Cortically induced blindness (CB) resulting from stroke damage to the early visual cortex leads to extensive, typically extrafoveal visual deficits and is known to alter large-scale oculomotor behavior. Here, we show that even with preserved foveal acuity, fixational oculomotor behavior is subtly altered in CB patients. Using high-precision eye tracking, we observed a small but consistent gaze offset toward the blind field during passive fixation, which disappeared during a high-acuity central task. Despite this offset, fixation precision in both tasks was comparable, and it was similar between CB patients and age-matched controls. Curiously, the underlying oculomotor dynamics were also similar across the two task conditions: Microsaccades exhibited nonsignificant directional tendencies, while ocular drift was biased away from the blind field. Our findings indicate that the adult oculomotor system dynamically adapts to asymmetric visual injury and/or input. We speculate that the small fixational offsets observed in CB may reflect an attentional pointer toward the blind field and/or a compensatory oculomotor rebalancing that counteracts an asymmetric visual drive following cortical damage. Together, these results reveal a surprising preservation of context-dependent fixation control following early visual cortex damage in adulthood.
Clark et al. (Tue,) studied this question.