Contact lens and process for fitting

Abstract

A contact lens with a central region ( 10 ) that is optimally less than approximately 1.9 millimeters in diameter and that is preferably overcorrected by approximately 25% to 100% over the correction needed for reading. Unexpectedly, the central region ( 10 ) does not impair distance vision, but compensates for presbyopia and therefore alows a user to focus on objects within a range of near and intermediate distances. A method for fitting the contact lens is also provided.

What is claimed is:  
     
         1 . A contact lens, comprising: 
 a circular central region overcorrected for near vision, wherein said central region is small enough to avoid impairing distance vision;    at least one ring shaped transition region extending radially outward from said central region;    a ring shaped outer region extending radially outward from said transition region corrected for distance vision; and    a ring shaped carrier region extending radially outward from said outer region;    wherein said transition region provides at least a partial diopter shift over said transition region between said overcorrection of said central region and said distance correction of said outer region.    
     
     
         2 . A contact lens according to  claim 1 , wherein said central region is between approximately 1 millimeter and approximately 2.5 millimeters in diameter.  
     
     
         3 . A contact lens according to  claim 2 , wherein said central region is between approximately 1.5 millimeters and approximately 1.9 millimeters.  
     
     
         4 . A contact lens according to  claim 1 , wherein said central region has a diameter of less than approximately 1.9 millimeters.  
     
     
         5 . A contact lens according to  claim 2 , wherein said central region has a diameter of approximately 1.5 millimeters.  
     
     
         6 . A contact lens according to  claim 2 , wherein said central region has a diameter of approximately 1.9 millimeters.  
     
     
         7 . A contact lens according to  claim 1 , wherein said central region is overcorrected for near vision by approximately 25% to approximately 100%.  
     
     
         8 . A contact lens according to  claim 1 , wherein said lens has at least a first transition region and a second transition region.  
     
     
         9 . A contact lens according to  claim 8 , wherein said lens has two transition regions and each of said transition regions is approximately 0.5 millimeters wide.  
     
     
         10 . A contact lens according to  claim 8 , wherein said transition regions are aspherical.  
     
     
         11 . A contact lens according to  claim 8 , wherein said transition regions are spherical.  
     
     
         12 . A contact lens according to  claim 8 , wherein said diopter shift across said first transition region is at a first constant radial rate and said diopter shift across said second transition region is at a second constant radial rate.  
     
     
         13 . A contact lens according to  claim 8 , wherein said first transition region provides a diopter shift of approximately 1.6 diopters, said second transition region provides a diopter shift of approximately 1.2 diopters, and said outer region provides a diopter shift of approximately 0.9 diopters.  
     
     
         14 . A contact lens according to  claim 8 , wherein said first transition region provides a diopter shift of approximately 1.1 diopters, said second transition region provides a diopter shift of approximately 0.8 diopters, and said outer region provides a diopter shift of approximately 0.6 diopters.  
     
     
         15 . A contact lens according to  claim 1 , wherein said outer region has a diameter of approximately 8 millimeters.  
     
     
         16 . A contact lens according to  claim 1  wherein optical correction of at least one of said regions is provided by a material with differing indices of refraction in different portions.  
     
     
         17 . A contact lens according to  claim 1 , wherein said lens is made from materials selected from the group consisting of conventional soft lens material, rigid gas permeable contact lens material, or hard contact lens material.  
     
     
         18 . An intraocular implant, comprising: 
 a circular central region overcorrected for near vision, wherein said central region is small enough to avoid impairing distance vision;    at least one ring shaped transition region extending radially outward from said central region;    a ring shaped outer region extending radially outward from said transition region corrected for distance vision; and    a carrier region extending radially outward from said outer region;    wherein said transition region provides at least a partial diopter shift over said transition region between said overcorrection of said central region and said distance correction of said outer region.    
     
     
         19 . A refractive surgical procedure, comprising: 
 shaping a human cornea to provide: 
 a circular central region overcorrected for near vision, wherein said central region is small enough to avoid impairing distance vision;  
 at least one ring shaped transition region extending radially outward from said central region;  
 a ring shaped outer region extending radially outward from said transition region corrected for distance vision;  
 wherein said transition region provides at least a partial diopter shift over said transition region between said overcorrection of said central region and said distance correction of said outer region.  
   
     
     
         20 . A contact lens having a pupil area, comprising: 
 a central accommodation zone covering approximately half of said pupil area overcorrected for near vision by between approximately 25% to approximately 100%;    at least one concentric transition region extending radially outward from said accommodation region; and    a concentric outer region extending radially outward from said transition region corrected for distance vision;    wherein said transition region provides at least a partial diopter shift over said transition region between said overcorrection of said central accommodation zone and said distance correction of said outer region.    
     
     
         21 . A contact lens according to  claim 20 , having an add power of between approximately 3.5 and approximately 3.9 diopters.  
     
     
         22 . A contact lens according to  claim 20 , having an add power of approximately 3.7 diopters.  
     
     
         23 . A contact lens according to  claim 20 , having an add power of between approximately 2 and approximately 3.5 diopters.  
     
     
         24 . A contact lens according to  claim 20 , having an add power of between approximately 2.4 and 2.8 diopters.  
     
     
         25 . A contact lens according to  claim 20 , having an add power of approximately 2.6 diopters.  
     
     
         26 . A process for aligning a central region of a contact lens, comprising: 
 marking a centered spot on a diagnostic contact lens; and    detecting whether a user's pupils would be aligned with said central region.    
     
     
         27 . A process according to  claim 26 , wherein said spot has a diameter of approximately 1.9 millimeters.