Artificial Intelligence for Lamellar Keratoplasty. / Künstliche Intelligenz bei lamellierenden Keratoplastiken.

The training of artificial intelligence (AI) is becoming increasingly popular. More and more studies on lamellar keratoplasty are also being published. In particular, the possibility of non-invasive and high-resolution imaging technology of optical coherence tomography predestines lamellar keratoplasty for the application of AI. Although it is technically easy to perform, there are only a few studies on the use of AI to optimise lamellar keratoplasty. The existing studies focus primarily on the prediction probability of rebubbling in DMEK and DSAEK and on their graft adherence, as well as on the formation of a big bubble in DALK. In addition, the automated recording of routine parameters such as corneal oedema, endothelial cell density or the size of the graft detachment is now possible using AI. The optimisation of lamellar keratoplasty using AI holds great potential. Nevertheless, there are limitations to the published algorithms, in that they can only be transferred between centres, surgeons and different device manufacturers to a limited extent.

Immediate postoperative topical lidocaine gel for the treatment of eye pain following corneal abrasion in descemet membrane endothelial keratoplasty (DMEK) under general anaesthesia: a pilot retrospective analysis.

BACKGROUND: Patients undergoing corneal abrasion as part of Descemet membrane endothelial keratoplasty (DMEK) under general anesthesia suffer from early burning pain postoperatively. This pain appears to be poorly treatable with systemic analgesics. This study aims to evaluate postoperative pain management using topical lidocaine gel after DMEK with iatrogenic corneal abrasion. METHODS: Retrospective analysis of 28 consecutive patients undergoing DMEK with corneal abrasion from October 19, 2021, to November 12, 2021, at a German university hospital. Patients during week 1 and 2 received peri-operative standard pain treatment (cohort S) and additional local lidocaine gel during week 3 and 4 immediately postoperatively (cohort L). RESULTS: 13 patients were included in cohort S and 15 patients in cohort L. At awakening all patients (100%) in cohort S reported burning pain, and six of 15 patients (40%) in cohort L reported burning pain. Burning pain scores were significantly lower in cohort L (p < 0.001 at awakening, p < 0.001 at 10 min, p < 0.001 at 20 min, p < 0.001 at 30 min, p = 0.007 at 40 min after awakening, and p < 0.001 at leaving recovery room). No significant differences between cohort S and cohort L were detected concerning surgical outcome during 1-month-follow-up (p = 0.901 for best corrected visual acuity). CONCLUSION: Patients undergoing DMEK with corneal abrasion suffer significant pain in the recovery room. A single dose of topic lidocaine gel reduces the early postoperative burning pain sufficiently and does not affect the surgical outcome.

Corneal Hydrops - Aetiology and Advanced Therapeutic Strategies. / Der korneale Hydrops ­ Ursachen und moderne Therapieansätze.

Acute hydrops refers to sudden corneal edema caused by rupture of Descemet's membrane (DM) - often in progressive keratectasia. It leads to a sudden decrease in visual acuity, pain, and foreign body sensation as well as an increased glare sensation. Acute hydrops usually heals with scarring within months, but complications such as corneal perforation, infectious keratitis, and corneal vascularization may occur. The prevalence in keratoconus patients is 2.6 to 2.8%. Risk factors include keratoconjunctivitis vernalis, atopic dermatitis, high keratometry, male gender, and eye rubbing. Keratoplasty should be avoided in the acute phase. The prognosis of the graft is reduced, and after scar healing of the hydrops, wearing contact lenses or glasses may be possible again. Conservative therapy alone with lubricants and hyperosmolar eye drops, prophylactic antibiotic eye drops to prevent superinfection, and topical steroids was long considered the only possible form of treatment. However, healing under conservative therapy takes an average of over 100 days. In the meantime, there are different surgical strategies that rapidly shorten the healing and thus the recovery phase of the patients to a few days. If the DM is detached without tension, a simple injection of gas into the anterior chamber can already lead to reattachment and thus to almost immediate deswelling of the cornea. If the DM is under tension, predescemetal sutures combined with a gas injection into the anterior chamber can flatten the cornea and reattach the DM. Mini-Descemet membrane endothelial keratoplasty (mini-DMEK) allows for sutureless closure of the DM defect by transplantation of a small (< 5 mm) graft. In cases of particularly large DM tears and very pronounced hydrops, suture loosening and relapse may occur after the placement of predescemetal sutures. Mini-DMEK can then lead to permanent healing, but in contrast to simple corneal sutures, it is usually performed under general anesthesia and by aid of intraoperative optical coherence tomography. The very good results with regard to the rapid healing prove that surgical therapy makes sense in the vast majority of patients with acute hydrops and should be initiated quickly.

