5 Mastering Descemet Stripping Endothelial Keratoplasty

Descemet stripping endothelial keratoplasty (DSEK), or Descemet stripping automated endothelial keratoplasty (DSAEK), is a technique for partial corneal transplantation. It involves removal of the recipient’s Descemet membrane and endothelium and replacement with donor posterior stroma, Descemet membrane, and endothelium and is currently the surgical procedure choice for endothelial dysfunction.1 However, the surgical technique for DSEK has undergone various transformations, thanks to the efforts of expert corneal surgeons who have been fine tuning and perfecting the procedure over the last 2 decades, before it evolved to DSEK as we know today.²

Prior to the era of endothelial keratoplasty (EK), corneal transplantation was limited to full-thickness penetrating keratoplasty (PKP). The initial series of the “posterior approach” posterior lamellar keratoplasties (PLKs) included deep lamellar endothelial keratoplasty (DLEK),^2,3,4 stemming from the initial experimental attempts by Ko and colleagues on rabbits in 1993.⁵ A similar approach was conceived by Dr. Gerritt Melles of Holland (known as the father of endothelial keratoplasty) and then adopted in the United States by Dr. Francis Price, who termed it Descemet stripping with endothelial keratoplasty, or DSEK.^2,6

As ongoing experimentation and experience with the procedure continued, improved modifications in surgical technique were conceptualized by Dr. Price, including corneal surface massaging and small paracentral keratotomy vent incisions to help remove graft interface fluid and improve adherence and rebubbling for graft detachments.^2,7 Dr. Mark Gorovoy used an artificial anterior chamber and introduced the variant that became known as Descemet stripping automated endothelial keratoplasty, or DSAEK, which included the use of a blade microkeratome for cutting donor grafts. This transition away from manual lamellar dissection improved postoperative outcomes, resulting from more consistent dissection depths and a smoother donor interface.¹

The adoption of DSEK in the United States has been rapid. From 2005 to 2014, the Eye Bank Association of America (EBAA) reported an increase in the number of endothelial transplants from 1429 to 28,961, with a simultaneous decrease in the number of full-thickness PK transplants from 45,821 to 38,919.^8,9 In an era where corneal transplantation is at an all-time explosion in innovation, corneal surgeons worldwide are building upon the foundation of DSEK to create new surgical techniques and inventions and to expand on indications for use.

5.1.2 Indications

With the increasing integration of DSEK into ophthalmology practice, the indications and threshold for use have expanded rapidly. In the mid-1980s and -1990s, pseudophakic and aphakic corneal endothelial decompensation due to cataract surgery or from the use of anterior chamber lenses constituted the primary indications. Today, DSEK is being done more commonly for Fuchs endothelial corneal dystrophy, failed EK grafts, under a previously failed PK or in conjunction with cataract surgery for Fuchs, known more commonly as a DSEK-triple. Rarer indications for DSEK include posterior polymorphous corneal dystrophy (PPCD), congenital hereditary endothelial dystrophy (CHED), and iridocorneal endothelial (ICE) syndrome, in the absence of visually significant corneal scarring.^2,9,10,11

5.1.3 Advantages and Disadvantages

Compared to traditional full-thickness transplantation, EK generally improves vision with lower rates of complication and with a faster visual recovery. This is inherently due to the less invasive nature of EK, allowing for maintenance of the eye and anterior chamber contour throughout the procedure, unlike the “open-sky” approach for PKPs. In maintaining the integrity of the anterior corneal curvature, there is considerably less induced corneal astigmatism, if any. Additionally, EK eliminates the risk of suture-associated complications, notably infection, neovascularization, and rejection.¹²

Given the overall predictability and ease in manipulation of a DSEK corneal donor graft within the anterior chamber, more surgeons continue to perform DSEK over Descemet membrane endothelial keratoplasty (DMEK) as their EK procedure of choice. Though highly controversial and unclear whether graft thickness is clinically important for best corrected visual acuity (BCVA), some corneal surgeons believe that the major disadvantage of DSEK, although less so with ultrathin DSEK, is the limitation in optimal vision due to optical degradation associated with the graft–host lamellar interface or persistent stromal haze. This results from the interface of posterior stromal tissue in a DSEK graft to the recipient stromal tissue.^13,14,15 A retained ophthalmic viscosurgical device (OVD) used during the surgery has also been shown to contribute.^2,16,17,18

The consideration to switch from DSEK to DMEK and pre-Descemet endothelial keratoplasty (PDEK) stems from this concept that these grafts may yield a more direct optical path and offer better visual and refractive outcomes and a faster visual recovery. Additionally, in minimizing the amount of stromal antigens present, there is also a lower graft rejection rate than with DSEK.^19,20,21,22 Nonetheless, at this point in time in current practice, surgeons performing DMEK will often have a DSEK corneal graft available, should the need for conversion to DSEK occur in cases where the DMEK graft does not behave as desired.²³

5.1.4 Preoperative Evaluation

The decision as to what type of anesthesia to choose varies among surgeons and cases. In general, for beginning DSEK surgeons or for complicated cases that are predicted to take longer, local anesthesia with peribulbar or retrobulbar block and adjunct intravenous sedation should be considered. Sometimes even general anesthesia may be needed. For more experienced surgeons, acceptable results and patient comfort are obtained with topical anesthesia in conjunction with intravenous sedation and preservative-free intracameral lidocaine.1^,7,24 Be aware that patients generally will experience the most discomfort during a scleral tunnel wound construction, tissue insertion and manipulation in the anterior chamber, air bubble injection (particularly with firm air fill), and wound suturing.

