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.
Highlights
Cerebral Visual Impairment (CVI) is a heterogenous disorder of brain-based visual impairment resulting from brain injury or disruption of development of retrochiasmatic visual pathways and vision processing regions of brain, commonly occurring during gestation at or around birth
The frequency of Not Applicable” (NA) responses was higher in the CVI group compared to the typical group: median number of 1 (75% quartile at 3 NAs) for the CVI group compared to 0 (75% quartile at 0 NAs) for the typical group; the difference in the number of reported NA responses for a participant was significant (MannWhitney U, p < 0.001) confirming the need to account for the NA response when comparing to neurotypical children to prevent bias
Our prospective study confirms that the HVFQI-51 clearly distinguishes the range of visually guided behaviors in children with an established clinical diagnosis of CVI and good visual acuity from neurotypical children
Summary
Cerebral Visual Impairment (CVI) is a heterogenous disorder of brain-based visual impairment resulting from brain injury or disruption of development of retrochiasmatic visual pathways and vision processing regions of brain, commonly occurring during gestation at or around birth. The presence of good visual acuity which often precludes further investigations (Sakki et al, 2018), the lack of readily available tools (Gorrie et al, 2019) or the knowledge and understanding of manifestations of CVI amongst clinicians and teachers (Fielder et al, 1993; Youngson-Reilly et al, 1994; McDowell, 2020) adds to the challenges of identifying HVFDs. diagnosing HVFDs is essential since they can cause significant visual disability in everyday activities and education especially, while visual acuity remains largely intact (Mercuri et al, 1998; Dutton and Jacobson, 2001; Fazzi et al, 2007; Saidkasimova et al, 2007; van Genderen et al, 2012). Prospective studies on children with an independent diagnosis of CVI and normal visual acuity are lacking at present in the published literature with only one retrospective study (van Genderen et al, 2012) reporting on children with good visual acuity and CVI and with suspected CVI using an abbreviated question inventory, adapted from the question inventory of Houliston et al (1999). We allowed the parents to use the NA option and comment on their analysis and utility within the questionnaire
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