Brain plasticity and residual visual functions in acquired cortical blindness: a systematic review of the literature

Background Acquired cortical blindness, traditionally considered irreversible due to the need for the integrity of the primary visual cortex, has recently been challenged by evidence demonstrating that patients can retain residual visual abilities through subcortical pathways, perilesional reorganization, and neuroplasticity mechanisms. Recent advances in functional neuroimaging and neuromodulation have accelerated the characterization of these processes, redefining cortical blindness as a condition with the potential for partial recovery rather than a permanent sensory loss. This systematic review aimed to synthesize the evidence published between 2021 and 2025 on the relationship between brain plasticity and residual visual function in adults with acquired cortical blindness, to characterize the current state of evidence, and to identify priorities for research in visual neurorehabilitation. Methods A systematic review with an analytical and descriptive approach was conducted following PRISMA 2020 guidelines. Seven databases (PubMed/MEDLINE, Web of Science, Scopus, ScienceDirect, SciELO, ClinicalKey, and Google Scholar) were searched for studies published between 2021 and 2025 in English and Spanish, applying predefined eligibility criteria. Methodological quality was assessed using the ROBINS-I Cochrane Collaboration tool and the SIGN classification, and the overall certainty of the body of evidence was additionally appraised using GRADE domains. Results Three studies met the eligibility criteria from an initial set of 15,245 records across seven databases. These studies comprised two quasi-experimental intervention studies and one longitudinal neuroimaging study. In all three studies, perilesional residual activity in V1, subcortical colicular pathways, and extrastriate circuits could be activated through targeted training, resulting in improvements in luminance detection, visual field recovery, and generalization of training gains. Confounding was identified as the most vulnerable domain in all studies due to the structural difficulty of implementing randomized designs in this population. Conclusion The available evidence, derived from only three small, non-randomized studies with moderate-to-critical risk of bias, suggests that plasticity-based interventions may improve selected residual visual functions by engaging residual neural substrates; however, the overall certainty of this evidence is low, and the findings should be interpreted as hypothesis-generating rather than as a basis for definitive clinical recommendations.