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Corneal melt after keratoprosthesis managed with graft, amniotic membrane transplantation
Punctal occlusion of the upper and lower eyelids and a lateral tarsorrhaphy complete the procedure.
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 Thomas John |
Bacterial adherence to ocular prosthetic devices has been well established in the ophthalmic literature, and any exposure of intracorneal prosthetic devices to the ocular surface should be permanently covered with tissue to deny bacterial access. Bacterial adherence and colonization of an intracorneal device can lead to infectious keratitis, corneal ulceration, corneal perforation and even endophthalmitis, which can result in loss of vision and loss of the eye. Additionally, any bacterial biofilm that may develop in the infectious site may inhibit antibiotic penetration, thus rendering the antibiotic ineffective.
In this column, I describe the surgical management of an exposed Boston keratoprosthesis secondary to recurrent corneal melt.
Case background
Figure 1 displays intraoperative full-field and slit lamp photographs (surgeon’s view) displaying extensive, recurrent corneal melt with a negative Seidel test. The initial corneal melt with keratoprosthesis plate exposure required an anterior lamellar keratoplasty to completely cover the exposed plate with an overlay amniotic membrane transplantation. This initial surgical procedure corrected the problem of prosthetic device exposure. Additionally, the corneal lamellar graft blended well with the surrounding cornea and ocular surface. However, this initial surgical procedure did not resolve the problem long term. The patient experienced a recurrent corneal melt with keratoprosthesis plate exposure and discomfort.
 Figure 1. Intraoperative full-field and slit lamp photographs displaying extensive, recurrent corneal melt with a negative Seidel test. Patient had a Boston keratoprosthesis without any complications and had a corneal melt 2 years following surgery. Corneal melt with plate exposure required an anterior lamellar keratoplasty with amniotic membrane transplantation. Patient experienced a recurrent corneal melt as shown in these intraoperative photographs. Images: John T
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Surgical technique
The dimensions of tissue loss should be quantitated (Figure 2) using surgical calipers in order to fashion the donor scleral graft tissue in an appropriate size to cover the exposed keratoprosthesis plate. Because the patient had a previous lamellar corneal graft in this region along with amniotic membrane transplantation, the area should be exposed and any tissue remnants removed (Figure 3).
The donor scleral graft is then cut to the required size to cover the plate of the Boston keratoprosthesis. The margins of the scleral graft should be beveled (Figure 4) to prevent a scleral step at the tissue margins. The scleral graft is first fixed in position using a few interrupted 9-0 nylon sutures.
 Figure 2. The area of corneal melt measured 8 mm × 4.5 mm. This measurement helps in designing the scleral graft. |
 Figure 3. The previous lamellar tissue that has melted is visible. The corneal lamellar remnants are removed. |
 Figure 4. The donor scleral graft tissue is fashioned to cover the area of recurrent corneal melt and the keratoprosthesis plate. The edges of the scleral graft are trimmed such that there is a smooth blending of the donor tissue to the ocular surface without any scleral step. |
 Figure 5. The donor scleral graft is attached to the recipient ocular surface with fibrin glue and 9-0 interrupted nylon sutures. |
 Figure 6. Amniotic membrane graft covers the scleral graft and is anchored with fibrin glue and a few interrupted 10-0 Vicryl sutures. |
 Figure 7. A second layer of amniotic membrane is placed to cover the entire cornea, scleral graft and the adjacent ocular surface. It is attached with fibrin glue. |
 Figure 8. The conjunctiva is mobilized after making relaxing incisions, and a conjunctival flap is created to cover the scleral graft and the footplate of the keratoprosthesis. An additional layer of amniotic membrane covers the conjunctival flap and the ocular surface. |
 Figure 9. Punctal occlusion of the upper and lower eyelids and a lateral tarsorrhaphy complete the surgical procedure. |
This is followed by attaching the scleral graft to the underlying ocular surface, keratoprosthesis plate and the melted cornea with fibrin tissue adhesive and ironing with a muscle hook. The superior margin of the scleral graft is tucked beneath the front plate of the Boston keratoprosthesis (Figure 5). Additional interrupted sutures are used as needed. The scleral graft is then covered with amniotic membrane graft and attached to the scleral graft with fibrin tissue adhesive and a few 10-0 Vicryl sutures (Figure 6). A second layer of amniotic membrane covers the scleral graft, keratoprosthesis and the surrounding ocular surface (Figure 7) and is attached with fibrin glue.
Following the scleral graft and the amniotic membrane transplantation, an additional layer of protective covering is offered by using the conjunctiva to create a conjunctival flap to cover this region (Figure 8). Relaxing incisions on the conjunctival tissue with additional blunt and sharp dissections allow adequate mobilization of the conjunctival tissue to cover the scleral graft and the overlying amniotic membranes. It is important to adequately mobilize the conjunctiva so that there are no forces that may subsequently contribute to tissue retraction and scleral graft exposure.
Next, a final layer of amniotic membrane covers the entire ocular surface. Amniotic membrane graft provides both mechanical coverage and anti-inflammatory effects and contributes to tissue healing and patient comfort. Lastly, punctal occlusion of the upper and lower eyelids and a lateral tarsorrhaphy complete this surgical procedure (Figure 9).
Such extensive surgical steps, with the use of donor scleral tissue and amniotic membrane, will help provide adequate coverage of the exposed keratoprosthesis plate, promote healing in the region and prevent access to potential bacteria that can otherwise threaten vision and the globe.
References:
- Cho BJ, Kwon JW, Han YK, Kim JH, Wee WR, Lee JH. Cosmetic improvement of nevus of Ota by scleral allograft overlay. Can J Ophthalmol. 2011;46(5):428-430.
- Mancino R, Aiello F, Ceccarelli S, et al. Autologous conjunctival epithelium transplantation and scleral patch graft for postlensectomy wound leakage in Marfan syndrome [published online ahead of print Feb. 17, 2012]. Eur J Ophthalmol. doi:10.5301/ejo.5000124.
- Mehendale RA, Dagi LR. Amniotic membrane implantation to reduce extraocular muscle adhesions to a titanium implant. J AAPOS. 2011;15(4):404-406.
For more information:
- Thomas John, MD, OSN Cornea/External Disease Board Member and OSN Surgical Maneuvers Editor, is a clinical associate professor at Loyola University at Chicago and in private practice in Oak Brook, Tinley Park and Oak Lawn, Ill. He can be reached at 708-429-2223; fax: 708-429-2226; email: tjcornea@gmail.com.
- Disclosure: Dr. John has no relevant financial disclosures.