The aim of this study was to assess the effect of various tube parameters on corneal endothelial cell density (ECD) after insertion of Ahmed valves.
Thirty-nine eyes of 33 patients with previous superotemporal (ST) Ahmed valve implantation and 20 eyes of 13 participants with previous uncomplicated phacoemulsification and intraocular lens implantation but no history of glaucoma surgery were evaluated. Various tube parameters were measured with anterior segment optical coherence tomography. ST, central, and inferonasal (IN) ECD and pachymetry were measured. Endothelial cell loss and corneal thickness in the ST cornea was compared with those in the IN cornea.
The mean age of the operated patients was 58 ± 22 years, and the mean time since glaucoma surgery was 2.5 ± 2.6 years. Thirty-two of the 39 study eyes were pseudophakic. The ECD was significantly lower in the ST endothelium than in the IN endothelium in eyes with glaucoma tube surgery (P < 0.001), although this relative reduction in ST ECD was not greater than that seen in pseudophakic control eyes (P = 0.16). In univariate analysis, tube angle relative to the cornea and distance from the tip of the tube to the cornea were significant risk factors for decreased ST endothelial cell loss when assessed relative to the IN ECD (P = 0.01 and P = 0.02, respectively). In multivariate analysis, only the distance of the tube tip to the cornea remained significantly associated with ST endothelial cell loss.
Although this was a retrospective study with inherent limitations, tubes that are closer to the cornea seem to lead to increased loss of adjacent endothelial cells.
*Department of Ophthalmology, University of California San Francisco, San Francisco, CA;
†Department of Ophthalmology, People's Hospital, Peking University, Beijing, China;
‡Francis I. Proctor Foundation, University of California San Francisco, San Francisco, CA; and
§Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD.
Reprints: Bennie H. Jeng, MD, Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, 419 W. Redwood St, Suite 470, Baltimore, MD 21201 (e-mail: firstname.lastname@example.org).
Supported in part by a grant from Research to Prevent Blindness, Inc, and That Man May See, Inc.
Presented in part at the Association for Research in Vision and Ophthalmology Annual Meeting, Seattle, WA, May 6, 2013; Cornea Society Fall educational symposium, New Orleans, LA, November 15, 2013; and American Academy of Ophthalmology Meeting, New Orleans, LA, November 18–19, 2013.
The authors have no conflicts of interest to disclose.
E. B. Koo and J. Hou contributed equally as primary coauthors.
Received August 11, 2014
Received in revised form September 23, 2014
Accepted September 24, 2014