Visual Behaviours (ViBes) in Cerebral Visual Impairment: Validating a Descriptive Tool to Support Diagnosis and Monitoring
Authors
Rachel F. Pilling, Louise Allen, Pamela Anketell, Raimonda Bullaj, Janet Harwood, Suzanne Little
Cerebral visual impairment (CVI) is the most common cause of visual problems in children in the UK. CVI occurs when the brain has trouble processing visual information, even if the eyes themselves are healthy. Kids with CVI might show unusual visual behaviors, such as not looking directly at things or having variable visual attention and fatigue.
Diagnosing CVI is tricky, especially in children who have other developmental delays or disabilities. Traditional tests, like reading eye charts, often don’t work well for these kids because they might not be able to follow instructions or cooperate fully. Doctors and teachers need a way to observe and record how children behave visually, but currently, there’s no clear, structured method for doing this. This makes it hard to diagnose CVI early and accurately, which can delay necessary help and support.
Main problem:
There’s a need for a simple, reliable tool that professionals can use to describe and measure children’s visual behaviors, especially those who cannot do standard vision tests.
Main Research Question
Can a new structured tool, called the ViBe matrix, reliably describe and assess visual behaviors in children suspected of having CVI, especially those who are pre-verbal or have complex needs? The goal was to see if the tool is valid (measures what it’s supposed to measure) and reliable (gives consistent results across different observers).
Methodology: How the Review Was Done
The study had two main parts:
1 Content Validation
Experts in children’s vision, including ophthalmologists, orthoptists, optometrists, and teachers, reviewed a list of 28 visual behaviors pulled from previous studies. They discussed and refined these into 33 clear descriptions, called "visual behavior descriptors." They then grouped these behaviors into three categories reflecting how children use their vision:
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- Awareness and attention (“See it”)
- Fixation and field (“Find it”)
- Motor Response (“Use it”)
Each behavior was rated on a scale from 0 to 4.
2 Inter-rater Reliability Testing
To test if different professionals agree when using the tool, six experts watched 17 short videos showing children exhibiting CVI-related behaviors. They used the ViBe matrix to score each video independently. Their scores were then compared statistically to see how consistent they were, using a statistical test called Cohen’s kappa.
Image Description: An optometrist examines the eyesight of a boy with cerebral palsy, while his younger brother plays nearby. Photo credit: Jodi Mora Igual.
Key Findings
Content Validity
The experts agreed on most of the behaviors and how to describe them. They created a user-friendly matrix that helps professionals observe and record visual behaviors systematically.
Reliability
The scoring agreement between different professionals was good, with a Cohen’s kappa of 0.67. This is considered moderate to strong reliability, suggesting that different experts using the test on the same patient would provide similar scores.
Implication of the Scores
The matrix facilitates a structured way to describe children’s visual strengths and difficulties, which is especially useful for children who cannot undergo standard testing.
Significance (Especially for CVI)
The ViBe matrix is important because it gives professionals a standardized way to describe what children with complex needs are doing visually. Instead of vague notes, they have clear descriptors that can be used to:
- Help diagnose CVI more accurately
- Track changes over time
- Communicate findings clearly across healthcare and educational services
- Identify specific areas where a child might need support or intervention
This structured approach can bridge the gap between health and education, ensuring children receive appropriate help sooner.
Conclusions
The study successfully developed the ViBe matrix, a tool that standardizes how visual behaviors are described and scored in children with complex needs and suspected CVI. It has shown good reliability across different observers, meaning it can be trusted to give consistent results. While the study used videos rather than live assessments, initial findings are promising, and future research will test its usefulness in everyday clinical and educational settings.
Key Takeaways
Main takeaway:
Having a clear, consistent way to observe and record visual behaviors will help professionals better identify children with CVI, especially those who are pre-verbal or have multiple disabilities. This can lead to earlier diagnosis and more tailored support.
- CVI is common but can be hard to diagnose in children with multiple disabilities.
- Standard tests used by pediatric eye care providers often aren’t suitable for children with complex needs.
- The ViBe matrix provides a structured, reliable way to assess behaviors suggestive of CVI in children with motor and speech challenges.
Pilling, R. F., Allen, L., Anketell, P., Bullaj, R., Harwood, J., & Little, S. (2023). Visual Behaviours (ViBes) in Cerebral Visual Impairment: Validating a Descriptive Tool to Support Diagnosis and Monitoring. The British and Irish orthoptic journal, 19(1), 44–51. https://doi.org/10.22599/bioj.290