Abstract
Purpose: :
Accommodative response is reduced in many children and young people with Down syndrome (DS) affecting as many as 100% of this population (Nandakumar and Leat, March 2009 Opt Vis Sci- In press). However, providing bifocals has not become standard clinical practice. The purpose of this on-going longitudinal study is to investigate the impact of bifocals on vision, visual perceptual skills and early literacy skills in a group of school children with Down syndrome. Eighty-five percent of the participants required bifocals and near visual acuity was improved with these lenses (Nandakumar and Leat, AAO,Anaheim 2008). Here we present the impact of bifocals on the rate of progress in literacy skills in this population.
Methods: :
Eleven children aged 8-18 with DS were followed for 6 months with single vision lenses and then for another 6 months with bifocals. A full battery of reading and visual perceptual tests was administered before and after bifocal prescription and monthly sub-tests of reading and writing (Woodcock Reading Mastery Test [WRMT], word identification, Dolch sight words, a number test and writing tasks)were administered to measure the rate of progress over the whole time period. Progress was also monitored through school reports and questionnaires from teachers about the child’s performance.
Results: :
There was an improvement in both literacy skills (p=0.0015) and visual perceptual skills (p=0.047) with bifocals. There was an overall significant improvement in all the monthly sub tests with bifocals (t-test = 0.019, 0.025 and 0.33 for the WRMT word identification, Dolch sight word list and number test respectively). Since this may be due to general development, we measured the rate of progress with time. This increased after bifocal prescription for 7 out of 8 subjects who performed the Woodcock test (Sign test, p=0.034). We observed better compliance with bifocal wear when compared to single vision lenses and there were reports of increased school expectations or improved reading grade levels at school for 75% of the children (6/8 school reports).
Conclusions: :
The evidence shows that the improved near visual acuity with bifocals leads to improved literacy skills over time and improved school performance. Prescribing bifocals when accommodation is reduced will likely help these children with Down syndrome to maximize their educational potential.
Keywords: accomodation • reading • visual acuity