Sir,

Skin retraction around optic stem of type-II Boston keratoprosthesis is a common complication. Left unchecked, the condition can progress and lead to infection, extrusion, and perforation. Correction often requires multiple skin revisions, including advancement or even ‘bucket-handle’ skin flaps and rarely even replacement of the keratoprosthesis. We describe the outcomes of repair in two cases using a forehead pericranial flap.

Case reports

Two patients underwent type-II keratoprosthesis insertion. Within few months, multiple skin advancement procedures were required because of skin retractions. Subsequently, they underwent a forehead pericranial flap procedure (below). Following this, they developed recurrent skin migration over the optic (Figure 1) requiring skin trephinations with skin biopsy punch, but this did not halt its recurrence. Further, 3-mm excision of skin around the stem, with suturing of skin edges to deeper tissue, arrested recurrences.

Figure 1
figure 1

Preoperative and postoperative pictures of both patients with skin retraction.

Full size image

The length of the forehead pericranial flap was measured as the distance between glabellar skin-crease and keratoprosthesis stem. A vertical incision involving skin, subcutaneous tissue, and galeal layer was created (Figure 2a). The keratoprosthesis was covered by wet gauze to avoid light-induced maculopathy (Figures 2b-d). Length of the required flap was estimated by using length of gauze fixed at the base of the flap pedicle and rotated between the vertical position and that required to bridge the defect.1 The outline flap was incised and peeled off the bone (Figure 2d). The flap was flipped so that periosteal surface faced the undersurface of the skin flap and passed through a sub-orbicularis tunnel using artery forceps through to the keratoprosthesis stem (Figure 2e). Eyelid skin was dissected from the keratoprosthesis stem to expose the area to be covered with flap (Figure 2f). The flap was trimmed to fit the exposed area (Figure 2g). The flap was sutured to the subcutaneous tissue using interrupted 6/0 vicryl mattress sutures. A small slit opening was fashioned in the flap for the stem of keratoprosthesis (Figures 2g and h). The forehead wound was closed in layers.

Figure 2
figure 2

Surgical technique. (a) Incision site marked in vertical, paramedian, glabellar skin-crease. (b) Incision deep to pericranium. Forehead incision with no. 15 Bard Parker blade (Swann-Morton, Sheffield, UK). (c) Desired flap size measured before dissection of the pericranial flap. (d) Flap fashioned with no. 15 Bard Parker blade and lifted from bone using a periosteal elevator, avoiding damage to the base. (e) Flap passed via subcutaneous dissection between flap base and medial canthus, preserving medial canthal tendon. (f) Flap pulled through over the keratoprosthesis optic. (g) Keratoprosthesis optic dissected proud through the flap. (h) Flap fixed to subcutaneous cut edges of the eyelid using 6.0 vicryl sutures.

Full size image

Comment

Patel et al2 described use of pericranial flaps in patients with lower eyelid cicatricial malposition. The vascularity and robustness of this flap lends itself to support bone or cartilage grafts in the skull and face;3, 4 closure of skull base and orbital defects;5, 6 sinus obliteration and fistula closure;7 support of free skin grafts;2 and soft-tissue augmentation.2, 8

The success of this technique in the above cases relates to high vascularity, thickness and strength of the pericranial tissue. Because the tissue surrounding optic stem is thickened and elevated in the early postoperative period, there is a tendency for the optic to lie flush with the periosteum and allow skin to overgrowth. Patients must therefore be counselled about the need for repeated skin removal, and a wider excision of tissue may be required. Based on these findings, we suggest a pericranial flap could be considered to cover the keratoprosthesis at an early stage in cases where vascularity around the skin is of concern. This is an excellent option where repeated skin revisions have failed to achieve a solution to recurrent skin retractions.