The Cologne-Mecklenburg-Vorpommern DMEK Donor Study (COMEDOS) - design and review of the influence of donor characteristics on Descemet membrane endothelial keratoplasty (DMEK) outcome

Background Posterior lamellar keratoplasty and especially Descemet membrane endothelial keratoplasty (DMEK) are gaining interest worldwide. Little is known about the influence of donor factors on DMEK outcome. Here we provide an overview of the existing peer-reviewed literature on this topic and present the design of the upcoming cooperation study COMEDOS (Cologne-Mecklenburg-Vorpommern DMEK Donor Study). Methods A literature search of PubMed and MEDLINE was conducted to retrieve articles published between September 2013 and May 2021. Seventeen peer-reviewed articles were selected. Design and concept of the prospective COMEDOS are outlined. Results Main interest parameters were the donor diabetes mellitus status, age, and lens status. There is a large heterogeneity regarding the sample size, study design, and investigated parameters. There seems to be a consensus that younger donors are associated with tighter rolls, a more difficult preparation, and unfolding setting. Diabetic donors seem to increase the risk of tissue tearing due to adherences and result more frequently in preparation failure. The COMEDOS aims not only to analyze the diabetes status of the donor, but also to correlate all donor systemic comorbidities and their ophthalmologic history to the DMEK clinical outcome. Furthermore, a correlation of Descemet membrane lamella preparation and surgery outcome is planned. Conclusion Currently, there is a lack of knowledge regarding the effect and impact of donor tissue characteristics on DMEK outcome and complications. An in-depth investigation is planned by the upcoming COMEDOS to close this knowledge gap

Mini-Descemet Membrane Endothelial Keratoplasty for the Early Treatment of Acute Corneal Hydrops in Keratoconus

Purpose: To describe a new surgical option for the treatment of acute corneal hydrops in keratoconus and to present the first results. Methods: This is a retrospective analysis of 3 patients who presented to our clinic with a massive corneal hydrops in acute keratoconus and were treated by mini-Descemet membrane endothelial keratoplasty (DMEK). According to the size and the shape of the gap in the patient's Descemet membrane (DM), 1 DMEK graft was trephined with a round 5-mm punch. The other grafts were trimmed with a razor blade to a width of about 3 mm and a length adjusted to the length of the defect of the recipients' DM. The graft was inserted with a regular intraocular lens shooter. Correct unfolding of the graft was controlled by using intraoperative optical coherence tomography. At the end of the surgery, the graft was attached to the posterior corneal surface by a small air bubble. Thereafter, the complete anterior chamber was filled with 20% SF6 gas. Results: All 3 patients (age 32 +/- 3 years on average) showed a rapid increase in uncorrected visual acuity from the logarithm of the minimum angle of resolution (LogMAR) 1.66 (+/- 0.46) before mini-DMEK to the LogMAR 1.2 (+/- 0.3) within 6 to 8 weeks after mini-DMEK. The thickest corneal point within the edematous cornea decreased in all 3 patients (1088 +/- 280 mu m before surgery vs. 630 +/- 38 mu m 1 week after surgery). One mini-DMEK failed in a first attempt. In this patient, the recipient DM was under strong tension and showed a pronounced dehiscence. Therefore, a small part of the recipient's DM around the preexisting gap in DM was removed before a second mini-DMEK graft was placed successfully. The other 2 patients developed partial graft detachment within 1 to 2 weeks after surgery. However, the corneas of these patients were dehydrated to physiological levels after mini-DMEK, and despite partial detachment, there was no relapse of the hydrops. Conclusions: Mini-DMEK could be helpful in patients with larger defects and detachments of DM in very ectatic corneas in the acute phase of corneal hydrops in acute keratoconus. These patients may not be successfully treated by intracameral gas application alone or in combination with pre-Descemetal sutures. Further investigations are needed to identify factors helping to decide on the best surgical approach in hydrops in acute keratoconus

Microscope-Integrated Optical Coherence Tomography-Guided Drainage of Acute Corneal Hydrops in Keratoconus Combined With Suturing and Gas-Aided Reattachment of Descemet Membrane

