Objectives: In this study, we report our experience at King Hussein Medical Center with Descemet stripping automated endothelial keratoplasty.

Materials and Methods: This study was conducted at King Hussein Medical Center of the Royal Medical Services during the period between January 2015 and January 2016. Patients who underwent Descemet stripping automated endothelial keratoplasty were enrolled in the study. We performed a comprehensive overview of the advantages of the surgery and analyzed the donor tissue selection criteria, indications, detailed surgical techniques of the procedure, and surgical outcomes.

Results: Our cohort included 13 patients. We had successful results for all of our patients, with final visual acuity of more than 6/12. The 2 indications for surgery were pseudophakic bullous keratopathy and Fuchs endothelial dystrophy.

Conclusions: Descemet stripping automated endothelial keratoplasty is becoming a revolutionary procedure in corneal surgery and replacing penetrating keratoplasty in many clinical situations.

Key words : Bullous, Endothelium, Fuchs, Recipient

Introduction

Partial thickness corneal surgery has evolved rapidly in the past 2 decades, replacing penetrating kera­toplasty, the criterion standard for many decades.¹ In 1998, posterior lamellar keratoplasty as first partial thickness procedure was used.² Other partial thick­ness procedures are deep lamellar endothelial keratoplasty, Descemet stripping endothelial kera­toplasty,³ Descemet stripping automated endothelial keratoplasty (DSAEK),⁴ Descemet membrane endo­thelial keratoplasty (DMEK),⁵ Descemet membrane automated endothelial keratoplasty,⁶ and DMEK without microtome.⁷

Descemet stripping automated endothelial kera­toplasty is a modified technique of Descemet strip­ping endothelial keratoplasty, where a microkeratome is used for the donor dissection.⁸ It was first described in 2006 by Dr. Mark Gorovoy.⁴ In the procedure, Descemet membrane and endothelium are stripped from the host cornea and replaced with a donor button consisting of posterior stroma, Descemet membrane, and endothelium. Descemet membrane endothelial keratoplasty is a technique where only Descemet membrane and endothelium are used to replace host tissue of Descemet membrane and endothelium without posterior stroma. A modification of DMEK was described in 2009 where a rim of stroma was left at the periphery of the donor tissue using microkeratome (Descemet membrane automated endothelial keratoplasty) and in 2010 manually without microkeratome.⁷

Among all partial thickness procedures, DSAEK is the most common type of endothelial keratoplasty performed worldwide.⁸ The aim of our study is to report our experience at King Hussein Medical Center with DSAEK.

Materials and Methods

This study was conducted at King Hussein Medical Center of the Royal Medical Services during the period between January 2015 and January 2016. Patients who underwent DSAEK were enrolled in the study. For our patients, we used precut tissue (prepared by the eye bank using a Moria micro­keratome; Moria Surgical, Antony, France). The donor tissue selection criteria were graft thickness < 130 μm, cap size of 9 mm, cell count of 3000 cells, age difference between recipient and host < 10 years, death to preservation < 12 hours, and death to surgery ≤ 5 days.

The surgeries were done under local peribulbar anesthesia, followed by the use of Honan balloon (The Lebanon Corp., Lebanon, PA, USA). The surgery technique that we used was started by creating temporal scleral incision with 5.5 mm width. Recipient descematorhexis was performed with the aid of reverse Sinskey hook and an anterior chamber maintainer. This was followed by inserting DSAEK tissue using a Busin glide (Moria) and pull-through technique. The temporal incision was sutured using 10/0 nylon suture, air was inserted, and complete air fill was maintained for 15 minutes. The air bubble size was reduced, and the patient was kept in the supine position for 1 hour and examined by slit lamp. Dilating drops (10% phenylephrine, 1% tropicamide) were used to avoid pupillary block. The patients were asked to stay in the supine position as much as possible during the first 24 hours to avoid graft detachment.

