Posterior Dislocation of Descemet Stripping Automated Endothelial Keratoplasty—A Case Report and Review

Abstract

In this study, we describe a case of graft dislocation into the vitreous cavity after Descemet stripping automated endothelial keratoplasty (DSAEK), and review the risk factors and complications of posterior dislocation. A 70-year-old female with disruption of the iris–lens diaphragm experienced DSAEK graft dislocation into the vitreous cavity during air re-bubbling at 1 week postoperatively. The corneal opacity hindered adequate visualization of the vitreous cavity for the immediate retrieval of the graft. Five days after re-bubbling, vitrectomy and corneal tissue removal was performed using a temporary Eckardt keratoprosthesis, and penetrating keratoplasty was subsequently performed. Two weeks after graft removal, a retinal detachment occurred. Silicon oil was used as a tamponade to reattach the retina. Three months after the last procedure, the retina was attached, and the cornea was clear. Posterior dislocation of DSAEK graft is a rare complication. A disrupted iris–lens diaphragm and previous vitrectomy are the main risk factors. Severe vision loss is more likely to occur when corneal tissue removal is delayed. In cases of delayed removal, it is advisable to take precautions to prevent possible retinal detachment.

1. Introduction

Descemet stripping automated endothelial keratoplasty (DSAEK) has become the procedure of choice for treating corneal endothelial dysfunction. Unlike penetrating keratoplasty (PK), where all layers of the cornea are replaced, in DSAEK, a partial graft, including the posterior stroma, Descemet membrane and endothelium, is performed. An intraoperative air bubble is used to promote the correct adherence of the DASEK graft to the original cornea [1].

One of the most common postoperative complications of this technique is corneal graft detachment, ranging from 1.5% [2] to 50% [3] in incidence. The incidence of this complication depends on several factors, such as the surgeon’s experience, the preparation of the recipient’s cornea, the size of the air bubble and its duration inside the anterior chamber (AC), previous PK and the presence of bleb [3,4,5].

In cases of graft detachment, re-bubbling is performed, with a large percentage of reattachment [6].

Graft dislocation into the vitreous cavity (posterior graft dislocation, PGD) has also been described in aphakic or pseudophakic eyes with an open posterior capsule [7,8,9,10,11,12,13].

Herein, we describe a case of PGD in an eye with a focal lack of integrity of the iris–lens diaphragm, previous vitrectomy and glaucoma surgery. Previous cases in the literature have been analyzed in an attempt to define the key factors for the proper management of this insidious complication.

2. Case Report

A 70-year-old female presented to the emergency department with pain and decreased vision in the right eye (RE). The patient had a history of glaucoma; she underwent RE trabeculectomy and iridectomy 6 years before, and cataract surgery 5 years before. The patient was on Brinzolamide/Timolol and Travoprost/Timolol eye drops for intraocular pressure (IOP) management.

The best-corrected visual acuity (BCVA) at presentation was counting fingers. A slit lamp examination showed hyperaemic conjunctiva with ciliary injection, corneal oedema, hypopyon (1 mm) and a shallow AC with inferotemporal iridocorneal synechiae. The IOP was measured to be 35 mmHg. The fundus oculi was not explorable due to corneal opacity.

An ultrasound examination showed heterogeneous debris in the vitreous and an attached retina. An endophthalmitis was suspected, and the patient was promptly taken to the operating room.

2.1. First Vitrectomy

Pars plana vitrectomy (PPV) 25 G was performed, and during surgery, a whitish and firmly adherent residual lenticular matter was noted and removed using a vitrectomy tip in the peripheral capsular bag protruding into the patent iridectomy (two o’clock position). The anterior and posterior capsules were opened at the two o’clock position to permit the retrieval of residual lenticular matter. Undiluted vitreous, aqueous humor and hypopyon samples were sent for cultures. The samples sent for culture were all found to be negative. The negative cultures and the residual lenticular matter found raised suspicion of an inflammatory etiology, instead of an infectious one.

At 3 months postoperative (PO), the BCVA was hand movement. Central corneal oedema was present (Figure 1).

Corneal pachymetry was 653 microns and endothelial cell count was undetectable due to corneal opacity. The IOP was 25 mmHg.

