The complex nature of CVI in terms of brain networks, higher visual processing dysfunctions and behavioural traits pose challenges in diagnosing this condition, which is now increasingly prevalent among school-aged children. 

For children to achieve their full developmental and learning potential, they need support from eye care professionals, parents and educators. 

This article presents some of the challenges of managing this complex condition, including examples of habilitational approaches. However, it is beyond the scope of this article to provide a detailed overview of specific strategies and interventions.

Ocular visual impairment (OVI) versus CVI

OVI and CVI can both lead to impairment of primary visual functions, such as reduced visual acuity, reduced contrast sensitivity, reduced colour vision and visual field defects.1-3 

However, the severity tends to fluctuate more in CVI.4 In ocular blindness, the visual cortex can be re-purposed to process non-visual information, leading to effective compensatory behaviours.5 

Neuroplastic reorganisation in children with CVI is, as yet, poorly understood and requires further research.5,6 

General approaches designed for children with OVI, such as making things brighter, bigger and bolder cannot always be applied to children with CVI due to the complex nature of the (higher) visual dysfunctions in this condition.1,5,7-9 

Different strategies need to be sought to manage their higher visual processing dysfunctions, such as reduced attention, and difficulties seeing in crowded and visually complex environments as well as impaired recognition of objects, faces and places. 

Due to the heterogeneous nature of CVI, a ‘one fits all’ approach is not appropriate. Instead, one needs to acquire a good understanding of the specific visual dysfunctions in each child to tailor the interventions to their individual limitations.5

Figure 1 Decluttering drawers with better storage solutions

Setting priorities for interventions

Dutton10 stress the importance of recognising the individual difficulties experienced by children with CVI as this leads to greater understanding and the implementation of strategies and practical solutions. 

Without this recognition, children are at risk of being criticised for their poor performance and clumsiness. 

After a detailed assessment of the child’s abilities and limitations, one needs to decide what outcomes the child and their caregivers desire. Lueck and Dutton6 make a distinction between:

  1. Children with profound visual impairment due to CVI, which is often accompanied by additional disabilities
  2. Children with functionally useful vision and cognitive challenges, and
  3. Children with functionally useful vision, who work at or near the expected academic level for their age group.

For each group, the habilitational goals and approaches are different due to the different abilities, needs and expected outcomes. Visual dysfunction can disrupt our daily activities in the domains of visually guided movement, access to information and social interaction.11,12 

Practical adaptations and modifications to the child’s surroundings help to create a less stressful environment in which a child can cope better.

Understanding the child’s visual world

In the context of planning habilitation strategies, assessment of basic visual functions, such as visual acuity, ocular motility, visual fields, contrast sensitivity and colour vision are carried out to appreciate the child’s visual limitations. 

Additionally, in-depth history-taking and direct observation of the child’s behaviour provide insight into how the child interacts with the world around them through the use of their vision.13 

Question inventories, such as ‘Insight Inventory’14 for children aged five to 12 and a vision of 6/60 Snellen or better (no date), can assist in detailed history taking15 and is freely available online. Practitioners can enter responses to questions to generate effective tailored habilitative approaches.16-18 

For children with profound visual impairment, the Visual Skills Inventory may be a more suitable tool.15

Management requires a team effort

For the child to be managed optimally, it is important to involve a team of healthcare and education professionals as well as the parents/carers of the affected child.19-22 

The optometrist’s role is to ensure that the child and their carers and teachers and other healthcare professionals (eg speech and language therapists, paediatricians, QTVIs) receive a detailed report, in which the visual impairments are explained in the context of everyday functioning along with proposed strategies and adaptations.

Habilitation approaches

Once the clinician has a good understanding of the child’s visual dysfunctions and the way they use their vision, and this has been explained to the caregivers and relevant parties, habilitation goals can be set. 

Goals included taking into account the child’s priorities and limitations. Approaches include optimising the environment, development of strategies and sight substitution.

Figure 2 Decluttering open shelves with boxes

Optimising the environment

In order to function well, one needs to create an optimal environment for the child and one needs to ensure learning material is accessible and matched to the developing needs of the child.23 

For children with CVI, the visual environment should be easy to access and not too complex.8 Tietjen24 separates what constitutes complexity into ‘environmental complexity’ and ‘task complexity’ in the context of creating optimal learning conditions. 

Environmental complexity includes the amount of visual information within the child’s field of vision, complexity of sensory input (visual and auditory), visual movement, distraction from light sources and the level of familiarity of the environment. 

Task complexity concerns the complexity of the target visual stimulus, the amount of simultaneous visual information within the task, the amount of sensory input required from the task, the distance from the task to the child (more distant objects result in a more visually complex presentation), the level of required motor skills for the task, the pacing of the task to allow for delayed visual processing and familiarity with the objects or images.