Blood-Aqueous Barrier Disruption in Penetrating and Posterior Lamellar Keratoplasty: Implications for Clinical Outcome. / Blut-Kammerwasser-Schranken-Störungen bei perforierender und posteriorer lamellärer Keratoplastik: Implikationen für das klinische Ergebnis.

BACKGROUND: The blood-aqueous barrier (BAB) separates immunoprivileged tissue of the eye from the blood circulation. Disruption of the BAB is therefore a risk factor for rejection after keratoplasty. PURPOSE: The present work provides a review of the work of our group and others on BAB disruption in penetrating and posterior lamellar keratoplasty and its implications for clinical outcome. METHODS: A PubMed literature search was performed to generate a review paper. RESULTS: Laser flare photometry provides an objective and reproducible method to assess the integrity of the BAB. Studies of the flare after penetrating and posterior lamellar keratoplasty demonstrate a mostly regressive disruption of the BAB in the postoperative course, which is influenced in extent and duration by multiple factors. Persistently elevated flare values or an increase in flare after initial postoperative regeneration may indicate an increased risk of rejection. DISCUSSION: In case of persistent or recurrent elevated flare values after keratoplasty, intensified (local) immunosuppression may potentially be useful. This could become important in the future, especially for the monitoring of patients after high-risk keratoplasty. Whether an increase of the laser flare is a reliable early indicator of an impending immune reaction after penetrating or posterior lamellar keratoplasty has to be shown in prospective studies.

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.

Outcomes of deep anterior lamellar keratoplasty and penetrating keratoplasty in keratoconic eyes with and without previous hydrops.

PURPOSE: The study aims to compare outcomes after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in keratoconic eyes with or without previous hydrops. METHODS: Retrospective analysis of 211 eyes who received PK (group 1, n = 74 [history of hydrops: n = 33]) or DALK (group 2, n = 137 [history of hydrops: n = 9]) from 2012 to 2019 at the Department of Ophthalmology, University of Cologne, Germany. Analysis included best spectacle-corrected visual acuity (BSCVA), complications, immune reactions, graft survival and keratometry, and subgroup analyses for subjects with or without previous hydrops. RESULTS: Follow-up was 34.0 ± 23.6 months in group 1 and 30.7 ± 22.5 months in group 2. No significant difference was found in the course of BSCVA between groups 1 and 2 (p = 0.182) and in postoperative BSCVA between eyes with and without previous hydrops, regardless of the surgical method (p = 0.768). Endothelial immune reactions occurred exclusively in group 1 and did not occur more frequently in eyes with previous hydrops (p = 0.377). A higher risk of complications for eyes with previous hydrops was observed (p = 0.022). There was no difference in astigmatism and maximum keratometry (Kmax) preoperatively and postoperatively between eyes with and without history of hydrops. CONCLUSION: The prognosis for visual outcome after keratoplasty including visual acuity, astigmatism, and Kmax for keratoconic eyes with previous hydrops is as good as for keratoconic eyes without previous hydrops, irrespective of the surgical method. However, eyes after hydrops seem to have an increased risk of complications.

[Keratoprostheses: Last Hope for the Most Severe Corneal Diseases]. / Keratoprothesen: letzte Hoffnung bei schwersten Hornhauterkrankungen.

