Boston type I keratoprosthesis assisted with intraprosthetic amniotic membrane (AmniotiKPro sandwich technique).

Abstract

Corneal melting remains a feared complication in patients with baseline inflammatory pathology (i.e. ocular burns, ocular cicatricial pemphigoid) and Boston type 1 keratoprosthesis (KPro) (Utine et al. 2011; Magalhães et al. 2013). Endophthalmitis is another issue related to KPro, having an incidence in the range of up to 17% according to international reports (Behlau et al. 2014). In this clinical scenario, patients may benefit from the concurrent use of anti-inflammatory and antiangiogenic factors. We report two cases with severe ocular surface inflammation and corneal blindness that were managed with a novel technique. Case 1. An 88-year-old man with history of rosacea presented with a 6-month history of decreased visual acuity and pain of the left eye. On examination, visual acuity was 20/100 in the right eye and light perception in the left; the cornea in the right eye showed stromal vascularization and generalized opacification. The left cornea showed central melting and a 2-mm central perforation. Corneal glueing with cyanocrylate was performed (Fig. 1A). The decision for Boston type 1 KPro assisted with an intraprosthetic amniotic membrane was made. Donor cornea is trephined using a Barron donor cornea punch 8.75 mm, and a 3.0-mm central trephination is made using a manual punch. Next, the front plate with stem is fixated downwards, and a cryopreserved amniotic membrane disc is positioned directly beneath the front plate. The donor cornea is placed after, creating a ‘sandwich’ between the front plate, the amniotic membrane disc and the donor cornea. The rest of the procedure followed without modifications. At postoperative day one, the KPro was in place and the amniotic membrane well attached (Fig. 1B). Visual acuity was 20/80 and Visante optical coherence tomography (OCT) shows the intraprosthetic amniotic membrane attached and filling the virtual space between the donor cornea and the anterior plate (Fig. 1C). Case 2. A 35-year-old man with previous history of sulphuric acid injury in both eyes and bilateral therapeutic penetrating keratoplasty 6 years ago came to our service. Visual acuity was light perception on both eyes. Biomicroscopic findings were notable for conjunctival hyperaemia and complete corneal conjunctivalization and opaque corneal grafts in both eyes (Fig. 1D). We performed the same surgical procedure to the left eye as for the case described previously. At day one, the patient showed a good postoperative appearance (Fig. 1E) and the visual acuity was 20/60. Anterior segment OCT reveals the intraprosthetic amniotic membrane attached (Fig. 1F). Four months later, the amniotic membrane is fully biointegrated, with no signs of lysis or epithelial defects (Fig. 1G). The visual acuity remains 20/60 and the OCT reveals no virtual space where the amniotic membrane used to be (Fig. 1H). The rationale for the intraprosthetic use of amniotic membrane in KPro is to ameliorate the postoperative inflammatory response, metalloproteinase activity and to promote the epithelization of the donor cornea in an ocular surface with an underlying severe inflammatory activity. Amniotic membrane has shown to be effective as a biological bandage, as a substrate for re-epithelization, as a suppressor of inflammation and as an inhibitor of scarring and angiogenesis (Hao et al. 2000). Organisms may have a path into the eye because of the potential space between the anterior plate and corneal stroma, which can lead to endophthalmitis (Kim et al. 2013). The amniotic membrane aims to reduce the gap between the optical stem and donor cornea. As far as we know, this is the first report of amniotic membrane with intraprosthetic placement for assistance of KPro implantation in the same surgical time.