Purpose: The treatment of acute corneal hydrops due to keratoconus has so far been limited to awaiting the spontaneous resorption of corneal edema, supportive care, and finally keratoplasty. A recent publication describes the surgical reattachment of Descemet Membrane (DM) facilitated by pre-Descemetic sutures and anterior chamber air/gas filling. Here, we present a novel microscope-integrated intraoperative optical coherence tomography (MI-OCT)guided technique for the immediate reattachment of DM in corneal hydrops due to keratoconus in 2 male patients with small central DM defects. Methods: Case series of 2 consecutive patients with acute corneal hydrops due to keratoconus. The novel technique consists of the MI-OCT-guided puncture and drainage of intrastromal fluid pockets combined with anterior chamber sulfur hexafluoride-fill and pre-descemetic sutures using a commercially available MI-OCT (iOCT; Haag Streit Surgical, Wedel, Germany). Results: After uneventful surgery, corneal edema showed fast resolution and DM was reattached to the corneal stroma. In both patient's central corneal thickness decreased after surgery and visual acuity improved. Conclusions: MI-OCT guided micropuncture of stromal edema combined with compression sutures and SF6 tamponade is a new therapeutic option in acute corneal hydrops with small Descemet membrane defects

Lutein and Brilliant Blue-Based Dye for Donor Preparation and Transplantation in Descemet Membrane Endothelial Keratoplasty

Purpose: Trypan blue (TB) is used for visualization of the endothelium-Descemet membrane graft during Descemet membrane endothelial keratoplasty (DMEK). However, TB is assumed to have a dose-dependent toxic effect on the corneal endothelium. We retrospectively compared a lutein/zeaxanthin and Brilliant Blue (LZ/BB)-based dye for preparation and transplantation of the graft in DMEK to TB. Methods: In 20 patients, a dye composed of 1% LZ /0.025% BB was used, and in 22 patients, 0.06% TB was used for graft visualization in DMEK. We evaluated the rebubbling rate, best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), and endothelial cell density (ECD) before and 3 and 6 months after transplantation. Results: Staining of endothelium-Descemet membrane with LZ/BB was faint but sufficient. There was no significant difference between both groups, except in CCT after 3 months, which was lower in the LZ/ BB group (P = 0.02). In the LZ/BB group, BSCVA improved from 0.48 +/- 0.39 before DMEK to 0.19 +/- 0.09 after 6 months (P < 0.05) (20% rebubbling rate). Donor ECD decreased from 2735 +/- 259 cells/m(2) preoperatively to 1876 +/- 316 cells/mm(2) (P < 0.0001) at 6 months (31.4%). CCT decreased from 642 +/- 130 mu m preoperatively to 519.8 +/- 38 mm (P < 0.0001) at 6 months. In the TB group, BSCVA improved from 0.43 +/- 0.27 to 0.17 +/- 0.14 (P = 0.0003) at 6 months (30% rebubbling rate). ECD decreased from 2825 +/- 263 to 1777 +/- 302 cells/ mm(2) (P < 0.0001) after 6 months (36.3%), CCT from 638 +/- 48 mu m preoperatively to 531 +/- 48 mu m (P < 0.0001) at 6 months. Conclusions: LZ/BB-based dyes are suitable for DMEK with outcomes comparable to TB. However, available formulas result in faint staining, discouraging their routine use in donors with assumed difficult preparation

Intraoperative Optical Coherence Tomography (MI-OCT) for the Treatment of Corneal Dystrophies