2.2. DSAEK

After a careful discussion with the patient, DSAEK surgery was scheduled for 1 month later. Since peripheral iridocorneal synechiae and shallow AC were present, we opted for a small size graft of 7.50 mm. The basal iridectomy was not performed, since an iridectomy was already present. The donor graft endothelial cell density was 2200 per mm², while the central graft thickness was 110 µm. An air bubble occupying 100% of the AC was injected into the eye, and sufficient pressure was achieved.

At 1-day PO, the donor graft was completely attached. The IOP was 9 mmHg with a negative Seidel test.

2.3. Re-Bubbling

At 1-week PO, incomplete inferior graft detachment was noted. An ultrasound examination revealed inferior serous choroidal detachment, probably due to a low IOP, of 8 mmHg. Air re-bubbling was scheduled on the same day in the operating theatre.

During re-bubbling, an air cannula was introduced in the area of graft attachment. However, due to a lack of visualization, air was inadvertently injected between the graft and recipient cornea, and the graft suddenly slid into the vitreous cavity through the iridectomy.

An ultrasound examination revealed the dislocated graft in the inferior vitreous cavity, together with the preexisting choroidal detachment.

Due to high ocular inflammation and severe bullous keratopathy, we decided to wait before graft retrieval. Efforts to reduce inflammation were made by administering high-dosage local and systemic corticosteroids (Dexamethasone, 75 mg per day, and Dexamethasone 2% eye drops, eight times a day) and hyperosmotic eyedrops (sodium chloride 5%, five times a day).

2.4. Second Vitrectomy with Eckardt Keratoprosthesis

No improvement in corneal oedema was achieved after 5 days of treatment (Figure 2A), and hence we opted for a PPV 25 G with temporary Eckardt keratoprosthesis. The endothelial graft was inferiorly adherent to the peripheral vitreous (Figure 2C). Using a bimanual technique, the graft was retrieved with vitreal forceps, whilst a vitrectomy around the graft was performed. A complete vitrectomy was then performed. The peripheral retina was then checked, and no retinal tears were seen. A 7.5 mm PK was performed at the end of the surgery, and air was used as tamponade (Figure 2D). The donor graft endothelial cell density was 2300 per mm².

An histologic examination of the graft revealed a complete absence of endothelial cells and no evident fibrotic metaplasia of the pre-Descemetic stroma (Figure 3).

One week after graft removal, the BCVA improved to counting fingers and the cornea was clear. Two weeks PO, the patient presented with decreased vision, from counting fingers to light perception. Fundus examination revealed a temporal retinal detachment associated with choroidal detachment. The IOP was 8 mmHg.

2.5. Third Vitrectomy

We immediately proceeded with a PPV 25 G to fix the detached retina. The corneal graft was sufficiently clear to allow the surgeon to visualize the retina well. A peripheral temporal retinal break was found, and no vitreous traction was present. Perfluorocarbon liquid (PFCL) was injected to reattach the retina, an endo-laser was applied around the break and PFCL–air–silicone oil 1000 cs exchange was performed.

Three months PO, the retina was well-attached, and the PK graft was clear. The patient’s vision was good enough to count fingers. The IOP was 6 mmHg.

At the last follow-up, 1-year PO, the BCVA decreased to hand movements, due to a fibrotic membrane behind the IOL. We opted not to remove the membrane, because of the risk of complications related to marked hypotony.

3. Discussion

Since Melles revolutionized the field of corneal transplantation with corneal endothelial transplantation, DSAEK has been applied in increasingly complex cases [14].

In decompartmentalized eyes, where there is direct communication between the anterior chamber and the vitreous cavity, posterior dislocation of the donor graft has been reported in 16 cases [7,8,9,10,11,12,13]. This direct communication may simultaneously increase the risk of graft detachment, and contribute to the posterior dislocation of the donor graft.

3.1. Risk Factors

The loss of integrity of the posterior capsule is the major risk factor. In the previous case reports, all eyes had undergone complicated intraocular lens placement or were aphakic before DSAEK surgery. Six eyes had a scleral fixation lens. Two eyes had an artificial iris lens: one in the sulcus, and one with scleral fixation. One eye had an iris fixation lens. One eye had a sulcus lens (

Table 1. Clinical findings before posterior dislocation of the DSAEK graft, management of graft retrieval and clinical outcomes. Intraocular lens (IOL), posterior chamber intraocular lens (PCIOL), penetrating keratoplasty (PK), pars plana vitrectomy (PPV), irrigation/aspiration handpiece (I/A), day (D), weeks (W), postoperative week (POW), no/yes (N/Y).

