Novel technique to improves graft unfolding in vitrectomized eyes during Descemet membrane endothelial keratoplasty

Abstract

Introduction

Descemet membrane endothelial keratoplasty (DMEK) is commonly used to treat endothelial pathologies in bicameral pseudophakic eyes with a normal depth of the anterior chamber. However, performing this procedure on eyes that have undergone vitrectomy carries a higher risk of complications. Therefore, this report presents a novel technique for improving the unfolding of a DMEK graft in a vitrectomized eye.

Presentation of case

A 49-year-old man with a history of complicated cataract surgery one year prior was referred to our clinic with pseudophakic bullous keratopathy in his left eye. The surgery involved a posterior capsular rupture, anterior vitrectomy, and implantation of a sulcus three-piece intraocular lens. DMEK and anterior vitrectomy were performed. However, the conventional tap technique was unsuccessful in unfolding the DMEK graft, owing to intraoperative hypotony and an inability to flatten the anterior chamber.

Discussion

To minimize excessive manipulation of the donor tissue, a 27-gauge cannula attached to a 3-cc syringe was used. A cannula was introduced through paracentesis near the edge of an unfolded DMEK graft. We then created a suction force by pulling back the plunger while slowly moving the needle backward during the graft unfolding. The postoperative course was uneventful, with a clear and fully attached DMEK graft.

Conclusions

This technique reduces the complexity of DMEK graft unfolding in vitrectomized eyes, enabling easier and more controlled unfolding. However, further research with larger patient populations is required to determine the clinical relevance of this method.

Highlights

• •Descemet membrane endothelial keratoplasty (DMEK) is commonly used to treat endothelial pathologies in bicameral pseudophakic eyes with a normal depth of the anterior chamber.
• •Performing DMEK procedure on eyes that have undergone vitrectomy carries a higher risk of complications which can negatively affect the viability of donor endothelial cells and increase the risk of complications.
• •We present a novel technique for improving the unfolding of DMEK grafts in vitrectomized eyes.

1. Introduction

Descemet membrane endothelial keratoplasty (DMEK) is an increasingly popular treatment for endothelial pathologies such as Fuchs' corneal dystrophy and pseudophakic bullous keratopathy [1]. This treatment promotes faster and superior visual recovery while also reducing the likelihood of rejection [2]. Bicameral pseudophakic eyes with a normal depth of the anterior chamber (A/C) are considered ideal candidates for DMEK [1]. Although this can be a relatively straightforward procedure for such patients, performing it on eyes that have undergone vitrectomy carries a higher risk of complication. Vitrectomized unicameral eyes allow direct contact of fluid from the anterior and posterior segments, which can make it challenging to maintain a shallow A/C and properly unfold the graft [3]. Moreover, deficiency of posterior support in these eyes tends to cause recurrent collapse during intraoperative maneuvers, impair the endothelial viability of the donor tissue, and increase the risk of complications such as endothelial cell loss, graft failure, and graft dislocation [4]. This can negatively affect the viability of donor endothelial cells and increase the risk of complications [5].

In this report, we present a novel technique for improving the unfolding of DMEK grafts in vitrectomized eyes.

2. Methods

This case has been reported in line with the SCARE criteria [6].

