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TOMAS A Moreno, Jin H Shen, Yuankai Tao, Karen M Joos; Feasibility of Intraocular Forward-Imaging B-scan Optical Coherence Tomography Probe to Guide Subretinal Injections. Invest. Ophthalmol. Vis. Sci. 2018;59(9):286. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Subretinal injections are increasing important for gene therapy but require micrometer accuracy. Therefore, we investigated the feasibility of a novel optical coherence tomography (OCT) probe continuously imaging a microneedle tip to perform subretinal injections.
A 36-gauge coplanar needle attached to a 25-gauge B-scan OCT (870 nm) probe was introduced through a trocar into the vitreous cavity of fresh ex-vivo porcine eyes. The proximal end was connected to a microliter pump, which released 20 µL (200 µL/min) of green-dyed balanced salt solution. Subretinal injections were performed by viewing a split-screen heads-up display (TrueVision Systems Inc., Santa Barbara, CA) with the simultaneous en face 3D surgical microscope image on the left and the real-time unprocessed continuous B-scan OCT image from the probe on the right. Observations were recorded.
The microneedle OCT probe successfully tracked the needle tip through the vitreous and retinal layers in real time to the desired subretinal location without entering the retinal pigment epithelium (RPE). It simultaneously imaged the needle tip and lifting of the retina from the RPE during injection. No focusing or tracking computer algorithms were required to maintain the needle tip image. The heads-up display permitted simultaneous real-time visualization of the microscope en face and B-scan OCT images to provide wide-field and localized inputs. The microneedle OCT probe also provided unique observations that were not readily seen en face. These included: 1) OCT visualization of the exact needle tip position at all times, 2) clear retinal imaging with subretinal injection performance despite corneal or lenticular media opacities, 3) RPE disturbance at the injection site, 4) imaging of the far peripheral retina, and 5) retinal edema formation during injection. Fluid reflux through the retinotomy was observed en face.
The novel microneedle OCT probe demonstrated capacity for subretinal injection delivery. The B-scan OCT device continuously imaged the needle tip traveling through the eye. It then visualized formation of the retinal bleb during injection.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
The microneedle OCT probe is performing a subretinal injection with the simultaneous en face microscope image and the B-scan OCT image displayed. (Arrows: needle tip, yellow; retina, red; subretinal fluid, green; RPE, blue; OCT probe, white).
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