Corneal blindness affects over 8 million adults and 1.5 million children worldwide, making it one of the top 5 causes of blindness. Depending on the recipient's corneal condition corneal transplantation may not be a viable treatment option. In such seemingly no-alternative situations, keratoprosthesis implantation can be an option in some patients. In terms of numbers, two types of keratoprostheses are currently used: 1. Keratoprostheses with biological haptics made of tooth or tibia bone. 2. The Boston type I-keratoprosthesis. Both types have optics made of PMMA. The most common complication is the formation of an optically disturbing retroprosthetic membrane behind the optic, which can usually be removed with YAG laser. Causes of blindness after keratoprosthesis implantation are glaucoma, endophthalmitis and retinal detachment. The extrusion rate of the Boston type I-keratoprosthesis seems to be higher than after keratoprosthesis implantation with biological haptic. Autoimmunological corneal diseases have increased extrusion rates and higher rates of endophthalmitis when compared to non-autoimmunological diseases. Visual outcomes after keratoprosthesis implantation are potentially very good and usually limited by extracorneal concomitant diseases. Advances in glaucoma diagnostic (OCT, implantation of intraocular pressure sensors), standard glaucoma prophylaxis by medication or surgery, modern retinal surgery and better treatment options in case of extrusion improve the prognosis of keratoprosthesis surgery. Still, the ideal technique for permanent anchoring of artifical optics in biological tissue has yet to be developed.

[Efficient Use of Corneal Grafts through Multimodal Donor Tissue Splitting]. / Effiziente Verwendung von Hornhauttransplantaten durch multimodales Spendergewebesplitting.

BACKGROUND: The reduced availability of corneal donor tissue in Ukraine requires the most effective use of the available grafts. The present work describes and evaluates a method to obtain several small diameter corneal grafts from a single donor cornea ("multimodal donor tissue splitting"). MATERIAL AND METHODS: This retrospective cohort study includes keratoplasty procedures performed at the Department of Corneal Pathology, State Institution, "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine", Odessa, Ukraine. The method of graft preparation includes either lamellar dissection of the entire graft or partial lamellar dissection to obtain two lamellar and/or full-thickness grafts. Grafts were not only cut in a circular manner, but the individual shape was also adjusted to match the shape of non-circular corneal defects. RESULTS: A total of 324 keratoplasties between January 2016 and December 2017, using 270 grafts, were included. In 54 cases (including 34 emergency situations), one transplant was used for two recipients. Of these, 43 were therapeutic keratoplasties and 11 peripheral lamellar keratoplasties due to grade III - IV recurrent pterygia. In two cases, two grafts for one patient were dissected from a single donor cornea. Out of 43 patients with curative keratoplasty, visual acuity improved in 28 eyes (65.1%) or remained unchanged in 15 eyes (34.9%). Postoperative visual acuity was dependent on the initial state of the eye, the localisation, the depth and the area of the corneal defect. In eyes with peripheral corneal localisation of ulcerations, even in the presence of corneal perforation, good functional results were obtained. CONCLUSION: If two or more grafts are obtained from a single donor cornea for different kinds of keratoplasty procedures, this reduces the need for corneal graft tissue and, consequently, the cost of preservation. Especially in regions with a high shortage of donor tissue, this provides additional tissue capacities for emergency situations.

Real Life Data on Efficacy and Safety of Topical NGF Eye Drops (Cenegermin). / Real-Life-Daten zur Wirksamkeit und Verträglichkeit von topischen NGF-Augentropfen (Cenegermin).

