Experimental Model to Evaluate Mechanical Closure Resistance of Sutureless Vitrectomy Sclerotomies Using Pig Eyes

Abstract

PURPOSE: The purpose of this study was to report a novel model for comparing mechanical resistance to intraocular pressure (IOP) increases with 23-gauge (23G) and 25G transconjunctival sutureless vitrectomy (TSV) sclerotomies in the immediate postoperative period using an experimental model of a vitrectomized eye. METHODS: This was a prospective, experimental, randomized, and observer-masked experimental study in which TSV 23G and 25G oblique sclerotomies, performed in same cadaveric pig eye, were subject to an increase in IOP. Mechanical resistance was determined by the resistance to intraocular fluid leak through the sclerotomy. The simultaneous use of the different sclerotomy diameters in the same eye avoided interindividual scleral resistance differences. RESULTS: This animal model allowed comparison of the effect of different sclerotomy diameters (23G and 25G) on incisional mechanical resistance. One hundred twenty eyes were included. In 60.7% of cases, the 23G sclerotomy first allowed intraocular fluid escape (leaked; P = 0.02). When comparing opening pressure values, 23G sclerotomies leaked at significantly lower pressure levels than 25G sclerotomies (P < 0.0001); 53% of the 25G incisions but only 16% of 23G incisions opened at pressure levels greater than 120 mm Hg. CONCLUSIONS: Oblique 23G sutureless sclerotomies offer less mechanical resistance to increases in IOP than do 25G sclerotomies. This animal model may become the basis for future studies to evaluate the advantages of using other types of incision or other surgical tools on sclerotomy closure capacity.