Abstract
Purpose: :
To study the architecture of 25-gauge vitrectomy incisions constructed in an oblique manner using two different techniques.
Methods: :
Two sets of incisions were constructed by passing a trocar into the bare sclera of a human cadaver eye using two different techniques. An Alcon 25-gauge trocar-cannula system was used.In Group 1, incisions were constructed by passing the trocar in an oblique manner into the sclera up to the bevel (2 mm), before turning the trocar vertically to enter the vitreous cavity. In Group 2, incisions were constructed by passing the trocar in an oblique manner into the sclera up to the beginning of the cannula (3 mm), before turning the trocar vertically to enter the vitreous cavity. The incisions were analyzed histologically.
Results: :
9 incisions were created in each group. In group 1, 4 of 9 incisions (44%) demonstrated a two plane structure, with an oblique initial segment followed by a vertical segment. The remainder of the incisions consisted of a single oblique plane of entry. The scleral fibers in the internal aspect of the wound were frayed in 7 out of 9 incisions (77%) in this group. In group 2, 3 of 9 incisions (33%) demonstrated a two plane structure, and the rest had a single oblique plane. The scleral fibers were frayed in 6 out of 9 incisions (66%) in the internal aspect of the wound in this group.
Conclusions: :
25-gauge sclerotomy wounds constructed in an oblique manner using either of these techniques may show a single plane or a 2 plane structure. The two techniques have a similar likelihood of producing a two plane structure.The internal aspect of the wound is disrupted in both techniques. In group 1, this may be due to turning the tip of the trocar vertically while it is still in the substance of the sclera. In group 2, this also may be due to turning the trocar vertically even though the tip is not within the sclera. Both techniques may shear scleral fibers.Oblique incisions have been proposed for 25-gauge vitrectomy to prevent wound leakage and hypotony. More recently the sutureless nature of these wounds has been questioned due to a reported higher risk of endophthalmitis. Our study of the incision architecture may offer an explanation for unpredictable wound integrity in 25-gauge sutureless vitrectomy.
Keywords: vitreoretinal surgery • sclera • microscopy: light/fluorescence/immunohistochemistry