Risk factors of implant exposure outside the conjunctiva after Ahmed glaucoma valve implantation

Purpose: To study possible risk factors in cases in which part of the device becomes exposed outside the conjunctiva after Ahmed glaucoma valve (AGV) implantation. Methods: Eleven eyes in which one part of the AGV was exposed outside the conjunctivae were compared with 44 random eyes that underwent the same operation by the same surgeon during the same time period but without any complications. Preoperative diagnosis, age, sex, implant location, number of previous ocular surgeries, and both associated ocular diseases and systemic diseases were taken into account in both the patient group and the control group to determine all possible causes. Results: Age, implant location, type of glaucoma, diabetes mellitus, and hypertension had no relation to implant exposure. However, the patient group had more ocular surgeries before AGV implantation than the control group (P = 0.006). Conclusion: We found that only the number of previous ocular surgeries was a possible risk factor for implant exposure. More effort should be made to decrease implant exposure outside the conjunctiva, and research should be performed to determine the proper treatment for implant exposure.