Half-top-hat--a new wound configuration for penetrating keratoplasty

To describe a new, simpler method of achieving the advantages of a lamellar wound configuration in penetrating keratoplasty (PKP)--the half-top-hat (HTH) configuration.

The donor corneal button was prepared in a top-hat configuration, as previously described. It consisted of a central, full-thickness part, 7-8 mm in diameter, surrounded by a peripheral lamellar wing of deep stroma and endothelium that was 0.5 mm in width (wing diameter 8-9 mm). The recipient bed was prepared by a straight full thickness trephination with a suction trephine. The donor button was positioned by sliding the peripheral wing under the recipient bed. Sixteen 10-0 interrupted sutures and a single continuous 16-bite 11-0 nylon sutures were placed. The interrupted sutures were passed so as to go through the wing, in order to ensure a good apposition of the wing to the inner corneal surface of the recipient. Anterior segment optical coherence tomography (Visante OCT) was used to image the position and alignment of the corneal graft postoperatively.

Ten eyes of 10 patients (mean (SD) age: 73.7 (11.4) years, 7 females) underwent HTH PKP. The donor lenticule diameter was 7.7 (0.3) mm (wing diameter 8.7 (0.3) mm). The mean follow-up time was 2.4 (0.7) months. The last median visual acuity was 20/200 (range 20/80-counting fingers), and the last IOP was 18.2 (8.8) mm Hg. No major intraoperative complications were noted. No postoperative events of graft rejection were documented. No anterior surface misalignment was noted either clinically or by OCT. One patient had a rise in IOP postoperatively.

Half-top-hat wound configuration is a valid alternative in penetrating keratoplasty. Its advantages include better apposition of donor and recipient corneas, improved tectonic strength to prevent graft dehiscence, the possibility of early sutures removal and being a simpler procedure to perform.