Abstract
Purpose :
To investigate the most relevant factors that produce shadowing effects on the area of interest (retina) caused by vitreoretinal instruments (VRI) during intraoperative optical coherence tomography (iOCT)-assisted vitreoretinal surgery and to design a novel instrument, which will counteract this limitation.
Methods :
The iOCT image data of fifty-four patients (54 eyes) who underwent a pars plana vitrectomy (PPV) were post-processed using a histogram-pixel analysis to determine their gray level caused by shadowing effects on the retina by 25-gauge VRI (forceps, silicon tipped canula, subretinal canula 41/25-gauge), and compared to control images without perceived shadowing. Analysis of main shadowing factors was performed based on the determined high-impact variables. The prototypes of iOCT compatible VRI with modified slitted distal tubing aiming to reduce the shadowing were tested in experimental conditions determining their gray level interference, which was compared to the baseline findings. Obtained data were analyzed statistically.
Results :
The study revealed that all VRI caused significant shadowing and interference. The most prominent shadowing effect of standard VRI was caused by steel made tubing and working tips of the forceps. Clear materials (silicon tip, polyamide) produced a very low and insignificant shadowing effect. Small size instrument’s tips (forceps’ jaws) irrespective of their density caused clinically irrelevant shadowing. Forceps exhibited a 36.21% lower gray level (25.47 ± 7.34 vs. 39.94 ± 6.57), while silicone-tipped cannula demonstrated a 43.96% lower gray level (22.89 ± 6.01 vs. 40.85 ± 2.26). The newly designed VRI exhibited a better gray level profile compared to standard VRI as the iOCT signal could pass through the double slitted distal tubing and image the area of interest. The produced shadow effect was deemed clinically irrelevant.
Conclusions :
A systematic quantification of iOCT image quality showed that all VRI caused significant shadowing of the area of interest, while shadowing effect caused by newly designed VRI was clinically irrelevant. The use of new iOCT compatible VRI may enhance the visualization of tissue behavior during sensitive tissue-manipulating maneuvers, hence improving its safety and efficacy. These new prototypes should be tested under clinical conditions.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.