"Separate the Wheat from the Chaff" - Descemet's Stripping Endothelial Keratoplasty Graft Failure due to Accidental Implantation of Full-Thickness Precut Tissue.

We present an interesting case of failed Descemet's stripping endothelial keratoplasty (DSEK) graft, due to accidental implantation of a full-thickness precut tissue. A repeat DSEK was planned, and during the surgery along with the DSEK graft, an extra thick corneal tissue was also retrieved. Careful evaluation of both the explanted tissues revealed that the primary surgeon failed to separate a precut DSEK graft and implanted the entire full-thickness tissue. After the repeat DSEK, there was improvement in corneal edema and visual acuity. Copyright:

Introduction

Descemet's stripping endothelial keratoplasty (DSEK) is an established keratoplasty technique, which involves replacement of the diseased recipient's endothelium with the posterior stroma, Descemet's membrane, and endothelium of the donor tissue. DSEK graft can be prepared either manually or automatically using a microkeratome, in the operating room during surgery, or surgeon can use precut eye bank tissue.[1] Use of a graft prepared from the precut tissue has gained widespread acceptance as the outcomes are comparable to the grafts prepared during the surgery.[2]

We report an interesting case of failed DSEK graft, due to the implantation of a full-thickness precut tissue, by the primary surgeon.

Case Report

A 59-year-old female presented to us with the complaint of decrease in vision in the left eye (OS) for the last 1 year. She gave a history of combined DSEK and posterior chamber (PC) iris–claw implantation performed for the aphakic bullous keratopathy in the OS, a year ago, and did not notice improvement in her vision after the surgery.

On examination, her best-corrected visual acuity (BCVA) was 20/50 in the right eye (OD) and hand movements in OS. OD showed a central corneal nebular opacity, PC intraocular lens, and normal fundus examination. OS showed edematous cornea, vitreous in the anterior chamber (AC), and an inferiorly subluxated PC retropupillary iris–claw lens [Figure 1a]. B-scan ultrasound showed clear vitreous cavity and an attached retina. Anterior-segment optical coherence tomography (AS-OCT, Optovue, Inc., Fremont, CA, USA) of the OS showed a thick endothelial graft of 610 μ thickness and a central corneal thickness (CCT) of approximately 1400 μ [Figure 2a]. A diagnosis of failed DSEK graft was made in the OS, and a repeat DSEK was planned. Under peribulbar anesthesia, the superficial epithelium was scrapped to have clear operating view. Through the main incision, with the help of a reverse Sinskey, the previous DSEK graft was peeled and separated from the host cornea. After the removal of the old endothelial graft, the cornea failed to clear as expected, and hence, an attempt was made to remove any residual tissue. To our surprise, a second graft tissue could be extracted in toto with ease. Anterior vitrectomy was performed, and a posterior lenticule from a new precut DSEK tissue was placed on a sheets glide, after separating it from the anterior cap. After confirming the right orientation of the graft, with the push through technique, the graft was inserted into the AC and attached to the host cornea with the help of an air tamponade. After 15 min, partial decompression of the air was done, bandage contact lens was placed, and the patient was asked to lie supine for 24 h. Both the explanted corneal tissues were examined carefully, which showed clear edges with a regular surface, the larger graft being the anterior stromal cap, and the smaller graft being the endothelial graft [Figure 3]. Postoperatively, the patient was prescribed topical prednisolone acetate 1% and 0.5% moxifloxacin hourly.

Figure 1

(a) Preoperative diffuse slit-lamp photograph showing dense corneal edema and a failed Descemet's stripping endothelial keratoplasty graft. (b) Postoperative diffuse slit-lamp photograph showing a clear cornea after repeat Descemet's stripping endothelial keratoplasty and retropupillary iris claw intraocular lens

Figure 2

(a) Preoperative anterior-segment optical coherence tomography image showing corneal edema and Descemet's stripping endothelial keratoplasty graft edema and an increased corneal and graft thickness. (b) Postoperative anterior-segment optical coherence tomography image showing resolution of corneal edema and a well attached Descemet's stripping endothelial keratoplasty graft

Figure 3

Both the explanted corneal tissues, the larger graft is the anterior stromal cap and the smaller graft is the posterior lenticule

One-month postoperatively, BCVA improved to 20/80. Cornea and DSEK graft was clear Figure 1b, which was confirmed on the AS-OCT Figure 2b. The CCT measurement was 570 μ on AS-OCT.

At the last follow-up of 6 months, the patient has a clear graft with BCVA of 20/60, intraocular pressure (IOP) was 14 mmHg, and the fundus evaluation showed altered foveal contour.

Discussion

Selective transplantation of the posterior corneal lenticule in DSEK avoids the potential complications of penetrating keratoplasty, such as wound dehiscence, wound infections, and high postoperative astigmatism, and provides structural integrity to the recipient with a minimal change in the refraction and faster visual recovery.[3] Graft failure after DSEK has been reported in 4%–47% of the cases.[4] Primary graft failure could be due to the poor quality of donor tissue or excessive surgical manipulation. Secondary graft failure could be due to the progressive endothelial cell loss, graft rejection. and raised IOP.[5]

An important surgical step in DSEK is the donor tissue preparation. It can be done either manually, or with automated microkeratome by a surgeon, intraoperatively, or surgeon can use the predissected tissue, which is prepared by an eye bank technician.[6] After trephination of donor cornea, the anterior cap is discarded and the posterior cap is placed in the AC after confirming the correct orientation and attached to the endothelium with the help of an air tamponade. The posterior cap is usually thin (<200 μm), and care is taken to implant only the posterior lenticule into the recipient eye.[7] Failure to recognize nonseparation of the two caps can result in implantation of the full-thickness donor tissue in toto, which will eventually cause graft failure.

In this case, it was understood that the precut DSEK tissue was implanted in toto in the recipient cornea, instead of the posterior lenticule, as the primary operating surgeon probably failed to recognize this crucial surgical step. This was discovered during the repeat DSEK surgery, as the two tissue caps were explanted one after the other. Interestingly, even though the preoperative AS-OCT measurement of the DSEK graft was approximately 600 μ, the demarcation line between anterior and posterior lamella could not be identified. Such an implantation of the entire corneal tissue as DSEK graft is rare to happen. In this case, old corneal tissue was explanted and was replaced with a new DSEK graft which was prepared properly by the operating surgeon, after separating the anterior cap from the posterior cap. Hence, we emphasize the point that the trainee corneal surgeons should be aware of tissue preparation in DSEK, and if they use the precut eye bank tissue, they should ensure that the correct posterior lenticule should be implanted in the recipient eye. Failure to recognize this can cause graft failure and wastage of a precious tissue.

In conclusion, this case highlights one of the possible causes of graft failure and importance of tissue preparation during DSEK, which can influence the clinical outcome. Further, a properly trained corneal surgeon is required to perform corneal transplant like DSEK. This case highlights one of the possible causes of graft failure and importance of tissue preparation during DSEK, which can influence the clinical outcome.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.