Aniridic keratopathy develops from limbal stem cell deficiency. Early epitheliopathy and conjunctivalization of the corneal surface starts peripherally and advances centrally with development of subepithelial fibrosis and stromal scarring in later stages. Before the development of significant corneal opacity, keratolimbal allograft or other limbal transplantation procedures can be attempted alone without a penetrating procedure to reverse the keratopathy. However, if the patient has advanced aniridic keratopathy as in our case, a penetrating procedure will be required. In this patient, there are two options: limbal stem cell transplantation followed by corneal transplantation or keratoprosthesis placement.

Holland et al. evaluated the success of keratolimbal allograft (KLAL) in aniridia and found that 74.2% of eyes achieved a stable ocular surface and 70% of subsequent penetrating keratoplasties (PKP) remained clear during the study period (mean follow-up 35 months). Long-term immunosuppression was required to improve the odds of maintaining a stable ocular surface [1]. The most likely cause of late failure is graft rejection which argues in favor of continuing immunosuppression beyond the first 2 years. Systemic immunosuppression with a combination of medications, often with cyclosporine/tacrolimus, azathioprine/mycophenolate, and oral prednisone, is required to reduce the risk of limbal graft rejection. Patients taking these medications should be monitored for toxicity, as discussed elsewhere in this book.

In recent years, the Boston keratoprosthesis has become an increasingly accepted option with the advantage of avoiding systemic immunosuppression and faster visual rehabilitation. Studies reporting outcomes of Boston KPro implantation in aniridics with follow-up of 17–28 months on average report visual improvement in 65–94% of patients. However, these patients need to be monitored for unique complications that can be seen after KPro implantation, including retroprosthetic membrane (RPM) formation, melting, worsening glaucoma, infectious keratitis, and device extrusion [2–4]. Although in traditional cases KPro implantation was considered after failure of prior grafts, in these patients KPro placement may be considered as the primary penetrating procedure in advanced keratopathy with or without prior failed KLAL.

Our approach to aniridic patients with limbal stem cell deficiency is as follows: In cases where the disease is limited to the epithelium and there is minimal to no stromal or endothelial disease, limbal transplantation, which is a non-penetrating procedure, is considered first-line treatment (assuming the patient is a good candidate for immunosuppression). Otherwise, when there is coexisting endothelial disease and/or history of previous graft failure, then KPro may be a preferred option given that the success rate with limbal transplant may be lower. If performing cataract surgery at the time of KPro in aniridic patients, we typically prefer to leave the patient aphakic and use an aphakic KPro given that these patients have a higher likelihood of having zonular instability.

After discussion with the patient, it was decided to proceed with Boston type 1 keratoprosthesis placement in the right eye. Her cataract was removed at the time of surgery and an aphakic KPro was placed. Postoperatively, she was treated with topical antibiotics (gatifloxacin) which was maintained at TID for prophylaxis. A 16.0 mm Kontur bandage contact lens was also placed (changed every 2 months). At postop week 2, she had 20/80 vision but at month 1 had started to develop an RPM with decrease in vision to 20/100 (Fig. 22.2). A YAG membranectomy was performed approximately 5 months postoperatively. The vision improved, but approximately 2 months later, the patient was noted to have circumferential melting around the KPro optic. It was noted that the holes of the KPro backplate were filled with RPM tissue although the optic remained clear.

It has been demonstrated that retro-backplate membranes may be a risk factor for corneal melting , possibly secondary to the impedance of aqueous providing nutritional support to the cornea. In a retrospective study, 100% of eyes that melted had evidence of retro-backplate membrane vs. 34% of eyes that did not melt. In addition, the retro-backplate membrane was thicker in the group that melted [5]. To compound this, patients with aniridia are likely to have an unstable ocular surface that may exacerbate the problem. Although this patient did not have any conjunctival disease, patients with conjunctival deficiency (Stevens-Johnson syndrome and mucous membrane pemphigoid) also appear to have a significantly greater risk of developing a melt after KPro [6].

The patient recovered well postoperatively but was noted to develop recurrent RPM which required YAG membranectomy approximately 4 months later. She began to develop increased intraocular pressures and was referred to the glaucoma service. Ultimately her IOP was uncontrolled with drops and oral medication, and she had a pars plana Baerveldt shunt placement approximately 10 months following the KPro replacement. Throughout her clinical course, she had episodes of persistent inflammation postoperatively and intermittent episodes of episcleritis related to her Baerveldt plate (Fig. 22.3 ), which at times required frequent topical prednisolone or oral steroids. Approximately 2.5 years after KPro replacement, she was found to have recurrent melting around the KPro optic again associated with a very thick retro-backplate RPM.

This patient has recurrent RPM formation, ocular surface inflammation, and most problematic, recurrent corneal melting likely stemming from these issues. Aniridia has been found to be an independent risk factor for RPM formation , although whether this is due to chronic inflammation or another mechanism remains unclear [7]. To our knowledge there is no literature regarding systemic immunosuppression in KPro patients ; however, due to this patient’s propensity to developing RPM and episodes of ocular inflammation, it was felt that decreasing inflammation could stabilize her ocular surface and perhaps prevent RPM formation. There is some data suggesting that systemic immunosuppression is useful and well tolerated in patients with multiple traditional grafts [8–10]. In addition, a replacement KPro was needed given the amount of melting around the KPro optic.

Patients with aniridia should be monitored carefully after KPro placement , and complications managed promptly. Although melting and device extrusion increases morbidity, prompt treatment including replacement of KPro if necessary usually results in return to baseline vision.

E.H. is a 41-year-old male who presented approximately 1 month after a chemical burn. He had sustained a workplace accident of anhydrous ammonia to both eyes, right greater than left. His eyes were flushed immediately afterward. While the left eye had mostly recovered, the right eye continued to have decreased vision, pain, and light sensitivity. On examination, he was counting fingers at 3–4 feet in the right eye and 20/25 in the left eye. He was noted to have superior and temporal ischemia, an epithelial defect covering most of the cornea as well as surrounding conjunctiva, edematous cornea, and cataract (Fig. 22.4 ). The left eye appeared normal. On presentation he was on ciprofloxacin four times a day, atropine once a day, and prednisolone acetate 1% every 2 h, all in the right eye. Over the next 9 months, he was managed with topical corticosteroids, oral corticosteroids, oral vitamin C, punctal plugs, amniotic membrane, and bandage contact lenses. Scleral lenses were attempted but with poor fit. He continued to have a persistent epithelial defect with decrease in vision to light perception. In addition, his intraocular pressure increased 4 months after presentation, necessitating maximal medical therapy and diode cyclophotocoagulation to achieve IOP control. Nine months following presentation, the patient had still a nearly complete epithelial defect of his cornea despite multiple treatment strategies attempted.