According to a recent gathering of experts sponsored by the National Institutes of Health (NIH), a brain-related condition known as cerebral visual impairment (CVI) has been identified as a primary cause of deteriorating vision from childhood in the United States and other developed nations. CVI, which affects a projected 3% of primary school children, presents visual difficulties that range from struggling to visually locate an object or person to comprehending a scene with intricate motion. This information, collated from both expert opinion and evidence, has been published in the field’s leading journal, Ophthalmology.
CVI often remains undiagnosed or misdiagnosed due to a general lack of awareness, causing years of unnecessary suffering for parents and children who might remain oblivious to the root cause of their vision problems. The co-author of the report, Lotfi B. Merabet, an associate professor of ophthalmology at Massachusetts Eye and Ear and Harvard Medical School, stresses the need for increased awareness.
The report also emphasizes the importance of identifying the signs of CVI early on to facilitate timely rehabilitation and accommodation strategies. This point is underscored by Melinda Y. Chang, an assistant professor of clinical ophthalmology at the University of Southern California, who also contributed to the report.
The report highlights five key features of CVI:
1. Brain involvement: CVI includes a range of visual impairments caused by an underlying brain abnormality that affects the development of visual pathways. This results in functional vision impairment that hampers day-to-day activities.
2. Unexplained visual dysfunction: Individuals with CVI may also have co-existing ocular issues. However, if the visual dysfunction is largely due to a visual processing issue in the brain, then CVI should be diagnosed.
3. Types of visual deficits: Visual dysfunction associated with CVI can be categorized as lower-order and higher-order visual deficits. Lower-order deficits may include impaired visual acuity, reduced contrast sensitivity, and a diminished visual field. Higher-order deficits could involve issues with recognizing faces and objects, spatial orientation, and perceiving complex motion.
4. Overlapping neurological disorders: CVI can occur simultaneously with other neurodevelopmental disorders, but it is not essentially a disorder of language, learning, or social communication. Conditions like cerebral palsy, autism, and dyslexia can have symptoms that overlap with CVI, leading to frequent misdiagnoses.
5. High risk of being overlooked: The underlying neurological abnormality may remain undetected or undiagnosed until later in life when functional vision deficits become noticeable to the individual. Screening for CVI should be considered in individuals who are at high risk of having had a neurological injury.
The report on CVI’s definition is based on a workshop hosted by the NEI in collaboration with the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and the National Institute of Neurological Disorders and Stroke (NINDS).
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