Systematic arcminute-scale fixational offsets in patients with early visual cortex damage

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.