Development and treatment of astigmatism-related amblyopia

Abstract

Blur induced by uncorrected astigmatism during early development can result in amblyopia, as evidenced by reduced best-corrected vision relative to normal, in measures of grating acuity, vernier acuity, contrast sensitivity across a range of spatial frequencies, recognition acuity, and stereoacuity. In addition, uncorrected astigmatism during early development can result in meridional amblyopia, or best-corrected visual deficits that are greater for, or are present only for, specific stimulus orientations. Astigmatism-related amblyopia can be successfully treated with optical correction in children as old as school age, but the amblyopia may not be completely eliminated with optical treatment alone, and the age at which optical treatment is most effective has yet to be determined. Future research on determining the period of susceptibility of the visual system to negative effects of uncorrected astigmatism and exploration of alternative or complimentary treatment methods, in addition to optical correction, are warranted.

Figure 1

Illustration of the location relative to the retina that horizontal and vertical line stimuli come into focus when accommodation is relaxed in non-astigmatic eyes (A–C) and in astigmatic eyes with with-the-rule astigmatism (greatest curvature in the vertical meridian, plus cylinder axis 90°, minus cylinder axis 180°) (D–H) (From Harvey et al., 2007).