Purpose
This study compared the outcomes after Descemet’s membrane endothelial keratoplasty (DMEK) in pseudophakic patients with the outcomes after DMEK combined with cataract surgery (triple-DMEK) in patients with Fuchs’ endothelial dystrophy (FED).
Design
Retrospective, single-institution, interventional, consecutive case series.
Methods
Outcomes of 114 DMEKs in patients with FED at a minimum of 1-year follow-up were reviewed. A total of 34 eyes (29 patients) were pseudophakic and underwent only DMEK (DMEK-only), and 80 eyes (56 patients) underwent triple-DMEK. Main outcome measurements included endothelial cell loss (ECL), best-corrected visual acuity (BCVA), central corneal thickness (CCT), and complications.
Results
At 1 month, ECL was 25% (±16%) and 35% (±15%) in DMEK-only and triple-DMEK groups, respectively. At 1 year, ECL was 33% (±13%) and 41% (±16%) in DMEK-only and triple-DMEK groups, respectively. There was statistically significantly less ECL after DMEK-only than after triple-DMEK at both 1 month (95% confidence interval [CI]: 1.67-15.02; P = .016) and 1 year (95% CI: 1.06-14.07; P = .034). CCT was significantly lower after DMEK-only than after triple-DMEK at 1 month but not at 1 year. BCVA was excellent and similar in the 2 groups. There were no cases of graft failure. Graft rejection and rebubbling rates were similar in DMEK-only and triple-DMEK groups: rejection occured in 8.8% and 8.75% of cases respectively ( P = .50), and rebubbling in 2.9% and 2.5% respectively ( P = .44).
Conclusions
Both the DMEK-only and the triple-DMEK groups had low rebubbling rates and good visual outcomes, but the combined triple-DMEK procedure resulted in significantly greater loss of endothelial cells than DMEK-only surgery at both 1 month and 1 year.
Descemet’s membrane endothelial keratoplasty (DMEK) is regarded as a modern standard in the management of corneal endothelial dysfunction. In DMEK, the endothelium and Descemet’s membrane are replaced with the corresponding layers from a healthy donor cornea, without the additional layer of donor stroma which accompanies DM and endothelium in Descemet’s stripping endothelial keratoplasty. DMEK has been shown to achieve faster visual rehabilitation, better visual outcomes, and lower rates of rejection than Descemet’s stripping endothelial keratoplasty. The reduction reported in endothelial cell density (ECD) following DMEK is 25%-40% within the first 6 months and is comparable to earlier endothelial keratoplasty techniques. The present authors previously noted that variability in donor tissue characteristics such as donor age, endothelial cell counts, and tissue preservation techniques may affect endothelial cell survival during and after the surgery.
The most common indication for endothelial keratoplasty in the developed world is Fuchs’ endothelial dystrophy (FED). , Patients with FED are at higher risk of developing corneal decompensation following cataract surgery. DMEK can be performed as a staged procedure before or after cataract surgery or combined with phacoemulsification in patients with both endothelial dysfunction and cataract. A study by Chaurasia and associates reported similar 6-month outcomes in DMEK in patients who were pseudophakic or undergoing concurrent cataract surgery.
The aim of the present study was to compare 1-month and 1-year outcomes of DMEK-only in pseudophakic eyes versus DMEK combined with cataract surgery (triple-DMEK) with respect to ECD decrease in patients with FED. Best-corrected visual acuity (BCVA), central corneal thickness (CCT), and complications were also recorded.
Subjects and Methods
This study was designed as a single-institution, retrospective, interventional, consecutive case series. It was approved by the authors’ institutional review board and adhered to the tenets of the Declaration of Helsinki. All patients signed an informed consent prior to surgery.
Recruitment and Inclusion
All DMEKs at this institution have been prospectively recorded in an anonymized corneal graft research database. The database was searched for all grafts meeting the following initial inclusion criteria:
Surgery
DMEK with or without combined phacoemulsification cataract surgery. Patients having DMEK-only surgery had all undergone previous cataract surgery with a posterior chamber intraocular lens (IOL) implant.
