Assessment of visual functioning in patients with severe motor and intellectual disabilities:

an investigation of visual acuity, visual response and severity.

Abstract

A vision specialist worked together with an occupational therapist to assess the objective refraction, visual acuity, and visual response of 50 institutionalized patients with severe motor and intellectual disabilities using the conventional methods. The results were compared with the Yokochi classification (revised Oshima classification) that classifies severity. Objective refraction tests revealed that 46% of the subjects had 2D or higher astigmatism. Quantitative visual acuity assessment could be performed on 30 subjects, for whom the mean decimal visual acuity was 0.088. Decimal visual acuity of less than 0.05 was only present in subjects with an intelligence level of A or B. Visual response was observed in 18 subjects that showed either optokinetic nystagmus, reflexive startle eyeblink or reactions induced by light perception, while 2 subjects did not exhibit any reactions induced by light perception. For both intelligence level and locomotive function level, ability to perform quantitative evaluation tended to increase as severity decreased. However, a relatively good grating acuity of 0.32 was seen in one subject with an intelligence level of A, the most severe level. This may be accounted for by differences in evaluation method, as assessment of intellectual disabilities is based on language comprehension, while grating ability is assessed by eye movement from visual perception. Cooperating with a specialist to evaluate visual functioning and exchange information may enable more accurate assessment of latent abilities that can then be reflected in severity classification and daily rehabilitation activities.