Purpose: Over 75% of children with Down's syndrome fail to accommodate accurately on near targets. This deficit must result in optically blurred images for near work. This present study set out to evaluate the controlled use of bifocal spectacles as an aid to near focusing. Although sometimes used clinically, no systematic studies of bifocals for children with Down's syndrome have been reported.
Methods: This was a comparative non-randomised interventional study. Thirty-four children with Down's syndrome of primary school age (5-11 years) took part, assigned in equal numbers to form two matched groups. All children received a full optometric assessment prior to entering the study. The treatment group was prescribed bifocal spectacles with a +2.50 addition, and the control group provided with single vision lenses to correct any clinically significant refractive error. Three follow-up visits were made over a 5-month period after spectacle provision.
Results: The treatment group showed consistently more accurate accommodation than the control group both through the bifocal segment, and, unexpectedly, through the distance part of the lens (p < 0.05). Compliance with new spectacles was high in both groups (>82% fully compliant).
Conclusions: Bifocals confer benefit to children with Down's syndrome who under-accommodate, both directly (better focusing through the bifocal) and indirectly (by encouraging improved accommodation through the distance part of the lens). Based on the results of this study, eye examinations of children with Down's syndrome should routinely include a measure of accommodation at near, and bifocal spectacles should be considered for those who show under-accommodation.