Ring focus spectacle lens for controlling myopia progression, and manufacturing method therefor

A ring-focus spectacle lens for controlling myopia progression, the ring-focus spectacle lens comprising a convex front surface, a concave rear surface, a plurality of correction zones for imaging light on a retina, and a plurality of astigmatism zones for imaging light in front of the retina, optical centers of the front surface and the rear surface being located on a same optical axis, the correction zones having a first refractive power and the astigmatism zones having a second refractive power that is greater than the first refractive power, the correction zones and the astigmatism zones being arranged in a staggered way in the ring-focus spectacle lens,

• wherein the front surface comprises a free-form surface composed of a plurality of first curved surfaces and a plurality of second curved surfaces, the plurality of first curved surfaces having a same radius of curvature, the plurality of second curved surfaces having a same or different radius of curvature, the radius of curvature of the first curved surfaces being greater than the radius of curvature of the second curved surfaces, the first curved surfaces and the second curved surfaces being joined in a staggered way in the free-form surface, the correction zones being defined at least by the first curved surfaces, and the astigmatism zones being defined at least by the second curved surfaces;
• wherein a first curved surface and an adjacent second curved surface are joined in a tangent and continuous manner or a transitional curved surface manner,
• for the tangent and continuous manner, the first curved surface and the adjacent second curved surface are tangent and continuous, such that an endpoint of the first curved surface and an endpoint of the second curved surface coincide at the joint point, and a tangent of the first curved surface and a tangent of the second curved surface have a same slope at the joint point, and an extension line of a connecting line connecting a center of the first curved surface and a center of the second curved surface passes through the joint point,
• for the transitional curved surface manner, a transition curved surface is provided between the first curved surface and the adjacent second curved surface, a starting point and an ending point of the transition curved surface being respectively joined with an ending point of the first curved surface and a starting point of the adjacent second curved surface, directions and values of curvatures of the first curved surface and the transition curved surface being same at a joint point of the first curved surface and the transition curved surface, and directions and values of curvatures of the second curved surface and the transition curved surface being the same at a joint point of the second curved surface and the transition curved surface, curvatures on the transition curved surface changing continuously.