Current perspective: Cerebral visual impairment—The impending doom

Abstract

Cerebral visual impairment (CVI) has emerged as an important cause of morbidity in young children. CVI children often have a large number of visual symptoms along with motor abnormalities. It is the need of the hour to build an integrated approach towards their management. This article aimed to provide a comprehensive view of the manifestations, evaluation, and management of children with CVI.

The prevalence of cerebral visual impairment (CVI) in children has been on the rise over the past few decades and is one of the leading causes of visual impairment in children in developed countries. A recent Indian study from South India noted that CVI was the cause of visual impairment in 33% of cases and CVI in combination with ocular causes was seen in another 11% of cases.[1]

The rise of CVI cases in India can be attributed to improved neonatal intensive care unit facilities, causing a reduction in neonatal mortality. Hypoxic ischemic encephalopathy is the most common cause of CVI in India[2] Other causes include meningitis,[3] hydrocephalus,[4] and retinopathy of prematurity.[5]

CVI occurs due to functional and anatomical abnormalities of the retro-geniculate visual pathways, including optic radiations, occipital cortex, and visual associative areas. Motor developmental abnormalities, along with visual cortex abnormalities, further increase the hurdles in the day-to-day functioning and development of the child.[6]

The management and rehabilitation of patients with CVI need a comprehensive approach and are challenging tasks.

Clinical Evaluation

The visual characteristics of children with CVI are distinctly different from those of those with purely ocular disorders and fluctuate according to their medical and environmental conditions and severity of involvement.[7] They tend to have a slow response to a visual stimulus and bring the objects closer to visualize them to prevent the crowding phenomenon.[8] The complexity of the backgrounds increases their difficulty in focusing on any particular object.[9] Subnormal color vision, contrast sensitivity, and visual field defects are usually present due to cortical injury.[10] Depending on the site of injury, some children may be able to perceive moving objects better than stationary ones, while others may be able to focus on a stationary object. Children with CVI who have good visual acuity may still have an associated loss of higher-order visual functions, for which the term cortical visual dysfunction has been suggested.[8] The cortical visual dysfunction can be in the form of astereognosis, akinetopsia, simultanagnosia, prosopagnosia, and topographic agnosia.

Children with CVI often present as diagnostic challenges due to variability in their visual characteristics and associated neurological morbidities. Various caregiver-based questionnaires have been designed for CVI screening, with CVI visual skills inventory questionnaires being extensively applied.[11]

The assessment of visual functions in CVI children is different from their typically developed counterparts. It is important to elicit a proper birth history and medical history of the child, with special emphasis on the history of prematurity, delayed crying, seizures, and medications during the neonatal period.

Visual acuity, contrast acuity, color perception, and visual fields can all be impaired to varying degrees, and a detailed assessment of each aspect is needed to understand the child’s functional vision. The methods to assess visual acuity depend on the age, cooperation, and cognitive function of the child. Preferential-looking tests, such as LEA Gratings, Teller Acuity Cards, and Cardiff Acuity Cards, can be used. Recognition acuity charts, such as LEA symbols, can be used in children with better cognitive functions.[12] Sweep visual evoked potential (VEP), as evaluated by Good, has been shown to be an objective method to assess visual acuity in these children; however, it may not be available universally. Many CVI patients have visual field defects in the form of bilateral inferior field or homonymous hemianopia.[11,13] and can be assessed with the help of LEA Wand or Satgunam’s pediatric perimeter.[14] In a child with relatively better vision contrast sensitivity can be recorded using LEA’s Hiding Heidi test.

However, these objective tests do not reflect the actual range of functional vision or the quality of the vision in children with CVI. A qualitative assessment of the visual acuity can be performed by looking at the central, steady, and maintained fixation. In the clinic, the child should be observed for visual alertness, curiosity, and sustained visual attention. The Roman-Lantzy scale has been designed for the assessment of visual and behavioral characteristics in terms of color preference, visual latency, need for movement, difficulty with novelty, visual field preferences, complexity (array, objects, faces, and sensory environment), difficulty with distance viewing, need for light, atypical visual reflexes, and difficulty with visually guided reach in children with CVI is most commonly used for the evaluation of functional vision in these children.[15]

