Rethinking cerebral visual impairment: Unitary and Umbrella conceptualizations as a potential way forward

Over recent decades, understanding and recognition of cerebral visual impairment (CVI) have increased considerably. CVI is now recognized as the likely leading cause of certifiable childhood visual impairment in both high and low-income countries. However, differences remain concerning its definition, conceptualization, terminology and diagnosis, including which brain based impairments of vision (BBIVs) should be encompassed within the term. We propose that differing approaches within the CVI literature may usefully be understood through two potentially complementary conceptualizations, which we describe as “Unitary CVI” and “Umbrella CVI.” Unitary CVI considers CVI to be a single clinical condition or disorder characterized by difficulties in visual function and/or functional vision not due to optics or eye disorders. “Umbrella CVI” conceptualizes CVI as encompassing a range of possible individual BBIVs that may occur alone or in combination. We examine the implications of these two differing viewpoints from the perspectives of definition, diagnosis, identification, research, teaching and support. Profiling the individual BBIVs may accord greater precision in understanding the causes of the resulting visual challenges, and may serve to unify the current differing concepts and terminologies, potentially enabling support to be best tailored to the needs of each affected individual. At the same time, the Unitary approach remains valuable where the nature and origin of specific impairments have yet to be established, and for epidemiological studies. Moreover, identification of “Probable CVI” with delineation of the consequent needs, also has an important role, particularly in locations where there are no resources available for formal diagnosis. We propose that Unitary and Umbrella CVI need not be competing concept frameworks, but may serve complementary purposes. Increasing understanding of individual BBIVs and their combinations may build upon existing CVI frameworks, offering a practical way forward toward ensuring that people with BBIVs are recognized, understood and receive customized support matched to their individual needs.