2.1. Case report

A 49-year-old man with a history of complicated cataract surgery one year prior to his visit was referred to our clinic with pseudophakic bullous keratopathy in his left eye. The previous surgery involved a posterior capsular rupture, anterior vitrectomy, and implantation of a sulcus three-piece intraocular lens. At presentation, the visual acuity of the patient was counting fingers of 1 ft. A slit-lamp examination revealed bullous keratopathy and vitreous strands in the A/C (Fig. 1A). Therefore, we decided to proceed with DMEK and anterior vitrectomy. The DMEK graft was preloaded into a Geuder cannula (Geuder AG, Heidelberg, Germany). The donor was 64 years old, and the diameter of the DMEK graft was 8.00 mm, matching the corneal diameter of the recipient. The endothelial cell count was 2640 cells/mm². The central epithelium was manually removed to enhance visibility of the A/Cs. A 2.4-mm clear corneal incision was subsequently made, accompanied by two side ports positioned 180° apart. Triamcinolone-assisted anterior vitrectomy was performed initially, followed by inferior surgical peripheral iridectomy using an anterior vitrectomy cutter with a vacuum of 250 mmHg and a cutting rate of 1. After staining the Descemet membrane with trypan blue (Visionblue, D.O.R.C International, Zuidland, The Netherlands) to improve visibility, an 8.5 mm Descemetorhexis was performed through paracentesis under cohesive viscoelastic (ProVisc, Alcon Laboratories, Inc., Fort Worth, TX, USA) using a reversed Sinskey hook. Next, the Descemet's membrane of the recipient was carefully removed. The viscoelastic agent was completely removed using a Simcoe irrigation and aspiration cannula. A Geuder cannula was then inserted through the main wound, and the graft was injected into the recipient A/C. The depth of the A/C was maintained using balanced salt solution (BSS) injection through paracentesis. The main corneal incision was closed using a single interrupted 10–0 nylon suture (Ethicon, Raritan, NJ, USA). Owing to intraoperative hypotony and the inability to flatten the A/C, the conventional tap technique was unsuccessful in unfolding the DMEK graft. To minimize excessive manipulation of the donor tissue, we used a 27-gauge cannula attached to a 3-cc syringe. A cannula was introduced through paracentesis near the edge of an unfolded DMEK graft. We then created a suction force by pulling back the plunger while slowly moving the needle backward during the graft unfolding (Fig. 2). This technique allows easier and more controlled unfolding of the DMEK graft. The graft was then unfolded, and the A/C was filled with air for 10 min, followed by a reduction in the air fill to 80 %. The postoperative course was uneventful, with a clear and fully attached DMEK graft (Fig. 1).

Fig. 1.

Clinical photos of the left eye before and after Descemet membrane endothelial keratoplasty (DMEK). (A) A preoperative slit-lamp examination showed bullous keratopathy and vitreous strands in the anterior chamber. (B) Postoperative slit-lamp examination showed improved corneal clarity with a 40 % air bubble. (C) Postoperative anterior segment optical coherence tomography revealed that the DMEK endothelial graft was well-attached, with a central corneal thickness of 563 μm.

Fig. 2.

An intraoperative illustration of the technique. A 27-gauge cannula attached to 3-cc syringe was used to introduce the cannula through paracentesis near the edge of the unfolded Descemet membrane endothelial keratoplasty graft. A suction force was then created by pulling back on the plunger while slowly moving the cannula backward during graft unfolding.

(Illustrations courtesy of Veldman, Peter, with permission.)

3. Discussion

DMEK has been widely adopted as the preferred treatment for corneal endothelial disorders among corneal surgeons globally [1,2]. Its high success rate, low risk of rejection, and rapid visual recovery have effectively overshadowed the challenges associated with the procedure [2]. However, unfolding the DMEK graft in vitrectomized eyes remains a challenging and unpredictable step in DMEK surgery [4]. The absence of posterior vitreous support in vitrectomized eyes can lead to recurrent collapse and deepening of the anterior chamber, making it difficult to unfold the graft. Additionally, the lack of vitreous counterpressure can cause air bubble in the anterior chamber, thereby exerting pressure on the lens-iris diaphragm and pushing it backward. This backward movement can hamper the ability of the diaphragm to securely hold the graft against the recipient stroma, thus increasing the risk of graft detachment [4,5].

Conventional tap techniques are generally ineffective in vitrectomized eyes. Therefore, several techniques have been proposed to address this challenge [4].

