Eye metrics often reflect visual conscious awareness, conscious content, and neural processing in cerebral blindness

Cerebral blindness is caused by damage to the primary visual pathway. Some people with cerebral blindness retain degraded vision and non-visual sensations and can perform visually guided behaviors within their blind visual field. These cases raise questions about visual conscious perception and residual neural processing in cerebral blindness. A major challenge in this research is that subjective reporting on experiences in the blind field can be unreliable. Alternatively, eye metrics offer a promising objective marker of conscious awareness, conscious content, and brain activity. In this study, we recorded visual stimulus-evoked pupil size, blink, and microsaccade responses in neurotypical participants and both the sighted and blind fields of cerebrally blind participants. For most patients, we found that eye metrics inferred conscious awareness in the blind field. Also, pupil size responded to both real and illusory stimulus luminance in the sighted field but not in the blind field. Furthermore, eye metrics were linked to visual stimulus-evoked occipital cortical field potentials in the blind field, suggesting residual cortical processing. These findings support eye metrics as an indicator of visual conscious perception and neural processing in cerebral blindness, with potential applications for tracking vision recovery following damage to the primary visual pathway.