Graph shows visual recovery after Descemet membrane endothelial keratoplasty (DMEK). BCVA indicates best-corrected visual acuity.
Slitlamp view of the cornea 1 month after Descemet membrane endothelial keratoplasty (patient 7). Note that the transplanted cornea is clear with an invisible anatomical interface between the donor and host tissues. In the periphery, the donor Descemet membrane (white arrows) overlaps the recipient Descemet membrane (black arrows), from which the central part has been removed by descemetorhexis during the surgery.
Optical computed tomographic image of the cornea 3 months after Descemet membrane endothelial keratoplasty (patient 18). Note the absence of a visible interface between the donor Descemet membrane and the overlying recipient posterior stroma.
Ham L, Balachandran C, Verschoor CA, van der Wees J, Melles GRJ. Visual Rehabilitation Rate After Isolated Descemet Membrane TransplantationDescemet Membrane Endothelial Keratoplasty. Arch Ophthalmol. 2009;127(3):252-255. doi:10.1001/archophthalmol.2008.619
To evaluate visual rehabilitation after Descemet membrane endothelial keratoplasty (DMEK) in the management of corneal endothelial disorders.
In this prospective, nonrandomized, clinical study, DMEK was performed in a first group of 35 consecutive patients with either Fuchs endothelial dystrophy or bullous keratopathy. The Descemet membrane was stripped from the recipient posterior stroma with the anterior chamber completely filled with air. Using a 3.0-mm clear corneal incision, an organ-cultured donor Descemet roll 9 to 10 mm in diameter was inserted into the recipient anterior chamber, positioned on the posterior stroma, and secured by completely filling the anterior chamber with air for 45 to 60 minutes.
Ten eyes had preexisting ocular disease or an early graft detachment. In the remaining 25 DMEK-treated eyes, best-corrected visual acuity was 20/40 (Snellen notation, 0.5) or more in 18 eyes (72%) within 1 month. At 3 months, best-corrected visual acuity was 20/40 (0.5) or more in 23 of 25 eyes (92%) and 20/25 (0.8) or more in 15 of 25 eyes (60%).
In most cases, DMEK results in functional visual rehabilitation within 1 to 3 months. Overall, visual recovery after DMEK may be faster and more complete than with other techniques for (lamellar) keratoplasty for treatment of corneal endothelial disorders.
clinicaltrials.gov Identifier: NCT00521898
Since 1998, we have introduced various concepts for posterior lamellar keratoplasty that enable replacement of the diseased corneal endothelium without corneal surface incisions or corneal sutures in the management of either Fuchs endothelial dystrophy and bullous keratopathy. In 1998, we introduced a technique in which an unsutured posterior lamellar disc could be transplanted through a 9.0-mm sutured scleral incision,1- 3 later popularized as “deep lamellar endothelial keratoplasty” (DLEK).4 In 2000, we modified the technique so that a folded taco-shaped posterior transplant was inserted through a self-sealing scleral tunnel incision and unfolded in the anterior chamber,5 later popularized as “small-incision DLEK.”6 In 2003, we described how the insertion of a folded donor posterior disc could be combined with descemetorhexis,7,8 a technique currently referred to as “Descemet stripping (automated) endothelial keratoplasty” (DSEK or DSAEK).9,10
Although these early endothelial keratoplasty techniques showed the feasibility of transplanting an unsutured donor posterior corneal disc, we assumed that selective transplantation of only the Descemet membrane (DM) and its endothelium would provide the best possible recovery of the optical performance of a cornea in endothelial disorders.11- 13 To test this hypothesis, we prospectively studied the visual rehabilitation rate after selective transplantation of the DM with its donor endothelium, tentatively termed “Descemet membrane endothelial keratoplasty” (DMEK).14- 16
From a first group of 35 consecutive patients who underwent DMEK,14 10 patients had concomitant ocular disease or early postoperative graft detachment. Hence, 25 patients (15 men and 10 women; age, 41 to 88 years) with either Fuchs endothelial dystrophy or pseudophakic bullous keratopathy were enrolled in our prospective study (Table). All patients signed an institutional review board–approved clinical research informed consent form. All DMEK procedures were performed by the same surgeon (G.R.J.M.), and the surgical procedures were the first series of DMEKs performed by that surgeon.
