Means for controlling the progression of myopia
A contact lens for use in controlling the progression of myopia has a central optical zone approximating the normal diameter of the pupil of the eye that gives clear central vision at distance for the wearer. An annular peripheral optical zone that is substantially outside the diameter of the pupil is formed around the central optical zone with greater refractive power than that of the central zone so that oblique rays entering the eye through the peripheral optical zone will be brought to focus at a focal plane that is substantially on or anterior to the peripheral region of the retina.
1. A contact lens comprising:
a central optical zone dimensioned to cover an area from a central axis of the contact lens up to between plus or minus 1 mm of a predefined pupil size, the central optical zone having a substantially uniform central zone refractive power for correcting myopia;
a peripheral optical zone disposed radially outward from said central optical zone; the peripheral optical zone occupying at least a portion of an annular zone defined by an inner diameter of 4.5 mm and an outer diameter of 8 mm; and
a transition zone between the central optical zone and the peripheral optical zone;
wherein the contact lens is designated for application to a myopic eye with said predefined pupil size,
wherein the peripheral optical zone has a peripheral optical zone refractive power that is greater than the central optical zone refractive power by more than 1 Diopter,
wherein the difference between the outer diameter of the peripheral optical zone and the inner diameter of the peripheral optical zone is at least 2 mm; and
wherein the peripheral optical zone refractive power is substantially uniform across the peripheral optical zone.
2. The contact lens of claim 1 , wherein the peripheral optical zone refractive power is between approximately 2.5 Diopters and 8 Diopters greater than the central optical zone refractive power.
3. The contact lens of claim 1 , wherein the transition zone comprises a gradation of refractive power between the refractive power of the central optical zone and the refractive power of the peripheral optical zone.
4. The contact lens of claim 1 , wherein the predefined pupil size is based on a population average that comprises the predefined pupil size and a range of other pupil sizes.
5. The contact lens of claim 1 , wherein the central optical zone is substantially circular in shape and the peripheral optical zone defines an annulus about the central optical zone.
6. The contact lens of claim 1 , designated for application to a myopic eye with the predefined pupil size and hyperopia in the periphery.
7. The contact lens of claim 2 , wherein the transition zone comprises a gradation of refractive power between the refractive power of the central optical zone and the refractive power of the peripheral optical zone.
8. The contact lens of claim 2 , wherein the predefined pupil size is based on a population average that comprises the pupil size and a range of other pupil sizes.
9. The contact lens of claim 2 , wherein the central optical zone is substantially circular in shape and the peripheral optical zone defines an annulus about the central optical zone.
10. The contact lens of claim 2 , wherein the contact lens is for application to a myopic eye with a specified pupil size and hyperopia in the periphery.
11. The contact lens of claim 2 , wherein the predefined pupil size is approximately 3.5 mm in diameter and the central optical zone is approximately 3.5 mm in diameter.
12. The contact lens of claim 11 , wherein the peripheral optical zone occupying at least a portion of an annular zone defined by an inner diameter of 6.0 mm and an outer diameter of 8 mm.