OBJECTIVETo evaluate the efficacy of "straight scleral tunnel incision" -trabeculectomy with a releasable suture supplemented with mitomycin C (MMC) on reducing intraocular pressure (IOP), complications, and corneal astigmatism in patients with primary angle-closure glaucoma (PACG).

METHODSTotally 217 acute or chronic PACG patients with occludable angle above 180 degrees and IOP above 21 mm Hg were divided into 3 groups. Patients in group A (98 cases, 128 eyes), B (71 cases, 95 eyes), and C (48 cases, 60 eyes) were treated with "straight scleral tunnel incision"-trabeculectomy with a releasable suture supplemented with MMC, releasable suture trabeculectomy with MMC, and trabeculectomy with MMC, respectively. IOP, complications, and surgically induced astigmatism (SIA) were evaluated preoperatively and up to 12 months postoperatively.

RESULTSIOP of 2 weeks after treatment was significantly lower than preoperative IOP in all the 3 groups (all P <0. 001). Success rates (IOP < or = 20 mm Hg) in group A, B, and C were 87.91%, 89.23%, and 83.72% respectively at 12 months after treatment (P = 0.256). The incidence of shallow anterior chamber and hypotony had no significant difference between group A and B, but both of them were lower than that in group C (P < 0.05). There were no significant differences in preoperative corneal astigmatism among the 3 groups. The corneal astigmatism after 2 weeks in group A (1.71 +/- 1.47D) was higher than that before operation (1.28 +/- 1.05D, P = 0.126). With 12 months gone, the astigmatism almost returned to preoperative levels. The corneal astigmatisms after 2 weeks in group B and C (1.99 +/- 1.20D and 2. 22 +/- 1.39D) were significantly higher than those before operation (1.20 +/- 0.85D and 1.18 +/- 0.93D, P = 0.002, P = 0.001), respectively. With 12 months gone, the mean astigmatisms in group B and C (1.87 +/- 0.91D and 1.90 +/- 1.16D) were still significantly higher than those before operation (P = 0.001, P = 0.003). The highest astigmatic polar values in group A, B, and C (1.00D, 1. 89D, and 1. 77D) occurred after 2 weeks, 1 month, and 1 month postoperation, respectively, which were significantly higher than those before operation (0.19 +/- 1.32D, 0.12 +/- 1.22D, and 0.17 +/- 1.25D, P < 0.01), respectively. With 12 months gone, they were 0. 03D, -0. 18D, and -0. 13D higher than those before operation, respectively. The rates of function bleb and thin-wall bleb were 71.43% and 26.37% in group A, 75.38% and 29.23% in group B, 72.09% and 25.58% in group C, respectively at 12 months after treatment There were no significant differences among the 3 groups.

CONCLUSION"Straight scleral tunnel incision" -trabeculectomy with a releasable suture supplemented with MMC can reduce complications and get satisfactory results in reducing IOP and SIA.