Operator-controlled scanning laser procedure designed for large-area epithelium removal

Abstract

Systems and methods for removing an epithelial layer disposed over a stromal layer in a cornea irradiate a region of the epithelial layer with a pulsed beam of ablative radiation. The ablative radiation is scanned to vary the location of the beam within the region in accordance with a pulse sequence. The pulse sequence is arranged to enhance optical feedback based on a tissue fluorescence of the epithelial layer. The penetration of the epithelial layer is detected in response to the optical feedback. The use of scanning with the pulse sequence arranged to enhance optical feedback allows large areas of the epithelium to be ablated such penetration of the epithelial layer can be detected.

1 .- 9 . (canceled) 
     
     
         10 . A method ablating an eye to remove an epithelial layer of the eye, the method comprising:
 generating a beam of an ablative radiation;   scanning the laser beam over a region of the eye to ablate the epithelial layer;   generating a signal with a fluorescent light sensor in response the beam of ablative radiation that irradiates the eye;   scanning the beam of ablative radiation in response to the signal.   
     
     
         11 . The method of  claim 10  wherein the sensor detects a first portion of the region comprising epithelium and a second portion of the region comprising an exposed Bowman's membrane and wherein the ablative laser beam is directed toward the first portion and away from the second portion. 
     
     
         12 . The method of  claim 10  further comprising detecting penetration of the epithelium in response to a first amount of fluorescence and detecting clearance of the epithelium in response to a second amount of fluorescence, the second amount smaller than the first amount. 
     
     
         13 . The method of  claim 12  wherein further comprising generating a message to an operator in response to the detection of penetration and stopping firing of the laser in response to clearance of the epithelium. 
     
     
         14 . A method for removing an epithelial layer disposed over a stromal layer in a cornea, the method comprising: irradiating a region of the epithelial layer with a pulsed beam of an ablative radiation; scanning the ablative radiation to vary a location of the beam within the region in accordance with a pulse sequence, wherein the pulse sequence is arranged in response to a plurality of ring shaped basis profiles, wherein at least some of the ring shaped basis profiles each comprise a plurality of pulses. 
     
     
         15 . The method of  claim 14 , wherein the plurality of pulses of at least one of the ring shaped basis profiles are spaced along a circular path. 
     
     
         16 . The method of  claim 15 , wherein the plurality of pulses of the at least one ring shaped basis profile each have a pulse center that lies on the circular path. 
     
     
         17 . The method of  claim 14 , wherein at least some of the ring shaped basis profiles each comprise a central portion corresponding to no ablation. 
     
     
         18 . The method of  claim 14 , wherein the plurality of pulses of at least some of the ring shaped basis profiles are each a plurality of circular pulses spaced along a circular path. 
     
     
         19 . The method of  claim 14 , wherein the pulse sequence is arranged in response to the plurality of ring shaped basis profiles and at least one disc shaped basis profile, wherein at least some of the ring shaped basis profiles include a central portion corresponding to no ablation and wherein the disc shaped basis profile includes a central portion corresponding to an ablation region. 
     
     
         20 . A method for removing an epithelial layer disposed over a stromal layer in a cornea, the method comprising: irradiating a region of the epithelial layer with a pulsed beam of an ablative radiation; scanning the ablative radiation to vary a location of the beam within the region in accordance with a pulse sequence, wherein the pulse sequence is arranged in response to a plurality of ring shaped basis profiles and at least one disc shaped basis profile, wherein at least some of the ring shaped basis profiles each comprise a plurality of circular pulses aligned along a circular path and a central portion corresponding to no ablation, wherein the disc shaped basis profile comprises a plurality of circular pulses aligned along another circular path, wherein the disc shaped central portion includes a central portion corresponding to an ablation region. 
     
     
         21 . The method of  claim 20 , wherein the circular pulses of at least one of the ring shaped basis profiles each have a pulse center that lies on the circular path of the ring shaped basis profile.