Environmental complexity

A good example of ‘environmental complexity’ is the classroom setting. McDowell and Budd25 demonstrated a positive effect on learning and behaviour of reducing general classroom clutter and the benefit of quiet spaces within the classroom for concentrated tasks. 

Decluttering is equally effective in the home environment and can be achieved by the use of plain floors and table coverings and the use of doors on cupboards and storage boxes rather than open shelves (see figures 1 and 2). Systematic storage with items on neat rows or in designated drawers can help visual search.11 

Removing unnecessary items to reduce clutter contributes to creating a calmer and less stressful environment.10 A quiet space can be created in the home environment too. 

This can be a permanent feature or a ‘pop up’ quiet space, for example in the form of a tent.26 Creating an optimal learning environment also includes the use of appropriate lighting and ensuring that the child is as comfortable as possible in terms of room temperature, posture and distractors.8,9

Task complexity

Task complexity concerns the complexity of the target stimulus. There can be many reasons why a child is unable to see and process the visual information of a specific task. 

For example, if a child has difficulties with reading, this may be due to primary visual dysfunctions, such as reduced visual acuity or impaired contrast sensitivity. 

Making the text bolder, brighter and larger, and increasing the contrast of the text are established adaptations. One also needs to take the line width of the text into account as this needs to be appropriate for the level of visual acuity.27 Field defects require a different approach. 

For example, McKillop and Dutton27 recommend a tilted workstation in order to access information on the bottom of a page in case of a lower field impairment. 

For some children, the reading difficulty can be due to crowding. Large print books can help as this increases the space between lines. Covering up a section of the page also reduces the crowding effect.10,21 

In summary, by making sure that the visual complexity of the task is matched to the child’s needs, one can ensure that learning can take place.

Figure 3 Optimising classroom layouts with the teacher and the board in the ‘seeing field’

Compensation strategies

Compensation strategies help children to make optimal use of their visual strengths while minimising the effect of their visual dysfunctions. 

For example, in hemianopia or hemi-inattention, children may not be able to locate things on one side of their body. It appears that some children with congenital focal brain damage naturally develop compensatory strategies for visual search in hemianopia.28 

Others may not naturally develop strategies. For those children, it tends to take longer to locate targets and the search patterns are less accurate and precise.29 

Although robust evidence for strategies for hemianopia in children is not available, 30 case studies have shown that engagement and visual attention can be improved when objects are placed on the child’s ‘good side’ and when story books are read with the book and parent on the ‘good side’.23 

Optimal classroom position with the teacher and the board on the ‘seeing field’ are other well-known strategies (see figure 3). Visual search abilities are often impaired in children with CVI. 

Children with simultanagnosia can learn to ‘build up’ the visual scene by establishing an anchor point in the middle of the chosen environment and exploring the environment in different directions from this anchor point.31 

Strategies for reading include rotating the text (in hemianopia), following the text with the finger, using rulers or magnifiers with reading lines, or drawing boundaries and borders around the text.8 

Different visual impairments and different habilitation goals demand different compensatory strategies; these will not be discussed in detail here.

Sight substitution

In some cases, children benefit from sight substitution. An obvious example is the use of Braille. The sense of touch can also be used simultaneously with vision to link tactile identification with visual information.8 

Physical guidance (hand-over-hand, or a tap on the elbow) are other ways of using touch to support or substitute vision. Speech technology is another form of sight substitution.8

Combining environmental adaptations, strategies and sight substitution

An example of a task that requires a combination of environmental adaptations, strategies for using remaining sight and sight substitution is mobilisation. 

Development of visually guided movement can be encouraged through use of tactile guidance (for example by pushing a toy pram or using a stick), verbal and visual cues, or by teaching the child to frequently look down to check the ground ahead.11,27 

Lam et al11 report on a child, who benefited from holding on to a parent’s hand and from verbal cues when he came to steps and kerbs. In his house and in the school, adaptations were made to the flooring to denote floor boundaries and special areas.

Patterns and clutter were reduced to simplify the visual environment. Any changes in the layout of their home were avoided to avoid stress. 

This enabled the child to navigate safely in his home environment. Dutton et al10 recommend children with lower field impairments to ‘look down, check and go’ when they need to negotiate rough or sloping ground. 

They also found that holding on to the elbow of an accompanying person was an effective strategy.


Timing of interventions

Early intervention is beneficial for children with CVI as it is well known that vision is important in the development of early cognitive, language, motor and social skills.6,19,20,22,32-36 

However, it is important to note that intervention is still beneficial years after the onset of CVI. 

A case report by McDowell and Dutton31 showed that identification, characterisation, and explanation of the impact of the visual difficulties years after onset were beneficial in terms of creating a better awareness of the specific visual difficulties, enabling the implementation of targeted strategies and leading to improvement of quality of life.

