Purpose: Accommodation is reduced in approximately 75% of children with Down's syndrome (DS). Bifocals have been shown to be beneficial and they are currently prescribed regularly. Clinical observations suggest the likelihood of improving accommodative ability after bifocal wear. The aim of the study is to evaluate the potential use of bifocals as a treatment for the reduced accommodation.
Methods: Clinical records of 40 children from the Cardiff Down's Syndrome Vision Research Unit, who were prescribed bifocals, were reviewed. Accommodation was noted before wearing the bifocals and during either their latest visit or when the children stopped using bifocals. Accommodation was reassessed during a follow up visit for the children who stopped wearing bifocals. Development of accommodation before bifocal commencement, age at bifocal prescription, gender, type of refractive error, visual acuity and the presence of strabismus were examined to evaluate their contribution to accommodation improvement.
Results: The accommodative ability of 65% (n = 26) of the children improved (through the distance part of the lens) after using the bifocals. More than half of those developed accurate accommodation without the use of bifocals (n = 14). Accommodative responses did not show any improvement with age before the children began wearing bifocals. Accurate accommodation was sustained after returning to single vision lenses in all examined children. The age distribution of the children on bifocal commencement was diverse. Presence of strabismus, refractive error type, visual acuity and gender did not have any effect on gaining improvement.
Conclusions: Bifocals are an effective correction for the reduced accommodation in children with DS and also act to improve accommodation with a success rate of 65%. Bifocal wear can therefore be temporary, i.e. a 'treatment' for the deficit, in at least one third of children.