The most challenging aspect of deep anterior lamellar keratoplasty (DALK), is what’s known as “Big Bubble” technique which injects air/fluid to fully separate the Descemet’s Membrane and stroma with a hydro-dissection needle. Big bubble technique requires micron accuracy to guide the needle to approximately 90% depth of cornea. Here, we developed and tested common-path swept source optical coherence tomography (CP-SSOCT) distal-sensor integrated hydro-dissection needles, which can accurately detect the needle position relative to corneal tissues with micron accuracy. The OCT distal-sensor was put inside a 30-gauge needle, which was also used for hydro dissection. A high-index elliptical epoxy lens was attached to the end of the single mode fiber to increase the signal to noise ratio inside the cornea. To control the position and insertion angle of the sensor, we customized the eye mount with an angular slide and a precise linear motor with Luer-slip. The needle was fixed outside, 100um from epithelium layer, to obtain the A-scan image to identify both epithelium and endothelium membranes at every 10° from 0° to 70° insertion angles. The needle was then inserted into bovine cornea and recorded A-scan images at each step. Freehand insertion test was performed with and without sensor guided needles. The results showed that the position of the epithelium and endothelium membranes were still identified from A-scan even at 70°. Sensor guided freehand test can reach 95% of cornea thickness on average without any perforation. These results are consistent with our hypothesis that CP-SSOCT fiber sensor can guide a needle insertion inside a cornea for Big Bubble technique.
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