|Year : 2020 | Volume
| Issue : 4 | Page : 249-254
Clinical outcome after Descemet membrane endothelial keratoplasty in vitrectomized eyes
Mohamed B Goweida
Department of Ophthalmology, Alexandria Main University Hospital,Department of Ophthalmology, Faculty of Medicine, Alexandria University, Alexandria, Egypt
|Date of Submission||19-Apr-2020|
|Date of Decision||29-Apr-2020|
|Date of Acceptance||27-May-2020|
|Date of Web Publication||28-Dec-2020|
FRCOphth, FRCS(Glasg), PhD, Mohamed B Goweida
Department of Ophthalmology, Alexandria Main University Hospital, 9 Hussein Hassab Street, Bab Sharki, Alexandria 21131
Source of Support: None, Conflict of Interest: None
Purpose The aim of the present study was to evaluate the clinical outcome after Descemet membrane endothelial keratoplasty (DMEK) in eyes with previous vitrectomy.
Patients and methods This is a retrospective review of medical records and surgical videos of all DMEK cases in vitrectomized eyes (total or anterior vitrectomy) that were done at Alexandria Main University Hospital, Alexandria, Egypt, between January 2015 and November 2019. The primary outcome measure was the improvement in best-corrected visual acuity. Secondary outcome measures were unfolding time and technique, endothelial cell loss, and rebubbling rate.
Results A total of 18 vitrectomized eyes of 18 patients with bullous keratopathy were included in this study. Follow-up duration ranged from 6 to 53 months, with a mean of 23.8±15.2 months. At the end of the follow-up, the best-corrected visual acuity improved from 1.9±0.5 log MAR units to 0.7±0.4 log MAR units. The mean endothelial cell density was 1136.6±204.4 cells/mm2, representing 53% loss of the mean preoperative donor endothelial cells (2388.3±114.8 cells/mm2). The mean graft unfolding time was 13.7±5.4 min. A total of 11 (61%) eyes needed rebubbling owing to postoperative Descemet membrane detachment.
Conclusion DMEK is an effective surgical modality for treatment of bullous keratopathy in vitrectomized eyes. Restoration of corneal clarity and significant visual improvement were possible in all patients, despite the need for complex surgical steps, prolonged surgical time, and the increased rebubbling rate.
Keywords: Descemet, ’s membrane, Descemet membrane endothelial keratoplasty, Fuchs’, endothelial dystrophy, pseudophakic bullous keratopathy, vitrectomy
|How to cite this article:|
Goweida MB. Clinical outcome after Descemet membrane endothelial keratoplasty in vitrectomized eyes. Delta J Ophthalmol 2020;21:249-54
|How to cite this URL:|
Goweida MB. Clinical outcome after Descemet membrane endothelial keratoplasty in vitrectomized eyes. Delta J Ophthalmol [serial online] 2020 [cited 2021 Apr 19];21:249-54. Available from: http://www.djo.eg.net/text.asp?2020/21/4/249/304941
| Introduction|| |
Endothelial keratoplasty (EK) has widely replaced penetrating keratoplasty in the surgical management of corneal endothelial disorders such as Fuchs’ endothelial corneal dystrophy and pseudophakic bullous keratopathy. Several techniques of EK have been described including deep lamellar endothelial keratoplasty (DLEK), descemet stripping endothelial keratoplasty (DSEK), descemet stripping automated endothelial keratoplasty (DSAEK), and Descemet membrane endothelial keratoplasty (DMEK) [1-3].
The uniqueness of DMEK over other EK techniques is the full retention of corneal anatomy, allowing the sole replacement of the diseased endothelium and Descemet’s membrane (DM), with a donor endothelium-Descemet membrane (EDM) layer without any posterior stromal lamellae. This selective and anatomical replacement of diseased layers provides several advantages, such as faster and complete visual rehabilitation, lower risk of immunologic rejection, and better quality of vision ,.
Since the introduction of DMEK by Melles et al. ,, its use in practice remained limited for several years. This was attributed to several challenges, including donor graft preparation, difficulties in handling and graft delivery to the anterior chamber (AC), and lastly, problems with positioning and unfolding of the EDM graft in the AC. Nevertheless, DMEK is currently on the rise, replacing DSAEK, and overcoming the challenges and the steep learning curve ,.
