Outcomes of Sutureless Small Incision Descemet's Stripping Automated Endothelial Keratoplasty: A Retrospective Study

doi:10.21203/rs.3.rs-5321771/v1

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Outcomes of Sutureless Small Incision Descemet's Stripping Automated Endothelial Keratoplasty: A Retrospective Study

https://doi.org/10.21203/rs.3.rs-5321771/v1

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Objective: To evaluate the outcomes of sutureless small incision Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK-SI) for treating corneal endothelial decompensation.

Methods and analysis: This retrospective study involved sixty eyes of sixty patients with corneal endothelial decompensation who underwent DSAEK-SI between January 2018 and June 2021 at Vietnam National Eye Hospital. All patients were followed for at least one year postoperatively. The endothelial graft was inserted into the anterior chamber through a 2.8mm main corneal incision using a Busin glide. Normal pressure air tamponade of the anterior chamber was applied to attach the graft to the recipient bed. The small incision required no sutures with no need to remove part of the air from the anterior chamber and end the surgery immediately after air tamponade. Patients were instructed to lie supine for at least 6 hours postoperatively. Patients with cataracts underwent combined phacoemulsification and intraocular lens implantation with DSAEK-SI.

Results: The success rate of the surgery was 93.3%. Postoperatively, the best spectacle-corrected visual acuity (BSCVA) improved from 20/3600 to 20/400 at discharge and reached 20/100 at 12 months. Mild astigmatism (0.5D to 2D) was observed in 91.8% of patients, with a mean cylinder of 0.9 ± 0.4D at 12 months. The endothelial cell loss rate at 12 months was 34.6 ± 16%. No graft dislocations or detachment were recorded.

Conclusions: The sutureless DSAEK-SI technique with a 2.8mm incision is an innovative approach that reduces surgical manipulation, shortens operative time, and minimizes complications, resulting in high success rates and optimal outcomes.

sutureless DSAEK

small incision DSAEK

DSAEK-SI

In recent years, corneal transplantation for the treatment of corneal endothelial diseases has developed rapidly, leading to significant improvements in outcomes. However, Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) remains the preferred method and yields ideal results in treating corneal endothelial damage, especially in complex cases where DMEK surgery is not indicated[1].

The conventional DSAEK procedure involves incisions ranging from 3 to 5mm, depending on the surgeon. With the advent of improved graft insertion tools, the DSAEK technique has evolved, allowing for smaller incisions and reduced surgical times, laying the foundation for sutureless small-incision endothelial keratoplasty. In 2017, Titiyal and colleagues introduced a 3.8mm sutureless technique in which the corneal tunnel was long enough to self-seal without the need for sutures. This technique employed air tamponade with a 30G needle for 12–14 minutes, similar to conventional DSAEK surgeries, to help the graft adhere to the recipient bed. At the end of the surgery, the air tamponade was reduced and replaced with balanced salt solution (BSS). These advancements improved outcomes by minimizing astigmatism and reducing operative time.

In our study, we further refined this technique by utilizing a 2.8mm sutureless incision and applying air tamponade with a 26G cannula at normal pressure. The surgery was completed without the prolonged high-pressure air tamponade of 10–15 minutes commonly used in DSAEK methods.

Study design and patients

All patients in this study underwent surgery performed by a single corneal surgeon at the Vietnam National Eye Hospital and were followed postoperatively according to a standardized protocol. For patients with coexisting cataracts, a combination of DSAEK-SI and cataract surgery with intraocular lens (IOL) implantation was performed. The patients with bullous keratopathy without stromal scarring, who were followed for at least one year postoperatively were included. The exclusion criteria were patients who declined to participate in the study or those lost to follow-up. Between January 2018 and June 2021, we performed DSAEK-SI surgery on 72 patients, 60 of whom (60 eyes) completed the one-year follow-up.

