Non-invasive and minimally invasive laser surgery for the reduction of intraocular pressure in the eye
Intraocular pressure in an eye is reduced by delivering a high resolution optical coherence tomography (OCT) beam and a high resolution laser beam through the cornea, and the anterior chamber into the irido-corneal angle along an angled beam path. The OCT beam provides OCT imaging for surgery planning and monitoring, while the laser beam is configured to modify tissue or affect ocular fluid by photo-disruptive interaction. In one implementation, a volume of ocular tissue within an outflow pathway in the irido-corneal angle is modified to create a channel opening in one or more layers of the trabecular meshwork. In another implementation, a volume of fluid in the Schlemm's canal is affected by the laser to bring about a pneumatic expansion of the canal. In either implementation, resistance to aqueous flow through the eye is reduced.
1. A method of reducing intraocular pressure in an eye, the eye having a Schlemm's canal with fluid therein, and one or more collector channels branching from the Schlemm's canal, the method comprising:
placing a focus of a laser beam into the Schlemm's canal; and
delivering the laser beam into the Schlemm's canal to initiate a photo-disruptive interaction with the fluid inside the Schlemm's canal to create a pneumatic effect that expands the Schlemm's canal by operating the laser beam with a pulse duration between 10 femtoseconds and 1 nanosecond and a pulse wavelength between 330 nanometers and 2000 nanometers; and
maintaining the focus of the laser beam inside the Schlemm's canal to avoid photo-disruptive interactions with tissue surrounding the Schlemm's canal.
2. The method of claim 1 , further comprises identifying one or more locations of the Schlemm's canal in which to deliver the laser beam.
3. The method of claim 2 , wherein the eye comprises a circumferential angle and the one or more locations of the Schlemm's canal are spaced apart around at least a portion of the circumferential angle.
4. The method of 2 , wherein the eye comprises a circumferential angle and identifying the one or more locations of the Schlemm's canal for laser beam delivery comprises:
obtaining images of the Schlemm's canal at a plurality of locations around at least a portion of the circumferential angle; and
for each of the images:
processing the image to determine a measure of an anatomical feature of the Schlemm's canal, and
designating the location from which the image was obtained as one of the identified one or more locations of the Schlemm's canal for laser beam delivery based on an evaluation of the determined measure relative to a threshold measure.
5. The method of claim 4 , wherein the threshold measure is indicative of an at least partially collapsed canal, and the location from which the image was obtained is designated one of the identified one or more locations for laser beam delivery when the measure of the anatomical feature is less than the threshold measure.
6. The method of claim 5 , wherein the plurality of images of the Schlemm's canal corresponding to the plurality of locations around at least a portion of the circumferential angle comprises cross-sectional images and the anatomical feature is a cross-section of the Schlemm's canal.
7. The method of claim 1 , further comprising:
obtaining OCT images of the Schlemm's canal while the laser beam is being delivered;
processing the images to obtain measures indicative of pneumatic expansion of the canal;
evaluating the images relative to a criterion of an acceptable pneumatic expansion; and
stopping the delivering of the laser beam when the acceptable pneumatic expansion is detected.
8. An integrated surgical system for reducing intraocular pressure in an eye, the eye having a cornea, a Schlemm's canal with fluid therein, and one or more collector channels branching from the Schlemm's canal, the system comprising:
a first optical subsystem including a focusing objective configured to be coupled to the cornea;
a second optical subsystem including: a laser source configured to output a laser beam, and a plurality of components configured to one or more of condition, scan, and direct the laser beam; and
a control system coupled to the second optical subsystem and configured to:
instruct the laser source to output the laser beam, for delivery through the first optical subsystem and the cornea, and into the Schlemm's canal,
instruct the plurality of components of the second optical subsystem to place a focus of the laser beam inside the Schlemm's canal, and
instruct the laser source to deliver the laser beam to initiate a photo-disruptive interaction with the fluid inside the Schlemm's canal to create a pneumatic effect that expands the Schlemm's canal, wherein the laser beam operates with a pulse duration between 10 femtoseconds and 1 nanosecond and a pulse wavelength between 330 nanometers and 2000 nanometers; and
to control the plurality of components of the second optical subsystem to maintain the focus of the laser beam inside the Schlemm's canal to avoid photo-disruptive interactions with tissue surrounding the Schlemm's canal.
9. The system of claim 8 , wherein the control system is further configured to identify one or more locations of the Schlemm's canal in which to deliver the laser beam.
10. The system of 8 , wherein the eye comprises a circumferential angle and, the second optical subsystem includes an optical coherence tomography (OCT) imaging apparatus configured to output an OCT beam, and the control system identifies one or more locations of the Schlemm's canal for laser beam delivery by being further configured to:
instruct the OCT imaging apparatus to output the OCT beam through the first optical subsystem and the cornea, and into the Schlemm's canal,
obtain OCT images of the Schlemm's canal at a plurality of locations around at least a portion of the circumferential angle; and
for each of the images:
process the image to determine a measure of an anatomical feature of the Schlemm's canal, and
designate the location from which the image was obtained as one of the identified one or more locations of the Schlemm's canal for laser beam delivery based on an evaluation of the determined measure relative to a threshold measure.
11. The system of claim 10 , wherein the threshold measure is indicative of an at least partially collapsed canal, and the location from which the image was obtained is designated the one of the identified one or more locations for laser beam delivery when the measure of the anatomical feature is less than the threshold measure.
12. The system of claim 8 , wherein the second optical subsystem includes an optical coherence tomography (OCT) imaging apparatus configured to output an OCT beam, and the control system is further configured to:
instruct the OCT imaging apparatus to output the OCT beam through the first optical subsystem and the cornea, and into the Schlemm's canal, while the laser beam is being delivered;
obtain OCT images of the Schlemm's canal while the laser beam is being delivered;
process the images to obtain measures indicative of pneumatic expansion of the canal;
evaluate the images relative to a criterion of an acceptable pneumatic expansion; and
instruct the laser source to stop the output of the laser beam when the acceptable pneumatic expansion is detected.