DOES TRANSPLANTATION OF THE BOWMAN LAYER REDUCE THE PROGRESSION OF KERATOCONUS? A SYSTEMATIC REVIEW

Abstract

Background: Keratoconus is a progressive corneal ectatic disorder that can severely impair vision. Bowman layer transplantation (BLT) has been proposed as a minimally invasive surgical option to stabilize ectasia and preserve vision in advanced keratoconus.

Objective: To systematically evaluate whether BLT reduces the progression of keratoconus and improves clinical outcomes, including keratometry, visual acuity, and contact lens tolerance.

Methods: A systematic review was conducted according to PRISMA 2020 guidelines. Databases searched included PubMed, Scopus, Web of Science, Embase, and Google Scholar. Studies were included if they reported BLT outcomes in keratoconus patients. Eleven studies met eligibility criteria, comprising prospective cohorts, retrospective series, and interventional case studies published between 2015 and 2025.

Results: Across studies, BLT significantly reduced keratometric values (average Kmax reductions of 5–7 D in many series) and maintained or improved best spectacle-corrected visual acuity. Long-term stability was demonstrated up to 7–8 years postoperatively. Complications were rare and generally minor, with isolated reports of hydrops, epithelial defects, and graft rejection. Surgical innovations, including femtosecond laser-assisted and onlay grafting techniques, enhanced outcomes and reproducibility.

Conclusions: BLT appears to stabilize keratoconus progression and preserve vision in advanced cases, delaying the need for keratoplasty. While current evidence supports its efficacy and safety, further multicenter randomized trials with standardized protocols are necessary to confirm long-term benefits and refine patient selection criteria.