This study was approved by the Ethics Committee of the Vietnam National Eye Hospital. Patients and their families were informed about the treatment options, risks, and complications associated with DSAEK-SI. Participation in this study was entirely voluntary.

Before surgery, data such as visual acuity, intraocular pressure, corneal thickness (measured by anterior segment optical coherence tomography, Carlzeiss Visante OCT 4000), and graft characteristics were documented. Postoperative data on visual acuity, intraocular pressure, corneal astigmatism, corneal thickness, graft condition (clarity, thickness, adherence, position, and endothelial cell density), and complications were recorded at 1 month, 3 months, 6 months, and 12 months. A good result was defined as the resolution of symptoms (glare, foreign body sensation, tearing), a clear cornea without epithelial bullae, and a well-centered, well-adhered graft. A poor result was defined by persistent graft detachment, eccentric graft placement, corneal edema with epithelial bullae, and the recurrence of symptoms.

Surgical technique:

Anesthesia

The surgery was performed under either general anesthesia or peribulbar anesthesia.

Recipient bed preparation: The patient's corneal diameter was measured, and a trephine was used to mark the recipient bed's circumference on the epithelial surface. The graft diameter was typically 3mm smaller than the patient's corneal diameter. In cases of thick epithelial edema, epithelial removal was necessary to achieve optimal anterior chamber visualization. A main incision, 2.8mm wide and 2mm long, was created at the 10 o'clock position for the left eye or the 8 o'clock position for the right eye. Two secondary incisions were made: one opposite the main incision to allow forceps insertion for pulling the graft into the anterior chamber, and a second oblique incision between the main and the first secondary incision for inserting the anterior chamber maintainer. Viscoelastic was injected to stabilize the anterior chamber. A reversed Sinskey hook was used to strip the Descemet's membrane along the marked recipient bed circumference. Finally, the viscoelastic was completely removed from the anterior chamber.

Graft preparation

Donor tissue was prepared using a microkeratome from the SightLife Eye Bank (USA). The donor corneal lenticule was cut with a trephine of the desired diameter and loaded onto the Busin glide.

Graft insertion and air tamponade

The donor lenticule was pulled into the anterior chamber using the "pull through" technique with forceps and the Busin glide, allowing it to unfold naturally. The incisions were closed by hydration without the need for sutures. Air was then introduced into the anterior chamber, and a reverse 27G needle attached to a 10ml syringe was used to center the graft. The graft was attached to the posterior surface of the recipient stroma by injecting a normal-pressure air bubble through the main incision. Unlike conventional DSAEK, no air-fluid exchange was needed and the surgery was finished without 10–15 minutes waiting. The patient was required to remain supine for at least 6 hours postoperatively.

For patients undergoing combined surgery of DSAEK-SI and cataract extraction with IOL implantation, DSAEK was performed after IOL implantation.

Postoperative care

Patients received oral antibiotics and topical eye drops, including moxifloxacin 0.5% four times daily for the first month, prednisolone acetate 1% four times daily for the first month with subsequent tapering, and artificial tears.

A detailed video of the technique is available at the following link: https://www.youtube.com/watch?v=fM_xjjuWDl8

Statistical analysis

The Wilcoxon t-test was used to compare visiual outcomes, corneal astigmatism, endothelial cell loss. Statistical analysis was performed using SPSS software, version 21.0 (SPSS Inc., Chicago, IL). The threshold for significance was p = 0.05.

Patient and Surgical Characteristics

This study included 60 eyes from 60 patients with complete one-year follow-up data. The average age was 63.6 ± 13.5 years (range: 29 to 86). Of the participants, 54.7% were male and 45.3% were female. Among the 60 eyes, 88.4% underwent isolated DSAEK-SI, while 11.6% had combined phacoemulsification and IOL implantation. Some surgical characteristics are detailed in Table 1.

