Spectrum of Visual Disorders in Children With Cerebral Visual Impairment

Abstract

Cerebral visual impairment is a visual function deficit caused by damage to the retrogeniculate visual pathways in the absence of any major ocular disease. It is the main visual deficit in children in the developed world. Preperinatal hypoxic-ischemic damage is the most frequent cause of cerebral visual impairment, but the etiology is variable. The authors set out to evaluate the presence of visual disorders not attributable to any major ocular pathology in a sample of children with central nervous system disease and to describe the clinical picture of cerebral visual impairment in this cohort. One hundred twenty-one patients with central nervous system damage and visual impairment underwent a protocol developed at the authors' center that included neurologic, neurophthalmologic, and neuroradiologic assessments (brain magnetic resonance imaging). Reduced visual acuity was found in 105 of 121 patients, reduced contrast sensitivity in 58, abnormal optokinetic nystagmus in 88, and visual field deficit in 7. Fixation was altered in 58 patients, smooth pursuit in 95, and saccadic movements in 41. Strabismus was present in 88 patients, and abnormal ocular movements were found in 43 patients. Of the 27 patients in whom they could be assessed, visual-perceptual abilities were found to be impaired in 24. Fundus oculi abnormalities and refractive errors were frequently associated findings. This study confirms that the clinical expression of cerebral visual impairment can be variable and that, in addition to already well-documented symptoms (such as reduced visual acuity, visual field deficits, reduced contrast sensitivity), the clinical picture can also be characterized by oculomotor or visual-cognitive disorders. Cerebral visual impairment is often associated with ophthalmologic abnormalities, and these should be carefully sought. Early and careful assessment, taking into account both the neurophthalmologic and the ophthalmologic aspects, is essential for a correct diagnosis and the development of personalized rehabilitation programs.

Recovery of visual functions after early acquired occipital damage

“…Sluggish pupillary reflex observed at this time is unexpected in occipital lesion, but less uncommon in blindsight and in the authors' experience of children with CVI. 12,25 A possible explanation of this initial clinical picture may be sought in anatomical, electrophysiological, and behavioural studies which suggest that the extra-striate cortex, and in particular the V5, are major contributors to the sparing of visuallyguided behaviours following lesions of the primary visual cortex incurred early in life. 26 With very rare exceptions, such visual processing through the extra-striate pathways does not allow conscious visual perception, and conscious residual motion perception is possible in humans only if some striate cortex remains intact.…”

“…6,7 The effects of early-acquired visual cortical lesions have been less extensively studied. [8][9][10] This is probably because in childhood, early-acquired lesions of the visual system are usually associated with extensive involvement of the retrochiasmatic visual pathways, leading to the wide spectrum of visual dysfunctions known as cerebral visual impairment (CVI), 11,12 whereas select ive injuries of the striate cortex are rare.…”

Novel genetic causes for cerebral visual impairment

“…[3][4][5] CVI can occur in isolation, but more often additional features are present, such as intellectual disability (ID), epilepsy and/or deafness. [6][7][8] An important cause of CVI is acquired damage to the brain, mainly the result of perinatal problems (eg, cerebral hemorrhage or periventricular leukomalacia), but also other types of acquired damage, such as congenital infection, hypoglycemia, meningitis, or head trauma, can be causal. 2 Furthermore, West syndrome and hydrocephalus can result in CVI.…”

Cognitive visual dysfunctions in preterm children with periventricular leukomalacia

“…Refraction disorders (corrected with glasses) were present in 19 children. Table I summarizes the neurophthalmological data of the 22 children according to the nosographic system recently proposed by Fazzi et al 2 …”

“…Studies have focused mainly on neurophthalmological aspects, such as visual acuity and visual field deficits, and on oculomotor dysfunction. 2 However, in his 2001 revision of the definition of CVI, Good 1 proposed extending the clinical spectrum of the impairment to include cognitive visual dysfunctions (CVDs) which, being linked to impairment of the ability to analyse and process visual information, manifest themselves through a disorder of higher visual abilities. 3 These dysfunctions, also grouped under the heading 'visualperceptual impairment', [4][5][6] can be associated with the neurophthalmological dysfunctions typical of CVI, or constitute the main clinical expressions of CVI in patients with normal or near-normal visual acuity ('higher-functioning CVI').…”