Cerebral Vision Impairment (CVI) is the leading cause of sight impairment in children in the UK. It occurs in adults alike, but is often overlooked as a cause for their visual difficulties. CVI can present in different ways, depending on the underlying visual processing dysfunctions. Common difficulties are: Only seeing one thing at a time, unable to control where to look, difficulties with reading and writing, finding going down stairs challenging, and feeling overwhelmed in cluttered or busy environments. Cirta Tooth supports patients, their families and carers to understand their visual impairments and gives advice about specific strategies for each individual.
This page contains information about CVI assessments with an introduction video, an outline of what happens in an assessment and 'Frequently Asked Questions'. If you want to dive deeper into some of the topics, please click here to explore publications on this topic by Cirta Tooth:
Cirta Tooth is an Associate member of CVI Scotland. This charity has developed a website with information for anyone wishing to understand more about CVI. Their website is well worth a visit!
CVI Appointments with Cirta Tooth
Face-to-Face
Cirta Tooth offers face-to-face CVI appointments at:
Cameron Optometry
5 St Vincent Street
Edinburgh EH3 6SW
Online
Online assessments coming soon
Watch this space!
Register your interest
To make enquiries, book an appointment, or register your interest in online assessments, contact Cirta Tooth:
CVI Introduction Video
CVI Assessments
What happens in a CVI assessment?
In the CVI clinic, your visual difficulties are assessed and addressed. You will receive a short ‘triage questionnaire’ prior to booking your consultation in order to make sure that the CVI clinic is the appropriate clinic for assessing and addressing your visual needs and to help us tailor the consultation to your needs and circumstances. This questionnaire will be reviewed by Cirta Tooth. You will subsequently be asked to complete a tailored Question Inventory with more in-depth questions about your visual issues, in order to prepare for the consultation.
The assessment includes further history-taking, visual function tests, an Austin assessment (if applicable) and direct observation. After the consultation you will receive a comprehensive report, which you can share with anyone you wish.
Link to Austin Assessment:
https://www.austinassessment.org/
What is not included in a CVI assessment?
The CVI assessment does not replace a sight test. It is therefore recommended that you attend your regular optometrist for a sight test and address any issues before your CVI assessment if you have not already done so.
CVI is a complex condition which is usually diagnosed by a team of healthcare professionals, including an ophthalmologist. It is not within the scope of the optometrist to diagnose CVI during a CVI assessment.
For a CVI assessment to be beneficial, a formal diagnosis is not required. Children with visual difficulties can be offered strategies specific to their situation and needs, regardless of the severity of these visual difficulties. It has been estimated that about one child in every classroom in mainstream education experiences one or more visual difficulties, related to visual processing. However, not every one of these children goes on to be diagnosed with CVI.
Visual Processing- sensory processing- cortical visual impairment- cerebral visual impairment
CVI is a term to describe the visual difficulties caused by damage to the parts of the brain that process vision. CVI is an abbreviation for 'cerebral vision impairment'. In some literature, the term 'cortical vision impairment' is used to refer to the same visual difficulties. Some professionals prefer the term 'sensory processing' to refer to processing vision as well as sound, or simply 'visual processing' to refer to processing vision. To add to confusion, the abbreviation CVI is also used for 'certificate of vision impairment'. Terminology can be confusing and overwhelming. What is more constructive than dwelling on the terminology, is to focus on identifying and addressing the visual difficulties. Cirta Tooth offers specialist assessments to support you in that process.
Reading difficulties- Dyslexia- Alexia- Visual stress
Reading difficulties can be caused by different underlying problems:
In dyslexia, a person has difficulty identifying speech sounds and learning how these relate to letters and words, also known as phonological processing. It refers to a neurodevelopmental disorder, rather than an acquired reading difficulty.
However, before a diagnosis of dyslexia is made, one needs to rule out other possible causes for their reading difficulties, for example a hearing or a sight impairment.
Eye conditions can render it difficult to read when the print is too small or too pale for a person to see due to reduced vision or contrast sensitivity. Some eye conditions cause patchy vision, tunnel vision or loss of vision in the middle, which means that letters or words are missing. These issues affect reading speed and text navigation.
Difficulties with text navigation can also be caused by eye movement control issues and impaired depth perception. Letters may appear to jump, move or multiply (double vision).
Finally, text navigation can also be affected by a number of visual processing disorders. For example, a person who is only able to see things on one side, may have trouble seeing the next word or the beginning of the next line. A person who is unable to process vision when there is too much crowding of the text will find it difficult to navigate through the text and may also have difficulties copying texts from other sources into their jotter.
Word and symbol recognition can be another cause for problems with reading. If these issues develop after an acquired cerebral lesion later in life, the term alexia is commonly used to describe the inability to comprehend written or printed words or characters such as musical notes.
In a CVI assessment, the focus is on reading difficulties related to visual issues as described above. When the underlying visual difficulty is identified, appropriate strategies can be offered to support literacy development in a child with CVI. In adults, strategies can be taught to support everyday reading tasks.
The term ‘visual stress’ is particularly popular among optometrists who prescribe coloured overlays to improve reading performance.
Autism, ADHD, Neuro-diversity
Autsim, ADHD and neuro-diversity can often mask CVI. This is due to the overlap in typical behaviours in these conditions. For example, a child who is unable to recognise faces and facial expressions might avoid social situations and a child who struggles with clutter needs to line up their toys as a strategy for finding what they need and may not be able to find their friends when they are standing in a group.
This publication by Chokron et al. (2020) explains the inter-relationships between CVI, autism and intellectual disability very well:
https://pubmed.ncbi.nlm.nih.gov/32298709/
Frequently Asked Questions
Resources
CVI Scotland
CVI Scotland is a web-based charity, developing knowledge and understanding about CVI and providing information for affected people and their families. The website contains a series of bite-size lessons about CVI, blogs from affected people and from professionals, a reading tool, videos about CVI, and much more!
The CVI Society
This society is a registered charity in England and Wales, which provides support to affected people and their families.
Scottish Sensory Centre
This website is primarily for (educational) professionals who support children with CVI
Koninklijke Visio (Royal Dutch Visio)
This is an expertise centre for people with vision impairment, based in The Netherlands.
Visio produced a 10 min video about CVI, explaining the condition using case examples:
What is CVI? The story of Christy, Floris and Bertine (English version)