Effect Of Ahmed Glaucoma Valve Implantation On Corneal Endothelial Cells

Objective:To observe the changes of corneal endothelial cell density and morphological parameters after Ahmed glaucoma valve implantation.To analyze the related factors, and evaluate the long-term safety of the surgery.Methods:Retrospective case study. The clinical data of glaucoma patients who underwent AGV implantation in Weifang eye hospital with regular follow-up records from June, 2010 to June,2015 were collected. The patients' intraocular pressure (IOP), number of antiglaucoma medications were recorded six months,one year,two years and over two years after AGV surgery , the cornea endothelial cell density (CECD) and its morphological parameters of superiortemporal,inferiortemporal,superiornasal,inferiornasal quadrant and central area were also examined. The CECD and morphological parameters were compared before and after AGV surgery and its related factors were also analyzed.Results:The completed clinical data of 45 patients (55 eyes) with glaucoma were collected. Postoperative follow up time was range from six months to four years.The results demonstrated that the CECD of superiortemporal quadrant decreased at one year after AGV surgery. The loss rate of CECD was 29.8±19.8%,24.9±19.2%, 43.7±23.6% at one year,two years and over two years postoperation respectively,the difference was statistical significant (p<0.01) when compared with that preoperation. Over two years follow up, the loss rate of CECD was central 17.7±17.8%,p=0.011;superiortemporal 43.7±23.6%,p<0.0001; inferior-temporal 26.2±25.5%,p=0.004; superiornasal 18.8±11.0%,p=0.014; inferiornasal 9.4±10.6%,p?0.375;in central area, superiortemporal, inferiortemporal, superior-nasal and inferiornasal quadrant respectively.In the superiortemporal quadrant where the drainage tube was inserted, the cornea endothelial cell morphological parameters (cell morphology, average cell area, percentage of hexagonal cells,standard deviation of cell area, coefficient of variation of cell area) changed significantly (p<0.05) when compared with that preoperation at one year,two years and over two years respectively postoperation. The CECD of superiortemporal quadrant decreased gradually as the postoperative time increases(R=0.433, p=0.005). The decrease of CECD has negative correlation with the tube inserting position in anterior chamber (AC) and the most minimal distance between the end of tube and the posterior surface of the cornea (R=-0.667, p<0.001; R=-0.514, p=0.001),no correlation was observed with the tube length in the AC and the angle between tube and posterior surface of the cornea (R=-0.28 ,p=0.05; R=0.036,P=0.42). The decreases of CECD and the endothelial cell morphological changes were significantly severer in eyes with the tube inserting through or anterior to Schwalbe line than in eyes with inserting through trabecular meshwork(p<0.05).Conclusions:This study found that the CECD decrease gradually after AGV implantation ,and the endothelial cell morphological changes were also observed.The endothelial cell loss and it's morphological changes were more obvious in the tube inserting quadrant,these changes have positive correlation with postoperative time,tube inserting position in the AC angle and the minimal distance between the tube end and posterior surface of the cornea, less effect of AGV implantation on cornea endothelial cells was observed in eyes with the tube inserting through trabecular meshwork.The CECD and endothelial cell morphological changes should be examined regularly after AGV surgery.