Bowman layer transplantation: 5-year results
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The purpose of this study was to evaluate the 5-year clinical results of isolated Bowman layer (BL) transplantation in the treatment of advanced keratoconus.
In this prospective, single-center, interventional case series at a tertiary referral center, 20 eyes of 17 patients with advanced keratoconus underwent BL transplantation, i.e. an isolated Bowman layer graft was positioned into a manually dissected mid-stromal pocket. Scheimpflug-based corneal tomography measurements, best corrected spectacle and contact lens visual acuities (BSCVA and BCLVA), endothelial cell density, and complications were evaluated up to 5 years after surgery.
Measured simulated and maximum keratometry (Kmean and Kmax) values were stable up to 5 years after surgery (P = .310 and P = .195 for 5 years compared to 1 month follow-up, respectively), following an initial decrease from pre- to 1 month postoperatively (P < .001 each). Mean LogMAR BSCVA remained stable (P > .99), after an initial improvement from pre- to 12 months postoperatively (P = .007). Mean BCLVA did not change from preoperative to 5 years postoperatively (P = .219). During all postoperative follow-ups, mean densitometry values were higher than preoperatively (P < .001). A corneal hydrops occurred in one eye at 4.5 years postoperatively; no other postoperative complications were observed. Kaplan-Meier analysis showed an estimated success rate of 84% at 5 years postoperatively. Endothelial cell density remained stable from before to 5 years after surgery (P = .319).
After early postoperative corneal flattening, topographies were stable up to 5 years after BL transplantation, preserving BCLVA and contact lens tolerance, potentially allowing long term postponement of penetrating or deep anterior lamellar keratoplasty.
KeywordsKeratoconus Deep anterior lamellar keratoplasty Progressive ectasia Bowman layer Corneal transplantation Surgical technique
Compliance with ethical standards
All patients signed an IRB approved informed consent; the study was conducted according to the Declaration of Helsinki and was registered at www.clinicaltrials.gov (study identifier NCT01686906).
Conflict of interest
Dr. Melles is a consultant for DORC International/Dutch Ophthalmic USA and SurgiCube International. Dr. Parker is a consultant for DORC International/Dutch Ophthalmic USA and Ziemer Ophthalmic Systems. Dr. Baydoun and Dr. Dapena are consultants for DORC International/Dutch Ophthalmic USA. The other authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.
All procedures performed in this study, involving human participants, were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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