What is CVI?


CVI Classifications

Throughout this website you will be introduced to many real people who have CVI (their names have all been changed). Connor is one, a little boy who is registered blind due to severe CVI. He has many further medical and developmental challenges and is considered to have complex needs. Katherine is a schoolgirl who has both CVI and ocular visual impairments, and is considered to have mild learning challenges. Mary is another. She is a well educated professional adult who also has CVI, but without any additional needs.

Connor relies on other people to help him with all his personal, social and developmental needs. Katherine needs some support, particularly where there are safety concerns, for example near roads, however is learning to become independent. Mary sometimes needs support but is fiercely independent.

Throughout this website, the necessity to view each person with CVI as a unique individual with unique vision, unique reactions to their vision and unique needs, will be repeated and reinforced many times. There is however a classification that helps understand the different challenges the same CVIs cause different people, depending on many factors, including their overall developmental level. This is particularly helpful when understanding behaviours and behavioural responses.

These groups do not categorise individuals, so if you view the individual people with these classifications as being understandable as belonging to a specific group, then you have yet to understand CVI. The groupings characterise the difficulties and resulting needs, not the people.

The classifications are broad, and provide are a useful and practical guide to help understand the different ways CVI may make the person feel and act. It is only with this understanding that we can learn how to help and support them individually and most effectively.

CVI Classification 1

Those with profound disabilities and CVI, diminishing the quality of not only their visual world, but also their ability to move independently, and their cognitive abilities.

Other expressions commonly used in relation to this group are:

  • GDD (Global Developmental Delay),
  • PMLD (Profound and Multiple Learning Difficulties)
  • MDVI (Multiple Disabilities and Visual Impairment)

The people in this group may not have the understanding to know what is happening around them. They may not be able to communicate their thoughts and feelings well to others. Their reactions may be very instinctive.

Yet as has been explained, each individual with CVI is unique, and needs to be understood as an individual with a unique profile of disabilities and needs.

Connor's behaviours and behavioural reactions are consistent with this classification.

CVI Classification 2

Those with CVI and further disabilities affecting movement and independence, but with normal cognitive function.

This group might include someone with a degree of cerebral palsy, who may need assistance walking or who may find speaking challenging, but is intellectually normal or high functioning.

The person in this group may well have a normal visual acuity, contrast sensitivity and visual field, but may have problems with visual guidance of movement, seeing the whole scene simultaneously and functioning in a busy and cluttered environment.

Because this person may have normal visual acuity, the challenges from the other problems in their visual world can go unnoticed and unrecognised, thus unsupported. These visual impairments are non-conscious, that is the person is not aware that they have them. Some professionals or family members may try to explain the resulting behaviours as a feature of other known disabilities, while others may think the person is not trying, or not applying themselves.

Without recognition, characterisation and understanding of their vision there can be no acknowledgement and support, and the person may well feel clumsy, useless or stupid, which of course they are not.

Katherine's visual difficulties fit in with this category. Katherine is considered to have mild learning difficulties, however this does not mean that Katherine does not have normal cognitive function. Katherine's learning difficulties can be explained in terms of her CVI not being understood, and information not being presented in a way she can fully perceive. This means that Katherine is unable to learn to the potential she is capable of.

CVI Classification 3

Those with CVI and no other challenges.

The visual impairment can range from having little or no vision, to having normal visual acuities, but with lack of visual field and / or perceptual difficulties owing to different functioning of the parts of the brain that are responsible for vision. They may have difficulties with recognition, possibly an inability to recognise faces, that are a cause of great social embarrassment.

The visual challenges go unrecognised, both by others and the person themselves, for many years.

This person will face multiple challenges on a daily basis, and may well develop coping strategies, that are likely to involve increasing levels of isolation. Sometimes the person may be labelled as autistic, or having an attention deficit disorder.

Mary is in this group.

In essence, any pattern of CVI can occur in the people whose circumstances fit into the descriptions of each of these three groups.

The groups are characterised by the nature and outcome of the people's additional abilities, not their CVI.


Your generous donations will be put to immediate use in supporting our charity...

Donate Here

About Us

At CVI Scotland we are devoted to helping people understand cerebral visual impairments, and together working towards developing the understanding of this complex condition.