Abstract
Purpose: :
Accommodative lag is present in three quarters of children with Down syndrome (DS). Bifocal spectacles are a successful aid in bringing the near image into focus in children with DS with defective accommodation. Clinical observations suggest the likelihood of accommodation activation after wearing bifocals. The aim of the study is to evaluate the potential use of bifocals as a treatment for the reduced accommodation in children with DS.
Methods: :
Clinical records of all of the children from the Cardiff Down Syndrome Vision Research Unit who were prescribed bifocals were reviewed (n=40). Distance refractive errors were fully corrected and bifocals addition was +2.50D in all cases. 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, 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 when looking through the distance vision lens after wearing bifocals for a mean of 3.4 years. Accurate accommodation was achieved by 14 out of the 26 children; this resulted in discontinuing bifocal wear. Accurate accommodation was sustained in all of the 14 children. The age distribution of the children on bifocal commencement was diverse (range= 4.96 - 14.64 years). Presence of strabismus, refractive error type 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 be temporary i.e. a 'treatment' for the deficit in at least one third of children.
Keywords: accomodation • spectacle lens • visual development: infancy and childhood