BACKGROUND: Topical NGF eye drops (Cenegermin) were approved in 2015 as an orphan drug for the treatment of neurotrophic keratopathy (NK). The active substance Cenegermin is a recombinant form of human NGF (nerve growth factor). OBJECTIVES: Presentation of efficacy and safety of Cenegermin for use in patients in an university real-life setting. MATERIAL AND METHODS: Retrospective study at the Köln University Eye Hospital from 2017 to 2019 with n = 11 eyes. Average follow-up was 13.5 ± 7.1 months. Reasons for treatment were neurotrophic keratopathy stage II and III, clinically mostly in combination with corneal neovascularization. RESULTS: Seven eyes with a NK II and 4 eyes with a NK III with a median observation period of 13.6 months (range 1.2 - 20.3 months) from a total of 11 patients were included. The median patient age was 42.8 ± 23.6 years (range 18 - 75 years). Before the start of therapy, the median erosion area measured 3.1 ± 1.4 × 1.9 ± 1.1 mm and the median ulcer area had a size of 2.3 ± 1.1 × 2.1 ± 0.8 mm. After the start of therapy with Cenegermin (application 6×/day), the epithelial defect closed in all 11 study eyes (100%) within 4 - 12 weeks (mean: 49 d ± 9 d). In 9 out of 10 patients (90%) pre-existing corneal neovascularization regressed significantly (p < 0.001). Before the start of therapy, a value in the Luneau test of 2.9 ± 1.9 (minimum 1/6, maximum 4/6) was found and rose to a median value of 4.2 ± 1.7 (minimum 2/6, maximum 6/6) after 18 months (p = 0.015). Therapy with Cenegermin had no long-term effect on intraocular pressure: the pressure ranged between 13.2 ± 4.1 mmHg (minimum 8 mmHg, maximum 21 mmHg). Under therapy with NGF eye drops, 67% of the patients, after an initial decrease, showed a long-term improvement in visual acuity (BSCVA) from 0.72 ± 0.31 to 0.46 ± 0.29 logMAR after 18 months (p = 0.005). Relapses in form of a corneal erosion in the long-term follow-up were observed in only one eye. One patient had to stop therapy because of local pain, no other local and systemic side effects were observed. CONCLUSION: This real-life series on the use of Cenegermin in a university context shows a good effectiveness of the substance for epithelial closure in various underlying diseases (100% within 12 weeks). There is a long-term improvement in vision and corneal sensitivity. Larger real-life cohorts with various underlying diseases should follow.

Postoperative pain following Descemet membrane endothelial keratoplasty (DMEK): a prospective study.

PURPOSE: To evaluate postoperative pain following Descemet membrane endothelial keratoplasty (DMEK). METHODS: Seventy-one patients completed perioperatively (day before surgery, day of surgery, 1st, 2nd, and 3rd day after surgery) four different questionnaires (a hospital internal protocol, QUIPS, PainDETECT®, and SF36) regarding their pain and other clinical parameters such as constipation, tiredness, vertigo, sleep disorders, concentration disorders, nausea, and emesis. All standardised questionnaires were evaluated to quantify average pain intensity as well as maximum pain intensity (NRS, 0 [no pain] to 10 [maximal pain], respectively). Analgesic treatment and intraocular pressure (IOP) during the perioperative stay were documented. RESULTS: Mean average pain intensity was 0.70 ± 1.64 before surgery, 1.97 ± 2.05 on the day of surgery, 1.39 ± 1.68 on day 1, 0.87 ± 1.36 on day 2, and 0.81 ± 1.24 on day 3 after surgery. Maximum pain intensity was 0.65 ± 1.81 before surgery, 3.35 ± 2.98 on the day of surgery, 2.68 ± 2.99 on day 1, 1.49 ± 2.15 on day 2, and 1.26 ± 2.02 on day 3 after surgery. During the first three postoperative days, over 90% of the patients stated no or well tolerable pain. Eighty-three percent had postoperatively no need for analgesics at all. On the first two postoperative days, maximum IOP correlated significantly with reported increased maximum pain intensity (p = 0.043 and p = 0.029, respectively). All patients had very little problems with constipation, tiredness, vertigo, sleep disorder, concentration disorders, nausea, and emesis. CONCLUSIONS: DMEK is associated with low postoperative pain intensity. Strong pain increase may indicate IOP elevation and should be further investigated and treated. CLINICAL TRIAL REGISTRATION: German Clinical Trial Register (DRKS00013995).

[Perioperative/Postoperative Anti-Inflammatory Therapy During/After Corneal Surgery/Transplantation]. / Perioperative/postoperative antientzündliche Therapie bei/nach Hornhautchirurgie/Hornhauttransplantation.

