The F-Sign Technique for Human Amniotic Membrane Orientation During Vitreoretinal Surgery

To describe a simple, reproducible marking technique to confirm correct epithelial orientation of human amniotic membrane (hAM) during subretinal implantation in complex vitreoretinal surgery for massive subretinal hemorrhage.

A single-surgeon case report of a patient with massive subretinal hemorrhage managed by 23-gauge pars plana vitrectomy, retinal turnover, and subretinal hAM implantation. Prior to intraocular insertion, an "F" letter mark was applied to the epithelial surface of the graft using gentian violet dye, enabling unambiguous identification of membrane orientation throughout folding and intraocular delivery.

The gentian violet "F" mark remained clearly visible at each surgical step - forceps insertion and subretinal placement - enabling immediate confirmation of graft orientation and correct apposition of the stromal surface against the retinal pigment epithelium. No intraoperative complications related to the dye were observed. Postoperative optical coherence tomography (OCT) confirmed anatomically correct graft positioning, stable retinal reattachment, and progressive improvement in best-corrected visual acuity (BCVA).

Gentian violet "F" marking of the hAM epithelial surface is a straightforward, safe, and reproducible adjunct for orientation verification in complex vitreoretinal surgery, where tissue transparency and repeated intraocular manipulation pose a significant risk of incorrect graft placement.