Helping Children with Cortical Visual Impairment see and understand their world

CVI is the leading cause of visual impairment in developed countries. Recent studies show that CVI is largely an undiagnosed condition. According to a research study done in 2021 in Bristol, 1 in 30 students are estimated to have CVI, Williams (2021). Yet, one of the most positive aspects to CVI is that improvement in vision may be expected through intentional and consistent intervention.

To understand cortical visual impairment (CVI), one needs to first understand how vision works. As David Eagleman explains (Eagleman, 2015), it is a much more complex process than many of us realize. Vision is more than just bringing back images that come through the eye to the brain. These images are transformed into electrochemical signals that need to be interpreted through the brain in order to become meaningful. Being able to see and interpret correctly what one is looking at is something that needs to be learned, much like riding a bike or walking. Seeing is a whole-body experience involving the visual cortex. Vision is developed by experiencing and interacting with the world around us.

Cortical visual impairment is a subset of cerebral visual impairment (Dr. Roman 2018, Advanced Principles of Cortical Visual Impairment). Cerebral visual impairment occurs when there is damage or disorder to the visual pathway and visual centers in the brain, including pathways serving visual perception, cognition, and visual guidance of movement (Lueck & Dutton 2015, Vision and the Brain). CVI describes damage to the visual system between the lateral geniculate nucleus (a structure in the thalamus that connects to the optic nerve), and/or optic radiations and the cortical area of the brain. CVI is a decreased response due to a neurological problem affecting the visual part of the brain. The analogy has been used to think of this visual pathway from the optic nerve to the visual cortex as the main highway for vision to be interpreted. When a traffic jam occurs, this highway becomes unusable. Cars are going to need to be rerouted in order to get where they need to go. Our brain is amazing in that when this main visual pathway is not usable due to damage, new routes can be formed that will, with proper intervention, provide meaning to those electrochemical signals coming into the eyes. Due to the plasticity of the brain, there is always the possibility of new routes being created. Early intervention is crucial, as this is when the brain is the most plastic, meaning having the ability to reorganize. Providing meaningful experiences and learning opportunities to aid in memory formation is the focus of intervention for CVI.

In order for CVI to be diagnosed, there are three criteria that need to be met (Dr. Roman 2018, Advanced Principles of Cortical Visual Impairment):   

1. An eye exam that does not explain the individual’s functional use of vision.
2. A history of a brain condition, trauma, or damage associated with CVI.
3. The presence of certain visual and behavioral characteristics.                                                               

There were originally ten characteristics that were used to help determine if a child had CVI, but this is slowly including additional characteristics as more research is being done. Multiple terms for these characteristics are included in this description of CVI. The first set of terms are from Dr. Roman-Lantzy’s work (Dr. Roman 2018, Advanced Principles of Cortical Visual Impairment) as they have set the foundation for a lot of research and work being done now, followed by more recent terms. The BaseKit has been designed with the intention to target these characteristics. The characteristics are as follows: 

• Color preference/need for color (impact of color) 
• Need for movement (impact of motion/impaired perception of motion) 
• Visual latency (response interval/wait time for looking and understanding) 
• Visual field preferences/neglect 
• Difficulties with visual complexity of object (object recognition) 
• Difficulties with complexity of array (impact of clutter) 
• Difficulties of complexity of sensory environment (sensory integration) 
• Difficulties of complexity of facial recognition (facial recognition/access to people)  
• Need for light (impact of light) 
• Difficulty with distance viewing (visual attention) 
• Difficulty with visual novelty (visual curiosity) 
• Absence of visually guided reach (visual guidance of upper limbs and also visual guidance of lower limbs)
• Atypical blink reflex

I do want to give credit for various assessments out in the field who have helped me in my work:

Credit for assessments out there:

CVI Range Assessment created by Dr. Christine Roman-Lantzy

Visual Skills Inventory created by Dr. Gordon Dutton

“What’s the Complexity” by Matt Tietjen

Upcoming assessments: CVI Protocol through Perkins University

Sensory Balance by Dr. Roman-Lantzy and Matt Tietjen