Abstract
Purpose: :
To investigate in vitro the dynamic wound morphology of unhealed 25- and 23-gauge sutureless sclerotomy wounds.
Methods: :
8 cadaveric heads of New Zealand white rabbits were obtained and the eyes enucleated with their conjunctiva intact to simulate an intact globe. Four eyes in each of 4 groups were analyzed: Group A: 25-gauge straight incision; Group B: 25-gauge angled (tunnel) incision; Group C: 23-gauge straight incision; Group D: 23-gauge angled (tunnel) incision. Intraocular pressure (IOP) was controlled with a 25- or 23-gauge infusion cannula. Three incisions were created in each eye including the infusion cannula using the either a 25 or 23 gauge trocar and cannula system. The incisions were imaged with anterior segment spectral domain optical coherence tomography (OCT) under variable IOP (low, medium, high) to simulate successive blinks or rubbing of the eye and to evaluate the wounds in a dynamic state. Finally, India ink was applied to the surface of the eye under variable IOP to evaluate for wound leakage. The eyes were then analyzed by frozen section.
Results: :
Gross examination revealed obvious leakage of intraocular fluid in groups A and C (straight incisions) under variable IOP with some developing conjunctival blebs. Groups B and D (angled incisions), however, had minimal to no gross leakage. Spectral domain OCT demonstrated open wounds in those groups with straight incisions under all IOP conditions, with a slightly more open wound under high IOP. Angled incisions, however, demonstrated less wound opening overall and better wound apposition under high IOP versus low IOP. Histological examination revealed India ink particles in all straight incisions with some penetration across the whole incision, while no India ink particles were observed in angled incisions.
Conclusions: :
Angled incisions have been proposed for sutureless vitrectomy to prevent wound leakage, hypotony, and the secondary risk of endophthalmitis. This study demonstrates that angled (tunneled) incisions provide better wound apposition under dynamic IOP conditions that simulate real world situations: blinking, squeezing or even rubbing of the eye.
Keywords: vitreoretinal surgery • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • endophthalmitis