Established care
Vision and cerebral visual impairment
CVI, cortical visual impairment, functional vision assessment, visual habilitation
The most commonly missed problem in children with brain injury. A child who cannot interpret what they see is often described as inattentive, uncooperative or more delayed than they are.
Either a medicines regulator has licensed it for this use, or clinical practice guidelines recommend it on the strength of controlled trials. This is the standard everything else on the scale is measured against — and for most children, the treatments at this level are the ones that will actually change their day.
Where it stands, condition by condition
The same therapy can be well supported for one problem and completely untested for another. This is the single most common place families are misled.
| Condition | Evidence | What that means here |
|---|---|---|
| Identifying CVI in children with cerebral palsy or brain injury | Established care | Standard of care. CVI is the leading cause of visual impairment in children in high-income countries, and it is substantially under-recognised in cerebral palsy. |
| Environmental and task adaptation for CVI | Established care | Reducing visual clutter, controlling contrast and lighting, allowing processing time — established practice and often the single most effective change. |
| Structured visual habilitation programmes | In clinical trials | Programmes to build visual behaviours are widely used; controlled evidence of benefit over adaptation alone is limited. |
| Correcting refractive error and treating ocular problems | Established care | Basic and frequently overlooked. A child can have CVI and need glasses. |
What it is
Cerebral visual impairment is a problem of interpreting what the eyes see, caused by injury to the visual pathways and processing areas of the brain rather than to the eye itself. Eye examination can be entirely normal.
It looks nothing like blindness as most people imagine it. The child may see better when an object moves, better in one part of the visual field, better against a plain background, worse in a cluttered room, worse when tired, worse when asked to look and reach at the same time.
Because the presentation is variable, it is persistently misread as inattention, distractibility, behaviour or global delay.
How it is meant to work
The same injuries that cause cerebral palsy — periventricular injury in prematurity, hypoxic-ischaemic injury, malformation — frequently affect the visual pathways, which are extensive and vulnerable.
Identifying it changes everything downstream. A child who cannot pick a toy out of a patterned rug is not refusing the task; a child who cannot look and move simultaneously is not uncooperative in physiotherapy.
This is why vision assessment belongs early in rehabilitation rather than as an afterthought: it determines how every other therapy should be presented.
What has actually been tested
- The case for identification is strong and uncontroversial: CVI is common in this population and routinely missed, and structured functional vision assessment finds it.
- The case for adaptation is likewise well accepted — plain backgrounds, high contrast, reduced clutter, one instruction at a time, extra processing time, positioning in the better visual field.
- The case for specific training programmes designed to improve visual function itself is weaker. Children do change over time, and separating that from the programme is difficult.
- Ordinary ophthalmology still matters. Refractive error, squint and cataract occur in these children too, and correcting them is simple and often neglected.
What we still do not know
- How much visual function can be improved by training, as opposed to how much the environment should be adapted around it.
- Which assessment framework performs best — practice varies considerably between countries.
- How CVI evolves through childhood in individual children.
Risks and costs
- The harm here is almost entirely from not looking: years of therapy delivered in a way the child cannot visually access, and capability consistently underestimated.
- Commercial “visual stimulation” products sold to families on the strength of the diagnosis.
Questions to ask before you agree
A centre that is doing good work will welcome these questions and answer them in writing.
- Has my child had a functional vision assessment, not only an eye examination?
- What should change at home and at school — background, contrast, lighting, clutter, timing?
- Do the physiotherapist, teacher and speech therapist know the findings and present tasks accordingly?
- Does my child also need glasses or squint treatment?
More in this section
Early detection and early intervention
The single highest-value thing in this whole field, and the one least often discussed in clinics selling treatment. Cerebral palsy can be identified in the first months of life, and that is when therapy does the most.
Established careGoal-directed, task-specific training
Not a brand of therapy but the principle underneath the ones that work: the child practises the actual task they are trying to learn, with enough repetition to matter.
Established careConstraint-induced therapy and bimanual training
For a child who uses one hand much more than the other, these are among the best-evidenced interventions in paediatric neurology — and both work, for different things.
Established carePhysiotherapy and strength training
Well supported when it is built around function and genuinely loaded — much weaker when it is passive stretching and generic exercise.
Established careOccupational therapy
The discipline that works on what the child actually does all day — dressing, eating, writing, playing, getting through a school morning.
Established careSpeech, language and communication
For a child who cannot speak clearly, giving them a way to communicate is among the most consequential interventions available — and the fear that it will stop them talking is unfounded.
Established careSpasticity and tone management
Medical and surgical treatment of tone, which works best when it is tied to a functional goal rather than to a number on a tone scale.
In clinical trialsTechnology-assisted rehabilitation
Useful mainly as a way of delivering more practice, not as a treatment in its own right — and that distinction decides whether it is worth the money.
In clinical trialsNamed physiotherapy approaches
Families are usually asked to choose between brands. The evidence says the brand matters far less than whether the session is active, goal-directed and repeated often enough.
In clinical trialsSensory therapies
Two things are sold under one word. Manualised Ayres Sensory Integration has been tested in trials; the sensory add-ons sold around it mostly have not.