['To evaluate the efficacy and complication of glaucoma drainage implant surgery with scleral graft, scleral flap and artificial biological dural graft as the tube coverage.', 'Thirty-five cases (35 eyes) with refractory glaucoma who underwent FP-7 Ahmed glaucoma drainage implantation from January 2009 to June 2011 were retrospectively studied. Kaplan-Meier survival curve was applied to analyze the probability of success rate of three different tube coverage, the log-rank test used to compare the difference between tubes, and Cox proportional hazards regression analysis performed to predict the risk factors for failure.', 'Conjunctival shrink back leading to exposure of tube coverage occurred in 6 eyes in artificial biological dural graft group. Intraocular pressure (IOP) elevation by encapsulated cystic blebs around the plate was seen in scleral flap group (2 eyes) and scleral graft group (1 eyes), respectively. The drainage tube exposure occurred in 1 eye in scleral graft group. Kaplan-Meier survival curve analysis showed that the success rate was 8/10, 3/9 and 14/16 in scleral graft group, artificial biological dural graft group and scleral flap group, respectively, at 12 month and 15 month. There was a significant difference among three groups (P = 0.009). The proportional hazards regression showed that artificial biological dural graft was statistically significant risk factors for failure (HR = 10.844, P = 0.015). Compared with pre-operation, the post-operative mean IOP was significantly decreased in all three groups. Postoperative IOP was not significantly different among three groups in different follow-up time point (F = 0.028 - 1.218, P > 0.05).'] Do [ A comparison study of glaucoma drainage implant with three different of tube coverages ]?