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Diagnosing Cerebral Visual Impairment in Children- Why and How?

by | Sep 1, 2020 | Manuscripts | 0 comments

Jannet Philip, B.S.Optometry

Graduate research student, Elite School of Optometry, Units of Medical Research Foundation, Chennai, in collaboration with SASTRA University Thanjavur, India

 

Introduction:

“Cerebral Visual Impairment (CVI) is a verifiable visual dysfunction which cannot be attributed to disorders of the anterior visual pathways or any potentially co-occurring ocular impairment” (1). The most common cause of CVI is perinatal hypoxia (termed Hypoxic-Ischemic Encephalopathy) (2). Cerebral visual impairment is a preferred term than Cortical visual impairment as it encompasses dysfunctions relevant to both striate and extrastriate regions. In CVI, ventral stream, or “WHAT” pathway and dorsal stream or “WHERE” pathway are affected, resulting in a defective object or spatial recognition (3). The clinical manifestations of CVI are vastly heterogeneous- constituting visual, cognitive, motor, and other dysfunctions- depending on the extent of damage to the brain, making diagnosis crucial. This write-up gives a brief description of why and how to diagnose CVI.

Figure 1: Image representing dorsal stream, ventral stream and their respective functions. (Image source: http://www.therabeat.com/news-and-events/2017/11/1/how-can-we-adapt-for-cortical-visual-impairments).

 

Why diagnose CVI?

  • Due to the enhanced neonatal care and survival of preterm babies, there is an increased prevalence of CVI that demands early identification and management (2).
  • Due to the involvement of Dorsal and Ventral streams, children with CVI can have issues with visual perceptual skills and cognitive functions interfering with the academic performance of the child. Studies have shown that visual perceptual difficulties can exist in children despite good visual acuity in CVI. In such cases, they tend to be undiagnosed in a general eye examination and require specific tests to understand the presence of learning-related visual issues (4).
  • Children with CVI can have concurrent disabilities and developmental delays. Hence, it is crucial to detect CVI at the earliest and integrate vision into the ––management protocol in order to improve the quality of life of the child.
  • Finally, diagnosing CVI is the first step towards prevention, management, counselling and rehabilitation!

 

How to diagnose CVI?

Given the broader clinical profile of CVI, the diagnosis has to take a holistic approach. It is pivotal to consider both structural as well as functional aspects (Table 1) and correlate both to achieve accurate diagnosis.

 

Classification Type Utility
Imaging techniques Conventional Magnetic resonance imaging(MRI)(5) Identifying risk factors of CVI
Functional MRI(fMRI) (6) Diagnosing and correlating with functions
Diffusion tensor imaging(DTI) (7,8) Detecting micro-structural level lesions
Clinical assessments Visual function tests (9) Understanding the functions of the eye
Functional vision tests (9) Understanding the performance of the child in a vision related task
Visual perceptual skill tests(10) Identifying visual perceptual skill deficits.
Community assessments Inventories (11-13) Screening and diagnose of CVI

Table 1: Structural and functional techniques used in CVI.

 

Recent advancements 

Eye tracking devices in combination with computerized tasks have been helpful in identifying visual processing dysfunctions in children just a few days after birth. This has been studied in children with neurological problems, visual impairments, and prematurity so that rehabilitation can be initiated in advance (7, 14). Virtual Reality (VR) has also been used in assessing functional vision in individuals with CVI that has shown the advantage of good ecological validity- resembling the real world scenario much similar to the daily activities of life. The functional findings from VR have been correlated with the structural defects, thus making diagnosis better and reliable (3, 15).

Most importantly, a multidisciplinary approach is required for managing CVI with the combined effort of Ophthalmologists, Optometrists, Rehabilitation specialists, Occupational therapists, Physiotherapists, and Special educators (9).

 

Conclusions

CVI is a brain-based visual condition that demands comprehensive assessment, early diagnosis and management. It is vital for eye care practitioners to understand the depth of the condition and the why and how aspects of diagnosing CVI in order to make a positive change in the well-being of a child with CVI!

 

References 

  1. Sakki, H. E., Dale, N. J., Sargent, J., et al. (2018). Is there consensus in defining childhood cerebral visual impairment? A systematic review of terminology and definitions. British Journal of Ophthalmology, 102(4), 424-432.
  2. Swaminathan, M. (2011). Cortical visual impairment in children—a new challenge for the future? Oman journal of ophthalmology, 4(1), 1.
  3. Bennett, C. R., Bauer, C. M., Bailin, E. S., et al. (2020). Neuroplasticity in cerebral visual impairment (CVI): Assessing functional vision and the neurophysiological correlates of dorsal stream dysfunction. Neuroscience & Biobehavioral Reviews, 108, 171-181.
  4. van Genderen, M., Dekker, M., Pilon, F., et al. (2012). Diagnosing cerebral visual impairment in children with good visual acuity. Strabismus, 20(2), 78-83.
  5. Cioni, G., Fazzi, B., Ipata, A. E., Canapicchi, R., et al. (1996). Correction between cerebral visual impairment and magnetic resonance imaging in children with neonatal encephalopathy. Developmental Medicine & Child Neurology, 38(2), 120-132.
  6. Yu, B., Guo, Q., Fan, G., et al. (2011). Assessment of cortical visual impairment in infants with periventricular leukomalacia: a pilot event-related FMRI study. Korean journal of radiology, 12(4), 463-472.
  7. Pel, J. J., Dudink, J., Vonk, M., et al. (2016). Early identification of cerebral visual impairments in infants born extremely preterm. Developmental Medicine & Child Neurology, 58(10), 1030-1035.
  8. Ortibus, E. L. S., Verhoeven, J., Sunaert, S., et al. (2012). Integrity of the inferior longitudinal fasciculus and impaired object recognition in children: a diffusion tensor imaging study. Developmental Medicine & Child Neurology, 54(1), 38-43.
  9. Swaminathan, M., & Deiva Jayaraman, N. J. (2019). Visual function assessment, ocular examination, and intervention in children with developmental delay: A systematic approach. Part 1. Indian journal of ophthalmology, 67(2), 196.
  10. Philip, S. S., Tsherlinga, S., Thomas, M. M., et al. (2016). A validation of an examination protocol for cerebral visual impairment among children in a clinical population in India. Journal of clinical and diagnostic research: JCDR, 10(12), NC01
  11. https://www.aao.org/disease-review/vision-screening-program-models (Retrieved on 3/8/2020)
  12. Gorrie, F., Goodall, K., Rush, R., et al. (2019). Towards population screening for cerebral visual impairment: Validity of the Five Questions and the CVI Questionnaire. PloS one, 14(3).
  13. Ortibus, E., Laenen, A., Verhoeven, J., et al. (2011). Screening for cerebral visual impairment: value of a CVI questionnaire. Neuropediatrics, 42(04), 138-147.
  14. Kooiker, M. J. G., Swarte, R. M. C., Smit, L. S., et al. (2019). Perinatal risk factors for visuospatial attention and processing dysfunctions at 1 year of age in children born between 26 and 32 weeks. Early human development, 130, 71-79.
  1. Bennett, C. R., Bailin, E. S., Gottlieb, T. K., et al. (2018). Assessing visual search performance in ocular compared to cerebral visual impairment using a virtual reality simulation of human dynamic movement. In Proceedings of the Technology, Mind, and Society (pp. 1-6).

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