Grating and recognition acuities of pediatric patients.

Acuities for gratings obtained by preferential looking (PL) that differed from expectations based upon the ophthalmologic examination prompted this study. Older pediatric patients (124 patients; mean age, 6.5 years) were tested by the PL grating test and a test of recognition acuity (pictures or letters). On the average, grating acuity was better than recognition acuity. In patients with dense amblyopia or foveal abnormalities, very large discrepancies between grating and recognition acuities were found. In nonamblyopic patients, acuities were no more discrepant than for children with normal eyes. Amblyopia was less dense by grating acuities than by recognition acuities; grating acuities were sensitive, however, to refractive and organic amblyopia but not to strabismic amblyopia. Possible explanations include the heterogeneity of patients' eye disorders, single vs. linear acuity, stimulus size and relative complexity of stimuli. These results can aid in evaluating PL grating acuities of preverbal patients, and suggest modifications of stimuli to investigate amblyogenesis.