Corneal Endothelial Cell Loss after Baerveldt Glaucoma Implant Surgery

Purpose To evaluate risk factors for corneal endothelial cell density (ECD) loss after Baerveldt glaucoma implant (BGI) insertion. Design Prospective cohort study. Participants Seventy-two patients (72 eyes) with glaucoma. Methods Before and 1, 2, 3, 4, and 5 years after anterior chamber BGI insertion, we evaluated the central corneal ECD (CCECD) and peripheral corneal ECD (PCECD) in the area of the tube; anterior chamber (AC) flare; tube insertion entry site position relative to Schwalbe’s line (SL), defined as all of the entry site behind SL (tube insertion position 1), less than 50% of entry site anterior to SL (tube insertion position 2), more than 50% but less than 100% of entry site anterior to SL (tube insertion position 3 [TIP3]), and all of the entry site in front of SL (tube insertion position 4 [TIP4]); anterior segment (AS) OCT tube parameters, including posterior cornea-to-tube tip distance, tube angle-to-posterior corneal surface distance, tube tip-to-anterior iris distance, tube length (TL), and tube angle-to-anterior iris distance. Main Outcome Measures Primary outcomes were CCECD and PCECD loss at 5 years. Secondary outcomes included prognostic factors for ECD loss: tube insertion entry site position relative to SL, AS OCT tube parameters, AC flare, and clinical factors including IOP. Results Sixty-four patients (64 eyes) completed the study. The mean percentage CCECD and PCECD losses at 5 years were 36.8% and 50.1%, respectively. On univariate analysis at 5 years, a lower CCECD was associated with TIP3. Tube angle-to-anterior iris distance, TL, and TIP3 were associated with lower PCECD at 5 years. Multiple regression analysis revealed TIP3 to be associated with both lower CCECD (standardized β coefficient, –0.27; P = 0.015) and PCECD (standardized β coefficient, –0.23; P = 0.028). A short TL (standardized β coefficient, 0.26; P = 0.016) also was associated with lower PCECD. The fastest rate of cell loss was associated with TIP3 for CCECD and TIP4 for PCECD. Conclusions Anterior chamber BGI insertion is associated with ECD loss greatest close to the tube. Tube insertion in the vicinity of, or anterior to SL, and short TL were associated with significant ECD loss with time.