The manipulation of the thin DMEK graft in the AC requires a pseudophakic bicameral eye with normal AC depth and intact iris-intraocular lens (IOL) diaphragm. Vitrectomized eyes have a more complex intraoperative setting, owing to lack of the posterior vitreous support. This may cause a very deep AC and intraoperative fluctuations in the position of the iris-lens diaphragm, which can hinder the graft unfolding . It has been advocated by some surgeons that DSAEK may be a more appropriate solution in these cases . Recently, with gaining more experience, surgeons have started to apply DMEK to more challenging situations including vitrectomized eyes ,.
This study presents the challenges, clinical outcome, and complications after DMEK in vitrectomized eyes with endothelial decompensation.
| Patients and methods|| |
This is a retrospective review of the medical records and surgical videos of all DMEK cases in vitrectomized eyes (total or anterior vitrectomy) that were done at Alexandria Main University Hospital, Alexandria, Egypt between January 2015 and November 2019. The study was conducted in accordance with the tenets of the Declaration of Helsinki and was approved by the Institutional Ethics Committee.
Data obtained from the clinical records included age, sex, underlying pathology, preoperative best-corrected visual acuity (BCVA), date and indication of DMEK, donor age, and endothelial cell density (ECD), as well as surgical details, including any intervention done with DMEK, postoperative complications, number of postoperative air injections, BCVA, and ECD at the end of the follow-up period.
Surgical videos were reviewed to report the time required and techniques adopted for graft unfolding, as well as any specific intraoperative events.
The corneo-scleral, button was mounted, endothelial side up on a corneal punch (Katena, Denville, New Jersey, USA). The endothelium was stained with 0.055% trypan blue (Monoblue; Arcadophta, Toulouse, France). The EDM was stripped from the corneal stroma by a technique previously described by Kruse et al.  ([Figure 1]), punched and further stained with trypan blue for 2 min, before loading it into a glass pipette (Geuder AG, Heidelberg, Germany). The size of the graft was detected by measuring the recipient white-to-white diameter to avoid an oversized graft.
Implantation of the prepared endothelium-Descemet membrane
The surgical technique involved creation of a 3-mm incision at 12 o’clock position and three paracenteses at 3, 6, and 9 o’clock positions ([Figure 2]). A descemetorhexis was then done under air or viscoelastic (Provisc; Alcon, Fort Worth, Texas, USA) using a reversed Sinskey hook, followed by an inferior peripheral iridectomy (PI) at 6 o’clock position using a vitreous cutter. The graft was then injected into the AC, and its orientation was confirmed by Moutsouris sign. If the graft was in the correct orientation, the process of unfolding was carried out. If the scroll was upside down, flipping was done using bursts of balanced salt solution (BSS; Alcon). Several maneuvers were used in the unfolding of the graft such as corneal surface tapping, shallowing of the AC, air bubble unfolding, manual unfolding , and the double bubble technique . After proper centration of the graft, the AC was filled with nonexpansile sulfur hexafluoride (SF6) 20% (Alcon). The patient was kept in a supine position for 1 h, and then slit-lamp examination was done to ensure the patency of the inferior PI. If the air bubble was covering the PI, some air was released from the paracentesis, to avoid postoperative pupillary block.
|Figure 2 Graft injection and unfolding. (a) Intraoperative view showing epithelial edema, dilated pupil, and residual silicone in the anterior chamber. (b) Removal of edematous epithelium revealing more anterior segment details and a decentered IOL. (c) Pupilloplasty using 10/0 prolene suture. (d) Graft injection. (e) Graft unfolding over the iris using a large air bubble. (f) Graft almost unfolded after removal of the bubble over the graft and injecting a small air bubble under the graft. IOL, intraocular lens.|
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Patients were instructed to keep a supine position most of the day till complete absorption of the AC bubble. The treatment regimen included topical Moxifloxacin (Vigamox; Alcon) every 6 h for 15 days and topical prednisolone (Econopred plus; Alcon) every 6 h tapered over 2 months and then replaced by topical fluorometholone (Flucon; Alcon). Topical lubricants were administered to hasten epithelial healing if the epithelium was removed at the time of surgery. Bandage soft contact lens fitting was done to treat nonhealing epithelial defects or persistent painful epithelial bullae. Follow-up examinations were scheduled at 1, 3, 7, 14, and 30 days and every 3 months postoperatively. DM detachments were treated by injection of air or SF6 in the operating theater under topical anesthesia.