Patients were followed up postoperatively after1 day, 1 week, 1 month, and then monthly after that. They were prescribed local prednisolone ophthalmic and ofloxacin ophthalmic eye drops after surgery. Investigations done included pentacam and pachy­metry.

Results

Thirteen patients were included in our series. Twelve of the patients had pseudophakic bullous kerato­pathy, and the remaining patient was phakic with Fuchs endothelial dystrophy. We had successful results for all of our patients with final visual acuity of more than 6/12.

Figure 1 shows the preoperative appearance of a patient with pseudophakic bullous keratopathy, and Figures 2 and 3 show the same patient’s post­operative appearance 1 day and 1 month after surgery. The patient’s final visual acuity was 6/9. The patient in our series who had Fuchs endothelial dystrophy showed corneal edema in right eye and guttata in left eye. Figures 4 and 5 show this patient’s pre- and postoperative appearances.

Discussion

Penetrating keratoplasty is a full-thickness corneal transplant procedure. It is still considered as the criterion standard transplant surgery by many surgeons worldwide. There are many disadvantages for the procedure, including expulsive choroidal hemorrhage (0.5%-1%), endothelial graft rejection and failure, decreased survival of regrafts, astig­matism, unexpected refractive outcomes, ocular surface-related problems, frequent visits, wound slippage and traumatic dehiscence, infection, and suture-related problems.

Many of the corneal pathologies are localized either anteriorly or posteriorly. Examples of anterior pathologies are keratoconus, viral keratitis, corneal stromal dystrophies, and degenerations. In such cases, a partial graft or deep anterior lamellar kera­toplasty may be used for better visual outcome. Other indications for deep anterior lamellar keratoplasty are descemetocele, small perforations, and severe thinning where a tectonic graft could be used. Posterior pathologies where DSAEK are indicated include Fuchs endothelial dystrophy, pseudophakic and aphakic corneal edema, endothelial decom­pensation, failed grafts, iridocorneal endo­thelial syndrome, and posterior polymorphous corneal dystrophy.

Advantages of DSAEK include that it allows vision improvement to 6/9 to 6/12, has a lower rejection rate than penetrating keratoplasty, results in faster visual rehabilitation, uses a small incision and astigmatic neutral surgery, and maintains globe integrity and less wound dehiscence. However, DSAEK may still limit the best-corrected vision due to the donor lamellar interface.^9-11

Figures 1 to 3 show our results for a patient with pseudophakic bullous keratopathy. The patient shown in Figures 4 and 5 was a 50-year-old male who had been referred with visual acuity of counting fingers of 0.5 m of the right eye and 6/6 of the left eye. Central corneal thicknesses measured 800 μm in the right eye and 690 μm in the left eye. He was phakic and had diffuse edema in his right cornea and guttata on the left. Pentacam showed anterior chamber depth (ACD) of 3.05 mm in the right eye. He underwent DSAEK, and his final visual outcome was 6/12 after 8 months.

Descemet stripping automated endothelial keratoplasty seems to be superior to penetrating keratoplasty in treating Fuchs endothelial kerato­plasty, although primary graft failure may be more common. Visual recovery is faster, and major ametropia and astigmatism are not induced.^10,12-14

The problem in phakic DASEK is the develop­ment in cataracts in such patients. In our opinion, this procedure should be done by expert surgeons. Usually patients who have phakic DSAEK often need phacoemulsification surgery within 18 to 24 months. Anterior chamber depth measurement is mandatory in such surgeries. Our recommendations are as follows: if ACD is > 3.0 mm, conduct DSAEK alone, depending on the refractive status of the patient; if ACD is 2.5 to 2.99 mm, perform either option, depending on the surgeon’s experience; and if ACD is 2.0 to 2.49 mm, perform phacoemulsification/­DSAEK.

In conclusion, DSAEK is becom ing a revolution­ary procedure in corneal surgery and is replacing penetrating keratoplasty in many clinical situations.

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