Purpose
To evaluate the change in the rate of loss of corneal endothelial cell density (CED) after Ahmed glaucoma valve (AGV) implant surgery in refractory glaucoma patients.
Methods
Medical records of refractory glaucoma patients who had undergone AGV (S2 or FP7, New World Medical, Rancho Cucamonga, CA, USA) implantation for treatment of refractory glaucoma were reviewed retrospectively. Patients who have got specular microscopy examination (Noncon Robo SP-8000; Konan Medical Inc, Tokyo, Japan) before surgery and at least 3 times after surgery by interval of 6 or more months were enrolled to the study. CED data at the corneal center before surgery and up to 5 years after surgery were collected. The rate of progressive loss in CED was determined by linear regression and compared with that of the control group. Control was collected from the contralateral eye of the subject, when the eye was diagnosed having glaucoma, receiving anti-glaucoma medication, and no history of previous ocular surgery. The relevant demographic factors were subjected to a correlation analysis to the rate of CED loss.
Results
Seventy two eyes of 72 refractory glaucoma patients were enrolled to the subject group, and compared to the 31 control eyes. Overall rate of loss in CED was − 7.0 ± 8.1% in subject group and - 0.1 ± 2.4% per year in the control for 45.3 months and 46.4 months of average follow-up respectively (p<0.001, Mann-Whitney U test). The annual loss rate decreased with time; −10.7% from baseline to 1 year after surgery, −6.9% from 1 year to 2 years, −4.2% from 2 years to 3 years, and −2.7% thereafter (p<0.001, 0.037, 0.230, and 0.111 respectively compared the control group, Mann-Whitney U test). Regression analysis indicated that the presence of an AGV implant (B = −6.895, P < 0.001) was the only independent factor significantly associated with more rapid CED loss, no other clinical factor affected to the rate of CED loss significantly.
Conclusions
There was a progressive CED loss for average of 46 month after AGV implantation. But the rate of loss in the CED was decreased with time; it was significantly greater compared to the control during the first and second year after surgery, but was not significantly different from the control group after 2 years from the surgery.