Surgical trauma, and foreign material - such as sutures or implants or antigens during tissue transplantation - may cause inflammatory reactions. Inflammatory reactions after surgical interventions distant from the vascularised limbus and without opening of the anterior chamber of the eye are usually very muted, because of the corneal immune and angiogenic privilege. A milestone in the therapy and prophylaxis of inflammation after corneal surgery has been the use of topical glucocorticoids since the 1950s. When these are used, it is important to consider the cataractogenic effect of long-term use, the possibility of steroid-induced increase in intraocular pressure (so-called steroid response), the increased risk for microbial infection and the inhibition of epithelialisation. The available glucocorticoids differ in their ability to penetrate into the eye (prednisolone best), their immunosuppressive activity (dexamethasone best) and their ability to induce a steroid response (loteprednol etabonate and fluorometholone least). Preservative-free formulations are only available for dexamethasone. The different properties must be taken into account when choosing the "best" glucocorticoid: If there is a risk of delay in epithelialisation of the wound, topical steroids should be avoided or if necessary, phosphate- and preservative-free dexamethasone should be used with caution. If efficiency in the posterior cornea or in the anterior chamber is important, e.g. after penetrating keratoplasty, prednisolone acetate should be used. If a steroid response is known, loteprednol etabonate or fluorometholone should be used. When allogeneic tissue is transplanted, long-term topical glucocorticoid use over 24 months or longer is necessary. After high-risk keratoplasty with allogeneic donor tissue, supplemental systemic immunosuppressive therapy with calcineurin inhibitors or mycophenolate mofetil over 6 to 12 months is recommended.

Intraoperative changes in corneal structure during excimer laser phototherapeutic keratectomy (PTK) assessed by intraoperative optical coherence tomography.

PURPOSE: Excimer laser phototherapeutic keratectomy (PTK) is a safe treatment for superficial corneal opacities, e.g., in corneal dystrophies or degenerations. Nevertheless, no standardized treatment protocols are available and intraoperative monitoring was not possible, so far. Here we evaluate the potential benefits of the intraoperative assessment by microscope-integrated intraoperative optical coherence tomography (MI-OCT) of corneal optical properties during PTK. METHODS: Retrospective study of eight patients (one male, seven females; age range, 43-80 years, mean = 66.1 years) using an 840-nm microscope-integrated spectral-domain OCT (iOCT; OptoMedical Technologies, Luebeck, Germany adapted to HS Hi-R Neo 900A, Haag Streit Surgical, Wedel, Germany). Images were acquired before and after corneal abrasion and after PTK. For PTK, a SCHWIND Amaris 750S excimer laser (SCHWIND eye-tech-solutions GmbH und KO. KG) was used. Parameters assessed were the central corneal thickness (CCT), changes in central depth-dependent corneal tissue intensity (TI), and corneal surface roughness (SR) in cross-sectional images of the cornea. RESULTS: Intraoperative monitoring using microscope-integrated OCT was possible in all patients at all time points. TI of the anterior corneal stroma decreased significantly (p = 0.037) after PTK (T1 = 15.1 ± 3.6, T2 = 15.0 ± 3.84, T3 = 13.7 ± 3.38), but not after corneal abrasion alone, indicating increased transparency caused by excimer laser PTK. CCT was significantly lower after corneal abrasion (p = 0.017), but not after PTK (T1 = 630.4 ± 70 µm, T2 = 544.1 ± 59.4 µm, T3 = 558.3 ± 52.5 µm. SR significantly decreased (p = 0.043) after PTK (T1 = 614.4 ± 37.5 pixels, T2 = 634.4 ± 35.6 pixels, T3 = 611.0 ± 40.3 pixels). CONCLUSIONS: Intraoperative OCT allows real-time imaging during PTK and the assessment of corneal optical transparency and its surface roughness. It has to be clarified in larger studies if these parameters correlate with later postoperative visual outcomes.

[Intraoperative Optical Coherence Tomography (MI-OCT) for the Treatment of Corneal Dystrophies]. / Die Bedeutung der intraoperativen optischen Kohärenztomografie (MI-OCT) bei der Behandlung von Hornhautdystrophien.

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, Descemet's 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.

