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.

What is claimed is:  
     
         1 . A method of treating a cornea of an eye of a patient to mitigate presbyopia, the eye having a pupil and a cornea, the method comprising: 
 identifying a multifocal ablation shape having a first region providing a near vision correction and a second region providing a far vision correction;    adjusting an ablation cut profile of the multi focal ablation shape in response to the 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;    ablating the eye with a series of laser beam pulses according to the adjusted ablation cut profile.    
     
     
         2 . The method of  claim 1 , wherein the ablation cut profile further comprises a third region providing an intermnediate optical surface having an optical power continuously varying between the first region providing near vision correction and the second region providing far vision correction, so as to provide intermediate vision correction with the intermediate optical surface.  
     
     
         3 . The method of  claim 2 , wherein the intermediate optical surface varies from a first optical power near the first region to a second optical power near the second region.  
     
     
         4 . The method of  claim 3 , wherein the difference in optical power between the first optical power near the first region and the second optical power near the second region has a range from about 1 to 4 D.  
     
     
         5 . The method of  claim 1 , wherein the first region is disposed centrally in relation to the pupil of the eye.  
     
     
         6 . The method of  claim 1 , further comprising scaling the ablation cut profile in relation to the size of the pupil.  
     
     
         7 . The method of  claim 6 , wherein the step of scaling of the ablation cut profile is done so as to scale the optical power of the ablation cut profile in relation to the size of the pupil.  
     
     
         8 . The method of  claim 7  wherein the optical power of the first region remains constant during the step of scaling.  
     
     
         9 . The method of  claim 7  wherein the optical power of the second region remains constant during the step of scaling.  
     
     
         10 . A system for treating a cornea of an eye of a patient to mitigate presbyopia with a multifocal ablation shape, the eye having a pupil and a cornea, the system comprising: 
 a laser for making a beam of an ablative light energy;    a processor in electrical communication with the laser and controlling a distribution of a series of laser beam pulses to ablate the multifocal shape on the eye, the multifocal ablation shape producing a first region of the cornea providing a near vision correction and a second region of the cornea providing a far vision correction, the processor determining the distribution of laser beam pulses in response to a signal related to a size of the pupil so as to balance the near vision correction and the far vision correction of the multifocal treatment for the patient.    
     
     
         11 . The system of  claim 10  wherein the first region providing near vision correction is disposed centrally in relation to the pupil of the eye.  
     
     
         12 . The system of  claim 10  wherein the near vision correction and the far vision correction are balanced with a variable of a refractive correction in response to the size of the pupil.  
     
     
         13 . The system of  claim 11  wherein the variable of the refractive correction includes a dimension across the refractive correction.  
     
     
         14 . The system of  claim 10  wherein the near vision correction and the far vision correction are balanced in response to the size of the pupil so as to scale a dimension across the first region providing near vision correction in relation to the size of the pupil.  
     
     
         15 . The system of  claim 10  wherein the near vision correction and the far vision correction are balanced in response to the size of the pupil so as to scale a dimension across the second region providing far vision correction in relation to the size of the pupil.