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Karen M Joos, Jin H Shen; Development of an intraocular B-scan optical coherence tomography (OCT)-guided micro-needle. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):366.
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© ARVO (1962-2015); The Authors (2016-present)
Real-time intraoperative B-scan optical coherence tomography (OCT) observation of intraocular surgery may enhance precise surgical techniques such as gene therapy delivery or sub-retinal surgery. A micro-needle was combined with a forward-imaging 25-gauge OCT probe to perform real-time imaging of the needle as it touches a retinal surface, perforates through the retina, and injects sub-retinal fluid.
The forward-imaging OCT probe has a disposable 25-gauge tip. A 36-gauge needle was welded to the probe tip with its end extending 3.5 mm with a smooth curve to permit imaging of the needle tip. Silicone tubing with a saline syringe was attached to the external proximal needle tubing. An electromagnetic controller was embedded within the handpiece to drive the 125 µm single-mode fiber optic actuator within the 25-gauge probe tip. A sealed 0.35 mm diameter GRIN lens (Go!Foton, Somerset, NJ) within the probe tip protected the fiber scanner and focused the scanning beam 3 to 4 mm distant. A VHR spectral-domain optical coherence tomography (SDOCT) system (870 nm, Bioptigen, Inc. Durham, NC) produced the B-scan images with the fiber optic oscillations matched to the engine's scanning rate. Real-time imaging trials of the needle tip as it touched the porcine ex vivo retinal surface, perforated the retina, and injected saline under the neurosensory retina to form a retinal detachment were performed.
A 36-gauge needle combined with the 25-gauge tip of the forward-imaging OCT probe formed an instrument capable of passing through a 23-gauge vitrectomy port. This probe has an internal scanning system so it can be held steady to produce a two-dimensional B-scan image. Unprocessed real-time OCT video showed the needle tip touching the surface of an ex vivo porcine retina without the aid of a surgical microscope. Reproducible guided perforation through the retina to the subretinal space was observed. Formation of a localized neurosensory retinal detachment coincided with initiation of the saline injection.
Real-time intraocular B-scan OCT visualization and feedback of surgical maneuvers can provide additional infromation about the targeted retinal layers during surgical intervention. An intraocular 25-gauge B-scan forward-imaging probe coupled with a 36-gauge needle developed to pass through 23-gauge ports was capable of real-time guidance of sub-retinal saline injection.
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