Non-Invasive Femtosecond Laser Glaucoma Surgery Guided by Micron-Resolution OCT

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Project Summary / Abstract The major objective of this proposal is to test the hypothesis that high-precision aqueous humor (AH) drainage channels, which connect the anterior chamber (AC) to Schlemm's canal (SC), created non- invasively and ab-interno with micron-resolution OCT (µ-OCT) image guided femtosecond laser trabeculectomy (IGFLT) will increase AH outflow and lower intraocular pressure (IOP) and therefore may be used as a non-invasive long lasting surgical treatment for glaucoma. Femtosecond (FS) laser pulses can be delivered through transparent and translucent tissue to perform high-precision, sub-surface surgical procedures with no collateral damage to adjacent or superficial tissue. These unique properties of FS laser- tissue interactions provide a marked advantage over traditional laser procedures for high-precision, sub-surface treatments. Based on these findings we believe that treatment of the trabecular meshwork (TM) area with FS laser pulses will provide improvements over traditional laser treatments such as argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT). We propose that using FS laser pulses to create high- precision drainage channels (ab-interno) through the TM and juxtacanicular tissue (JCT) will restore the normal AH outflow facility of the eye and therefore lower IOP. To reliably create such drainage channels the exact determination of the location of the TM and SC is required. We propose to develop and use a laboratory prototype of a µ-OCT image guided FS laser system to ensure the accurate placement of the drainage channels. Major benefits of IGFLT are: 1) ab-interno, non-invasive procedure without any incisions or wound to the surface, 2) exact placement of the channels with micron accuracy, 3) accurate control of the AH outflow increase by creating the required channel cross section, 4) potential longevity due to minimized collateral tissue damage, 5) surgery can be performed as a quick outpatient procedure, 6) potential repeatability due to small treatment zone with no damage to adjacent tissue. To test our hypotheses we propose the following Specific Aims: 1) Develop an optical delivery system which couples a surgical femtosecond laser beam with a near infrared µ-OCT beam, allowing µ-OCT image guided delivery of FS laser pulses for the creation of high-precision aqueous humor drainage channels from the anterior chamber to Schlemm's canal. 2) Demonstrate µ-OCT image guided femtosecond laser trabeculectomy using ab-interno delivery of a near infrared FS laser beam through a gonioscopic contact lens by creating outflow channels of predetermined geometry which connect the AC to SC in human cadaver eyes. Evaluate the quality and dimensions of the channels with various imaging techniques. Create technical requirements for clinical technology development. 3) Evaluate the effect of µ-OCT image guided FS laser created channels on AH outflow facility in human cadaver eyes using standard perfusion methods. Optimize treatment protocols for predetermined IOP reduction. Confirm final technology requirements for a portable clinical prototype planned to be developed and tested in a subsequent future project.