Table 1

Surgical characteristics
Indications	Bullous keratopathy	75%
	Fuchs' dystrophy	15%
	ICE syndrome	3.3%
	Other (graft failure, glaucoma, viral endotheliitis)	6.7%
Graft diameter	7.5 mm	11.3%
Graft diameter	8.0 mm	88.7%

Successful rate

The surgical success rate at one year was 93.3%. Graft failure occured in 4 eyes, including 1 eye with unexplained graft failure, 1 eye with graft rejection, 1 eye with CMV endothelial keratitis, and 1 eye with ICE syndrome.

Visiual outcomes

The average preoperative visual acuity was 20/3600, with 90.5% of patients having a visual acuity of less than 20/400. The average best-corrected visual acuity (BSCVA) for all eyes at discharge and at the 12-month follow-up was 20/400 and 20/100, respectively, which was significantly higher than the preoperative visual acuity (p = 0.005). For patients without retinal pathology (5 eyes), the BSCVA was 20/300 at discharge and improved to 20/45 at the 12-month follow-up (p < 0.001).

Corneal Astigmatism

Preoperative corneal astigmatism was not recorded due to corneal edema. The average corneal astigmatism in 56 eyes with graft survival at the 6- and 12-month follow-up was 0.92 ± 0.5D and 0.9 ± 0.4D, respectively. The difference was not statistically significant (p = 0.066). Of these 56 eyes, 91.8% had astigmatism ranging from 0.50 to 2.00D, 8.2% had astigmatism between 2.00 and 3.00D, and no eyes had astigmatism greater than 3D.

Endothelial cell loss

Endothelial cell density (ECD) was recorded before and after cutting with a microkeratome at the SightLife Eye Bank (USA) and during follow-up examinations. In the successful group, 53 eyes had measurable ECD at 12 months. The average preoperative ECD was 2645 ± 309 cells/mm². At 6 months postoperatively, the average ECD was 1755 ± 457 cells/mm², and at 12 months, it was 1668 ± 327 cells/mm². The endothelial cell loss rate at 6 and 12 months was 32.7 ± 13.5% and 34.6 ± 16%, p = 0.322, respectively.

Complications

In our study, no cases of graft detachment or dislocation were observed postoperatively. All grafts remained well-attached and centered at all follow-up visits. Graft rejection was observed in 3 eyes, leading to graft failure. Early postoperative intraocular pressure (IOP) elevation due to pupillary block by an air bubble was seen in 4 eyes. These 4 eyes were treated with cycloplegic eyedrops (Mydrin-P). After 3 hours, the air bubble block resolved in 2 eyes, while the other 2 required partial air removal through the main incision. All patients experienced resolution of early IOP elevation within one day. Late postoperative IOP elevation occurred in 2 eyes, both of which were controlled with anti-glaucoma medication. One patient with a history of CMV-related endotheliitis developed persistent endotheliitis immediately after grafting, leading to graft failure.

Endothelial cells play a crucial role in maintaining corneal transparency. DSAEK surgery for endothelial decompensation offers several advantages over penetrating keratoplasty, including faster visual recovery, less nerve damage, and preservation of ocular integrity due to the small incision size of only 3–5 mm. In recent years, the development of instruments for graft insertion into the anterior chamber has allowed for refinements in DSAEK, including smaller incision sizes and a sutureless approach. Many authors have made individual modifications to the technique, all aimed at simplifying the surgical procedure while achieving good postoperative outcomes and minimizing complications. To the best of our knowledge, this is the first study in the literature to use the smallest incision size (2.8 mm) without sutures, along with normal-pressure air injection to adhere the graft to the stromal bed. This technique allows the surgery to be completed immediately after air injection, without the need to wait 10–15 minutes as in conventional methods.

