CASE OF THE MONTH: May 2024
Dislocation of Posterior Lamellar Corneal Graft into the Vitreous Cavity with Viable Endothelial Cells
Descemet stripping automated endothelial keratoplasty (DSAEK) is a partial thickness corneal transplant used for management of corneal edema due to corneal endothelial dysfunction. The procedure involves removal of the host Descemet membrane and endothelial cell layer, with replacement with corneal endothelium, Descemet’s membrane, and partial thickness stroma, known as a posterior lamellar graft. Rarely, the graft may dislocate into the posterior segment, particularly in eyes that are aphakic, have undergone prior pars plana vitrectomy (PPV), or previous complicated intraocular lens surgery. Such scenarios pose a high risk for poor visual outcomes given their association with complications including fibrovascular membrane formation and rhegmatogenous retinal detachment (RRD). Here, we present a case of intraoperative DSAEK graft dislocation into the vitreous cavity in a previously vitrectomized eye with a scleral-sutured intraocular lens (SSIOL) and describe the histopathology of the retrieved specimen showing viable endothelial cells after remaining in the vitreous for one week.
A 55-year-old man with no prior ocular history presented to the hospital following a traumatic motor vehicle accident. Visual acuity (VA) was hand motion (HM) upon arrival, and intraocular pressure (IOP) was 5 mmHg. Ophthalmologic examination was notable for a full-thickness, superior corneal laceration, associated with a shallow anterior chamber, posteriorly dislocated lens, hyphema, significant iris loss, and a right lower eyelid margin-involving laceration. The patient was taken for same-day surgical exploration of the right globe, in addition to corneal laceration repair, anterior vitrectomy, and eyelid laceration repair. Vitreous hemorrhage and choroidal effusions were noted intraoperatively as well. Ten weeks following this initial repair, PPV, pars plana lensectomy (PPL), and SSIOL fixation were performed. Vision one month later improved to 20/300, though continued to be limited due to significant corneal edema, commotio retinae, and traumatic mydriasis.
Due to unresolving corneal edema lasting over 6 months following initial trauma, a DSAEK was planned. Unfortunately, this was complicated by rapid loss of the posterior lamellar graft which slipped between the missing superior iris tissue and the scleral sutured lens. Given that there was no further view of the donor graft, the procedure was aborted, and all wounds were sealed. The patient returned one week later for combination PPV, explantation of the first graft, and planned posterior lamellar graft transplantation. Upon visualizing the fundus, the initial posterior lamellar graft was noted to be resting on the macula and a soft tip cannula was used to attempt removal with careful attention to avoid unnecessary mechanical trauma to the donor graft. However, this method did not provide enough traction, and MST forceps were then successfully employed to grasp the graft and remove it through a 3.5 mm sclerotomy. During the removal process, the tissue edges of the dropped graft were partially manipulated, but centrally it remained untouched. A new posterior lamellar graft was then successfully placed with the assistance of two basket sutures (10-0 prolene sutures placed 2.0 posterior to the limbus, and anterior to the SSIOL) to prevent the tissue from falling into the posterior segment again. The retrieved graft from the initial DSAEK surgery was sent for histopathological examination and showed patchy endothelial loss of varying severity, with areas of viable endothelial cells in the specimen (up to 25 endothelial cells per single high-power field). The new posterior lamellar graft remained attached and cleared well with a best corrected VA of 20/250 by POW1, and 20/80 3 months post operatively, with remaining vision likely limited due to traumatic retinal pathology.
In the era of reducing waste, this prompts consideration regarding the potential reuse of the graft for re-transplantation, and its potential applicability in similar surgical scenarios in the future. One prior case report demonstrated graft dislocation into the vitreous 3 days following Descemet membrane endothelial keratoplasty (DMEK), with successful same-day retrieval and reimplantation without removing the graft from the eye. Another case report on intraoperative DSAEK graft dislocation into the vitreous showed successful same-operation retrieval using perfluorocarbon liquid without requiring explantation. However, a case series of 8 eyes with posterior segment DSAEK graft dislocation all required eventual replacement donor grafts; only one eye in this series had a graft retrieved and reimplanted at time of dislocation, but it ultimately failed and required replacement 2 months later.
Overall, while the dislocation of corneal graft tissue into the posterior segment remains a rare complication, it may be worthwhile to take precautionary steps in eyes at risk. Our multi-disciplinary approach highlights the importance of timely graft retrieval, and with histopathology demonstrating the potential for viable endothelial cells, implicating the possible reuse of dislocated tissue in the appropriate clinical setting.