Learning to see after early and extended blindness: A scoping review

Abstract

PurposeIf an individual has been blind since birth due to a treatable eye condition, ocular treatment is urgent. Even a brief period of visual deprivation can alter the development of the visual system. The goal of our structured scoping review was to understand how we might better support children with delayed access to ocular treatment for blinding conditions.MethodWe searched MEDLINE, Embase and Global Health for peer-reviewed publications that described the impact of early (within the first year) and extended (lasting at least 2 years) bilateral visual deprivation.ResultsOf 551 reports independently screened by two authors, 42 studies met our inclusion criteria. Synthesizing extracted data revealed several trends. The data suggests persistent deficits in visual acuity, contrast sensitivity, global motion, and visual-motor integration, and suspected concerns for understanding complex objects and faces. There is evidence for resilience in color perception, understanding of simple shapes, discriminating between a face and non-face, and the perception of biological motion. There is currently insufficient data about specific (re)habilitation strategies to update low vision services, but there are several insights to guide future research in this domain.ConclusionThis summary will help guide the research and services provision to help children learn to see after early and extended blindness.

Electrophysiological properties of layer 2/3 pyramidal neurons in the primary visual cortex of a retinitis pigmentosa mouse model (rd10)

“…In relation to humans, rd10 mice show an earlier loss of rod and cone photoreceptors and a critical period that coincides with retinal degeneration. In humans, for most cases, retinal degeneration begins after the critical period (Hamel, 2006 ; Hartong et al, 2006 ; Sahel et al, 2014 ), while there is evidence that altered and reduced visual experience around early childhood can impact visual properties later in life, even if visual experience is restored (Maurer, 2017 ; Segalowitz et al, 2017 ; Caravaca-Rodriguez et al, 2022 ; May et al, 2022 ; Xiang et al, 2023 ). This needs to be considered for the assessment of possible vision restoration approaches in the rd10 mouse model as well as in human patients.…”

Project Prakash: Merging Basic Science and Societal Service in Vision Research

“…In fact, it turns out that children who experienced 8–17 years of visual deprivation since birth improved significantly in both contrast sensitivity (Kalia et al, 2014b; Ye et al, 2021) and visual acuity (Ganesh et al, 2014) following treatment. Counter to common belief, these visual skills developed independently of age of treatment, a proxy for years of visual deprivation (though a recent meta-analysis suggests that final post-treatment visual acuity may partially depend on the duration of visual deprivation [May et al, 2022]). Importantly, despite these impressive improvements in spatial vision, the visual acuity outcomes of late-sighted children never reach perfect 20/20 Snellen acuity levels, consistent with the idea of a critical period for high acuity vision (Maurer, 2017).…”