New adjustable suture technique for trabeculectomy.

PURPOSE To describe an adjustable suture (AS) experimental model that allows for tightening, loosening and retightening of the suture tension in trabeculectomy. METHODS Standard trabeculectomy was performed in fifteen pig eyeballs. All pig eyes were tested twice: one test with conventional suture in both flap's corners (conventional suture group) and another test with a conventional suture at one corner and an adjustable suture in the other corner (AS group). The order in which each test was performed was defined by randomization. Intraocular pressure was measured at three time points: T1) when the knots were tightened; T2) when the AS was loosened or the conventional knot was removed; and T3) when the AS was retightened in the AS group or five minutes after the knot removal in the conventional suture group. RESULTS The mean Intraocular pressure was similar between the two groups at time point 1 (p=0.97). However, significant Intraocular pressure differences were found between eyes in the conventional and adjustable suture groups at time points 2 (12.6 ± 4.2 vs 16.3 ± 2.3 cmH₂O, respectively, p=0.006) and 3 (12.2 ± 4.0 vs 26.4 ± 1.7 cmH₂O, respectively; p=0.001). While the conventional technique allowed only Intraocular pressure reduction (following the knot removal; T2 and T3), the AS technique allowed both Intraocular pressure reduction (T2) and elevation (T3) through the management (loosening and retightening) of the suture. CONCLUSION This experimental model provides an effective noninvasive postoperative mechanism of suture tension adjustment.