Risk of corneal decompensation requiring corneal graft after Ahmed or Baerveldt valve implantation in a tertiary-care center
Authors: Laurence Bussières1, Mélanie Hébert1 William Yip1, Nicolas Chapdelaine1, Caroline Lajoie2. 1Université Laval, 2CHU de Québec.
Author Disclosures: L. Bussières: None. M. Hébert: Funded grants or clinical trials; Name of for-profit or not-for-profit organization(s); Bayer Fighting Blindness Canada, Vision Health Research Network. W. Yip: None. N. Chapdelaine: None. C. Lajoie: None.
Abstract Body:
Purpose: Rates of corneal decompensation after glaucoma drainage device implantation vary in the current literature with rates reported in the Ahmed versus Baerveldt study and the Ahmed Baerveldt Comparison study ranging from 7 to 17% at one year. The purpose of this study was to determine the risk of corneal decompensation requiring corneal grafts after Ahmed or Baerveldt valve implantation in a tertiary-care center.
Study Design: Retrospective cohort study.
Methods: All patients operated with a glaucoma drainage device at the CHU de Québec - Université Laval between 2000 and 2021 were considered for inclusion. Patients lost to follow-up before 6 months postoperatively were excluded. Relevant data were extracted such as preoperative and postoperative intraocular pressures (IOP) as well as maximum IOP, best-corrected visual acuity, glaucoma medication, presence of underlying pathologies, and complications. The primary outcome was incidence of corneal decompensation after implant leading to corneal graft and the secondary outcome was graft survival at follow-up.
Results: A subgroup of 121 patients of the total 914 patients were randomly sampled to be included in the analysis, of whom 45 received the Ahmed implant and 76 patients received the Baerveldt implant. Median [Q1, Q3] age at first implantation was 71 [60, 79] years and 52% were male. Most patients were diagnosed with open angle glaucoma (62%), followed by neovascular glaucoma (12%), closed-angle glaucoma (11%), and uveitic glaucoma (5%). Median [Q1, Q3] follow-up duration was 46 [24, 71] months which did not differ significantly between the two cohorts. At follow-up, 10 patients (23%) in the Ahmed cohort required a corneal graft compared to 12 (16%) in the Baerveldt group (p=0.344). Among these, 4 patients (40%) in the Ahmed group and 5 (46%) in the Baerveldt group suffered a graft decompensation (p=0.801). Time to onset of corneal decompensation requiring graft and time to onset of graft decompensation were not significantly different between both groups (p=0.555 and p=0.435, respectively). Only one graft rejection was noted in the entire cohort in a patient from the Baerveldt group.
Conclusions: Our study suggests that current studies in the literature underestimate the incidence of corneal decompensation following glaucoma drainage devices and patients should ideally undergo specular microscopy and pachymetry as preoperative workup to assess for corneal decompensation risk.
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