Background The surgical treatment of corneal dystrophies develops rapidly as the use of lamellar corneal grafting techniques continue. While penetrating keratoplasty was the gold standard for treating a variety of dystrophies a few years ago, the affected layers of the cornea can, nowadays, be selectively replaced or ablated using laser technology. Of particular importance for these methods is optical coherence tomography, which has recently been integrated into surgical microscopes (MI-OCT). Methods Literature overview from PubMed and Google.scholar.de supplemented with own imaging data. Results The MI-OCT enables the intraoperative real-time monitoring of different ophthalmic surgical procedures, such as deep anterior lamellar keratoplasty, Descemets membrane endothelial keratoplasty, as well as minimally-invasive procedures, such as phototherapeutic keratectomy. In addition, it enables an evaluation of the cornea, but also of structures of the anterior chamber, in situations in which the cornea, for example, is clouded by an edema. Conclusion Microscope-integrated, intraoperative optical coherence tomography (MI-OCT) represents a useful supplement to the normal surgical microscope. It is superior to the sole surgical microscope, especially in already severely clouded corneas, and represents a sensible supplement, especially for novel lamellar transplantation procedures. Prospective randomized trials are necessary to increase safety and efficacy when using MI-OCT for different indications

Surgical treatment options for congenital/infantile corneal opacities and anterior segment dysgenesis

Background Due to the risk of amblyopia congenital and infantile corneal opacities have a narrow therapeutic window, frequently with a complex surgical treatment. Objective The present study gives an overview of the current treatment options for congenital and infantile corneal opacities. Methods The results of a literature search are presented and own clinical data and examples are shown. Results In children ophthalmologic operations are surgically more demanding and the prognosis is generally worse. Surgical options include phototherapeutic keratectomy, crosslinking, corneal sutures, sectoral iridectomy, block excision and lamellar, penetrating, and auto-keratoplasty. An equally important part of the treatment is conservative treatment, when necessary with bandage lenses, glasses, contact lenses and occlusion. Discussion Whenever possible treatment of congenital and infantile corneal opacities should be limited to the affected layers/areas. Nevertheless, children and parents have to be prepared for many examinations, sometimes with the patient under anesthesia and should be well-informed about the prognosis and the risks

Corneal Nerve Alterations After Descemet Membrane Endothelial Keratoplasty: An In Vivo Confocal Microscopy Study

Purpose: Recent studies have identified diminishment of corneal nerves as another hallmark of Fuchs endothelial corneal dystrophy. This study aimed to analyze changes in corneal nerves after Descemet membrane endothelial keratoplasty (DMEK). Methods: Twenty-five patients were assessed for nerve alterations preoperatively and 1 week, 4 months, and 20 months after DMEK surgery. Morphology of the central subbasal nerve plexus was quantified by in vivo confocal microscopy. Results: The total nerve length (481.2 +/- 81.9 vs. 1536.0 +/- 123.8 mu m per frame, P < 0.0001), total nerve number (2.2 +/- 0.3 vs. 7.2 +/- 0.5 per frame, P < 0.0001), number of main nerve trunks (1.8 +/- 0.2 vs. 3.5 +/- 0.3 per frame, P < 0.0001), and number of nerve branches (0.5 +/- 0.2 vs. 3.7 +/- 0.4 per frame, P < 0.0001) were significantly decreased 1 week after DMEK compared with preoperative measurements. Ten months postoperatively, corneal nerves recovered to preoperative values. Central corneal sensation significantly reduced postoperatively (5.1 +/- 1.0 vs. 6.0 +/- 0.0, P = 0.001), but recovered during follow-up (10 months: 6.0 +/- 0.0). Conclusions: DMEK diminishes the density and the function of subbasal corneal nerves early after transplantation. However, a complete recovery of corneal nerve density and function up to preoperative values occurs within 4 to 10 months

Fuchs Endothelial Corneal Dystrophy: Clinical, Genetic, Pathophysiologic, and Therapeutic Aspects

Fuchs endothelial corneal dystrophy (FECD) is a bilateral corneal endothelial disorder and the most common cause of corneal transplantation worldwide. Professor Ernst Fuchs described the first 13 cases of FECD more than 100 years ago. Since then, we have seen far-reaching progress in its diagnosis and treatment. In the field of diagnostics, new technologies enable the development of more accurate classification systems and the more detailed breakdown of the genetic basis of FECD. Laboratory studies help in deciphering the molecular pathomechanisms. The development of minimally invasive surgical techniques leads to a continuous improvement of the postoperative result. This review highlights and discusses clinical, genetic, pathophysiologic, and therapeutic aspects of this common and important corneal disorder