Process monitoring and control during laser-based refractive index modification of intraocular lenses in patients
Methods and related apparatus for real-time process monitoring during laser-based refractive index modification of an intraocular lens. During in situ laser treatment of the IOL to modify the refractive index of the IOL material, a signal from the IOL is measured to determine the processing effect of the refractive index modification, and based on the determination, to adjust the laser system parameters to achieve intended processing result. The signal measured from the IOL may be a fluorescent signal induced by the treatment laser, a fluorescent signal induced by an external illumination source, a temporary photodarkening effect, a color change, or a refractive index change directly measured by phase stabilized OCT.
1. A method for real-time process monitoring during laser-based refractive index modification of an intraocular lens (IOL), comprising:
treating the IOL with a laser beam to modify a refractive index of the IOL at selected locations, including scanning the laser beam in a predefined scan pattern in the IOL, the scan pattern includes at least one circular pattern;
while treating the IOL with the laser beam, measuring an image of a signal from the IOL, the signal being indicative of a refractive index change of the IOL;
determining a processing effect of refractive index modification of the IOL based on the measured image, including detecting at least one circular pattern of the signal in the measured image and detecting any non-uniformity of intensity of the signal in an angular direction along the circular pattern of the signal to determine a non-uniformity of the processing effect of the refractive index modification of the IOL in the angular direction; and
based on the detected non-uniformity of intensity, further treating the IOL with the laser beam to reduce or eliminate the non-uniformity of the processing effect of the refractive index modification of the IOL in the angular direction.
2. The method of claim 1 , wherein the signal measured from the IOL is a fluorescent signal induced by the treatment laser beam.
3. The method of claim 1 , further comprises illuminating the IOL with an external illumination source, wherein the signal measured from the IOL is a fluorescent signal induced by the external illumination source.
4. The method of claim 1 , further comprises illuminating the IOL with a light source, wherein the signal measured from the IOL is a temporary photodarkening effect.
5. The method of claim 1 , further comprises illuminating the IOL with a broadband visible light source, wherein the signal measured from the IOL is a color change.
6. The method of claim 1 , wherein measuring the image of the signal from the IOL includes measuring a refractive index change of the IOL using phase stabilized swept-source OCT.
7. The method of claim 1 , wherein the laser beam is a femtosecond pulsed laser beam.
8. The method of claim 1 , wherein the IOL is formed of a crosslinked acrylic polymer.
9. The method of claim 1 , wherein the predefined scan pattern includes multiple concentric rings, wherein the step of determining a processing effect of refractive index modification of the IOL includes detecting a plurality of concentric circles of the signal in the measured image and detecting any non-uniformity of intensity of the signal in an angular direction along each of the plurality of concentric circles of the signal.
10. The method of claim 9 , wherein the step of further treating the IOL with the laser beam includes scanning the laser beam within the IOL in selected portions of the multiple concentric rings.
11. The method of claim 1 , wherein the step of further treating the IOL with the laser beam includes adjusting one or more parameters of the laser beam.