The success rate of DSAEK-SI surgery in our study was 93.3%, which is comparable to traditional DSAEK surgeries. Shih et al. reported a success rate of 88% [2], while Price et al. conducted a five-year study on 165 eyes, achieving a success rate of 95% [3]. With experienced surgeons, the success rate can reach up to 100% [4]. In these studies, DSAEK surgery was performed with a 5 mm incision, using sutures or forceps to insert the graft into the anterior chamber. After 8–10 minutes of air injection, approximately 30% of the air bubble was replaced with balanced salt solution (BSS) [2, 3]. Titiyal et al. conducted a study on 27 eyes undergoing sutureless DSAEK with a 3.8 mm incision and Busin glide for graft insertion. After 15 minutes of air injection, approximately 50% of the air was replaced with BSS, and the results showed no graft failures, with a 100% success rate [1]. Foster et al. reported a 95.2% success rate in a study of 105 eyes undergoing DSAEK with a 3 mm incision [5]. In Foster's study, the graft was inserted into the anterior chamber using forceps, with a 10-minute wait after air injection before replacing approximately 40% of the air bubble with BSS [5]. Our improved DSAEK-SI technique, using a sutureless 2.8 mm incision with no waiting after air injection and no replacement of the anterior chamber air bubble with BSS, has achieved a high success rate comparable to traditional DSAEK surgery.

DSAEK-SI surgery replaces only the diseased posterior corneal layer while preserving the anterior corneal layer. The surgery uses an air bubble to adhere the graft to the posterior stromal bed, and a 2.8 mm incision to insert the graft into the anterior chamber. This small incision minimally impacts the anterior corneal curvature and can self-seal by hydration. The improvement in surgical technique has helped patients avoid astigmatism caused by sutures. In our study, postoperative astigmatism at 12 months was 0.9 ± 0.4D. Terry reported a mean corneal astigmatism of 1.19D in 100 eyes following DSAEK with a 5 mm incision and sutures [6]. Koenig et al. performed DSAEK with a 4.2 mm incision and sutures on 26 eyes, resulting in a mean corneal astigmatism of 2.26 ± 1.48D [7] .

A concern with DSAEK-SI is the potential for increased endothelial cell (EC) loss due to the higher risk of trauma to the graft when passing through the small incision. However, we observed that using the Busin glide to insert the graft allows it to roll with the endothelial side facing inward, thus protecting the ECs. In our study, endothelial cell loss at 12 months was 34.6 ± 16%, which is comparable to Terry's study and lower than Ishii's, both with the same one-year follow-up period [8, 9]. In Titiyal's study on sutureless DSAEK, endothelial cell loss at 6 months was 18.19% [1], lower than our results; however, the study only reported on a 6-month period and requires longer follow-up to assess long-term endothelial cell loss.

Table 2

Comparison of Endothelial Cell Loss Rates Between Studies
Author	Year	n	Incision Size (mm)	Graft insertion technique	Air bubble removal	Follow-up time (months)	Endothelial Cell Loss Rate (%)
Terry[8]	2008	80	5	Forceps	Yes	12	35 ± 13
Ishii [9]	2016	225	5	Busin glide	Yes	12	58.4
Titiyal[1]	2015	27	3.8	Busin glide	Yes	6	18.19
Foster[5]	2011	105	3	Forceps	Yes	9.4	44.1
Our Study	2020	53	2.8	Busin glide	No	12	34.6 ± 16

The graft is inserted into the anterior chamber using the Busin glide, and it unfolds automatically under continuous irrigation through an anterior chamber maintainer. This reduces surgical manipulation and minimizes the risk of endothelial cell loss [10]. The use of the Busin glide has limited endothelial cell loss to 20–30% after 6–12 months, significantly lower than the 61% loss observed with suture or taco techniques [11].

One standout feature of DSAEK-SI surgery is the small incision size (2.8 mm), which can close postoperatively without the need for sutures. This allows for better maintenance of the anterior chamber and reduces suture-induced astigmatism. Consequently, the graft typically adheres and centers fully after air injection, minimizing the need for additional graft adjustments and reducing endothelial cell damage.