Incidence and Clinical Course of Immune Reactions after Descemet Membrane Endothelial Keratoplasty: Retrospective Analysis of 1000 Consecutive Eyes.

PURPOSE: To analyze the incidence and clinical course of graft rejection episodes after Descemet membrane endothelial keratoplasty (DMEK). DESIGN: Retrospective analysis of a consecutive, interventional case series. PARTICIPANTS: One thousand eyes that underwent DMEK from July 2011 through August 2015 at the Department of Ophthalmology, University of Cologne. METHODS: All cases with follow-up of at least 1 month were included (mean follow-up, 18.5 months). Patients with a graft rejection episode were followed up for 1 additional year. MAIN OUTCOME MEASURES: Incidence of graft rejection, best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), endothelial cell density (ECD), and need for regraft. RESULTS: Nine hundred five cases met the inclusion criteria. A graft rejection episode developed in 12 patients (estimated probability of rejection at 1 year, 0.9%; at 2 years, 2.3%; at 4 years, 2.3%). At time of rejection, 9 of 12 patients had stopped corticosteroids. Five patients were symptomatic and 7 did not note the rejection episode. Intensified topical corticosteroid therapy was started immediately after diagnosis of rejection. Two eyes decompensated and required a regraft, whereas the remaining 10 eyes required no regraft (BSCVA, 0.27±0.28 logarithm of the minimum angle of resolution [logMAR]; CCT, 554.1±39.1 µm at last visit before rejection vs. BSCVA, 0.21±0.15 logMAR; CCT, 540.0±15.0 µm 3 months after rejection). One year after the rejection episodes, BSCVA and CCT in these eyes remained unchanged when compared with the last visit before rejection (BSCVA, 0.15±0.11 logMAR; CCT, 533.8±26.0 µm). Significant changes were observed for ECD values (1741±274.5 cells/mm2 at last visit before rejection vs. 1356±380.3 cells/mm2 after 3 months [P = 0.04] and 1290±359.0 cells/mm2 after 1 year [P = 0.01]). CONCLUSIONS: The risk for graft rejection after DMEK is low, and an even smaller minority requires a regraft. After intensified local corticosteroid therapy, most patients show stable visual acuity and CCT, although ECD decreases. The occurrence of immune reactions up to 2 years after surgery predominantly in patients not receiving corticosteroids supports the prolonged use of corticosteroids after DMEK.

Effect of corneal collagen crosslinking on subsequent deep anterior lamellar keratoplasty (DALK) in keratoconus.

PURPOSE: The purpose was to investigate the impact of ultraviolet light corneal collagen crosslinking (UV-CXL) on the success rate and clinical outcome of subsequent deep anterior lamellar keratoplasty (DALK) in eyes with keratoconus (KC). METHODS: Medical records of 101 consecutive eyes with KC scheduled for big-bubble DALK surgery were screened retrospectively for details of previously performed UV-CXL, as well as intra- and postoperative complications of DALK surgery. Main outcome measures were intraoperative success rates (big-bubble formation, conversion to penetrating keratoplasty (PK)), postoperative complications, best corrected visual acuity (BCVA), endothelial cell density (ECD), and central corneal thickness (CCT) within 18 months of follow-up. RESULTS: Out of the 101 KC eyes, eight eyes (7.9%) had a history of previous UV-CXL. Surgical failure, defined as conversion to PK due to macroperforation, occurred in 17 eyes (16.8%) of 93 eyes without and in none with previous UV-CXL (P < .001). Failure to achieve a big-bubble occurred in 37 eyes (40.2%) without previous UV-CXL and in two eyes (25%) with previous UV-CXL. Microperforations of Descemet's membrane were observed in ten eyes (20.7%) without and in 14 eyes (15.2%) with previous UV-CXL (P = .16). No significant differences could be detected for either the postoperative complication rate (P ≥ .18) or the clinical outcome parameters at 18 months follow-up, including BCVA, ECD and CCT (P ≥ .08) for eyes with or without UV-CXL. CONCLUSIONS: In DALK surgery, prior UV-CXL does not seem to affect the rate of intra- or postoperative complications, the success rate, or its clinical outcome.