Author	Lens Status	Prior Vitrectomy	Iris Status	Presence of Glaucoma Tube	Visual Acuity Before DSAEK	Timing of DSAEK Graft Retrieval	Method of DSAEK Graft Retrieval	Anterior Segment Outcomes	Posterior Segment Outcomes	Final Visual Acuity
Afshari et al. [7]	Sulcus IOL	Anterior vitrectomy	Normal	N	20/100	Time of dislocation	PPV	Graft reattachment, failure, and repeat DSAEK at POW 8	Cystoid macular edema and epiretinal membrane requiring PPV with membrane peeling	20/40
	Sutured PCIOL	PPV	Iris rim remnants only	N	20/400	Time of dislocation	I/A	PK at POW 2	No complications	20/400
	Sutured PCIOL	Anterior vitrectomy	Peripheral iris–corneal synechiae	N	Counting fingers at 3 feet	7 D	PPV	PK at time of PPV	No complications	20/126
	Sutured PCIOL	PPV	Surgical changes	Y	Hand movements	9 D	PPV	PK at POW 8	No complications	20/30
	Aphakic	PPV	Normal	N	Hand movements	6 W	PPV	PK at POW 6	Total retinal detachment	No light perception
	Sutured PCIOL	Anterior vitrectomy	Extensive synechiae	Y	20/100	4 W	I/A	Repeat DSAEK	Epiretinal membrane, rhegmatogenous retinal detachment	Hand movements
	Aphakic	Anterior vitrectomy	Large superior sector iridectomy	N	Counting fingers at 6 inches	Time of dislocation	PPV	Repeat DSAEK	No complications	20/400
	Sutured sulcus artificial iris	Anterior vitrectomy	Aniridia	N	20/60	9 W	PPV	Repeat DSAEK	No complications	20/60
Grueterich et al. [8]	Dropped lens in the vitreous cavity	No	Subtotal iris loss	N	Hand movements	Time of dislocation	PPV	Graft reattachment	No complications	-
Xu et al. [9]	-	-	-	-.	-	-	Bimanual PPV with vitreous cutter and forceps	PK at time of PPV	-	-
Sng et al. [10]	Sutured sulcus artificial iris	PPV	Aniridia	N	20/60	Time of dislocation	Graft retrieval using forceps	Graft reattachment	No complications	20/70
Suh et al. [11]	Aphakic	-	-	-	-	-	-	-	-	-
Singh et al. [12]	Sutured PCIOL	Anterior vitrectomy	Iris defect superiorly	N	-	12 W	PPV, graft left in place with retinotomy	Repeat DSAEK	Total retinal detachment with proliferative vitreoretinopathy	Hand movements
	Sutured iris lens	PPV	Iris defect temporally	N	-	3 W	PPV, part of the graft left in place with laser barrier	Repeat DSAEK	Tractional retinal detachment	20/400
	Aphakic	-	Normal	N	20/100	2 W	PPV, graft–retina complex removed	-	Tractional retinal detachment, macula-off	20/50
Kam et al. [13]	Sutured PCIOL	-	Aniridia from 9 to 6 h	N	20/200	3 D	Prone position	Graft reattachment	No complications	20/30

).

This complication is more common in pseudophakic than in aphakic eyes. Two reasons may explain this. Firstly, DSAEK is more commonly performed in pseudophakic eyes than in aphakic eyes [15]. Moreover, surgeons are likely to use different techniques to avoid the incidence of dislocation in aphakic eyes [4,16].

For the same reasons, this complication is less common in eyes with aniridia than those with normal iris or with a partial defect of it. Six eyes had normal iris, two had aniridia, four had iris defects, and three had total iris loss (Table 1).

In our case, despite the iris and an intraocular lens in the bag, the graft was displaced in the vitreous cavity across the iris and posterior capsule breach that had been iatrogenically induced during the surgery for suspected endophthalmitis.

Also, previous vitrectomy (both anterior and via pars plana) is a second, major risk factor. All eyes that experienced a posterior dislocation of grafts had undergone a previous vitrectomy (Table 1). The lack of a vitreous may facilitate the graft’s dislocation by increasing turbulences between the anterior and posterior chambers. Furthermore, the air displaces more rapidly in the posterior chamber.