Apart from cortical impairment, these children may have ocular morbidities, which add to the disability of the child. Ocular features include nystagmus, strabismus, accommodation dysfunction, uncorrected refractive errors, cataracts, optic nerve atrophy, and oculomotor abnormalities.[16]

Neuroimaging has a limited diagnostic role, and normal neuroimaging does not rule out CVI. It may demonstrate brain abnormalities, such as periventricular leukomalacia, cerebral infarction, cystic encephalomalacia, and periventricular hemorrhage, depending on the time, mechanism, and extent of the injury.[17]

Nonetheless, it may help to determine the prognosis. In various studies, cystic leukomalacia has been found to have a poorer prognosis.[18-20] On the contrary, the involvement of optic radiations and striate cortex had a better prognosis.[21]

Management

Interventions for CVI should be started as early as possible, as neural plasticity is greatest in the first few years of life. The foremost step in management is parent and family counseling. It is important for the parents and family to understand and accept the pathology. The prognosis should be properly and empathetically explained. The parents should be made aware of the various government schemes, special schools, and services available for CVI children.[22]

Visual stimulation therapy aims to stimulate the visual cortex with colored, bright-illuminated moving objects. The therapy should begin with illuminated objects to seize the attention of the child and gradually shift to non-illuminated colored objects. The session should be conducted in relatively low light; a completely dark atmosphere and flashing of light should be avoided to prevent the triggering of seizures in susceptible children.

The visual response initially is slow, with difficulty in reaching the object despite seeing it. Children might also encounter difficulty in focusing on a large number of objects at a time. Thus, the stimulus needs to be provided slowly and steadily, as crowding can cause visual fatigue.

Various forms of vision therapy aid in the development of object fixation, localization, object tracking, development of hand–eye coordination, and environmental awareness. The therapy should be provided by a trained vision intervention specialist. The objects should be sequentially presented, and there should be active engagement of the child.

Table 1 summarizes the various forms of vision therapy and their utilization.

Table 1.

Vision therapy and utilization

Aim of therapy	Objects used
Visual awareness	Glow ball in a partially lit room
	Patterned colored charts
	Colored utensils
Visual attention	Glow balls
	Pom poms, glittery shiny flowing patterns
	Moving objects
	High-contrast cards with simple patterns
	Translucent beads
Visual perception (includes visual memory, depth perception, visual closure, and discrimination)	Matching, sorting, and labeling activities based on color, size, shape, and function of objects
	Labeling pictures
	Picture matching games
	Picture sequencing and finding pairs
	Pattern copying and vision memory
Scanning activities	Moving eyes in all gazes
	Searching picture details
	Hiding and searching for objects
Tracking activities	Rolling and tracking a ball
	Following a beam of flashlight
	Tracking shadows
	Bouncing balloons
Eye–hand coordination activities	Cutting and pasting activities
	Clay dough
	Joining dots
	Painting with cotton buds
	Catching and throwing balls
	Climbing activities using ladders and slides
	Threading beads of straw bottle tops

*Activities vary according to age, severity, and type of vision loss. *Duration of the session depends on the disability and needs of the child

Adequate refractive correction followed by amblyopia therapy, whenever present should be prescribed. The child may require surgery for presence of congenital cataract and strabismus.

Finally, proper rehabilitation in the form of low vision aids and environmental modification should be given to the patient according to the demand of his functional visual acuity.

Rehabilitation in the form of speech and language therapy, mobility training, and educational and occupational therapy can help these children be self-sufficient.

Due to the improved survival of premature children and those with central nervous system diseases, CVI has already emerged as one of the leading causes of visual impairment in children in developed countries and is rising rapidly in India. Due to a lack of awareness among both healthcare professionals and parents and a scarcity of resources, most of these children are not able to live a functional life. We are looking to the future when this generation will grow up to become an economic and social liability, rather than a force to be reckoned with. It is extremely critical to take cognizance of the disease and provide early intervention and appropriate rehabilitation. Targeted interventions and tailored approaches by a multidisciplinary team of pediatric neurologists, pediatric ophthalmologists, physiotherapists, optometrists, and trained teachers can aid in the integration of these children into society.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.