A method for causing visual images on the foveas of a patient to be differentially displaced from their default position by determining an optimal amount of displacement for each eye to maximize visual acuity while maintaining binocular vision, and fabricating lenses to achieve the determined differential displacements by use of two prisms of different dioptric strength. Optical devices, including eyeglasses and contact lenses, displace the images on the foveas of a patient by an amount sufficient to mitigate problems caused by non-fully functional foveas.