The Boston keratoprosthesis in herpetic keratitis.

OBJECTIVE: To evaluate the role of an artificial cornea (Boston Keratoprosthesis [KPro]) in herpetic corneal graft failures. METHODS: A series of 17 herpetic eyes of 14 patients with failed transplantations, treated with implantation of a corneal graft with a KPro, was reviewed. Outcomes measured were retention of the device, visual acuity at 1 week, best visual acuity, last assessed visual acuity, time of follow-up, and complications. RESULTS: Follow-up ranged between 6 and 72 months (median, 14 months). All patients had improvement in postoperative visual acuity, with 16 (94%) of 17 eyes getting better than preoperative visual acuity within 1 week. Of the 17 eyes, 15 (88%) achieved a best visual acuity of 20/25 to 20/70 and, at the last examination, 11 eyes (73%) were still in that range. Four patients with prolonged preoperative inflammation and ulceration at KPro placement had resolution of inflammation within days. The KPro had no extrusions. Complications included retroprosthesis membrane in 3 eyes and 1 tissue melt in an early case. CONCLUSIONS: The KPro can be of value in patients with graft failure from herpetic keratitis, even in the inflamed stage. We believe that herpetic keratitis is not a contraindication for KPro use.

Importance of nutrition to corneal grafts when used as a carrier of the Boston Keratoprosthesis.

PURPOSE: Necrosis, melt, and perforation have historically been frequent around a Keratoprosthesis (KPro), even resulting in extrusion or endophthalmitis. Autoimmune diseases such as Stevens-Johnson Syndrome (SJS) and Ocular Cicatricial Pemphigoid (OCP) have been notorious in this respect. The purpose of this study was to compare the frequency of tissue melt after implantation of two designs of the Boston KPro, one allowing much better access of nutrition from the aqueous humor to the carrier graft. METHODS: We retrospectively reviewed charts of 157 eyes implanted since 1990 with a poly (methylmethacrylate) Boston KPro, including 79 eyes implanted with the model having 8 small (1.3-mm diameter) holes in the back plate, and 78 eyes implanted with the older solid back plate. We compared the frequency of tissue melts between the two KPro designs, for all implants as well as for subgroups based on preoperative diagnosis. RESULTS: In total, 48/157 eyes (31%) developed some degree of tissue melt around the stem, including 8/79 eyes (10%) in the back plate with holes group and 40/78 eyes (51%) in the solid back plate group (P < 0.0001). Among the melts in the back plate with holes group, 4/8 (50%) suffered from an underlying autoimmune disease such as SJS or OCP. CONCLUSIONS: The Boston KPro design with a back plate containing holes protects the overlying corneal tissue from necrosis and melts. This improved situation is likely due to increased aqueous access and better nutrition to the corneal graft cells. In addition, this study confirms earlier work regarding the particular corneal fragility of patients with autoimmune diseases.

Protection of the ocular surface after keratoprosthesis surgery: the role of soft contact lenses.

PURPOSE: To evaluate the short-term therapeutic value of soft contact lenses in patients with keratoprosthesis. METHODS: Nineteen patients with a collar button-shaped keratoprosthesis were fitted with a soft contract lens and evaluated for the protective effect on the surrounding cornea. RESULTS: The lenses were found to be highly protective against evaporative damage to the corneal surface around the device. They were well tolerated and could remain clean and in place for months. One infection occurred. CONCLUSION: A soft contact lens can be of considerable protective value to the cornea surrounding a keratoprosthesis.

Management of vitreoretinal complications in eyes with permanent keratoprosthesis.

OBJECTIVES: To evaluate the spectrum and treatment of posterior segment complications in eyes that had undergone successful keratoprosthesis (KPro) placement and to determine whether transeyelid vitrectomy techniques could be effectively used in eyes otherwise vulnerable to surface exposure. DESIGN: In the last 10 years, 110 patients received a Dohlman-Doane KPro at the Massachusetts Eye and Ear Infirmary, Boston. We evaluated 22 eyes in 18 patients that required subsequent vitreoretinal surgery to treat posterior segment complications. One surgeon using modified vitreoretinal techniques, as described below, performed all vitreoretinal procedures. RESULTS: The posterior segment complications included 6 cases of retro-KPro membranes, 13 cases of retinal detachments, and 5 cases of isolated vitreous opacity. All 6 retro-KPro membranes were effectively removed by vitrectomy without significant complication and 3 of these patients enjoyed improvement of visual acuity of at least 5 Snellen lines. Of 13 cases of retinal detachment, 6 patients had some improvement in visual acuity, 5 showed no appreciable change, and 2 had some decline in the final visual acuity. In all 5 cases of isolated vitreous opacity, the media was effectively cleared with pars plana vitrectomy. Three patients enjoyed improvement of visual acuity of at least 3 Snellen lines. Four cases of transeyelid vitrectomy were attempted and anatomical success was achieved in all 4 and vision improved in 3 of these patients. No special surgical complications were encountered in any of the 22 eyes as a result of these modified surgical techniques. MAIN OUTCOME MEASURES: Best preoperative and postoperative visual acuity and anatomical success were evaluated in relation to the preoperative posterior segment complication. CONCLUSIONS: Modified vitreoretinal surgical techniques can be effectively and safely used to treat posterior segment complications in patients with KPro devices. Retro-KPro membranes and other vitreous opacities were the most amenable to treatment. Retinal complications posed a special challenge. However, all of these cases highlight that modified vitrectomy techniques can be used in eyes with permanent KPro devices. These techniques can be performed without additional risk to the eye. Additionally, we demonstrated that transeyelid vitrectomy techniques could be used effectively to manage complications in eyes with severe ocular surface disease without undue exposure of vulnerable tissues.