Rapid fine-scale sensorimotor plasticity in human foveal vision.

The foveola is the most important region of the human retina, yet little is known about how the visuomotor system responds to subtle visual disruptions in this region. Using an Adaptive Optics Scanning Light Ophthalmoscope (AOSLO) for high-resolution retinal imaging and retinal-contingent stimulation, we show that even a minute foveolar scotoma (≈0.03 degrees2) produces measurable perceptual deficits and triggers fine-scale reorganization of fixation behavior. Observers, without explicit reports of awareness of the loss, rapidly adopt new preferred retinal loci shifted by ≈5 arcmin to bring stimuli into a visible region. These loci fall in regions of lower cone density than neighboring regions, suggesting that fixation control is not solely determined by sampling efficiency and involves trade-offs between sensory and motor factors. These findings uncover a fine scale visuomotor plasticity and suggest oculomotor biomarkers for detecting early retinal disease before symptoms emerge.