Impact of corneal donor lens status on two-year course and outcome of Descemet membrane endothelial keratoplasty (DMEK).

PURPOSE: Our purpose was to investigate the impact of lens status of corneal donors on the two-year course and clinical outcome of Descemet membrane endothelial keratoplasty (DMEK). METHODS: In 181 DMEK surgeries, 136 phakic and 45 pseudophakic donor corneas were grafted. In this retrospective audit we compared the lens status of corneal donors regarding the outcome measures best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), and endothelial cell density (ECD) at 1, 3, 6, 12, and 24 months, as well as intra- and postoperative complication rates and graft detachment rates requiring re-bubbling. RESULTS: Comparing the use of phakic and pseudophakic donor tissue in DMEK surgery, BSCVA results revealed no significant differences during the two-year course (p ≥ 0.087). CCT showed significantly lower values at 1 month (553.8 ± 56 vs. 625.2 ± 119 µm; p < 0.001) and 6 months follow-up (530.6 ± 49.9 vs. 557.3 ± 47 µm; p = 0.026) for phakic donor tissue recipients, but were comparable later (p ≥ 0.173). ECD values were statistically higher 6 (1915 ± 390 vs. 1565 ± 420 cells/mm2; p < 0.001) and 24 months postoperatively (1772 ± 384 vs. 1375 ± 377 cells/mm2; p = 0.030) in phakic donor tissue recipients. Mixed regression analyses demonstrated a significant association between ECD results and donor lens status (p = 0.029) and donor ECD (p = 0.028), but donor age did not show significant influence (p = 0.241). CONCLUSION: ECD is higher in phakic corneal donors and appears to remain at a higher level during the course resulting in initially faster reduction of corneal edema compared to pseudophakic DMEK grafts. Nevertheless, pseudophakic transplants with high ECD seem to produce comparable functional results in recipients after a two year course.

Impact of donor graft quality on deep anterior lamellar Keratoplasty (DALK).

BACKGROUND: To evaluate main features of donor tissue that may influence clinical outcome or complication rate after deep anterior lamellar keratoplasty (DALK). METHODS: Donor tissue parameters of 84 consecutive corneal donor grafts used for big-bubble DALK surgery between June 2011 and December 2014 in 84 eyes of 84 patients with disorders of anterior corneal stroma were correlated to clinical outcome parameters of recipient eyes 12 months after surgery and 3 months after total suture removal. Main donor tissue parameters included age), post-mortem time, overall preservation time, preservation time after split and prior to transplantation, and preservation technique. Clinical outcome parameters included best spectacle corrected visual acuity (BSCVA), central corneal thickness (CCT), endothelial cell density (ECD) and complication rates. Pearson's correlation, linear regression analysis for clinical outcome parameter and logistic regression analysis for postsurgical complication rates were applied. RESULTS: Corneal donors were mean aged 67.4 ± 12.5 years with a post-mortem time of 20.7 ± 14.7 h and ECD of 2641.0 ± 362.8 cells/mm2. Overall preservation time was 16.3 ± 6.3 days. Recipients showed mean BSCVA 12 months postoperatively of 0.60 ± 0.36 logMAR, endothelial cell loss was 4 ± 16%, and central corneal thickness was 571.7 ± 54.2 µm. 3 months after total removal of sutures, BSCVA was 0.20 ± 0.10 logMAR, endothelial cell loss was 17 ± 24%, and central corneal thickness was 590.9 ± 55.5 µm. Loosening of sutures occurred in 20%, and Descemet detachment in 16%. None of the clinical outcome parameters or complication rate after DALK showed a significant association with donor tissue parameters. CONCLUSIONS: Donor corneas, independent of excision techniques or preservation method, with donor age ≤ 88 years, post-mortem time ≤ 63 h, overall preservation time ≤ 14 days for cold storaged donor tissue and ≤35 days for organ culture, and preservation time after split prior to grafting ≤96 h, seem to be applicable as safe donor tissue for DALK surgery.