From donor globes obtained fewer than 36 hours postmortem, corneoscleral buttons were excised and stored by organ culture in modified Eagle minimum essential medium at 31°C.15,17 After 1 week of culture, endothelial cell structure and viability were evaluated and the corneoscleral buttons were mounted endothelial side up on a custom-made holder with a suction cup. The DM was stripped from the posterior stroma so that a 9.5-mm-diameter flap of posterior DM with its endothelial monolayer was obtained.18 Because of the elastic properties of the membrane, a Descemet roll formed spontaneously, with the endothelium at the outer side. Each Descemet roll was then stored free floating in organ culture medium until transplantation 5 to 10 days later.
In recipient eyes, a 9.0-mm-diameter epithelial mark was made to outline the area of DM excision. A 3.0-mm tunnel incision was made just within the limbus, entering the anterior chamber just at the mark. With an inverted Sinskey hook (DORC [Dutch Ophthalmic Research Center International], Zuidland, the Netherlands), a circular portion of the DM was scored and stripped from the posterior stroma so that a 9.0-mm-diameter descemetorhexis was created, and the central portion of the DM was removed from the eye.7,8
The donor Descemet roll was stained with a 0.06% trypan blue solution (VisionBlue; DORC) and sucked into a custom-made injector (Hippocratech, Rotterdam, the Netherlands) to transfer the tissue from the culture medium vial to the anterior chamber.11- 15 Using the injector, the donor Descemet roll was inserted into the anterior chamber and the graft was oriented endothelial side down (donor DM facing recipient posterior stroma) using careful indirect manipulation of the tissue with air and fluid. While maintaining the anterior chamber with fluid and air, the graft was gently spread out over the iris. An air bubble was injected underneath the donor DM to position the tissue onto the recipient posterior stroma.11- 15 The anterior chamber was completely filled with air for 45 to 60 minutes, followed by an air-liquid exchange to pressurize the eye.
Of 35 consecutive patients (35 eyes) who underwent DMEK, 4 eyes were excluded from the analysis because of limited visual potential. Six eyes showed incomplete attachment of the donor graft to the posterior side of the recipient stroma, or the grafted cornea did not clear within 2 to 3 weeks. In these eyes, a second transplantation procedure was performed using DSEK.7- 10
In the remaining 25 eyes in which DMEK was performed, 18 eyes (72%) achieved a best-corrected visual acuity of 20/40 (Snellen notation, 0.5) or better within 1 month (Figure 1 and the Table). Within 3 months, 23 of the 25 eyes (92%) achieved a best-corrected visual acuity of 20/40 (0.5) or better, and 15 of the 25 eyes (60%) achieved a best-corrected visual acuity of 20/25 (0.8) or better (Figure 1 and Table). Usually the level of anatomical restoration was so high that only the edges of the transplant could be visualized at slitlamp examination (Figure 2), whereas the graft could not be identified with imaging techniques (Figure 3).
Findings in our first series of patients who underwent DMEK showed that, if an eye has good visual potential and if the DMEK transplant is attached in the early postoperative phase and is functional, 90% of eyes achieved Snellen acuity of 20/40 (0.5) or better within 3 months, the threshold for a driver’s license in many countries. More importantly, 60% of eyes achieved a visual acuity of 20/25 (0.8) or better within 1 to 3 months. In 2 eyes, visual recovery was incomplete at 3 months: 1 eye (patient 10) had a partial detachment of the DM transplant and, in another eye (patient 2), relatively low visual acuity was achieved despite good anatomical restoration of the transplanted cornea.
