Abstract
Purpose::
23 and 25 gauge (G) transconjunctival sutureless vitrectomy surgery has been previously described with good safety and efficacy results. No study thus far has evaluated the physiologic and histologic outcomes after 23G and 25G vitrectomy surgery. Thus, this study will describe the physiologic and anatomical outcomes after sutureless transconjunctival 23G and 25G vitrectomy.
Methods::
Both institutional review board (IRB) and institutional animal care and use committee (IACUC) approval was obtained prior to the study. Twelve New Zealand white rabbits were randomized to 23G and 25G vitrectomy surgeries using angled or straight incisions. After a complete vitrectomy, trypan blue (0.10%) was injected into the eyes to evaluate physiologic leakage at 6 hours, 1 day, 3 days, and 7 days after surgery. The animals were then euthanized at day 7 and the eyes were enucleated for histological analysis by frozen sectioning. Statistical analysis was performed using a t-test, Mann Whitney test of Chi-square, and one way ANOVA with Stat View.
Results::
Leakage of trypan blue was noted from 4/37 ports (10.8%) with straight incisions versus 2/35 ports (5.7%) with angled incisions. 23G incisions had an equal number of sclerotomies with physiological leakage as compared to 25G incisions (3/36 ports or 8.3%). After enucleation, gross examination was performed on each eye. The 25G system resulted in 11/19 external open wounds with straight incisions and 4/17 external open wounds with angled incisions (p=0.04). The 23G system resulted in 15/18 open external wounds with straight incisions while angled incisions resulted in 7/18 open external wounds (p=0.017). The average wound area formed after the 25G surgery was 223.1 mm2 and 115.7 mm2 for straight versus angle incisions respectively (Figure 1, p=0.02). The average wound area formed after the 23G surgery was 160.3 mm2 and 85.2 mm2 for straight versus angle incisions respectively (p=0.001). Depth analysis of wounds showed a characteristic pattern of largerexternal entry widths, smaller middle scleral wound widths, and slightly larger interal wound widths. The mean wound width for 25G straight was 281.4 mm and the mean wound width for 25G angled was 209.1 mm (P=0.405). The mean wound width for 23G straight was 454.7 mm and the mean wound width for 23G angled was 292.6 mm (p=0.001).
Conclusions::
Both 23G and 25G vitrectomy surgery resulted in similar physiological outcomes. Anatomical analysis showed statistically similar results in using 23G angled incisions, 25G straight incisions, and 25G angled incisions. For 25G surgery, either incision can be used; however, only angled incisions should be used in 23G surgery.
Keywords: vitreoretinal surgery • sclera • wound healing