Orthokeratological contact lenses and design methods therefor

Abstract

The present invention provides an orthokeratological contact lens to be worn on a patient's cornea and methods for prescribing the same. The contact lens comprises a parabolic lens having an inner surface configured to face an epithelium of the patient's cornea, wherein the parabolic lens is adapted to reshape the cornea by way of epithelium tissue growth. In a pre-treatment configuration, an outer surface of the epithelium does not conform to the contours of the inner surface of the parabolic lens such that there exits a gap comprising a hypertrophy volume that is disposed between the epithelium and the parabolic lens.

1 . An orthokeratological contact lens to be worn on a patient's cornea, comprising:
 a lens that is adapted to reshape the cornea by way of epithelium or stromal tissue growth.   
     
     
         2 . The contact lens of  claim 1 , wherein the lens is parabolic. 
     
     
         3 . The contact lens of  claim 2 , wherein the lens has an inner surface configured to face the epithelium of the patient's cornea. 
     
     
         4 . The contact lens of  claim 3 , wherein, in a pre-treatment configuration, an outer surface of the epithelium does not conform to the contours of the inner surface of the parabolic lens such that there exits a gap between the epithelium and the parabolic lens. 
     
     
         5 . The contact lens of  claim 4 , wherein the gap comprises a hypertrophy volume. 
     
     
         6 . The contact lens of  claim 5 , wherein after the patient has worn the parabolic lens for a sufficient amount of time, the hypertrophy volume is filled by stroma and epithelium tissue, thereby achieving the desired refractive adjustment of the cornea. 
     
     
         7 . The contact lens of  claim 3 , wherein the parabolic lens helps reshape the cornea when worn by the patient because the epithelium conforms the contours of the inner surface of the parabolic lens over time. 
     
     
         8 . The contact lens of  claim 2 , wherein the parabolic lens includes a plurality of zones. 
     
     
         9 . The contact lens of  claim 8 , wherein the plurality of zones comprises 4 separate zones. 
     
     
         10 . The contact lens of  claim 8 , wherein the plurality of zones comprises a treatment zone, an inverse zone, an alignment zone and a peripheral zone. 
     
     
         11 . The contact lens of  claim 8 , wherein each zone includes a predetermined width and curvature. 
     
     
         12 . The contact lens of  claim 3 , wherein the parabolic lens is configured to rest on the cornea with an optimum pressure on the eye tissue so as to impart desired change without significant compression of the epithelium or migration of cells. 
     
     
         13 . The contact lens of  claim 5 , wherein the parabolic lens is adapted to promote epithelial and stromal cell hypertrophy into the hypertrophy volume, thereby creating a new lens shape forms that corrects a myopic condition. 
     
     
         14 . A method of determining a prescription for an orthokeratological contact lens for reshaping a patient's cornea, comprising:
 determining a refractive error prescription of the cornea;   calculating an epithelium and stromal volume of the cornea; and   making an appropriate volume adjustment based upon the epithelium and stromal volume of the cornea.   
     
     
         15 . The method of  claim 14 , wherein the contact lens comprises a parabolic lens. 
     
     
         16 . The method of  claim 15 , wherein the parabolic lens comprises a plurality of zones including a treatment zone, an inverse zone, an alignment zone and a peripheral zone. 
     
     
         17 . The method of  claim 16 , further comprising the step of determining the curvature and width of the inverse zone, alignment zone and peripheral zone. 
     
     
         18 . The method of  claim 17 , further comprising the step of determining a largest allowable treatment zone using the equation: TZ=OD−2*PZ−2*AZ−2*IZ, where TZ is the width of the treatment zone, OD is the overall diameter of the contact lens, PZ is the width of the peripheral zone, AZ is the width of the alignment zone, and IZ is the width of the inverse zone. 
     
     
         19 . The method of  claim 14 , wherein reshaping the patient's cornea is achieved by outward movement of epithelium tissue. 
     
     
         20 . The method of  claim 14 , wherein calculating the epithelium and stromal volume of the cornea is performed using traditional eye examination and refraction techniques.