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Thomas Bende, Haroun Al-Mohamedi, Bianca Schäfer, Theo Oltrup, Guido Mieskes, Martin Leitritz, Michael S. Berlin; Fiberoptic Partial Coherence Interferometry (PCI): A Novel Approach to Locate Schlemm’s Canal for MIGS Surgery. Invest. Ophthalmol. Vis. Sci. 2016;57(12):6505.
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© ARVO (1962-2015); The Authors (2016-present)
Feasibility study for targeting Schlemm’s canal (SC) and overlying trabecular meshwork from across the anterior chamber without a goniolens or contrast agent by using an infrared laser based fiberoptic PCI to enable goniolens free Excimer Laser Trabeculostomy (ELT) MIGS surgery.
After determining the wavelength with the greatest transmission through the sclera of porcine eyes was determined by spectroscopy, an apparatus was built. This device uses a laser based time domain (TD)PCI-interferometer, driven by a linear motor (PI-type M-663) with a spatial resolution of 0.1 μm in the reference path and a GRIN fiber (GIF625-10, Ø62.5 µm Core,Ø125 µm Cladding, 0.275 NA,) in the measuring path, a SLD (1300nm) with a bandwidth of 85nm and a detector, all of which were linked via computer. A model was then created to simulate SC within sclera: a piece of fresh porcine sclera was split and a spread of oil was inserted within the split sclera. This sclera/oil /sclera sandwich was then evaluated from varying distances with the apparatus to determine whether the tissue borders could be identified. The system was optimized by a polarization controller in the measuring path and various means of focusing and collimating the laser light.
The wavelength with the greatest transmission through the sclera is +/- 1300 nm. The SNR was 68dB, the measuring depth averaged 18mm and the resolution was 9µm. All surfaces of scleral sandwich are clearly detectable.
Schlemm’s canal location distal to the trabecular meshwork could be feasibly determined from within the eye by fiberoptic PCI. Improving the SNR will better enable such tissue recognition and localization in a human eye.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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