The current study shows the advantage of a pars plana approach such as PPV combined with PKP. All procedures were performed without complications. Under a wide-viewing system, PPV could be completed without the use of an artificial cornea. Any residual vitreous following PPV could be removed with the shaving technique. Without treatment these patients with complex needs may have gone blind, but following the combined surgery, the visual function of the patients significantly improved, and the mid-term survival rates were excellent. There were no cases of retinal detachment following surgery. Despite the improvement in corneal transparency and visual recovery, the requirement for additional glaucoma surgeries was relatively high. Patients may have a better quality of life if IOL implantation and PKP are performed simultaneously.
There are three suggestions regarding the importance and the efficacy of the posterior approach during PKP: First, the prevention of retinal detachment (including proliferative vitreous retinopathy) is very important. An iris defect, or aphakia with vitreous prolapse, often accompanies complex cases following an injury that requires iris repair and IOL scleral fixation (or suture) combined with PKP. It seems appropriate for anterior segment surgeons to perform PPV due to the increased risk of retinal detachment following an incomplete vitrectomy such as anterior vitrectomy in posterior capsule rupture, or IOL suture. If there is a complication in the posterior segment during PPV, such as a retinal break, it can be rapidly responded to.
Second, the posterior approach in simple cases could be performed without difficulty. Since our case series did not include severe corneal opacity, all procedures could be performed with a wide-viewing system (without any artificial corneas such as Eckardt temporary keratoprosthesis). The use of PPV with a temporary keratoprosthesis has been reported. Yokogawa et al. published a report on the combined treatment of PKP, or DSAEK using an artificial cornea.[8, 15, 16] In our experience, we had no trouble performing a simple PPV including the creation of a posterior vitreous detachment, and shaving of the peripheral vitreous body.
Third, the technical difficulty of PKP in the post-vitrectomized eye could be reduced. During surgery, a globe rupture could be easily repaired using a posterior infusion. In cases of globe rupture, the shape of the eye can be repaired, and a suture placed once the situation is stable. The suture procedure would be easier without a posterior infusion.
The results of this study show that the combined procedure of PKP, PPV, and IOL-suture could be a safe and effective approach for patients requiring anterior segment surgery. Despite the increasing number of scleral fixations, in the present study the preferred method was an IOL-suture.
There were limitations to this study, such as the relatively small number of participants, differing aetiologies, and different treatment protocols. Despite the success of the procedure, cases required glaucoma surgery. Two cases required an Ahmed valve, one needed a Baerveldt implant, and one case needed filtrating surgery (trabeculectomy) after PKP. One case was treated with a simultaneous glaucoma implant, (Baerveldt) PKP, PPV, and IOL-suture surgery. According to past reports, the combined surgery of PKP and Ahmed valve implantation had a negative impact on the graft survival. However, in the present study, the glaucoma shunt tubes were placed into the pars plana, because tube implantation to the pars plana has been shown to result in better corneal graft survival rates and reduce complications compared with implantation into the anterior chamber.[25–29] Since the type of glaucoma surgery was selected according to either the patient’s condition or the glaucoma surgeon’s preference, only one case was treated by trabeculectomy. In the future, long-term studies regarding the correlation between glaucoma surgery and keratoplasty will be necessary for further development.