Sorkin et al. [7] described the placement of a posterior pars plana infusion to stabilize the anterior chamber. However, this procedure can present with potential complications, particularly for unfamiliar anterior segment surgeons. For example, they reported a retinal detachment in one of 12 eyes, which may have been attributed to a retinal break related to sclerotomy. Hayashi et al. [8] described a double-bubble technique that utilizes two air bubbles to assist in pressurization and unfolding. This technique involves placing a small bubble on top of the graft to aid in the unfolding process while simultaneously injecting a larger bubble beneath the graft to ensure proper fixation. Furthermore, Yoeruek et al. [9] designed a hydrophilic methacrylate sheet for insertion into the A/C to create a double anterior-chamber-like structure in vitrectomized eyes. This innovative approach aims to minimize fluctuations in the iris-intraocular lens diaphragm, flatten the A/C, and enhance the unfolding process. The DMEK graft was injected onto a hydrophilic methacrylate sheet and unfolded. Continuous air injection was maintained through a 30-gauge cannula while the hydrophilic methacrylate sheet was removed. The seven eyes that underwent DMEK using this technique showed no intraoperative or postoperative complications. Saad et al. [10] introduced the C-Press technique in a study involving 11 vitrectomized eyes that had undergone DMEK. They found that previously described methods such as pars plana infusion and the double-bubble technique were not consistently effective in all vitrectomized eyes. After inserting the DMEK graft, a cannula was carefully inserted into the Descemet side of the graft, moved back and forth, and irrigated with a balanced salt solution to open the graft. Another cannula was used to apply external pressure to the central cornea. This gentle pressure maintained the graft opening by reducing the A/C depth. Subsequently, the initial cannula was removed and 20 % SF6 gas was introduced. The procedure did not result in any intraoperative complications. However, two patients developed graft detachment that required re-bubbling.

Our novel technique demonstrates promising potential for DMEK lenticule unfolding. However, it is crucial to acknowledge potential challenges encountered in such eyes with specific anatomical features. One concern raised is the possibility of lenticule slippage behind the IOL, particularly in eyes lacking a complete posterior capsule. To mitigate this risk, we advocate for utilizing pre-marked DMEK grafts and addressing any IOL instability or iris defects prior to graft injection. Additionally, maintaining a small pupil size with intracameral miotics can facilitate safe manipulation and minimize the chance of slippage. Another potential challenge pertains to achieving complete air fill in vitrectomized eyes. We recommend addressing IOL stability and iris defects, followed by meticulous wound closure and BSS fill to create a controlled environment for air injection. Maintaining a complete air bubble for a brief period before controlled deflation can further improve success rates. Finally, it is important to emphasize the minimal risk of DMEK lenticule aspiration through the cannula. While the narrow opening and targeted approach minimize this risk, it is essential to clarify that the intended purpose is to remove minimal fluid near the graft edge, not to aspirate the graft itself. The aspiration maneuver aims to gently remove a small amount of fluid near the graft's edge, facilitating its unfolding. The primary objective is to prevent complete anterior chamber collapse, which could hinder manipulation. The narrow cannula opening significantly reduces suction force, further minimizing the risk of inadvertent lenticule engagement. Maintaining gentle aspiration targeted away from the lenticule and focusing on the periphery further reduces the risk of unintended contact.

Assessing these emerging techniques reveal no universally applicable approach for surgical intervention in vitrectomized eyes. Therefore, familiarizing oneself with various techniques is recommended to ensure that the most appropriate technique can be applied when necessary. Here, our technique greatly facilitated the unfolding of the scrolled tissue in the area where the graft opening was required. This approach helps prevent unnecessary disturbances in the anterior chamber and minimizes excessive manipulation that may impact the endothelial cells or displace the graft. However, a comprehensive prospective study is required to identify the long-term effects of this procedure.

Consent

Written informed consent was obtained from the patients for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Ethical approval

No IRB approval is needed for case reports. However, this case report was prepared according to the ethical standards of the human ethics in accordance with the Helsinki Declaration.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Guarantor

Dr. Wael Otaif.

Research registration number

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• 2.Unique identifying number or registration ID: researchregistry9653
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CRediT authorship contribution statement

WO: Data collection for cases, drafting part of the manuscript, and Literature review. MK: Research idea and manuscript revision. WO and MK: Shared in writing the clinical/surgical draft of the manuscript.

Declaration of competing interest

The authors declare no conflicts of interest.