Methods and systems for changing a refractive property of an implantable intraocular lens
A method of altering a refractive property of a crosslinked acrylic polymer material by irradiating the material with a high energy pulsed laser beam to change its refractive index. The method is used to alter the refractive property, and hence the optical power, of an implantable intraocular lens after implantation in the patient's eye. In some examples, the wavelength of the laser beam is in the far red and near IR range and the light is absorbed by the crosslinked acrylic polymer via two-photon absorption at high laser pulse energy. The method also includes designing laser beam scan patterns that compensate for effects of multiphone absorption such as a shift in the depth of the laser pulse absorption location, and compensate for effects caused by high laser pulse energy such as thermal lensing. The method can be used to form a Fresnel lens in the optical zone.
1. A method of altering a refractive property of an implantable intraocular lens having an optic body including an optical zone and a peripheral zone surrounding the optical zone, comprising:
generating a pulsed laser beam using a pulsed laser source and a light delivery optical system, the pulsed laser beam including a plurality of laser pulses; and
irradiating the optical zone of the intraocular lens with the light beam by delivering focus spots of the laser pulses within the optical zone,
wherein the laser pulses includes a first plurality of laser pulses each having a first pulse energy configured to modify a refractive index of the optical zone, and a second plurality of laser pulses each having a second pulse energy which is 1/100 to 1/10 of the first pulse energy, wherein the first plurality of laser pulses are delivered to the optical zone according to a scan pattern, and each of the second laser pulses is delivered to the optical zone at a location related to a corresponding one of the plurality of first laser pulses and precedes the corresponding first laser pulse by a predetermined time interval, whereby each second laser pulse heats the optical zone to form a transient thermal lens that defocuses the corresponding first laser pulse;
wherein the optical zone comprises a material configured to change its refractive index upon irradiation by the first plurality of laser pulses, thereby altering a refractive property of the intraocular lens.
2. The method of claim 1 , wherein the optical zone comprises a crosslinked acrylic material, and wherein irradiation with the light beam produces a predetermined change in the refractive index of the crosslinked acrylic polymer.
3. The method of claim 2 , wherein the change in refractive index relative to the pre-irradiation refractive index at a location within the crosslinked acrylic polymer is linearly related with a total energy of the irradiation with the light source within a defined total energy range.
4. The method of claim 1 , further comprising:
before the irradiating step, implanting the intraocular lens in a patient's eye, wherein the irradiating step is performed while the intraocular lens is in the patient's eye.
5. The method of claim 1 , wherein the irradiating step is performed while the intraocular lens is outside of any patient's eye.
6. The method of claim 1 , wherein the predetermined time interval is 100 ps to 100 ns.