Relation among accommodative facility, lag, and amplitude in elementary school children.

Normative data for accommodative lag, facility, and amplitude of children have been presented in the literature for each of the parameters separately. This paper delineates the relation among accommodative amplitude, lag, and flexibility for grade school children. Approximately 200 children were screened. Those who wore corrective lenses, had uncorrected acuity worse than 6/9 (20/30) in either eye, had strabismus, had a refractive error outside the range from 0.00 to +0.75 D; or astigmatism greater than 0.50 D were excluded from the study. Of the 123 who remained, 53% had a deficit in accommodative facility, 26% had a deficit in lag, and 25% had a deficit in amplitude from that which would be expected from their age. Sixteen percent had deficits in both facility and lag. Eighteen percent had deficits in both amplitude and lag. Twenty-four percent had deficits in both facility and amplitude. Only 4% had deficits in all three of the accommodative functions considered--amplitude, lag, and facility. Clinically, these results indicate that when a patient's accommodative dysfunction is examined all facets of accommodation--lag, facility, and amplitude--need to be evaluated.