Abstract
Purpose :
Partial thickness corneal surgery such as deep anterior lamellar keratoplasty (DALK), reduces endothelial rejection rates, intraoperative complications, and preserves endothelial cell density compared to full thickness surgery. We previously showed a vertical razor edge cannula could be an effective tool for deep stromal “big bubble” injections in ex vivo rabbit cornea, but the approach may be challenging due to visual obstruction. This study evaluated the hypothesis that robotic vertical cannula insertion with depth guidance achieves deeper pneumodissection with less technical demand than a freehand approach.
Methods :
Procedures were performed on mature ex vivo rabbit eyes by an expert surgeon under a surgical microscope with embedded optical coherence tomography (OCT). A 20G vertical cannula was inserted into the deep stroma using one of three techniques at random: 1) freehand approach with no depth feedback (Fig. 1a, N=4), 2) OCT microscope guidance (N=4), or 3) robotic with OCT (Fig. 1b, N=4). After insertion, the vertical cannula was replaced by a 20G blunt needle and air was injected. Pneumodissection depth was measured using B-mode OCT imaging, and the number of perforations were recorded. User workload was quantified by the NASA task load index (TLX).
Results :
The average cornea thickness was 944.86µm. Average pneumodissection depth was significantly deeper for robotic samples than by freehand (90.6% vs 51.1%, Fig. 1c) or OCT guided (81.1%, Fig. 1d) approaches. The robotic technique was the only approach to generate a big bubble (Fig. 1e). The robotic assisted approach significantly reduced mental demand (7.5 vs. 14.75 and 14.5, P<0.05), physical demand (5.5 vs. 12.25 and 12.75, P<0.05) and perceived effort (5.75 vs. 12.5 and 12.0, P<0.05) compared to freehand and OCT guided approaches, respectively (Fig. 2).
Conclusions :
The vertical razor edge cannula is an effective tool for the “big bubble” technique. Use of OCT guidance with robotic vertical cannula insertion significantly reduced the mental and physical demand of the DALK procedure and increased pneumodissection depth. Robotic vertical cannula insertion is a promising approach to simplify the DALK procedure.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.