Long-term outcomes of Boston typeIkeratoprosthesis for Chinese severe corneal blindness

Abstract

Background Corneal blindness is associated with the change of corneal structure, and conventional keratoplasty cannot regain vision in these eyes.Keratoprosthesis is well used for patients unsuitable for standard keratoplasty.Boston type Ⅰ keratoprosthesis is one of the most commonly employed in the world, but it has not been well used in China. Objective This study was to evaluate the long-term outcome and safety of Boston type Ⅰ keratoprosthesis in China. Methods A pilot study was carried out for a descriptive prospective clinical trial under the approval of Ethic Committee of Henan Provincial People's Hospital and Henan Eye Institute.Sixteen eyes of 15 patients with severe corneal blindness which were not suitable for usual management were recruited, with the gender being males and ages of (50.4±13.0) years.The causes of blindness included thermal and chemical injury in 8 eyes of 7 patients, herpes simplex keratitis in 3 eyes of 3 patients, Stevens-Johnson syndrome in 1 eye of 1 patient, mechanical trauma in 2 eyes of 2 patients and infectious keratitis in 2 eyes of 2 patients.Fourteen of the 16 eyes received therapeutic keratoplasty once or more before, and 7 eyes had glaucoma history, pseudophakia was in 5 eyes and aphakia was in 4 eyes.The best corrected visual acuity (BCVA) is 0.05 in 1 eye, finger counting in 7 eyes and hand motion in 8 eyes.Implantation of Boston type Ⅰ keratoprosthesis was performed on the 16 eyes and followed-up for (47.5±23.8) months (ranged from 19 throughout 84 months) after obtaining of written informed consent from each patient.The postoperative BCVA, postoperative complication and eye numbers of keratoprosthesis in site were recorded. Results The surgeries of Boston type Ⅰ keratoprosthesis or combination procedures, such as lens or intraocular lens (IOL) extraction, iridectomy, cyclitic membrane removal and vitrectomy were successful in all the eyes.One month after surgery, the postoperative BCVA was obviously improved in 14 eyes, with the BCVA≥1.0 in 3 eyes, 0.5≤BCVA<1.0 in 4 eyes and 0.1≤BCVA<0.5 in 7 eyes, the vision was unchanged in 2 eyes due to end-stage glaucoma before operation.BCVA remained ≥0.1 in 9 eyes at the end of following-up duration.Postoperative complications included retromembrane proliferation in 7 eyes, corneal melting in 6 eyes and glaucoma in 4 eyes.Severe postoperative complications were fungal keratitis, endophthalmitis and device extrusion respectively and keratoprosthesis prolapse, so penetrating keratoplasty was carried out to replace the keratoprosthesis.Implanted Boston type Ⅰ keratoprosthesis was in site in 13 eyes at the end of following-up. Conclusions The Boston typeⅠkeratoprosthesis might be a viable method to provide visual recovery for the eyes with severe corneal blindness unsuitable for standard keratoplasty.It is mandatory for long-term follow-up and prevention and management of postoperative complications. Key words: Corneal transplantation; Corneal diseases/surgery; Prosthesis implantation; Treatment outcome; Postoperative complications; Visual acuity; Chinese; Prospective studies