| Results|| |
A total of 18 eyes of 18 patients (seven males and 11 females) were included in the study, having a mean age of 60.9±13.1 years. All patients had bullous keratopathy as indication for DMEK. One patient underwent DMEK for a second time as a result of previously failed DMEK graft that has been done elsewhere. A total of eight patients had previous pars plana vitrectomy with complete vitreous removal and 10 patients had anterior vitrectomy in the setting of a complicated anterior segment surgery. Ocular comorbidities included glaucoma (n=7), dilated pupil (n=3), AC IOL (n=6), decentered IOL (n=1), and iridectomy or iris defect (n=5). All patients have completed at least 6 months of follow-up (range, 6–53 months, mean, 23.8±15.2 months). [Table 1] shows the preoperative pathologies, ocular comorbidities, and causes of bullous keratopathy in the studied eyes.
|Table 1 Preoperative pathologies, ocular comorbidities, and causes of bullous keratopathy|
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The mean donor age was 62.4±6.1 years, with a mean death to surgery time of 8.5±1.1 days, and a mean ECD of 2388.3±114.8 cells/mm2.
The preoperative mean BCVA was 1.9±0.5 log MAR units, which improved at the final visit to 0.7±0.4 log MAR units (P<0.001). The final BCVA was limited by posterior segment pathologies, including epimacular membrane in three eyes, myopic macular scars in two eyes, and glaucomatous optic nerve damage in two eyes. The mean ECD at the end of the follow-up period was 1136.6±204.4 cells/mm2, representing 53% loss of donor endothelial cells (P<0.001).
DMEK was combined with exchange of an AC or decentered IOL with a posterior iris claw lens (artisan; Ophtec BV, Groningen, The Netherlands) in seven eyes, with iris reconstruction in five eyes ([Figure 3]) and with synechiolysis in one eye. These secondary procedures were done before graft injection to restore an intact iris-IOL diaphragm and to facilitate the process of unfolding.
|Figure 3 One of the cases after Descemet membrane endothelial keratoplasty, iris reconstruction, closure of a large superior iridectomy, and anterior chamber intraocular lens exchange with a retropupillary iris claw lens. A nonvisually significant graft fold is evident inferotemporal.|
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The mean time from delivery of the graft into the AC till complete graft unfolding was 13.7±5.4 min. Although many maneuvers were adopted for graft unfolding, the most frequently successful technique (done in nine eyes) was using a large air bubble to unfold the graft over the iris, followed by removal of air and reinjecting it under the graft. Other successful techniques used were the double bubble technique in five eyes and manual unfolding in four eyes.
Graft detachment was observed in 11 (61%) eyes, necessitating rebubbling in all of them. Six eyes required more than one rebubbling, and two eyes with iris defects required three and five rebubblings owing to escape of air into the vitreous cavity.
At the end of the follow-up period, all patients have had a clear cornea with no signs of endothelial failure. However, two eyes have experienced attack of rejection owing to noncompliance to medications. They were treated successfully with topical steroids with full recovery.
| Discussion|| |
DMEK has recently gained a wide global acceptance and is currently offered by most corneal surgeons as a procedure for treatment of corneal endothelial disorders. The excellent visual and clinical outcomes, accompanied with the low risk of rejection, have overcome the challenges associated with the procedure ,.
DMEK in vitrectomized eyes is regarded as one of the most challenging situations, especially during the process of unfolding of the EDM. Deep AC, fluctuating iris-IOL diaphragm, mono-cameral eye, and globe collapse are all consequences of lack of the vitreous support. These factors result in tendency of the graft to curl up or scroll, leading to prolonged operative time, more graft manipulations, and may end up to significant endothelial cell loss (ECL) and possible graft failure. Furthermore, vitrectomy may have been performed in the setting of, or following a complicated cataract surgery, resulting in some additional challenges, such as the presence of a large iris defect and a decentered or AC IOL. These factors, hence, should be corrected before injecting the graft, adding more time and difficulties to the surgical procedure ,.
