[A multicenter clinical trial of collar-button type keratoprosthesis implantation for the treatment of corneal blindness in high-risk transplantation].

Objective: To evaluate the efficiency and safety of collar-button type keratoprosthesis (c-bKPro) implantation for corneal blindness in high-risk transplantation in China. Methods: It was a case series study. High-risk corneal blind patients who planned to undergo c-bKPro implantation were prospectively and continuously enrolled in the Eye Hospital of Shandong First Medical University, Ophthalmology Division of Chinese PLA General Hospital, Zhongshan Ophthalmic Center , Department of Ophthalmology in Eye & ENT Hospital of Fudan University, and Eye Hospital of Wenzhou Medical University from July 2019 to January 2020. The cure for blindness and surgical success were assessed based on visual acuity (VA)≥0.05. The complications and keratoprosthesis retention rate were recorded to determine the safety of the surgery. Results: Thirty-seven subjects (eyes) were included, of which 32 were male and 5 were female, aged 27 to 72 years old. The indications of c-bKPro implantation were corneal graft failure (21 eyes, 56.8%), chemical injury (8 eyes, 21.6%), thermal burn (5 eyes, 13.5%), unexplained corneal opacity (2 eyes, 5.4%), and corneal perforation (1 eye, 2.7%). Two patients withdrew from the clinical trial at 3 months postoperatively. Thirty-five patients were followed up for 6 months, and 31 were followed up for 12 months. The VA was ≥0.05 in 83.8% of eyes at 6 months and in 81.8% of eyes at 12 months. Among the 11 eyes diagnosed with concurrent glaucoma, 6 eyes achieved a VA of ≥0.05. At 12 months, the c-bKPro retention rate was 100%. The surgical complications included retroprosthetic membrane formation (5 eyes, 16.1%), persistent corneal epithelial defects (5 eyes, 16.1%), macular edema (4 eyes, 12.9%), new-onset glaucoma (4 eyes, 12.5%; including one eye withdrawn from the study at 3 months), sterile corneal melting (2 eyes, 6.5%), sterile vitritis (1 eye, 3.2%), and infectious keratitis (1 eye, 3.2%). Conclusions: C-bKPro implantation is an effective and safe option for treating corneal blindness in high-risk transplantation in China. Improved visual outcomes could be achieved in most cases, with a relatively low incidence of postoperative complications.