Higher Visual Function Deficits in Children With Cerebral Visual Impairment and Good Visual Acuity

Abstract

In clinical practice Cerebral Visual Impairment (CVI) is typically diagnosed by observation of abnormal visually guided behaviors which indicate higher visual function deficits (HVFDs) suggesting abnormal brain development or brain damage in a child with a suitable clinical history. HVFDs can occur even in the presence of good visual acuity and may remain undiagnosed because the good visual acuity does not prompt further investigation. This leads to a lack of understanding of the child's visual perceptual difficulties. In a prospective study, we determined the spectrum of HVFDs in a group of children with history suggestive of brain damage or disruption of brain development and an independent diagnosis of CVI in comparison with typically developing children with a structured 51 question inventory, the Higher Visual Function Question Inventory (HVFQI-51) adapted from the Cerebral Vision Impairment Inventory, CVI-I. Here, we show that the HVFQI-51 can detect a range of HVFDs in children with CVI with good visual acuity and clearly distinguishes these children from typically developing children. HVFDs in our study group could mostly be attributed to dorsal stream visual processing dysfunction though the spectrum varied between children. We report on the inclusion of the "not applicable" response option in analysis providing a picture of HVFDs more in tune with the overall disability of each child. We also propose a subset of 11 questions (Top-11) which discriminate between children with CVI vs. behaviors seen in typical children: this provides both a potential screening tool for initial assessment of HVFDs and a measure of CVI-related impairment, and needs further validation in a secondary independent sample.

Keywords: cerebral visual impairment (CVI); children; good visual acuity; higher visual function deficits; low vision; questionnaire; screening; structured question inventory.

FIGURE 1

HVFQI-51 scores for CVI (in red and hatched) and typical (in blue) groups. Boxplots show 25th and 75th percentile of group data with the median shown as the narrowest part of the box; whiskers show data range. (A) Full Likert overall scores for HVFQI-51. (B–E) Scores for HVFQI-51 for “Rarely,” “Sometimes,” “Often,” and “Always” dichotomies (see Table 3). (F) Scores for the Top-11 subset of HVFQI-51. (G) Individual scores for the Top-11 subset of HVFQI-51 for typical children (blue dots) and children with CVI (red stars) as a function of age (in years); data for 3 children whose binocular visual acuity was slightly worse than 0.2 are marked by black rings.

FIGURE 2

The distribution of scores for each question for children with CVI (red) and typical children (blue). For children with CVI, the median is shown in red right-pointing triangles; the mean is shown in red stars. For typical children, the median is show in blue left-pointing triangles; the mean is shown in blue dots. Error bars represent the 25th and 75th percentiles. To avoid overlapping of the plots, data for typical children is moved rightward by 10% of the unit. C1–C7 mark the 7 categories in Dutton et al. (2010). Questions in the Top-11 (vertical lines) and Dutton’s Five (half circles) are marked on the horizontal axis (see Table 4).