Special considerations for pars plana tube-shunt placement in Boston type 1 keratoprosthesis

The Boston type 1 keratoprosthesis has been successfully used in eyes with a poor prognosis for a conventional penetrating keratoplasty. The Boston Type 1 Keratoprosthesis Study Group reported significant postoperative vision improvement with a high rate of graft retention. However, glaucoma has significantly limited visual potential in patients with otherwise successful transplants. Given a crowded anterior chamber, scarring, and/or inability to visualize the anterior segment after the keratoprosthesis implantation, vitrectomy and pars plana tube placement is frequently necessary for intraocular pressure control. In addition, the need for optimal contact lens fitting after surgery necessitates a modified surgical technique for the combined procedure to avoid complications and to achieve optimal visual rehabilitation. We present our technique in a case series of combined vitrectomy and pars plana glaucoma shunt placement for the Boston type 1 keratoprosthesis.