UNDER THE UMBRELLA OF CVI

Cortical vision impairment or CVI is an umbrella term for vision impairments that are caused by a disorder in the visual areas of the brain. Recent research has found it’s not just the visual cortex or occipital lobe responsible for vision but the white matter and ventricles of several other areas of the brain including parietal, temporal and frontal lobe. At a basic level, the front of the brain ‘thinks’, ‘understands’ and ‘behaves’; the middle ‘feels and moves the body, and hears and understands language’; while the back ‘sees’ (Professor Gordon Dutton, 2013) Eyes take in information  sent as electrical signals down different pathways to the back of the brain. From here it is sorted out and interpreted in different ways such as connecting to language concepts and memories. Damage to any of these brain pathways could lead to an interruption in visual processing making it hard for people with CVI to understand what they are seeing.
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Statistics about CVI:

• 1 in 200 people have CVI
• 50% of the brain is devoted to vision
• 60% of people with Cerebral Palsy have CVI
• 50% of people with hydrocephalus have CVI
• 30% of babies born before 30 weeks have CVI
• 40% of people with Down Syndrome have CVI

 
Characteristics of CVI

• Not appearing to have a vision impairment- A person with CVI usually will have no abnormality of their eyes however they have challenges with visual functioning. The person may appear to look directly at people and ‘see’ objects- but the difficulty is in them processing and understanding what they are looking at and making sense of it.
• Variability of visual function the person’s visual skills may vary from day to day.  Their vision will be affected by level of seizure activity, attention, energy, and illness. Other factors may affect their level of vision such as familiarity of the environment, lighting, complexity of the visual information and background noise.
• Visual Inattention The person may have difficulty attending to visual stimuli for more than a few minutes and tire from visual activities quickly.
• Difficulty with visual clutter- The person may have difficulty seeing objects or pictures placed closely together on a messy background but can see when they are further apart or placed on a plain black background. They may bring an object closer to their face to look at it which blocks out non important visual information in the background.
• Colour Preferences- The person may recognise some colours more easily than shapes. Usually bright red, magenta or yellow or  metallic sparkly objects are more visually interesting.
• Movement enhances vision- People with CVI often see moving objects more easily than stationary objects. Therefore if showing them a new toy, you could  shake it slowly in front of them to gain their visual attention.
• Face Recognition- The person may have difficulty recognising people’s faces and rely on your voice or tactile cues (feeling your watch or ring) to recognise you.
• Picture Recognition- The person may recognise the real object but not the photo or symbol representing the same object. This makes using visual communication systems really difficult!
• Sensitivity to glare- They may respond better visually if working in a dimly lit room or when the object they are meant to focus on is backlit.

If you suspect your child or a client you are working with has CVI they need an assessment from an experienced orthoptist to assess their visual functioning in every day environments. Completing a visual skills inventory prior to this assessment would be very helpful. Professor Gordon Dutton has developed an excellent one for parents and therapists to use https://www.ulster.ac.uk/research/topic/biomedical-sciences/research/optometry-and-vision-science/vision-resources/professionals/cerebral-visual-impairment-assessment
Most state schools in Queensland run an annual paediatric Low Vision Clinic. You could also contact Senses Australia or Vision Australia for more information and resources.
 
References:
www.visionaustralia.org  Handout: CVI General Information
Roman-Lantzy, C. (Eds.) (2018). Cortical Visual Impairment Advanced Principles, Louisville, KY: APH Press.
Roman-Lantzy, C. (2018) Cortical visual impairment: An approach to assessment and intervention. Second Edition. New York, NY: AFB Press.
Roman-Lantzy, C. (2007). Cortical visual impairment: An approach to assessment and intervention. New York, NY: AFB Press.
Roman, C., Baker-Nobles, L., Dutton, G. N., Luiselli, T. E., Flener, B. S., Jan, J. E., Lantzy, A., Matsuba, C., Mayer, D. L., Newcomb, S., & Nielsen, A. S. (2010). Statement on cortical visual impairment. Journal of Visual Impairment and Blindness, 104(3), 69-72.
Roman-Lantzy, C. A., & Lantzy, A. (2010). Outcomes and opportunities: A study of children with cortical visual impairment. Journal of Visual Impairment and Blindness, 104(10), 649-653.
Newcomb, S. (2010). The reliability of the CVI range: A functional vision assessment for children with cortical visual impairment. Journal of Visual Impairment and Blindness, 104(10), 637-647.
Cortical Visual Impairment: An Approach to Assessment and Intervention Christine Roman-Lansky
Dutton, GN ( 2013) Types of impaired vision in children related to damage to the brain, and approaches towards their management. Proceedinmgs of the South Paciufic educators for the Visually Impaired.
 
Dutton, G.N. & Bax, M. (2010). Visual impairment in children due to damage to the brain. Clinics in Developmental Medicine No 186. MacKeith Press, London.
 
Fazzi E., Signorini S.G., Bova, S.M., La Piana, R., Ondei, P., Bertone, C., Misefari, W., Bianchi, P.E., (2007). Spectrum of visual disorders in children with cerebral visual impairment.  Journal of Child Neurology, 22, 294-301.
 
Guzzetta. A., Tinelli, F., Del Viva, M.M., Bancale, A., Arrighi, R., Pascale, R.R., Cioni, G.,(2009). Motion perception in preterm children: role of prematurity and brain damage. Neuroreport, 20, 1339-1343.
 
Little Bear Sees: How Children with Cortical Visual Impairment Can Learn to See http://littlebearsees.org/