Ahmed Glaucoma Valve as a Risk Factor for Penetrating Keratoplasty Failure

Background and objectives: Penetrating keratoplasty is a surgical procedure with a history spanning over a century. The objective is to identify the incidence and potential risk factor of graft failure after performing penetrating keratoplasty in eyes with Ahmed valve tube. Methods: This retrospective study conducted on 24 patients whom penetrating keratoplasty and glaucoma shunt surgery have been performed for them from February 2017 to December 2022 at North eye center/ Erbil city. The follow up was obtained for determining the risk factors associated with keratoplasty failure. Results: Half of the patients with glaucoma drainage devices have a successful penetrating keratoplasty surgery. Age was not a risk factor for penetrating keratoplasty failure, relative risk (RR)=0.85, CI=0.38-1.88, P=0.682). Also, the following factors were not a risk for keratoplasty failure; sex (RR=1,CI=0.45-2.23, P=1), sequence of surgery of Ahmed valve prior to penetrating keratoplasty (RR=0.57,CI=0.20-1.53, P=0.206), eye laterality (RR=1.23,95%CI=0.47-3.25, P=653), aphakia (RR=4.0,CI=0.12-136.95, P=0.215) and pseudophakia (RR=5.71,CI=0.52-62.66 P=0.154), history of vitreoretinal surgery is the risk factor for penetrating keratoplasty failure (RR=3.4,95%CI=1.63-7.10,P=0.002), chronic diseases (RR=0.79,95%CI=0.34-1.86,P=0.615) and intraocular pressure>21 mmHg (RR=1.214,95%CI=0.54-2.75,P=0.653) are also risk factors for decreasing success of penetrating keratoplasty. Conclusion: In our study, Ahmed valve is a risk factor for failure of pentrating keratoplasty surgery which is 50%. Age, gender, Ahmed valve prior to penetrating keratoplasty, lens status and operated eye were not a risk factor in pentrating keratoplasty failure in those who underwent glaucoma drainage device. Whereas, vitreoretinal surgery, chronic diseases and intraocular pressure were observed as risk factors in penetrating keratoplasty failure.