Spectrum of Visual Dysfunction Detected by a Novel Testing Protocol Within a Special School Eye Care Service

Abstract

Introduction: Children with special educational needs are more likely to have vision problems than peers in mainstream education. Reports focus on visual acuity and refraction, overlooking visuoperceptual difficulties, including cerebral visual impairment. This article reports on the feasibility and outcomes of visual function testing performed during in-school visual assessments.

Method: A retrospective chart review was undertaken of children participating in a special school vision programme. The testing strategy included acuity, fields, contrast sensitivity, eye movements, accommodation, stereopsis, visual attention, refraction and a parent-completed questionnaire. The testing method was chosen based on the child's ability to engage with testing.

Results: 78 cases were identified (mean age 9.6 years). Low vision (worse than 6/19) was identified in 31%. All six tests of visual function were completed by 44% (mean 5.1; range 2-6). The mean number of atypical responses was 1 (range 0-4). Almost half (49%) showed at least one atypical response, most commonly visual attention (35%) and 25% had atypical eye movements.

Discussion: Overall, only 20% of children in the special school setting demonstrated a normal response to each test they were able to complete. Acuity testing alone does not demonstrate the atypical visual function of a child with special needs. Using techniques which require minimal cognitive, speech or motor function, a range of visual functions can be elicited during in-school testing. This testing strategy has the advantage of demonstrating areas of visual (dys)function impacting on the child's ability to access learning which can be immediately fed back to teaching staff and carers.

Keywords: Cerebral visual impairment; Children’s visual acuity; Competing Interests.