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Cortical Visual Loss
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
This relay ends at striate cortex, and beyond it information diverges into a large array of “extra-striate” visual regions. Lesions of these regions cause the second type of cortical visual impairment. Extra-striate deficits are not so typified by retinotopy, but instead show functional specificity, affecting certain types of visual processing but not others. Although there are many cortical regions involved in vision, they can be divided roughly into two main functional streams, a ventral and a dorsal pathway (1). The ventral pathway consists of medial occipitotemporal structures that are involved in processing color and form and in object recognition. For this reason, it is sometimes called the “What” pathway. The dorsal pathway refers to lateral occipitoparietal structures that are involved in motion processing and spatial functions such as attention, localization and targeting eye or hand movements. This is sometimes called the “Where” pathway, though some view the dorsal pathway's role more as preparing responses to the visual environment, an “Action” pathway (2). In this chapter, we follow this useful division, considering disorders of color processing or object recognition under the heading of ventral pathway disorders, and problems of motion or spatial processing as dorsal pathway disorders (3) (Figure 20.1).
Trends in low vision education
Published in John Ravenscroft, The Routledge Handbook of Visual Impairment, 2019
Amanda Hall Lueck, Gregory L. Goodrich
The majority of students classified with visual impairments in schools in the United States have low vision. In addition, most children with visual impairments have multiple disabilities (Hatton, Ivy and Boyer, 2013; Kirchner and Diamant, 1999). As educators have adjusted to these population shifts, another one has occurred in recent years with the increase in children with visual impairments due to disorders of the visual brain (called cerebral/cortical visual impairment or CVI). This increase has been related to the increased survival rate of very low birth weight premature infants and improved medical care of newborns with life-threatening conditions (Dutton and Lueck, 2015). CVI is now the major cause of visual impairments in children in high-income countries and is increasing in low-income countries (Dutton and Lueck, 2015). New methods for identification, assessment and interventions are required for children with this complex condition (Lueck and Dutton, 2015; Lueck, Dutton and Chokron, in press), and these must be introduced in basic professional training programmes for a variety of service providers and in ongoing professional development programmes.
Minimising crisis points in paediatric palliative care: the ACT care pathways in action
Published in Rita Pfund, Susan Fowler-Kerry, Sister Frances Dominica, Perspectives on Palliative Care for Children and Young People, 2017
Mary was a five-year-old girl with very severe neurodisability following birth asphyxia. She had severe spastic quadriplegia, epilepsy and cortical visual impairment. She had an unsafe swallow and was totally gastrostomy fed. She recognised familiar voices and smiled, but she had little head control.
Causes of Blindness and Visual Impairment in Early Childhood at a Low Vision Service in Mexico City: A 15-year Review
Published in Ophthalmic Epidemiology, 2021
Juan Alberto López Ulloa, Helen Burn, Ana María Beauregard
ONA was the second most common diagnosis. This differs from most other studies from Latin America with the exception of Brazil, where ONA accounted for 12.5%-22.5% of all cases.7 Cortical visual impairment (CVI) represents one of the most common causes of childhood blindness in high income countries16 …, but not in LMIC. Considering some records at our Centre were incomplete and that we do not have an attending neurologist, probable cases of cerebral or visual pathways pathology may have been mistakenly recorded as either optic nerve or other. In Israel, CVI has also caused complications when recording paediatric diagnoses. Mezer et al. argue that CVI cases grouped with ONA may have artificially increased the prevalence of the latter.17 The increase in preterm deliveries in Mexico has not only increased the incidence of ROP, but also of CVI. Further research into the matter should be pursued in light of the current findings.
Targeted panel sequencing identifies a novel NR2F1 mutations in a patient with Bosch–Boonstra–Schaaf optic atrophy syndrome
Published in Ophthalmic Genetics, 2019
Sung Eun Park, Jihei Sara Lee, Seung-Tae Lee, Hye Young Kim, Sueng-Han Han, Jinu Han
Cortical visual impairment (CVI) is known to be the major cause of visual impairment in children (1). CVI is a collective term of visual dysfunction caused by the damage to parts of the brain responsible for vision, such as optic tract, optic radiations, and visual cortex. Patients with CVI tend to also have neurological problems such as delayed development, intellectual disability or seizures. While abnormalities of brain structures are found in up to 90% of patients with CVI, no identifiable causes are found in the rest. The underlying genetic causes of CVI are currently not well known. A previous study has identified that four genes (AHDC1, NGLY1, NR2F1, PGAP1) are associated with CVI (2). Herein, we report a patient with delayed development, intellectual disability, and optic atrophy who was eventually diagnosed as Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS).
Working with children with cortical visual impairment who use augmentative and alternative communication: implications for improving current practice
Published in Augmentative and Alternative Communication, 2022
Fei Luo, Sarah W. Blackstone, Jesse Canchola, Christine Roman-Lantzy
Cortical visual impairment (CVI) is a brain-based visual impairment caused by atypical structures or damage to visual pathways and/or visual processing centers of the brain (Chang & Borchert, 2020; Huo et al., 1999). This impairment is associated with multiple medical conditions such as hypoxic-ischemic encephalopathy, prematurity, seizures, hydrocephalus, trauma, and infections (Keptal & Donahue, 2007). CVI differs from ocular visual impairments, which are caused by conditions or diseases in the eye or optic nerve. Children with CVI can see, but have difficulty interpreting what they see, placing them at high risk for delays across developmental domains.