Corneal-scleral orthokeratology contact lens
A corneal-scleral orthokeratology contact lens is formed of rigid gas permeable material with uniform arc lengths in the treatment area even when the corneal curvature varies and asymmetric blends or splines called minor zones, where the portion of the blend or spline is shorter toward the lens center and broader toward the lens edge, and relieve the treatment area of all centering responsibility, transferring it to the limbal-scleral region. The method of determining the total sagittal height of an eye at a given chord diameter to predetermine exact fitting parameters and predict unaided visual outcome trial lenses, with exact chord and sagittal height values used to match the sagittal height of an eye, the sagittal value may be obtained from some ocular topographers. A computer program can easily take the sagittal information and design an optimum lens.
1. A rigid gas permeable corneal-scleral orthokeratology contact lens, comprising:
a) a treatment zone of the lens having a central posterior treatment surface having a predetermined constant arc length consistent for different chord lengths of corrective base curves of the treatment zone
b) a second portion of the corneal-scleral orthokeratology contact lens extending over the peripheral cornea, the limbus and a small portion of the scleral surface of an eye, whereby lens centering is relieved from the treatment zone of rigid gas permeable corneal-scleral orthokeratology contact lenses.
2. The invention in accordance with claim 1 wherein the second portion of the contact lens transfers lens centering responsibility from a central posterior treatment surface area of the contact lens to the scleral surface of the eye.
3. The invention in accordance with claim 1 comprising a zone of asymmetric blends connecting the base curves wherein the inward most portion of each blend is less then the outward portion.
4. The invention in accordance with claim 1 comprising major zones, more than one of which major zones is used for providing orthokeratology treatment when said corneal-scleral orthokeratology contact lens is positioned on an eye of the wearer of the lens.
5. The invention in accordance with claim 4 wherein two of the major zones are for treatment, and a third of said major zones is used for the control of the sagittal height of the overall treatment area of the eye.
6. The invention in accordance with claim 1 wherein the corneal-scleral orthokeratology contact lens further comprises three major edge zones, a first of the edge zones being an outer most edge zone to align with a portion of the sclera and the limbus to center the lens.
7. The invention in accordance with claim 6 wherein the corneal-scleral orthokeratology contact lens further comprises an inward curve for control of the overall sagittal height of the lens.
8. The invention in accordance with claim 6 wherein the corneal-scleral orthokeratology contact lens comprises a major edge zone that vaults the peripheral cornea.
9. The invention in accordance with claim 1 wherein the corneal-scleral orthokeratology contact lens comprises;
a first edge zone being an outermost edge zone to align with a small portion of the sciera and the limbus to center the lens;
a second major edge zone having an inward curve controlling the overall sagittal height of the lens; and
a third major edge zone vaulting the peripheral cornea.
10. The invention in accordance with claim 1 wherein the central posterior treatment surface has substantially the same arc length for each different corrective base curve experienced as the eye adjusts to correction as a result of wearing the lens.
11. The invention in accordance with claim 10 wherein the central posterior treatment surface with substantially the same arc length for each different corrective base curve experienced as the eye adjusts to correction resulting from eye lid bearing pressure being advantageously used to controllably alter the predefined shape of the cornea.