia further (P<0.05) but not the incidence of amblyopia (P>0.30). The level of significance of the association of refractive errors with squint/amblyopia was itself significantly higher (P<0.01) than that between a family history of squint or 'lazy eye' on the one hand and squint and/or amblyopia on the other hand. 72 ± 3% of all cases of esotropia and/or amblyopia in this sample of children had a refractive error of +2.00 DS or more spherical hypermetropia in the more emmetropic eye, or + 1.00D. or more spherical or cylindrical anisometropia. Since there is a close association between the refraction and how, when, and whether a child presents with squint and/or amblyopia, it would seem reasonable to reconsider refraction as a basis for screening young children for visual defects.