Abstract
Purpose: :
An increased risk of endophthalmitis has been reported in small-gauge vitrectomy surgery. Air-fluid exchange following pars plana vitrectomy (PPV) is thought to reduce fluid outflow through sclerotomies via surface tension of an intraocular air bubble and thereby prevent postoperative wound leakage and hypotony; however the consequences of air tamponade on ocular surface fluid inflow are uncertain. An association between air tamponade following sutureless PPV and endophthalmitis has also been reported, yet the pathophysiologic mechanism is unclear. This study examines the influence of air-fluid exchange (internal wound air tamponade) on ocular surface fluid entry through sutureless 23-gauge PPV sclerotomies prior to wound healing.
Methods: :
Pars plana vitrectomy was performed in human cadaveric eyes using sutureless 23-gauge (23g) incisions followed by internal wound tamponade with an air bubble (n=12) or balanced salt solution (n=13). India ink was applied over sclerotomy sites while the intraocular pressure was varied to simulate postoperative conditions. The presence of India ink particles within incisions and the vitreous cavity was evaluated by histologic analysis.
Results: :
All wounds (n=25) had histologic evidence of proximal wound contamination. The rate of distal wound contamination was 77% and 67% in fluid and air tamponade eyes respectively. The rate of vitreous cavity contamination was 45% and 50% in fluid and air tamponade eyes respectively. Incarceration of vitreous in 23g wounds was seen histologically in three of the fluid tamponade eyes but none of the air tamponade eyes.
Conclusions: :
In this small study there is no significant difference in 23g sutureless PPV wound contamination from ocular surface fluid in comparing air versus fluid internal tamponade of sclerotomies. Both methods of internal wound tamponade may predispose to the entry of ocular surface fluid into eyes in the immediate postoperative period at a high rate. A larger study is warranted.
Keywords: vitreoretinal surgery • wound healing • microbial pathogenesis: experimental studies