A key difference in our improved technique compared to previous methods is the air tamponade step. We inject air into the anterior chamber at normal pressure, allowing the graft to adhere to the stromal bed without maintaining a high-pressure air bubble for 10–15 minutes, as suggested by other authors. This improvement eliminates the need for air-fluid exchange, simplifies the surgical procedure, shortens operation time, and minimizes damage to endothelial cells caused by high-pressure air bubbles.

Graft dislocation and detachment are common complications after DSAEK surgery. Although anterior chamber air injection is performed to reattach the graft, the risk of graft failure remains high. Graft dislocation or detachment often occurs within the first week post-surgery but can appear up to six weeks later [12]. In Nahum's study of 1334 eyes, the rate of graft dislocation or detachment was 3.7%, and all grafts were successfully reattached by reinflating the anterior chamber with air [12]. Similarly, Bhalerao reported a graft detachment rate of 3.5% in 80 eyes, with 77 grafts reattached after reinflation, though 25 eyes still experienced graft failure [13]. In Suh's study of 118 eyes post-DSAEK, 23% of eyes experienced graft detachment [14]. In our study, after DSAEK-SI surgery, the graft detachment rate at all follow-up visits was 0%. This improved technique significantly reduced the graft detachment rate compared to traditional DSAEK surgery, where detachment is the most common complication.

Several technical improvements contributed to this success: the small, sutureless incision limits corneal deformation, allowing the graft to adhere more easily to the physiological curvature of the recipient bed; the use of the Busin glide and forceps to pull the graft into the anterior chamber reduces the risk of graft inversion; normal-pressure air tamponade in the anterior chamber; and crucially, maintaining the air bubble in the anterior chamber without replacing it with BSS. We believe that fluid in the anterior chamber postoperatively could penetrate the interface and cause graft detachment when the patient changes head position. The air bubble remains in the anterior chamber long enough to help the graft adhere firmly to the stromal bed. These improvements have effectively prevented early graft detachment post-surgery.

The improvements in DSAEK-SI surgery offer substantial benefits for both surgeons and patients. For surgeons, the use of a 2.8 mm sutureless incision significantly shortens the procedure time and allows the surgery to conclude immediately after air injection, eliminating the need for a 10–15 minutes wait. For patients, these advancements promote faster visual recovery, reduce postoperative astigmatism, and minimize complications, particularly those related to graft dislocation or detachment. Additionally, the rate of endothelial cell loss remains comparable to that of traditional DSAEK surgery.

Contributors:

Le Xuan Cung: Conception and design of the study, write articles, Luong Thi Anh Thu: Collection and analysis of data, write articles, Duong Mai Nga: Interpretation of data, Pham Ngoc Dong: Approval of the manuscript

Funding: The authors have not indicated any specific grant for this research from any funding agency, whether public, commercial, or non-profit.

Conflict of interest: The authors declare no competing interests

Patient consent for publication: All patients gave their informed consent prior to their inclusion in the study

Ethics approval: Ethics Committee of the Vietnam National Eye Hospital, Hanoi, Vietnam (approval number: 132).

Titiyal JS, Tinwala SI, Shekhar H, Sinha R. Sutureless clear corneal DSAEK with a modified approach for preventing pupillary block and graft dislocation: case series with retrospective comparative analysis. International ophthalmology. 2015;35(2):233-240.
Shih CY, Ritterband DC, Palmiero P-M, et al. The use of postoperative slit-lamp optical coherence tomography to predict primary failure in descemet stripping automated endothelial keratoplasty. American journal of ophthalmology. 2009;147(5):796-800. e1.
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No competing interests reported.

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Outcomes of Sutureless Small Incision Descemet's Stripping Automated Endothelial Keratoplasty: A Retrospective Study

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I. INTRODUCTION

II. MATERIALS AND METHODS

III. RESULTS

IV. DISCUSSION

V. CONCLUSION

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