Influence of incisional vitreous incarceration in sclerotomy closure competency after transconjunctival sutureless vitrectomy

Abstract

Purpose: To evaluate the influence that vitreous incarceration may exert on the presence of postoperative conjunctival blebs over sclerotomies after transconjunctival sutureless vitrectomy (TSV). Blebs are formed by incisional leakage due to incompetent closure.

Methods: Experimental study in which 23-gauge TSV was performed in 146 cadaveric pig eyes. Once the vitrectomy was finished, triamcinolone was injected inside the vitreous cavity for staining residual vitreous, one of the superior cannulas was extracted over the light probe, and the other cannula was removed with the plug inserted. Postoperative conjunctival blebs in superior sclerotomies were assessed by anterior-segment optical coherence tomography (AS-OCT) in a masked fashion; nondetectable blebs were classified as grade 0 (B0), thin bleb (≤half scleral thickness) as grade 1 (B1), and thick bleb (>half scleral thickness) as grade 2 (B2). Postoperative incisional vitreous entrapment was evaluated by slit-lamp photographs in a masked way; no incarceration was classified as grade 0 (V0), thin incarceration as grade 1 (V1), and thick incarceration as grade 2 (V2).

Results: Conjunctival blebs were found in 13.7% of the sclerotomies (11.3% bleb-B1, 2.4% bleb-B2). Vitreous incarceration was found in 96.5% of the sclerotomies without bleb (B0), 81.8% of the incisions with bleb-B1, and 14.3% of the wounds with bleb-B2. Vitreous incarceration was significantly associated with the absence of conjunctival bleb (P < 0.001).

Conclusions: Vitreous incarceration in sclerotomies is related to less incisional leakage in our experimental model. Maneuvers that reduce vitreous entrapment, such as the interposition of a nonhollow probe during the cannula extraction, could decrease the sclerotomy closure competency.

Keywords: conjunctival bleb; experimental model; sclerotomy closure; vitrectomy; vitreous incarceration.