Eyes with AC IOLs are not good candidates for DMEK, as the implant will be traumatizing to the graft during unfolding. Some surgeons prefer leaving the IOL in the AC and perform a DSAEK or a DMEK ,, whereas others prefer to exchange the IOL with a scleral or iris fixated posterior implant, and then proceed to DMEK . In this case series, the author felt that the AC implant was a contributing factor to the endothelial failure, and it is wiser to be replaced with a retropupillary iris fixated lens, to facilitate DMEK surgery and to ensure long-term graft survival.
Several unfolding techniques have been adopted in this case series. Traditional techniques used in nonvitrectomized eyes, such as tapping and shallowing of the AC, are usually not successful in vitrectomized eyes. Among the used techniques, three were found successful; the first is unfolding the graft over the iris using a large air bubble , the second is the double bubble technique , and the last one is the manual unfolding. It is hence, recommended that these techniques should be used from the start, which may avoid the prolonged surgical time during trying other traditional unfolding methods ,.
Improvement in BCVA was substantial, from a mean of 1.9±0.5 log MAR units to 0.7±0.4 log MAR units at the end of the follow-up period. The final BCVA was less than that in similar publications in nonvitrectomized eyes ,,,, despite the restoration of corneal clarity, which may be attributed to the preexisting posterior segment comorbidities. Nevertheless, considering publications discussing vitrectomized eyes, these visual results were comparable to Yoeruek et al , who have reported a final BCVA of 0.9±0.6 log MAR units, and were less than those by Hayashi and Kobayashi  (0.16±0.15 log MAR units) and Yamada et al.  (0.37±0.19 log MAR units). As previously mentioned, visual results are dependent on the posterior segment pathology, which varies from one case series to another.
ECL (53%), in this study, was higher than other published DMEK studies in vitrectomized eyes. Yoeruek et al.  reported a 39% cell loss at 6 months and a 46% loss at 12 months. Yamada et al.  reported 41% cell loss in their vitrectomized cohort with sutured posterior chamber IOL. Hayashi and Kobayashi  used the double bubble technique in six vitrectomized eyes, with ECL of 40% at 6 months. The higher percentage of ECL in the current study can be attributed to the longer mean follow-up period (23.8±15.2 months), compared with other studies with a maximum follow-up period of only 12 months.
This case series presents a high rate of DM detachment, necessitating rebubbling in 61% of the cases. Yoeruek et al.  had a 55% rebubbling rate in their case series, whereas Yamada et al.  reported 25% and Hayashi and Kobayashi  reported 17% rebubbling rate. This may be explained by the larger number of eyes with iris defects and those requiring IOL exchange in the current study. Despite meticulous intraoperative attempts to correct these defects, air or SF6 can still migrate to the vitreous cavity in the early or late postoperative period through any small defect in the iris-IOL diaphragm. Loss of air tamponade may result in DM detachment and the need for rebubbling. Strict supine position is crucial in the first few hours postoperatively to avoid escape of gas to the vitreous cavity.
Some surgeons advocate intraoperative measures to address difficulties in vitrectomized eyes. Sorkin et al.  recommended the placement of a posterior pars plana infusion, to stabilize the anterior segment. They have reported comparable unfolding time and techniques to nonvitrectomized eyes, as well as similar ECL and rebubbling rate. However, the placement of a posterior infusion carries the risk of possible complications, especially for the anterior segment surgeons who are not acquainted with such step. Moreover, Sorkin and colleagues reported one case, among their case series of 12 eyes, that developed retinal detachment after surgery, which may be owing to a sclerotomy-related retinal break. Yoeruek and Bartz-Schmidt  used a temporary hydrophilic methacrylate sheet in the AC in seven vitrectomized eyes. The off-label use of this temporary diaphragm may limit fluctuations in the iris-IOL diaphragm and facilitate the process of unfolding.
The limitations of this study include its retrospective design, the small sample size, and the absence of serial follow-up of the cases. However, the results are encouraging for performing DMEK in vitrectomized eyes, based on the long-term visual results of most cases and the acceptable ECD. The novelty of this study was the combination of DMEK with other surgical steps such as IOL exchange, iris reconstruction, and pupilloplasty.
| Conclusion|| |
In conclusion, DMEK is an effective surgical modality for treatment of bullous keratopathy in vitrectomized eyes. Restoration of corneal clarity and significant visual improvement were possible in all patients, despite the need for complex surgical steps, the prolonged surgical time, and the increased rebubbling rate.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]