In summary, management of CVI requires collaboration between the child’s caregivers, healthcare and education professionals. The child’s specific visual dysfunctions need to be understood and characterised. 

Habilitative approaches need to be adapted to the child’s needs, goals and expected outcomes. Attention should be given to the complexity of the environment as well as the task itself.

Approaches include:

  1. Adaptations and modifications to the environment and the learning material
  2. Compensation strategies
  3. Sight substitution

Early intervention and ongoing assessment ensure appropriate support at each stage of a child’s learning and development. 

  • Cirta Tooth is a specialist low vision optometrist, working in both private practice and the hospital eye service.

References

  1. Dutton, GN. 2003. Cognitive vision, its disorders and differential diagnosis in adults and children: knowing where and what things are. Eye 17, pp. 289–304. doi: 10.1038/sj.eye.6700344
  2. Huo, R, Burden, SK, Hoyt, CS and Good, WV. 1999. Chronic cortical visual impairment in children: aetiology, prognosis, and associated neurological deficits. British Journal of Ophthalmology 83(6), pp. 670-675. doi:10.1136/bjo.83.6.670
  3. Fazzi, Eet al. 2007. Visual disorders in children with cerebral visual impairment. Journal of Child Neurology 22(3), pp. 294-301. doi:10.1177/0883073807300525
  4. Chang, MY and Borchert, MS. 2020. Advances in the evaluation and management of cortical/cerebral visual impairment in children. Survey of Ophthalmology 65, pp. 708-724. doi:10.1016/j.survophthal.2020.03.001
  5. Bennett, CR, Bauer, CM, Bailin, ES and Merabet, LB. 2020. Neuroplasticity in cerebral visual impairment (CVI): assessing functional vision and the neurophysiological correlates of dorsal stream dysfunction. Neuroscience and Behavioral Reviews 109, pp. 171-181. doi:10.1016/j.neubiorev.2019.10.011
  6. Dutton, GN and Lueck, AH. 2015. Vision and the brain: Understanding cerebral visual impairment in children. Edited by Lueck, AH and Dutton, GN. New York: AFB Press.
  7. Martin, MBC et al. 2016. Cerebral versus ocular visual impairment: The impact on developmental neuroplasticity. Frontiers in Psychology 7. 1958. doi:10.3389/fpsyg.2016.01958
  8. Swift, SH, Davidson, RC and Weems, LJ. 2008. Cortical visual impairment in children: presentation, intervention and prognosis in educational settings. Teaching Exceptional Children Plus 4(5), 14065727.
  9. Groenveld, M, Jan JE and Leader, P. 1990. Observations on the habilitation of children with cortical visual impairment. Journal of Visual Impairment and Blindness 84(1), pp. 8-25.
  10. Dutton, GN et al. 2004. Association of binocular lower visual field impairment, impaired simultaneous perception, disordered visually guided motion and inaccurate saccades in children with cerebral visual dysfunction: a retrospective observational study. Eye 18, pp. 27-34. doi:10.1038/sj.eye.6700541
  11. Lam, FC, Lovett, F and Dutton, GN. 2010. Cerebral visual impairment in children: a longitudinal case study of functional outcomes beyond the visual acuities. Journal of Visual Impairment and Blindness 104(10), pp. 625-635. doi:10.1177/0145482X1010401008
  12. Pease, A, Goodenough, T, Borwick, C, Watanabe, R, Morris, C and Williams, C. 2021. Development of a core outcome set for evaluative research into paediatric cerebral visual impairment (CVI), in the UK and Eire. British Medical Journal Open 11. e051014. doi:10.1136/bmjopen-2021-051014
  13. Dutton, GN. 2013. The spectrum of cerebral visual impairment as a sequel to premature birth: an overview. Documenta Ophthalmologica 127, pp. 69-78. doi: 10.1007/s10633-013-9382-1
  14. Insight Inventory. [No date]. Approaches for visual perceptual difficulties. Available at: https://ctebvi.org/Conf2017/Workshops/407/407%20-%20Insight.html [Accessed: 17 January 2023].
  15. Dutton, GN and Bax, M. 2010. Visual Impairment in children due to damage to the brain. London: Mac Keith Press.
  16. Philip, SS and Dutton, GN. 2014. Identifying and characterising cerebral visual impairment in children: a review. Clinical and Experimental Optometry 97(3), pp. 196-208. doi: 10.1111/cxo.12155
  17. Tsirka, A, Liasis, A, Kuczynski, A, Vargha-Khadem, F, Kukadia, R, Dutton, G and Bowman, R. 2020. Clinical use of the Insight Inventory in cerebral visual impairment and the effectiveness of tailored habilitational strategies. Developmental Medicine and Child Neurology 62(11), pp. 1324-1330. doi: 10.1111/dmcn.14650.
