Substrates of negative accommodation

Negative accommodation refers to a unique phenomenon, sparsely documented in rare individuals, whereby evanescent increases in vision (described as "flashes" of clear vision) accompany a decrease in the overall plus power of the eye. Complementing less than a handful of dated studies, a few recent personal communications from eye care clinicians claim to have objectively assessed negative accommodation (e.g., by retinoscopy). Whereas negative accommodation may explain informal accounts claiming occasional improved visual acuity in uncorrected myopes, its mode of operation is not established. We sketch a potential mechanism by which negative accommodation may operate, if it exists.