Method and systems for laser treatment of presbyopia using offset imaging

Abstract

An ophthalmic surgery system and method for treating presbyopia by performing ablative photodecomposition of the corneal surface. The offset image of a variable aperture, such as a variable width slit and variable diameter iris diaphragm, is scanned in a preselected pattern to perform ablative sculpting of predetermined portions of a corneal surface. The scanning is performed to ablate an optical zone sized to match the patient pupil with a peripheral transition zone outside the pupil. The shape of the ablated optical zone is different from the shape of the final optical correction on the anterior surface of the cornea. The optical zone corrects for near-vision centrally and far-vision peripherally. A movable image displacement mechanism enables radial displacement and angular rotation of the profiled beam exiting from the variable aperture. The invention enables wide area treatment with a laser having a narrower beam than the treatment area, and can be used in the treatment of many conditions in conjunction with presbyopia such as hyperopia, hyperopic astigmatism and irregular refractive aberrations.

1 . A method of treating an eye of a patient to mitigate presbyopia, the eye having a pupil and a cornea, the method comprising:
 identifying a multifocal shape modification for the cornea, the shape modification including a first region providing a near vision correction centrally and a second region providing a far vision correction peripherally;   adjusting the size of the shape modification in response to a size of the pupil so as to provide a balance of the near vision correction provided by the first region and the far vision correction provided by the second region for the patient; and   modifying the shape of the cornea according to the adjusted shape modification.   
     
     
         2 . The method of  claim 1 , wherein the adjusted shape modification further comprises a transition zone disposed beyond the pupil. 
     
     
         3 . The method of  claim 1 , wherein the multifocal shape modification further comprises a third region disposed between the first region and the second region, the third region providing an intermediate vision correction. 
     
     
         4 . The method of  claim 3 , wherein the third region has a varying optical power that continuously varies between the first region and the second region. 
     
     
         5 . The method of  claim 4 , wherein the optical power of the third region varies over a range from about 1 to 4 D. 
     
     
         6 . The method of  claim 1 , further comprising scaling the shape modification in relation to the size of the pupil. 
     
     
         7 . The method of  claim 6 , wherein the optical power of the first region is substantially unchanged during the step of scaling. 
     
     
         8 . The method of  claim 6 , wherein the optical power of the second region is substantially unchanged during the step of scaling. 
     
     
         9 . The method of  claim 1 , wherein the size of the pupil is selected to correspond to its size when dilated at night. 
     
     
         10 . The method of  claim 1 , further comprising adjusting the size of the shape modification corresponding to an anticipated healing-induced shape change. 
     
     
         11 . The method of  claim 1 , wherein the eye comprises a first refractive error and the shape modification substantially corrects the first refractive error, the first refractive error being selected from the group consisting of myopia, hyperopia, astigmatism and irregular aberration. 
     
     
         12 . The method of  claim 1 , wherein the shape modification has an aspheric shape. 
     
     
         13 . A system for reshaping an eye of a patient to mitigate presbyopia, the eye having a pupil and a cornea, the system comprising:
 a processor comprising a tangible medium comprising instructions that when executed cause the processor to:
 identify a multifocal shape modification for the cornea, the shape modification including a first region providing a near vision correction centrally and a second region providing a far vision correction peripherally, and 
 adjust the size of the shape modification in response to a size of the pupil so as to provide a balance of the near vision correction provided by the first region and the far vision correction provided by the second region for the patient; and 
   an eye modification assembly for modifying the cornea according to the adjusted shape modification.   
     
     
         14 . The system of  claim 13 , wherein the adjusted shape modification further comprises a transition zone disposed beyond the pupil. 
     
     
         15 . The system of  claim 13 , wherein the multifocal shape modification further comprises a third region disposed between the first region and the second region, the third region providing an intermediate vision correction. 
     
     
         16 . The system of  claim 15 , wherein the third region has a varying optical power that continuously varies between the first region and the second region. 
     
     
         17 . The system of  claim 16 , wherein the optical power of the third region varies over a range from about 1 to 4 D. 
     
     
         18 . The system of  claim 13 , wherein the multifocal shape modification is scaled in relation to the size of the pupil. 
     
     
         19 . The system of  claim 18 , wherein the optical power of the first region is substantially unchanged by the scaling. 
     
     
         20 . The system of  claim 18 , wherein the optical power of the second region is substantially unchanged by the scaling. 
     
     
         21 . The system of  claim 13 , wherein the eye comprises a first refractive error and the shape modification substantially corrects the first refractive error, the first refractive error being selected from the group consisting of myopia, hyperopia, astigmatism and irregular aberration. 
     
     
         22 . The system of  claim 13 , wherein the shape modification has an aspheric shape.