Helping Children with Cortical/cerebral Visual Impairment see and understand their world

Cortical/cerebral visual impairment is a diagnosis where the visual processing areas of the brain are impacted at some level and the individual has difficulty interpreting what they are seeing. CVI can be a result of trauma to the brain, whether this be congenital or acquired later in life. Due to the brain being involved, there are often other challenges that contribute to the misunderstanding of these students and the lack of the level of intervention needed. These challenges can include the inability to communicate verbally, the inability to move one’s limbs, difficulty with cognitive tasks, and being prone to seizures, among others.

Cortical/Cerebral visual impairment (CVI) is now recognized as the leading cause of visual impairment. It is believed this is largely due to an increased survival rate of preemies along with technological advances. There is also the aspect of CVI being confused/misdiagnosed with other diagnoses, whether these be low vision disorders or learning disorders among other things. Despite more attention given to CVI, it remains largely underdiagnosed. Results from a 2019 University of Bristol study estimated an astonishing 1 in 30 students has CVI. Even when largely underdiagnosed, CVI is now considered an epidemic in the area of visual impairment.

To understand cortical/cerebral visual impairment (CVI), one needs to first understand how vision works. Out of all our senses, vision is the most dominant sense. There are studies that say 50% of our brain is dedicated to vision (Research by University of Rochester, 2011). To put this into perspective, according to the American Academy of Audiology the auditory sense only uses 3% of our brain while the tactile sense uses around 10% (study by ScienceDaily). Vision is not something that happens in the eyes. The visual system is not a camera. Vision is actually a learned, complex process. It is a much more complex process than many of us realize. The images that come through the eyes and travel through the optic nerves to the visual cortex are actually 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 a learned function, much like riding a bike or walking. Seeing is a whole-body experience involving the visual cortex. Vision is trained-up by experiencing the world around us. 

The term cortical/cerebral visual impairment is now more widely used as it acknowledges that there can be 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 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 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. The exciting thing about CVI that drew me to it is that with this intervention there is the possibility of new neural pathways being formed so a child can learn how to recognize and access their environment by building their visual skills. Providing meaningful experiences and learning opportunities to aid in memory formation is the focus of intervention for CVI.

There were originally ten Characteristics Dr. Roman identified to help determine if a child had CVI, but this is changing as additional characteristics are being recognized 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 first Characteristics with the intention of adding more. 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

Two main things I have learned in my journey with working with students with CVI: there is always some degree of vision present, no individual is completely blind from CVI, and CVI is complex. Each child with CVI is unique and there is no one size fits all approach. Intervention for each student needs to be carefully thought out and takes time. 

As with anything to do with the brain, research is showing us how much more there is to learn. CVI is an evolving field where not all students may fit in the descriptions above as more characteristics are being discovered. I look forward to keeping up with the research and continuing to develop the VistaQuest BaseKit to incorporate new findings into practice.

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