Lens and method for retarding myopia progression
Provided herein is concentric annular multi-zone lens for retarding myopia progression in a human eye. The lens comprises: a plurality of correcting zones for forming a focused image on a retina of the human eye so as to correct refractive error of the human eye, wherein the correcting zone having a similar refractive power; a plurality of defocusing zones for forming images anterior to the retina so as to generate myopic defocus; and a defocusing power increasing region, in which refractive powers of defocusing zones being increasingly relatively positive towards the periphery of the lens so as to generate larger amplitude of the myopic defocus at the periphery of the retina; wherein the plurality of correcting zones and the plurality of defocusing zones are alternated in the concentric annular multi-zone lens.
1 . A concentric annular multi-zone lens for retarding myopia progression in a human eye, the concentric annular multi-zone lens comprising:
a plurality of correcting zones for forming a focused image on a retina of the human eye so as to correct refractive error of the human eye, wherein the plurality of correcting zones has a same refractive power, and wherein the plurality of correcting zones includes a central correcting zone;
a plurality of defocusing zones for forming images anterior to the retina so as to generate myopic defocus, wherein the plurality of correcting zones and the plurality of defocusing zones are alternated in the concentric annular multi-zone lens;
a defocusing power increasing region, in which refractive powers of defocusing zones are increasingly relatively positive towards a periphery of the lens, wherein the defocusing power increasing region includes a first defocusing zone of the plurality of defocusing zones, the first defocusing zone immediately surrounding the central correcting zone such that the first defocusing zone is lowest in refractive power among the defocusing zones in the defocusing power increasing region, and wherein the first defocusing zone is more positive in refractive power than the central correcting zone; and
a defocusing power constant region, in which refractive powers of defocusing zones are the same, wherein the defocusing power constant region is located after the defocusing power increasing region towards the periphery of the lens, and the refractive powers of the defocusing zones in the defocusing power constant region are the same as the refractive power of the last defocusing zone in the defocusing power increasing region, wherein the refractive powers of the defocusing zones in the defocusing power increasing region are configured to increase based on a measured relative peripheral refractive error of the human eye to compensate for diminishing myopic defocus at the periphery of the retina.
2 . The concentric annular multi-zone lens of claim 1 , wherein the refractive powers of the defocusing zones in the defocusing power increasing region are increased with a stepwise power increment.
3 . The concentric annular multi-zone lens of claim 2 , wherein the stepwise power increment is between 0.25D and 1.5D.
4 . The concentric annular multi-zone lens of claim 1 , wherein the defocusing zones in the defocusing power increasing region include 2 to 10 defocusing zones.
5 . The concentric annular multi-zone lens of claim 1 , wherein the defocusing zones in the defocusing power increasing region further comprise a second defocusing zone located after the first defocusing zone towards the periphery of the lens, the first defocusing zone having a first refractive power for forming a first anterior image shell, the second defocusing zone having a second refractive power being more positive than the first refractive power for forming a second anterior image located anterior to the first anterior image.
6 . The concentric annular multi-zone lens of claim 5 , wherein the defocusing zones in the defocusing power increasing region further comprise a third defocusing zone being located after the second defocusing zone towards the periphery of the lens, the third defocusing zone having a third refractive power being more positive than the second refractive power for forming a third anterior image shell located anterior to the second anterior image.
7 . The concentric annular multi-zone lens of claim 6 , wherein the defocusing zones in the defocusing power increasing region further comprise a fourth defocusing zone being located after the third defocusing zone towards the periphery of the lens, the fourth defocusing zone having a fourth refractive power being more positive than the third refractive power for forming a fourth anterior image shell located anterior to the third anterior image.
8 . The concentric annular multi-zone lens of claim 7 , wherein the first refractive power, the second refractive power, the third refractive power and the fourth refractive power are increased by a stepwise power increment.
9 . The concentric annular multi-zone lens of claim 8 , wherein the stepwise power increment is between 0.25D and 1.5D.
10 . The concentric annular multi-zone lens of claim 5 , wherein the refractive power of the first defocusing zone is relatively more positive than the central correcting zone by 1.00D to 4.0D.
11 . The concentric annular multi-zone lens of claim 1 , wherein the concentric annular multi-zone lens is in the form of a contact lens comprising an optical surface including 4 to 40 alternating correcting and defocusing zones.