Additional important considerations include the depth of the chamber, severity of endothelial disease, level of corneal scarring and visibility into the anterior chamber, status of the other eye, shape of the pupil, and lens status. If the indication for DSEK is a failed graft, knowing the previous size of the graft will help plan the size for descemetorhexis and graft diameter.

If phakic with a higher-grade cataract, in the setting of endothelial disease, a DSEK triple procedure, involving cataract extraction with intraocular lens (IOL) implantation, may be indicated. With DSEK, the shape of the lenticule may produce a hyperopic shift. Targeting a spherical equivalent of approximately −1.00 when choosing the IOL will generally minimize a hyperopic surprise. The grading of the cataract, endothelial disease, guttae, level of edema, and scarring should be noted and are critical for determining whether to use two procedures—DSEK followed by cataract removal, cataract removal followed by DSEK, or a single DSEK-triple.^25,26 With regard to order, a DSEK followed by cataract extraction and IOL implantation performed as two separate procedures allows for more accurate corneal topography and IOL measurements and optimizes postoperative visual outcomes. Cataract extraction and IOL implantation followed by DSEK is the ideal route for mild endothelial disease, where a DSEK may not be needed.

Generally, a DSEK-triple is elected in the presence of endothelial dysfunction and a cataract and has been shown to be as effective as DSEK alone. Given the ease of carrying out DSEK today, cataract extraction alone is attempted only if endothelial compromise and corneal guttata are minimal, in the setting of Fuchs. Additionally, in cases where there are anesthesia risks or the patient experiences difficulty in remaining in the supine position for prolonged periods, the threshold to proceed with a DSEK-triple is lowered.

5.1.5 Medical Management of Endothelial Disease

Prior to delving into surgical intervention for corneal edema secondary to endothelial corneal disease or decompensation, it is important to recognize that, in clinical practice, a stepwise approach to management includes first attempting medical interventions to treat corneal edema in order to improve visual outcomes. Identifying the etiology for corneal decompensation is critical to effective management. Depending on the etiology, medical interventions for corneal edema include topical sodium chloride 5% dehydrating drops and ointments, intraocular pressure–lowering agents, topical steroids, and evaporative techniques (e.g., use of a hair dryer to dry the cornea), in cases of Fuchs endothelial corneal dystrophy, and supportive treatment for ruptured bullae in the same manner as for a corneal abrasion include topical antibiotics, cycloplegics, and a bandage contact lens. Alternative nonmedical therapies include excimer laser phototherapeutic keratectomy (PTK), amniotic membrane graft, and/or a conjunctival flap, depending on the underlying etiology and degree of condition severity.²⁷

5.2 Surgical Technique: DSEK Step by Step

In DSEK, the Descemet membrane and endothelium are stripped in the host eye (descemetorhexis), producing a smooth posterior stream bed in the host.²⁸

An automated microkeratome is used to prepare the donor tissue, producing a smoother stream bed and potentially less irregularity in the graft–host interface, carried out either by the surgeon or previously prepared from an eye bank. The order of whether to prepare the host cornea or donor graft first is surgeon dependent. Host preparation first minimizes corneal tissue wastage should the decision be made not to proceed further with the case, while preparing the graft first ensures that the host Descemet membrane and endothelium are removed only once the graft has been confirmed to be present and appropriately prepared for use. The donor tissue is then inserted into the anterior chamber and attached to the host posterior stroma.

5.2.1 Host Preparation

Corneal Marking

Ink an 8–0 corneal marker 360 degrees and center onto the cornea. This will be the landmark for descemetorhexis creation and scoring (► Fig. 5.1).

Fig. 5.1 Steps of host preparation in a Descemet stripping endothelial keratoplasty (DSEK)-triple procedure. (a) An 8–0 corneal marker is inked with a marking pen and (b) corneal marker centered and applied on the cornea. (c) Two short, vertically positioned paracenteses are made adjacent to the limbus, approximately 120 to 180 degrees apart. (d,e) Cataract extraction with intraocular lens implant is then carried out. (f,g) The Descemet membrane is scored using a bent 25-gauge needle through each of the paracenteses. (h) A 23-gauge Gorovoy irrigating Descemet stripper cannula is used to remove the host Descemet membrane and endothelium. Residual Descemet membrane is removed with forceps followed by irrigation aspiration. (k) Air is injected into the anterior chamber to detect remnants and to test whether the air bubble will hold post–graft placement. (l) The main wound is then enlarged under an air bubble.

Stay updated, free articles. Join our Telegram channel

Join