Can we Assess Vision if Someone Can’t Tell Us What They See?
Image of a young boy. He is facing towards the camera and reaching towards a green felt-tipped pen in front of him.
Why Functional Vision Assessment Can Be So Important for People with Complex Disabilities
For many people, an eye test involves reading letters on a chart and making choices regarding which lenses provide the clearest image. But for individuals who are non-verbal, minimally verbal, intellectually impaired, or have complex developmental or neurological disabilities, this type of testing is often inaccessible. These individuals may not be able to describe blurred vision, explain what they are struggling to see, identify letters or pictures consistently, or communicate how vision affects their daily life. As a result, standard clinical testing is often inaccessible. We need a different approach to understand how the person is seeing and functioning in the world around them.
Clinical assessment alone is not enough
There are alternative tests we can use to assess vision for people who cannot read a letter chart, and a clinical eye examination is still important, since it allows us to assess the health of the eyes, identify eye disease, determine whether glasses may help, and gather information about how the visual system is functioning, but for people with complex disabilities, we need to look more closely, because, these clinical findings will not uncover challenges they may be experiencing in everyday life.
“Your daughter has good vision, but she cannot always access her vision.”
A person may have healthy eyes, but still struggle significantly to use their vision functionally. I often describe this to families as having good vision, but not being able to access their good vision. Think about if you had a really great computer setup, but then a terrible internet connection: sometimes, you might be able to complete your work, but at other times, it doesn’t matter that you have a fantastic computer, because you still can’t access the internet.
A person with functional vision problems may find it difficult to:
Visually locate objects
Recognise faces
Safely navigate unfamiliar environments
Cope with busy visual spaces
Maintain attention during visual activities.
These challenges can affect communication, mobility, learning, emotional regulation, participation, and independence. In many cases, the most important information about vision comes not from formal testing, but from behaviour.
For people who cannot easily tell us what they can or cannot see, behaviour often becomes a form of communication. A child who constantly looks away during visual tasks, a person who becomes distressed in bright or cluttered environments, or someone who relies heavily on touch rather than vision may all be giving us important clues about how they are experiencing the visual world.
Sometimes these behaviours are assumed to be purely sensory, behavioural, developmental, or attention-related. While those factors may absolutely play a role, vision can also be a significant contributing factor that is easily overlooked. This is where a functional vision assessment can be particularly valuable.
So how is a functional vision assessment different?
Rather than focusing only on eyesight or eye health, a functional vision assessment looks at how a person actually uses their vision in everyday life. It relies much more heavily on observation, interaction, environmental context, and real-world functioning than on verbal responses or chart-based testing.
The assessment may explore how a person visually engages with people and objects, how they respond to movement or light, whether they can visually locate preferred items, how vision impacts mobility and safety, and whether visual fatigue or overload may be contributing to distress or disengagement. It also considers environmental factors such as lighting, clutter, contrast, and working distance, along with strategies or supports that may improve access and participation.
Importantly, the goal is not simply to answer the question: “What can this person see?” but rather: “How is this person using their vision?”
This distinction is particularly important within the NDIS space. For many individuals with complex disabilities, vision can significantly impact communication, emotional regulation, learning, engagement, and independence. Functional vision assessments can therefore help identify practical supports and environmental modifications that improve learning, participation, and quality of life.
This may involve recommendations around lighting, use of contrast, reducing visual clutter, assistive technology, magnification, positioning, or strategies for carers, therapists, and educators. Functional vision assessment can help ensure that any AAC communication systems are visually accessible, help prevent falls and injuries, and sometimes, understanding the role vision is playing can completely change how a behaviour or support need is interpreted.
For families, support coordinators, plan managers, and allied health professionals, understanding the difference between a clinical eye examination and a functional vision assessment is incredibly important. A person may technically “pass” an eye test, while still experiencing substantial real-world visual difficulties that affect their daily functioning and form barriers to them achieving their NDIS goals.
For people with complex communication or cognitive disabilities, vision assessment is rarely as simple as asking someone to read the smallest line on a chart. Instead, it often requires careful observation, flexibility, collaboration, and an understanding that vision is about far more than eyesight alone. Often, the most meaningful information about vision is found not in the clinic room — but in the person’s behaviour and interaction with the world around them.
If you want to learn more, please peruse our website. For more information about how our service aligns with NDIS, please see our two-page flyer. We are happy to discuss with families, support coordinators and plan managers how our service may help their participants attain their NDIS goals. Our reception is staffed 10am to 2.30pm Mondays and Thursdays, so please call us, or send us an email any time. We hope to hear from you soon!