Visual rehabilitation after DMEK may exceed that after conventional penetrating keratoplasty (PK) and earlier endothelial keratoplasty techniques such as DLEK and DSEK or DSAEK. Although a visual acuity of 20/40 or better at 6 months has been reported in more than 60% of eyes that underwent DSEK or DSAEK,9,19- 22 few eyes may achieve a visual acuity of 20/25 or better. After PK, only 40% to 50% of eyes may achieve a visual acuity of 20/40 or better at 1 year.23 Furthermore, the outcome after PK may be overrated in the literature because the final postoperative visual acuity often requires high cylindrical corrections that are not tolerated binocularly because of anisotropia. Thus, the true percentage of eyes with a binocular functional outcome of 20/40 or better after PK may be lower.24
Compared with PK and DSEK or DSAEK, care after DMEK may be further reduced because the procedure can be performed through a 3.0-mm self-sealing clear cornea tunnel incision. As a result, there is little change in the refractive power and minimal induced astigmatism; thus, most patients can continue to use their preoperative eyeglass corrections for up to 3 months after surgery or until new eyeglasses are prescribed.25,26
In our study, early graft detachment and preexisting ocular diseases affecting the visual potential and corneal decompensation immediately after cataract surgery, were used as exclusion criteria because the objective of our study was to determine the visual rehabilitation that could be achieved with DMEK. A relatively high number of patients referred to our institute for endothelial keratoplasty had concomitant ophthalmic conditions. Inclusion of these groups would result in uncertainty about the cause of reduced visual acuity after transplantation. For example, in patient 2, incomplete visual recovery can probably be attributed to atrophic changes in the macula that could not be visualized before transplantation because of the presence of corneal edema.
In particular, the presence or absence of cataract may complicate endothelial keratoplasty. If a patient has Fuchs endothelial dystrophy combined with cataract, cataract extraction may be performed before commencing DMEK for 2 reasons. First, 10% to 30% of eyes will achieve satisfactory visual acuity after cataract extraction, allowing postponement of transplantation and averting its long-term disadvantages. Second, a combined procedure (eg, phacoemulsification and DMEK in 1 surgical session) may be averted because the use of viscoelastic during the procedure is prone to graft detachment.13 With Fuchs endothelial dystrophy in the presence of a clear crystalline lens, leaving the crystalline lens in situ has the advantage of maintaining some accommodative power (patients 6, 8, 18, and 20; Table). However, virtually all phakic patients with DMEK in our series developed some anterior subcapsular lens opacity despite pupillary constriction during surgery, which may be attributed to mechanical damage by the stationary air-fill of the anterior chamber at the end of the procedure and/or the use of corticosteroid therapy postoperatively.
In endothelial keratoplasty, the various procedures available may have led to a different scope of surgical indications. A limiting factor of DMEK is the need for at least some corneal transparency to enable detailed visualization of the thin graft during surgery. Patients with Fuchs endothelial dystrophy with limited edema but good visual potential may, therefore, be considered eligible for DMEK. In more complicated cases with limited visual potential, DSEK or DSAEK may still be the preferred treatment method. For example, in patients with long-standing pseudophakic bullous keratopathy with limited corneal transparency, the thicker DSEK or DSAEK graft is more easily visualized than an isolated donor DM in DMEK. In patients with advanced glaucoma in the presence of a draining device (tube) or with an extremely shallow anterior chamber, unfolding of the graft can be much more challenging in DMEK than in DSEK or DSAEK. As a consequence, future comparison of the visual outcome with various techniques may be biased by patient selection.
In conclusion, although the incidence of DMEK graft detachment has declined in the last 2 years, early detachment remains the most challenging problem in DMEK, requiring repositioning or retransplantation.27 However, our study shows that, 10 years after the first endothelial keratoplasty series was performed, the concept has evolved to the point where most patients obtain functional visual rehabilitation within 1 to 3 months after surgery.
Submitted for Publication: June 23, 2008; final revision received July 17, 2008; accepted July 17, 2008.
Corresponding Author: Gerrit R. J. Melles, MD, PhD, Netherlands Institute for Innovative Ocular Surgery, Laan op Zuid 88, 3071 AA, Rotterdam, the Netherlands (http://www.niios.com).
Financial Disclosure: Dr Melles is a consultant for DORC [Dutch Ophthalmic Research Center International BV]/Dutch Ophthalmic USA.