A scleral lens has an optical zone, a peripheral zone and a sagittal depth control zone between the optical zone and the peripheral zone. The sagittal depth control zone may be configured to raise the optical zone above the level of a person's eye when the scleral lens is in use and create a tear layer between the optical zone and the person's eye. Tear flow control features are provided in the sagittal depth control zone.
1. A contact lens, comprising:
material forming a lens of suitable size to fit a person's eye and extend over at least a portion of the sclera of the person's eye;
the lens having an optical zone, a peripheral zone and a sagittal depth control zone between the optical zone and the peripheral zone;
the sagittal depth control zone being configured to raise the optical zone above the level of a person's eye when the lens is in use and create a tear layer between the optical zone and the person's eye; and
tear flow control features in the sagittal depth control zone, the tear flow control features comprising ports that penetrate through the material of the lens, the ports being elongated to form slots, and the slots being oriented to slant nasally as the slots extend radially outward.
2. The contact lens of claim 1 in which the ports consist of three ports.
3. The contact lens of claim 1 further comprising a hinge in the lens material, the hinge being located radially outward from the sagittal depth control zone.
4. The contact lens of claim 3 in which the hinge is formed by a zone having an anterior radius of curvature smaller than its posterior radius of curvature.
5. The contact lens of claim 1 in which:
the optical zone has a posterior surface with a base radius of curvature; and
the sagittal depth control zone comprises a zone having a radius or radii of curvature different from the base radius of curvature.
6. The contact lens of claim 5 in which the sagittal depth control zone comprises plural zones.
7. A contact lens, comprising:
material forming a lens of suitable size to fit a person's eye and extend over at least a portion of the sclera of the person's eye;
the lens having an optical zone and at least one zone radially outward from the optical zone;
tear flow control features in the at least one zone, the tear flow control features comprising elongated slots forming ports that penetrate through the material of the lens, the elongated slots being oriented to slant nasally as the elongated slots extend radially outward; and
a hinge in the lens material, at least a portion of the hinge being located radially outward from the elongated slots.
8. The contact lens of claim 7 in which the ports consist of two to six ports.
9. A method of forming a contact lens for application to a person's eye comprising the steps of:
forming a lens of suitable size to fit a person's eye and extend over at least a portion of the sclera of the person's eye;
providing the lens with an optical zone, a peripheral zone and a sagittal depth control zone between the optical zone and the peripheral zone;
the sagittal depth control zone being configured to raise the optical zone above the level of a person's eye when the lens is in use and create a tear layer between the optical zone and the person's eye; and
providing the lens with tear flow control features in the sagittal depth control zone, the tear flow control features being formed as ports that penetrate through the material of the lens, the ports being formed as elongated slots, the slots being oriented to slant nasally as the slots extend radially outward.
10. The method of claim 9 further comprising forming a hinge in the lens material, the hinge being located radially outward from the sagittal depth control zone.
11. The method of claim 9 in which:
the optical zone is provided with a posterior surface with a base radius of curvature; and
the sagittal depth control zone is provided at least by a zone having a radius of curvature different from the base radius of curvature.
12. The method of claim 11 in which the sagittal depth control zone comprises plural zones.