The presence of iridocorneal synechiae has been described in two eyes [7], as in our case. Synechiae may facilitate air passage into the posterior chamber by reducing the AC’s depth or deforming the iris’s shape. This does not adequately allow air to push the graft against the recipient cornea.

Filtrating bleb also facilitates air displacement out of the AC facilitating graft detachment and the need of re-bubbling [17]. Although this complication had been described previously in two patients with tubes, it had never been described in an eye undergoing trabeculectomy surgery [7].

3.2. Preventing PGD

Considering actions to reconstitute the iris–lens diaphragm before performing DSAEK can be an essential first step in managing these challenging cases.

Additionally, various techniques have been described to reduce the intraoperative and postoperative risks of primary graft detachment (PGD). Patel et al. proposed the use of a transcorneal Prolene suture to enable safe graft delivery and anchoring onto the recipient cornea [4].

Three limbus-to-limbus Prolene sutures, arranged in a pattern resembling the spokes of a wheel, were used to prevent PGD during surgery. This temporary barrier can remain in place postoperatively until the graft is securely attached [16].

3.3. Graft Survival

Most eyes experiencing posterior dislocation required a replacement of the donor graft (Table 1). This outcome is congruent with previous reports, where histological analyses of displaced grafts revealed a significant reduction in endothelial cell density or total endothelial cell loss [7,18]. Similarly, in our case, a complete absence of endothelial cells was observed.

This may be the consequence of graft manipulation and inflammatory reaction in the vitreous cavity. Additionally, the timing of graft recovery may play a critical role, as prolonged intervals could exacerbate endothelial cell loss [7].

In some cases, the retrieved graft was reattached to the cornea at the time of dislocation. It was possible because posterior dislocation occurred intraoperatively, allowing the graft to be repositioned immediately after retrieval. In two out of five cases, corneal clarity was achieved [7,8,10].

3.4. Complications

Similarly to the dislocation of nuclear part of the lens in the vitreous chamber, complications after posterior dislocation of graft include cystoid macular oedema and epiretinal membrane proliferation [7]. Furthermore, delayed intervention can lead to retinal detachment [7,12].

In the histopathologic examination of posteriorly dislocated grafts, inflammatory cells and fibrocellular tissue were reported, which are likely to contribute to vitreous traction, cystoid macular oedema, and rhegmatogenous retinal detachment, just as the inflammatory reaction does in the case of a dropped lens nucleus [7,12]. Hence, the early removal of the posteriorly dislocated graft is recommended to improve outcomes.

In contrast to DSAEK, in DMEK, the risk of fibrous proliferation and retinal detachment following PGD may be lower. DMEK involves the transplantation of a graft without stroma in which keratocytes are present—this may result in a much lower risk of developing inflammation and retinal detachment if the graft drops onto the retina [19]. Nonetheless, data are required to confirm this hypothesis.

3.5. Management

Corneal clarity must be one of the immediate outcomes to reach a sufficient vitreal visualization. As shown in Table 1, early surgical timing is associated with fewer graft-related retinal complications (EMC, epiretinal membrane, tractional retinal detachment).

The most relevant finding of our case is that, if corneal clarity is not sufficient and cannot be achieved within a few hours from the onset of the PGD using conservative treatments (removal of epithelial, hypertonic drops), it is mandatory to convert to PK through a temporary keratoprosthesis.

If the graft is removed late, inflammatory adherence to the vitreous will likely to occur. Careful graft manipulation must be performed to avoid retinal breaks. Peripheral vitreous shaving and 360° preventive laser photocoagulation may be considered to reduce the risk of retinal detachment [12].

4. Conclusions

We described a case of DSAEK graft dislocation into the vitreous cavity, which is a rare condition with a few identified risk factors: an altered iris–lens diaphragm with posterior capsule opening, a previous vitrectomy, the presence of peripheral anterior synechiae and filtering bleb. The patient had all the risk factors described in the literature. Based on our experience, we strongly suggest that, in the presence of any risk factor for PGD, re-bubbling should be performed with the highest care (i.e., in theatre, by experienced operators, possibly using a peribulbar block).

If dislocation in the vitreous cavity occurs, the graft should be removed as soon as possible to decrease the risk of inflammatory retinal detachment. Yet, cornea clarity is frequently poor in these cases, making surgery even more challenging. If corneal clarity is not restored within few hours, we recommend urgently performing a vitrectomy with temporary keratoprosthesis, and following PK to prevent inflammatory vitreoretinal complications.