Purpose
To compare the long-term results of Descemet’s stripping automated endothelial keratoplasty (DSAEK) and Descemet’s membrane endothelial keratoplasty (DMEK) in fellow eyes for treatment of Fuchs endothelial corneal dystrophy.
Methods
This study is a 2-centered, retrospective case series of 64 patients (128 eyes) with DSAEK followed by DMEK. The main outcomes measured were best spectacle-corrected visual acuity (BSCVA) and duration of time to achieve BSCVA as well as eye preference.
Results
Preoperative median logarithm of the minimum angle of resolution (logMAR) BSCVA was similar in eyes receiving DMEK 0.36 ± 0.26 and DSAEK 0.42 ± 0.34 ( P = .266). The average follow-up time needed for the DMEK eyes to achieve BSCVA was faster than that of DSAEK (277 days vs 490 days, P = .0014). With long-term follow-up, the BSCVA of the DMEK eyes [0.09 ± 0.10 logMAR] and DSAEK eyes [0.11 ± 0.16 logMAR] did not show a statistically significant difference ( P = .069). Twenty-two of the 64 preferred the DMEK eye, 17 patients preferred the DSAEK eye ( P = .423), and 25 patients did not have a preference. In the DMEK group, the average spherical equivalent was −0.08 compared with the DSAEK group at 0.06 ( P = .2854).
Conclusion
In our fellow eye study with long-term follow-up, DMEK and DSAEK had comparable levels of BSCVA and patient satisfaction. The DMEK eyes reached their BSCVA sooner, whereas the DSAEK eyes improved over a longer time frame. A greater number of patients had 20/25 and 20/20 vision in the DMEK group; however, the difference was not statistically significant. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
E E ndothelial keratoplasty (EK) was developed to remove and replace the pathologic sections of the cornea while maintaining the healthy tissue. It has largely supplanted full thickness penetrating keratoplasty (PK) for the treatment of Fuchs endothelial corneal dystrophy (FED). As compared with PK, EK has a more rapid rehabilitation and predictable refractive outcome, eliminates suture-related complications, and has less incidence of graft rejection.
Posterior lamellar surgery was first performed by Charles Tillet in 1956, but the technique lay relatively dormant until Gerritt Melles reintroduced posterior lamellar keratoplasty (PLK) in 1999. Mark Terry modified the technique, which he renamed as deep lamellar endothelial keratoplasty (DLEK). Gerrit Melles first described stripping of the host Descemet membrane and endothelium (descemetorhexis), which he called Descemet stripping endothelial keratoplasty (DSEK) in 2005. Francis Price first reported a series of patients undergoing DSEK in the United States and described it as a refractively neutral corneal transplant. Mark Gorovoy further modified the DSEK procedure by using a microkeratome to prepare the donor tissue that he called “Descemet stripping automated endothelial keratoplasty” (DSAEK). The combination of the descemetorhexis and microkeratome-prepared donor tissue led to its wide adoption. Gerrit Melles further modified EK when he described stripping of the donor tissue to transplant only the Descemet membrane and endothelium (DMEK) providing an intuitively near-perfect anatomic restoration of the cornea. , ,
DSAEK is still the most common EK procedure performed because of familiarity of many surgeons with the technique, its adaptability to abnormal anterior segment anatomy, the technical challenges with the placement of the DMEK donor tissue, and the increased complexity in management of the postoperative graft detachments , (see Table 1 ). Through the efforts of many surgeons, and in particular Mark Terry, innovations and standardization of the technique of the steps of the surgery have increased the utilization of DMEK surgery.
| Domestic Surgery Use | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 |
|---|---|---|---|---|---|---|---|
| Total endothelial keratoplasty procedures | 24,987 | 25,965 | 27,208 | 28,327 | 28,991 | 30,336 | 30,650 |
| DSEK, DSAEK, DLEK procedures | 23,465 | 23,100 | 22,514 | 21,868 | 21,337 | 19,526 | 17,428 |
| DMEK or DMAEK procedures | 1,522 | 2,865 | 4,694 | 6,459 | 7,628 | 10,773 | 13,215 |
| PDEK | 21 | 26 | 6 | ||||
| Other EK | 7 | 11 | 1 |
There have been numerous clinical series comparing the relative strengths and drawbacks of DSAEK vs DMEK. The majority of these series compare 2 groups of patients, or in smaller series, fellow eye cohorts. In general, these studies demonstrate that DMEK provides more rapid visual rehabilitation with higher patient satisfaction at 6- to 12-month follow-up. However, there are only a limited number of studies showing long-term outcomes in these procedures.
