Impact of Glaucoma Surgery on Corneal Graft Survival After Keratoplasty: A Systematic Review and Meta-Analysis

Precis: Glaucoma surgery impacts corneal graft survival differently by procedure type, with GDDs being most effective at reducing intraocular pressure. However, graft survival rates are comparable across trabeculectomy, CPC, and GDDs. Trabeculectomy improves visual acuity best but often requires additional interventions.

Purpose: To investigate the impact of different glaucoma procedures on corneal graft survival and corneal endothelium health.

Methods: We searched PubMed, Cochrane Library, Scopus, and Web of Science, to identify eligible studies. Studies were included based on predetermined criteria. The primary outcome was corneal graft survival, and secondary outcomes included intraocular pressure (IOP) control, visual acuity, antiglaucoma medications, additional glaucoma surgery, and postoperative complications. Meta-analyses were conducted using random-effects models, and heterogeneity was assessed using the (I2) test.

Results: Our results included 27 studies involving 905 patients were analyzed. However, there were no randomized comparative studies. The overall proportion of corneal graft survival at last follow-up was 66.4%, with the three subgroups of trabeculectomy, cyclophotocoagulation (CPC), and Glaucoma drainage devices (GDD) showing similar survival rates of 66.6%, 64.8%, and 65.6%, respectively. Short term graft survival (6 months) was similar across groups, however 2-year survival favoured trabeculectomy. GDDs were the most effective in reducing IOP with an average reduction of 21.4 mmHg compared to 18.9 mmHg for trabeculectomy and 14.8 mmHg for CPC. CPC yielded the best improvement in visual acuity reported as BCVA. GDD required the fewest postoperative antiglaucoma medications. Trabeculectomy had the highest proportion of patients needing additional surgery for glaucoma. The most common complications were hypotony, uveitis and tube obstruction.

Conclusion: There were no significant differences in corneal graft survival rates among various glaucoma surgical techniques, but these findings must be interpreted with caution due to the limitations of primary research. GDDs effectively reduced IOP and minimized the need for antiglaucoma medications. Trabeculectomy may be associated with the greatest visual acuity improvement but may carry a higher likelihood of requiring further glaucoma surgery.