A Review of Scleral Flap Shape on Trabeculectomy Outcomes

Introduction: Trabeculectomies are amongst the most common surgical procedures to lower intraocular pressure (IOP). Scleral flap dimensions are a key factor in influencing aqueous outflow and subsequent IOP reduction, especially in the early postoperative period. Despite the substantial diversity of scleral flap shapes that is used in practice, there is little information comparing outcomes between them. In this study, we review the literature on the uses and outcomes of various scleral flap shapes. Methods: A literature review was performed using the databases: MEDLINE, SCOPUS, and Web of Science. Search terms for relevant studies included the following: trabeculectomy AND (square OR triang* OR rectang* OR polygon* OR arc OR shape) AND flap. Results: Our initial literature search revealed 71 unique articles, six of which met our inclusion and exclusion criteria and were reviewed. Four articles reported the use of triangular flaps, one rectangular flap, one square flap, and two arc-shaped flaps. The data from each article were reviewed for the following: 1. Surgical technique; 2. Early postoperative intraocular pressure reduction; 3. Final postoperative intraocular pressure reduction; 4. Postoperative complications. Conclusions: A myriad of scleral flap shapes is utilized in surgical practice. Essentially all of the trabeculectomy procedures, regardless of scleral flap shape, achieved substantial reductions in IOP with similar success rates. However, due to the variability in surgical technique and lack of direct comparison, we cannot definitively conclude or deny that one flap shape is superior to another. We believe our review provides the most comprehensive analysis of scleral flap shape to date and highlights its importance in regulating aqueous flow, especially in the early postoperative period.