The purpose of this study is to compare the long-term outcome of DSAEK vs DMEK. In our clinical experience, we noticed that the eyes undergoing DSAEK continued to show improvement for several years postoperatively. We hypothesized that with longer follow-up, the visual outcomes between DSAEK and DMEK would be more closely aligned. To test our hypothesis we performed a review of all patients who underwent DSAEK and DMEK in our practices and isolated a subgroup of patients who had undergone DSAEK in one eye and DMEK in the second eye for the treatment of Fuchs corneal dystrophy. We were able to identify 64 patients with at least 5-year follow-up in the DSAEK eye and performed a chart review of those patients as well as seeing them for follow-up in the clinic. We recorded the best spectacle-corrected visual acuity (BSCVA), refractive error, and duration of time to achieve the BSCVA. We asked the patients which eye they thought was the better eye with their BSCVA. In a subgroup of these patients, we analyzed the thickness of the donor tissue used in DSAEK.
METHODS
This study is a 2-centered, retrospective case series of patients who initially underwent DSAEK for FED followed by DMEK in the fellow eye, performed by 2 surgeons (R.W.W. and D.D.V.) from 2010 to 2018. The size of the study was determined by the number of patients who fit the criteria for inclusion and had at least 5-year follow-up in the DSAEK group. No sample size calculation was performed. The project was approved by the SUNY Upstate IRB (Syracuse, New York) and Advarra IRB (Columbia, Maryland) and published on IRB Net.
One hundred and twenty eyes in 64 patients were identified. Preoperative BSCVA was recorded as well as the procedure performed, and eye, sex, age, and any associated ocular comorbidities. At each visit, the patient underwent a slit lamp examination and intraocular pressure reading. A refraction was performed starting at 1 month postoperatively and then at each subsequent visit. The patients’ uncorrected and best corrected visual acuity was recorded as well as any ocular comorbidities. In addition, each patient was asked to evaluate which eye he or she preferred with the best spectacle-corrected vision. The vision was measured in Snellen acuity and then converted to the logarithm of the minimum angle of resolution (logMAR) for statistical analysis. In one clinic (R.W.W.), all patients underwent a corneal OCT (optical coherence tomography; Optovue, Fremont, California, USA) at each postoperative visit. In these patients, the lenticular thickness of the DSAEK lenticule was measured and followed over time.
Analyses and graphs were performed using Excel (Microsoft Corp, Redmond, Washington, USA) and SPSS software, version 19.0 (SPSS Inc, Chicago, Illinois, USA). Descriptive statistics are reported as the mean ± standard deviation (SD) for continuous variables and count (%) for categorical variables. Paired 2-tailed t -tests were used to assess differences in continuous parameters, and McNemar tests were used to compare categorical variables. A P value of .05 was selected for the threshold of statistical significance.
Surgical Techniques
DSAEK
All surgeries were performed under monitored anesthesia care. Twenty minutes before surgery a retrobulbar block was administered with a 50:50 mixture of lidocaine 2% with epinephrine and bupivacaine 0.5% (Edge Pharma, Syracuse, NY, USA). A pressure patch was applied to allow the anesthetic to diffuse.
After being taken to the operating room, the patients were prepped and draped in the standard fashion. Initially, a crescent blade was used to make a partial thickness groove 5 mm in length in clear cornea temporally, and then 2 vertical paracentesis incisions were made 2 clock hours from the main incision with a 15-degree blade. An ink marked dull 8.0-mm trephine (Katena, Parsippany, New Jersey, USA) was used to mark the central cornea. The previously made groove was entered with a 2.6-mm keratome. Either air or cohesive viscoelastic was injected to stabilize the anterior chamber and facilitate stripping. A reverse Sinskey hook was used to outline and initiate a 5-mm central descemetorhexis in one center (R.W.W.) and an 8-mm central descemtorhexis in another center (D.D.V.). This was completed using either a tying forceps or a 23-gauge Gorovoy Irrigating Descemet stripper (Walcott Rx Products, Ocean View, New Jersey, USA), and then the Descemet membrane and endothelium was removed. An irrigating aspirating handpiece was used to evacuate the cohesive viscoelastic or air. If the view was poor due to long-standing corneal edema, VisionBlue (DORC, Exeter, NH, USA) was used to ascertain whether there were any residual Descemet tags or islands of residual Descemet tissue.
A Barron corneal punch (Katena) was used to excise an 8- or 8.5-mm donor lenticule depending on the corneal diameter. The precut donor button was obtained from either the Central New York Eye Bank or the Eversight Eye Bank in Ann Arbor, Michigan. The donor tissue had a specular cell count >2000 mm 2 . After extension of the corneal incision to 5 mm, the tissue was inserted by 1 of 2 methods. In the first, a sheets glide was placed through the incision and into the anterior chamber. Cohesive viscoelastic was placed over the sheets glide as well as on the donor endothelium, and the donor tissue was brought into the field using a spoon. It was placed endothelial side down and then slid into the anterior chamber using a bent 27-gauge needle. The tissue would unfold spontaneously after the glide was removed, and a single 10 nylon suture (Ethicon Inc, Somerville, New Jersey, USA) was placed in an X fashion partially closing the wound. Alternatively, a Charlie 2 forceps (Storz Ophthalmic Instruments; Bausch & Lomb, California, USA) was used to grasp and place the donor graft into the eye through a 5-mm incision.