Indications
Clinically significant FED. The diagnosis of FED was based on the presence of its classical clinical signs and confirmed with in vivo confocal microscopy (IVCM) if there was any doubt. In pseudophakic cases, FED was differentiated from pseudophakic bullous keratopathy by the presence of the clinical signs of FED in the fellow eye or by IVCM demonstrating the classic strawberry-like pattern of FED, rather than the polymegathism and enlarged endothelial cells seen with pseudophakic bullous keratopathy.
Follow-up
At least 1 year of follow-up data available. A total of 114 DMEK grafts that met the inclusion criteria were divided into 2 groups: there were 34 eyes of 29 patients in the DMEK-only group and 80 eyes of 56 patients in the triple-DMEK group.
Study Outcomes
The main outcome of the study was a comparison of mean endothelial cell loss (ECL) between the 2 groups at 1 month and at 1 year. ECL was calculated by comparing the 1-month and 1-year ECD with the donor ECD by using IVCM. Additional outcome measurements included postoperative BCVA, slit lamp biomicroscopy, and measurement of CCT using pachymetry. The incidence of postoperative complications was also reported, specifically the rates of rebubbling, graft rejection and graft failure.
Statistics
All statistical analyses were performed using Prism version 8.0.1 software (GraphPad, San Diego, California). Numerical variables were described as mean ± SD for normally distributed data. Normality was confirmed by Shapiro-Wilk testing. A comparison between preoperative and postoperative data was performed using the Student t test and Mann-Whitney U test where applicable. A P value <.05 was considered statistically significant.
Surgical Technique
All operations were performed directly by or under the supervision of a single surgeon (E.J.H.), using a standardized technique. All patients had neodymium-yttrium aluminum garnet (Nd:YAG) laser iridotomy before surgery. Donor preparation was performed immediately before transplantation using the submerged cornea using backgrounds away (SCUBA) technique. In combined cases, phacoemulsification was performed with implantation of a posterior chamber foldable acrylic IOL (Tecnis PCB100; Johnson & Johnson, New Brunswick, New Jersey) and thorough viscoelastic removal. After the patient’s DM was stripped using a reverse Sinskey hook (Duckworth and Kent, United Kingdom), a Geuder injector (Geuder AG, Germany) was used to introduce the donor DM scroll. The graft was positioned centrally using a standardized no-touch technique, as previously described. Air was injected underneath the graft. All corneal incisions were tightly sutured with 10-0 nylon sutures. The anterior chamber (AC) was completely filled with air to a high intraocular pressure (IOP), assessed by digital palpation and was left in place for 10 minutes. Some air was then released to achieve palpably normal IOP.
Follow-Up Protocol
Patients were positioned on their backs for 2 days after surgery. The IOP was checked at 1 to 2 hours postoperatively. If the IOP was above 30 mm Hg, a small amount of air was released. The patients were followed at 1 to 2 days and 1 week and then at 1, 3, 6, and 12 months, with additional visits as clinically indicated. IOP was measured at each visit by Goldmann applanation tonometry. CCT was measured using a Pachmate 2 ultrasonic pachymeter (DGH Technology, Exton, Pennsylvania). ECD was measured at the 1-month and 1-year visits by using IVCM (Confoscan 4 machine; Nidek Technologies, Fremont, California). The best image of the endothelium was chosen from multiple images of the central cornea, and the machine’s automated counting mode was used, with manual correction for any double-counted cells. ECL was calculated using donor ECD as baseline.
Results
Patient demographics and donor details are summarized in Table 1 . The mean age was significantly lower in the triple-DMEK group than in the DMEK-only group (95% CI: −14.13 to −6.301; t test, P < .001).
| Total | DMEK-only Group | Triple-DMEK Group | P Value | |
|---|---|---|---|---|
| Recipients | ||||
| Eyes/patients | 114/86 | 34/30 | 80/56 | – |
| Females | 69 (60.5%) | 19 (55.9%) | 50 (62.5%) | .51 |
| Age, y | ||||
| Mean ± SD | 69.6 ± 10.69 | 76.8 ± 8.2 | 66.6 ± 10.2 | <.0001 |
| Donor | ||||
| Age, y | ||||
| Mean ± SD | 67.7 ± 11.0 | 70.0 ± 9.7 | 66.7 ± 11.5 | .15 |
| ECD, cells/mm 2 | ||||
| Mean ± SD | 2,639 ± 195 | 2,630 ± 194 | 2,643 ± 197 | .75 |
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