Reply: A New Composite Eyeball-Periorbital Transplantation Model in Humans: An Anatomical Study in Preparation for Eyeball Transplantation

Sir: We thank Nidal F. AL Deek for his valuable comments on our recent publication.1 As mentioned, our study is the first report on the composite eyeball-periorbital graft that aims to address blindness. The most important challenge in whole-eye transplantation is ischemia time. Thus, in our study, we aimed to focus on vascularization of the allograft. As presented in the article, the periorbital area has robust interconnections between the internal and external carotid systems. The three main branches of the external carotid artery have connections with the ophthalmic artery (Table 1), and the ophthalmic artery collateral circulation allows for eye perfusion.2,3 In our model, we included the superficial temporal artery and the facial artery in the composite eyeball-periorbital transplantation flap. These arteries represent two of the main external carotid artery branches that have connections with the ophthalmic artery. Maxillary artery connections to the ophthalmic artery are provided by the middle meningeal artery, the infraorbital artery, and the sphenopalatine artery. Thus, we did not include the maxillary artery in the flap. Based on literature reports, ligation of the ophthalmic artery close to the internal carotid artery does not cause major ischemia to retinal perfusion, because retrograde perfusion of the central retinal artery is possible by means of the external carotid artery system.4Table 1.: Summary of the Branches of the Ophthalmic Artery and Their Anastomoses to the External Carotid ArteryThe composite eyeball-periorbital transplantation flap is composed of orbital content, periorbital soft tissues, and the orbital bony pyramid. To prevent iatrogenic damage to the connections between the external and internal carotid systems, to preserve the lacrimal secretion and drainage system, and to protect bony attachments of the extraocular muscles and canthal ligaments, we performed a box osteotomy. Box osteotomy is a technique frequently performed for mobilization of the whole bony orbit in cases of hypertelorism, and long-term results of box osteotomy did not show any complications related to bone resorption or bone perfusion.5 During orbital osteotomies, the periosteal attachments between orbit and periorbital soft tissues are preserved and periosteal circulation provides bone nutrition. To protect periosteal circulation, we avoided periosteal stripping. Neck and face dissections were performed in the sub–superficial musculoaponeurotic system plane to facilitate easy access to the vessels. When we reach the limits of the box osteotomy, the dissection plane is deepened on the subperiosteal level for osteotomies. In our model, besides the optic nerve, the first and second divisions of the trigeminal nerve and cranial nerves III, IV, and VI are included in the composite eyeball-periorbital transplantation flap. In addition, inclusion of related branches of the facial nerve (frontal and zygomatic) is important for orbicularis oculi function. Our model enables dissection and incorporation of these branches, which is straightforward and should be considered and included during cadaver mock transplantation studies of the composite eyeball-periorbital transplantation flap. The average dissection time for the composite eyeball-periorbital transplantation flap was approximately 360 minutes. The technique included both the intracranial and extracranial approaches, which extended dissection time. Specifically, the intracranial dissections and box osteotomy lengthen the procedure time during composite eyeball-periorbital transplantation flap harvest. The flap is dissected by one surgeon; however, certain parts of the operation can be performed by using a two-team approach, which will reduce the dissection time of the composite eyeball-periorbital transplantation flap. DISCLOSURE None of the authors has any commercial associations or financial disclosures that might pose a conflict of interest. Maria Siemionow, M.D., Ph.D., D.Sc.Department of Plastic and Reconstructive SurgeryCleveland ClinicCleveland, OhioDepartment of OrthopaedicsUniversity of Illinois at ChicagoChicago, lll. Mehmet Bozkurt, M.D.Department of Plastic and Reconstructive SurgeryCleveland ClinicCleveland, OhioDepartment of Plastic, Reconstructive, and Aesthetic SurgeryBagcilar Training and Research HospitalIstanbul, Turkey Fatih Zor, M.D.Yalcin Kulahci, M.D.Department of Plastic and Reconstructive SurgeryCleveland ClinicCleveland, OhioDepartment of Plastic SurgeryGulhane Military Medical AcademyAnkara, Turkey Safak Uygur, M.D.Department of Plastic and Reconstructive SurgeryCleveland ClinicCleveland, OhioDepartment of Orthopaedic SurgeryUniversity of IllinoisChicago, lll. Can Ozturk, M.D.Department of Plastic and Reconstructive SurgeryCleveland ClinicCleveland, OhioDepartment of Plastic, Reconstructive, and Aesthetic SurgeryRoswell Park Cancer InstituteBuffalo, N.Y. Risal Djohan, M.D.Frank Papay, M.D.Department of Plastic and Reconstructive SurgeryCleveland ClinicCleveland, Ohio