Air was injected under the donor corneal tissue levitating the tissue against the host cornea and the tissue was manipulated so that it was well centered. A second 10 nylon suture was placed completely closing the incision. Additional air was injected into the eye placing the tissue against the host cornea in the proper position. A roller was used to squeegee any residual fluid from the interface. Topical cyclopentolate drops (CuraScript SD, Lake Mary, Florida, USA) were placed to dilate the pupil. After 10 minutes, a partial air fluid exchange was performed to maintain the intraocular pressure and reduce the air fill sufficiently to prevent pupillary block. Topical tobramycin 0.3% and dexamethasone sodium phosphate 0.1% (Tobradex; CuraScript SD) drops were given as well as another drop of cyclopentolate. A pressure patch was applied, and the patient was taken from the operating room on a stretcher and left in the recovery room for an hour in a supine position. After an hour, the patient was checked at a slit lamp to ensure that the tissue was in good position without signs of pupillary block. Additional tobramycin 0.3% and dexamethasone sodium phosphate 0.1% (Tobradex; CuraScript SD) was given before either lightly reapplying the pressure patch or taping the eyelid. The patients were then discharged and seen the next day. The patients were maintained on tobramycin 0.3% and dexamethasone sodium phosphate 0.1% 4 times a day for 1 week and then changed to prednisolone forte 1% solution initially 4 times a day and then tapered to once per day over the course of 1 year.
DMEK
All surgeries were performed under monitored anesthesia care. Before going to the operating room, a laser peripheral iridectomy was created inferiorly using a yttrium-aluminum-garnet laser in 30 patients or a peripheral iridectomy was created intraoperatively in 34 patients. Two drops of pilocarpine 1% were used to constrict the pupil.
In all cases, a retrobulbar block was administered with a 50:50 mixture of lidocaine 2% with epinephrine and bupivacaine 0.5% 20 minutes before surgery. A pressure patch was applied to allow the anesthetic to diffuse. The patients were then brought into the operating room and prepped and draped in the usual sterile fashion. The donor tissue was prepared first. The donor button obtained from the University of Iowa Eye Bank or the Eversight Eye Bank had been partially stripped, and an S stamp placed and then precut to 8.0 mm, with a specular cell count >2000 mm 2 . Using a tying forceps the endothelium and Descemet membrane was gently lifted under balanced salt solution (BSS) and then the remainder of the donor cornea was removed. The donor Descemet membrane and endothelium was then replaced in the donor block. VisionBlue solution (DORC) was added to the BSS to stain the tissue.
Attention was then turned to the patient. The host cornea was lightly ink marked with a reusable slightly dulled 8.5-mm trephine serving as a template for Descemet’s striping. A 3.0-mm groove was made at the limbus temporally using a crescent blade. Two horizontal paracentesis incisions were made 2 clock hours from the main incision with a 15-degree blade. A 2.6-mm keratome was then used to enter the anterior chamber through the partial thickness groove. Cohesive viscoelastic or air was placed in the anterior chamber. A reverse Sinskey hook was used to score and initially strip the Descemet membrane. A 23-gauge Gorovoy Irrigating Descemet stripper (Walcott Rx Products, Ocean View, NJ, USA) or a tying forceps was used to complete the central 8.5-mm descemetorhexis. The viscoelastic or air was removed with an irrigation-aspiration handpiece. If the view was poor, trypan blue was used to ensure that there were no residual islands or tags of the Descemet membrane present.
The donor tissue was then prepared for placement. BSS was used to irrigate around the tissue diluting the trypan blue. Gentle aspiration was then used to suction the tissue into a Straiko modified Jones tube apparatus (GWSG, Portland, Oregon, USA). After extension of the clear corneal incision to 3.2 mm, the tube apparatus was then placed through the incision temporally and the donor tissue gently irrigated into the anterior chamber. The temporal incision was closed with a 10-0 nylon suture (Ethicon Inc). Using a no touch tapping technique and gentle irrigation, the tissue was unfolded and centered in the proper orientation verified by the S stamp. A small air bubble was injected underneath the tissue levitating it against the host cornea, and then a more complete fill was performed using 20% SF6 gas. The gas bubble was left in the anterior chamber for 10 minutes after which the bubble was reduced to 80%. Tobramycin 0.3% and dexamethasone sodium phosphate 0.1% (Tobradex; CuraScript SD) drops were then applied. The eye was patched and shielded, and the patient transferred on a stretcher to the recovery area. After 1 hour supine, the patient was examined at the slit lamp to ensure that the tissue was in good position and the gas bubble was superior to the inferior peripheral iridectomy. Before gentle reapplication of the patch or taping of the eyelid, an additional drop of tobramycin-dexamethasone sodium phosphate was given. The patients were then discharged to be seen the following day. At that appointment, the tobramycin-dexamethasone drop was continued 4 times a day for a week and then changed to prednisolone phosphate starting 4 times a day and then tapered to once per day over the course of 1 year.