[Biomaterials or Donor Tissue - What is the Future of Tissue Engenieering for Cornea Reconstruction?] / Keratin, Kollagen oder doch Spendergewebe ­ wo liegt die Zukunft in der Entwicklung neuer Biomaterialien zur Hornhautrekonstruktion?

For the replacement of corneal tissue, corneal grafts or amniotic membrane are still used as a standard material. Since this is biological tissue, there is only a limited standardization regarding preparation, tissue properties and behaviour after transplantation. In addition, there is a risk of disease transmission, and the availability of both human corneas and amniotic membrane is insufficient in many regions of the world, which is why alternative biomaterials have been explored for many years now. Among the natural biomaterials, materials based on collagen or keratin provide characteristics that make them good candidates for corneal tissue replacement. However, there are still many unsolved problems, particularly regarding the degradation after implantation and the seam strength of the materials. Initial clinical studies with different biomaterials based on collagen prove their good biocompatibility to integrate and their low immunogenicity. Currently, there is no biomaterial that meets the requirements in every situation. It can be assumed that different biomaterials will be available in the future, which, depending on the underlying corneal disease, will fulfill different functions and thus make a patient- and disease-specific care possible.

[Complications of DMEKeratoplasty: Avoid, Recognize and Treat]. / DMEK: Probleme vermeiden, erkennen, lösen.

Descemet membrane endothelial keratoplasty (DMEK) has evolved into a routine surgical procedure for posterior lamellar keratoplasty. After its introduction more than 10 years ago, several modifications in grafting technique and postoperative treatment regimen helped to improve its safety and reproducibility. Although DMEK offers faster and better improvements in visual acuity, as well as less graft rejections when compared to Descemet's stripping (automated) endothelial keratoplasty (DS[A]EK), difficulties when implementing this technique hamper the widespread use in many areas. However, different strategies help to reduce the rate of intra- and postoperative complications, making DMEK the method of choice for most patients with corneal endothelial diseases. Certain techniques help to reduce the endothelial damage during graft preparation; correct matching of donor age and recipient's anterior chamber depth eases intracameral unfolding of the DMEK graft, the use of SF6 gas for anterior chamber tamponade reduces the need for additional rebubblings, and the correct frequency and duration of postoperative topical steroid treatment helps to reduce the development of cystoid macular edema and graft rejections. Further standardization, but also individualization, of DMEK helps to offer this treatment option to patients with more complex anterior segment situations like anterior synechia, larger iris defects and glaucoma drainage devices.

[Mid- and Longterm Experiences with the Boston-Keratoprosthesis. The Cologne and Salzburg Perspective]. / Mittel- und langfristige Erfahrungen mit der Boston-Keratoprothese. Die Kölner und Salzburger Perspektive.

Background Eyes with severe corneal opacifications and insufficient prognosis for high-risk corneal transplantation can be considered for the implantation of a Boston-keratoprosthesis. Since 2013, this technique of "artificial" corneal replacement is provided to high-risk eyes at the Department of Ophthalmology, University of Cologne and for 9 years at the University of Salzburg. In the meantime, a type I Boston keratoprosthesis (BI-KPro) has been implanted in 24 eyes in Cologne and in 28 eyes in Salzburg. Methods In this article, results and complications according to BI-KPro are discussed, both from the literature in PubMed, as well as from our own experiences. Results Twenty-four eyes of 22 patients had been provided with a BI-KPro since September 2013, of which only one keratoprosthesis could not be obtained thus far, and an increase in visual acuity could be achieved in 23 eyes (96%). On average, 1.5 revisions per eye were required during the postoperative course. Since 2007, a BI-KPro has been implanted in 28 eyes in Salzburg. In 62% (16 of 26 eyes), visual acuity increased postoperatively, with a complication rate of 81% in a longer follow-up period. In both cohorts, the spectrum of complications ranged from retroprosthetic membrane formation, to secondary glaucoma, to infectious keratitis with or without graft melting, to vitritis, to endophthalmitis. Conclusion The range of possible complications according to BI-KPro is broad, but the BI-KPro represents currently the most widely used form of artificial corneal replacement in high-risk eyes and leads to visual improvement in most patients.