  18. Duke, RE, Chimaeze, T, Kim, MJ, Ameh, S, Burton, K and Bowman, R. 2021. The effect of insight questions inventory and visual support strategies on carer-reported quality of life for children with cerebral palsy and perceptual visual dysfunction in Nigeria: a randomized controlled trial. Frontiers in Human Neuroscience 15. 706550. doi: 10.3389/fnhum.2021.706550
  19. Hyvärinen, L. 2009. Assessment of visual processing disorders in children with other disabilities. Neuro-Ophthalmology 33(3), pp. 158-161. doi: 10.1080/01658100902842658
  20. Sahli, E, Kiziltunc, PB and Idil, A. 2021. Visual habilitation in young children with visual impairment. Child Care Health and Development 48(3), pp. 378-386. doi: 10.1111/cch.12935
  21. Fellenius, K, Ek, U and Jacobson, L. 2001. Reading strategies in children with cerebral visual impairment caused by periventricular leukomalacia. International Journal of Disability, Development and Education 48(3), pp. 283-302. doi: 10.1080/10349120120073421
  22. Erickson, KA, Hatton, D,Toy, V Fox, D and Renne, D. 2007. Literacy in early intervention for children with visual impairments: insights from individual cases. Journal of Visual Impairment and Blindness 101(2), pp. 80-95.
  23. Zihl, J and Dutton, GN. 2015. Cerebral visual impairment in children. Wien: Springer-Verlag.
  24. Tietjen, M. 2021. The “What’s the Complexity?” Framework. Available at: https://pcvis.vision/educators-and-therapists/the-whats-the-complexity-framework/ [Accessed: 9 January 2023].
  25. McDowell, N and Budd, J. 2018. The perspectives of teachers and paraeducators on the relationship between classroom clutter and learning experiences for students with cerebral visual impairment. Journal of Visual Impairment and Blindness 112(3). doi:10.1177/0145482X1811200304
  26. Little, S and Dutton, GN. 2014. Some children with multiple disabilities and cerebral visual impairment can engage when enclosed by a ‘tent’: is this due to Bálint syndrome? British Journal of Visual impairment 33(1), pp. 66-73. doi:10.1177/0264619614553860
  27. McKillop E and Dutton, GN. 2008. Impairment of vision in children due to damage to the brain: a practical approach. British and Irish Orthoptc Journal 5, pp. 8-14.
  28. Tinelli, F, Guzzetta, A, Bertini, C, Ricci, D, Mercuri, E, Ladavas, E and Cioni, G. 2011. Greater sparing of visual search abilities in children after congenital rather than acquired focal brain damage. Neurorehabilitation and Neuro Repair 25(8), pp. 721-728. doi:10.1177/1545968311407780
  29. Zhang, X, Manley, CE, Micheletti, S, Tesic, I, Bennett, CR, Fazzi, EM and Merabet, ME. 2022. Assessing visuospatial processing in cerebral visual impairment using a novel and naturalistic static visual search task. Research in Developmental Disabilities 131. 104364. doi:10.1016/j.ridd.2022.104364
  30. Waddington, J and Hodgson, T. 2017. Review of rehabilitation and habilitation strategies for children and young people with homonymous visual field loss caused by cerebral vision impairment. British Journal of Visual Impairment 35(3), pp. 197-210. doi:10.1177/0264619617706100
  31. McDowell, N and Dutton, GN. 2019. Hemianopia and features of Bálint syndrome following occipital lobe hemorrhage: identification and patient understanding have aided functional improvement years after onset. Case Reports in Ophthalmological Medicine. 3864572. doi:10.1155/2019/3864572
  32. Spolidoro, M, Sale, A, Berardi, M and Maffei, L. 2009. Plasticity in the adult brain: lessons from the visual system. Experimental Brain Research 192, pp. 335-341. doi: 10.1007/200221-008-1509-3
  33. Baird, SM, Mayfield, P and Baker, P. 1997. Mothers’ interpretations of the behavior of their infants with visual or other impairments during interactions. Journal of Visual Impairment and Blindness 91(5), pp.467-483.
  34. Morgan et al. 2021. Early intervention for children aged 0 to 2 years with or at high risk of cerebral palsy: International clinical practice guideline based on systematic reviews. Journal of the American Medical Association Pediatrics 175(8), pp. 846-858. doi: 10.1001/jamapediatrics.2021.0878
  35. Micheletti, S, Merabet, LB, Galli, J and Fazzi, E. 2022. Visual intervention in early onset visual impairment: a review. European Journal of Neuroscience. Doi: 10.1111/ejn. 15841
  36. Lueck, A, Dutton, G and Chokron, S. 2019. Profiling children with cerebral visual impairment using multiple methods of assessment to aid in differential diagnosis. Seminars in Pediatric Neurology 31, pp. 5-14. doi:10.1016/j.spen.2019.05.003