Triple procedure: combined with phacoemulsification with placement of an intraocular lens
A combined procedure was performed in addition to DSAEK and DMEK in some eyes. In all cases, the phacoemulsification with intraocular lens implantation was performed first. If the patient was undergoing DSAEK, the pupil was dilated with mydriacyl 1% (CuraScript SD) and phenylephrine hydrochloride 2.5% (CuraScript SD) before entering the operating room. If the patient was undergoing DMEK, no dilating drops were given, and instead, after placement of the temporal groove and the paracentesis incisions as described above, lidocaine 4% preservative free, epinephrine 1:1000 preservative free, and BSS (mixed 1:1:3) (Edge Pharma) were injected into the anterior chamber to dilate the pupil.
In all cases of DSAEK and DMEK, cohesive viscoelastic was placed in the anterior chamber. A sharp Utrata forceps was used to initiate and complete a continuous curvilinear capsulorhexis. BSS was injected for hydrodissection, and the nucleus was then rotated. Phacoemulsification of the nucleus was performed using a chop technique to fragment and remove the nucleus. The residual cortical material was removed with irrigation and aspiration. After capsular polishing, cohesive viscoelastic was used to facilitate injecting the intraocular lens into the capsular bag. The residual viscoelastic was then removed from the anterior chamber with the I/A handpiece. Miochol (CuraScript SD) was then injected into the anterior chamber to constrict the pupil, and then either the DSAEK or DMEK procedure was performed in the manner described above.
RESULTS
The demographic data of all patients are described in Table 2 . One hundred and twenty-eight eyes of 64 patients (40 female and 24 male) aged 70.18 ± 9.61 years (range, 44-89 years) were included. All patients were diagnosed with FED. Twenty-nine patients underwent DMEK alone and 35 patients had DMEK combined with phacoemulsification and posterior chamber intraocular lens implantation. Thirty-three patients had the DSAEK procedure alone and 31 patients had DSAEK combined with phacoemulsification and posterior chamber intraocular lens implantation. There were no intraoperative complications in either group.
| Variables | DMEK (n = 64) | DSAEK (n = 64) |
|---|---|---|
| Women, No. (%) | 40 (62.5) | 40 (62.5) |
| Age, mean (SD) (y) | 70 (10) | 68 (10) |
| Eyes (OD:OS) | 29:35 | 35:29 |
| Combined with cataract extraction (N) | 35 | 31 |
Preoperative BSCVA, operative eye, best postoperative BSCVA, and days required to achieve BSCVA are recorded and summarized in Table 3 . The preoperative BSCVA in the DMEK group was 0.36 ± 0.26 logMAR (Snellen acuity 20/46), compared with the DSAEK group, 0.42 ± 0.34 logMAR (Snellen acuity 20/52). ( P = .266). The average follow-up time for the DMEK eyes was 1311 days (3.6 years) and for the DSAEK eyes 2456 days (6.7 years). The time to achieve BSCVA in the DMEK eyes was 277 days (SD = 308) compared with the DSAEK eyes at 490 days (SD =501) ( P < .0014).
| Variables | DMEK (n = 64) | DSAEK (n = 64) | P Value |
|---|---|---|---|
| Preoperative BSCVA, logMAR (SD) | 0.36 (0.26) | 0.42 (0.34) | .266 |
| Days to achieve BSCVA (SD) | 277 (308) | 490 (501) | .0014 |
| Best Postoperative BSCVA, logMAR (SD) | 0.09 (0.10) | 0.11 (0.16) | .069 |
| Number achieved >20/25 vision (%) | 47 (73) | 41 (64) | .2008 |
| Number achieved 20/20 vision (%) | 33 (51) | 26 (41) | .0896 |
| Average total follow-up time days (SD) Years | 1311 (553) 3.6 y | 2456 (705) 6.7 y | <.0001 |
| Patient preference of procedure (N) | 22 | 17 (25 same) | .423 |
| Postoperative manifest SE (SD) | −0.08 (1.2) | 0.06 (1.2) | .2854 |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
