Vitrectomy-assisted biopsy: An in vitro study on the impact of cut rate and probe size

Purpose: The aim of this study was to optimize the technique of performing vitrectomy-assisted biopsy of intraocular tumors by comparing the cytohistological findings in specimens obtained with different vitrectomy probes and cut rates. Methods: Vitrectomy-assisted biopsies were taken from a fresh porcine liver. For each sampling, the vacuum level was 300 mm Hg. The following parameters were compared; cut rate (60, 600 and 6,000 cuts per minute [cpm]), probe type (standard and two-dimensional cutting [TDC]), and probe diameter (23-gauge and 25-gauge). The specimens were assessed by automated whole-slide imaging analysis and conventional light microscopy. Results: Seventy-two biopsies were analyzed for the number of hepatocytes, total area of tissue fragments, and total stained area of each microscope slide. For all probe types, these parameters were significantly and positively correlated with the cut rate. TDC probes led to significantly higher scores than those of standard probes, independent of the cut rate. There were no significant differences in results when using 23-gauge or 25-gauge standard probes. Light microscopic examination demonstrated well-preserved cells sufficient for cytohistological analyses in all investigated cases. Conclusions: The higher the cut rate, the larger is the amount of aspirated cellular material. There were no significant differences between 23-gauge and 25-gauge biopsies. Cut rates up to 6,000 cpm did not adversely affect the cytohistological features of the samples.