Dual defocus lens

A dual defocus lens applied directly to an eyeball having a retina, comprising:

• a refractive-error correction part, comprising:
• a central optical region, been concentric to the refractive-error correction part, and having a retinal image of the central optical region imaged within a central area of the retina;
• a first defocus region;
• been concentric to and closely adjacent to the central optical region, and having a retinal image of the first defocus region, which is concentrically to the retinal image of the central optical region, imaged within the central area of the retina;
• and
• a second defocus region, positioned within the first defocus region and been concentric to and away from the central optical region, and having a retinal image of the second defocus region out of the retina, a radius of curvature of the first defocus region is larger than a radius of curvature of the second defocus region;
• a positioning part, been concentric to the central optical region and been closely adjacent to the refractive-error correction part, a radius of curvature of the positioning part is larger than a radius of curvature of the central optical region which is larger than the radius of curvature of the first defocus region;
• and
• a periphery part, been concentric to the central optical region and been closely adjacent to the positioning part.