Suppressing Pro-Apoptotic Proteins by siRNA in Corneal Endothelial Cells Protects against Cell Death.

Corneal endothelial cells (CE) are critical for the cornea's transparency. For severe corneal damage, corneal tissue transplantation is the most promising option for restoring vision. However, CE apoptotic cell death occurs during the storage of donor corneas for transplantation. This study used small interfering (si)RNA-mediated silencing of pro-apoptotic proteins as a novel strategy to protect CE against apoptosis. Therefore, the pro-apoptotic proteins Bax and Bak were silenced in the human corneal endothelial cell line (HCEC-12) by transfection with Accell™siRNA without any adverse effects on cell viability. When apoptosis was induced, e.g., etoposide, the caspase-3 activity and Annexin V-FITC/PI assay indicated a significantly reduced apoptosis rate in Bax+Bak-siRNA transfected HCECs compared to control (w/o siRNA). TUNEL assay in HCECs exposed also significantly lower cell death in Bax+Bak-siRNA (7.5%) compared to control (w/o siRNA: 32.8%). In ex vivo donor corneas, a significant reduction of TUNEL-positive CEs in Bax+Bak-siRNA corneas (8.1%) was detectable compared to control-treated corneas (w/o siRNA: 27.9%). In this study, we demonstrated that suppressing pro-apoptotic siRNA leads to inhibiting CE apoptosis. Gene therapy with siRNA may open a new translational approach for corneal tissue treatment in the eye bank before transplantation, leading to graft protection and prolonged graft survival.

Efficacy, Confounders and Safety of the Preserflo Microshunt. / Wirksamkeit, Einflussfaktoren und Sicherheit des Preserflo Microshunt.

BACKGROUND: Glaucoma is a leading cause of blindness worldwide. We evaluated the efficacy, confounders, and safety of the Preserflo Microshunt over a one-year follow-up period. METHODS: In this retrospective monocentric study, 111 eyes were evaluated. 83 eyes had primary open angle glaucoma, and 28 eyes secondary open angle glaucoma. Intraocular pressure (IOP), visual acuity, number of glaucoma medications, complications, and reoperations were evaluated postoperatively, at 1, 3, 6, 9, and 12 months. The influence of age, sex, type of glaucoma, previous surgery and lens status was also analysed. Bleb revision was indicated if corrected IOP exceeded 18 mmHg. RESULTS: Intraocular pressure significantly decreased from 24.50 ± 8.94 to 14.62 ± 4.86 mmHg (4 - 32 mmHg; p < 0.001), the number of medications from 3.19 ± 1.14 to 0.98 ± 1.39 (0 - 4; p < 0.001). Confounders of interest did not affect efficacy. Bleb revision was performed in 22.5% of eyes and a cyclophotocoagulation was performed in 9.9% of eyes. Complete surgical success (IOP ≤ 17 mmHg, IOP reduction ≥ 20%, without medication) was achieved in 36.9% (n = 41) and qualified success (with medication) in 51.4% (n = 57) of eyes. Transient hypotension (≤ 5 mmHg) occurred in 19.8% after primary implantation and in 1.8% after bleb revision (duration ≤ 3 months). CONCLUSION: To date, the Preserflo Microshunt has demonstrated good efficacy and a low risk profile.

UV light-mediated corneal crosslinking as (lymph)angioregressive pretreatment to promote graft survival after subsequent high-risk corneal transplantation (CrossCornealVision): protocol for a multicenter, randomized controlled trial.

BACKGROUND: Good vision highly depends on the transparency of the cornea, which is the "windscreen" of the eye. In fact, corneal blindness due to transparency loss is the second most common cause of blindness worldwide, and corneal transplantation is the main cure. Importantly, the cornea is normally avascular but can secondarily be invaded by pathological (blood and lymphatic) vessels due to severe inflammation, and the survival prognosis of a corneal graft mainly depends on the preoperative vascular condition of the recipient's cornea. Whereas transplants placed into avascular recipient beds enjoy long-term survival rates of > 90%, survival rates significantly decrease in pathologically pre-vascularized, so-called high-risk recipients, which account for around 10% of all performed transplants in Germany and > 75% in lower and middle-income countries worldwide. METHODS: This parallel-grouped, open-randomized, multicenter, prospective controlled exploratory investigator-initiated trial (IIT) intends to improve graft survival by preconditioning pathologically vascularized recipient corneas by (lymph)angioregressive treatment before high-risk corneal transplantation. For this purpose, corneal crosslinking (CXL) will be used, which has been shown to potently regress corneal blood and lymphatic vessels. Prior to transplantation, patients will be randomized into 2 groups: (1) CXL (intervention) or (2) no pretreatment (control). CXL will be repeated once if insufficient reduction of corneal neovascularization should be observed. All patients (both groups) will then undergo corneal transplantation. In the intervention group, remaining blood vessels will be additionally regressed using fine needle diathermy (on the day of transplantation). Afterwards, the incidence of graft rejection episodes will be evaluated for 24 months (primary endpoint). Overall graft survival, as well as regression of corneal vessels and/or recurrence, among other factors, will be analyzed (secondary endpoints). DISCUSSION: Based on preclinical and early pilot clinical evidence, we want to test the novel concept of temporary (lymph)angioregressive pretreatment of high-risk eyes by CXL to promote subsequent corneal graft survival. So far, there is no evidence-based approach to reliably improve graft survival in the high-risk corneal transplantation setting available in clinical routine. If successful, this approach will be the first to promote graft survival in high-risk transplants. It will significantly improve vision and quality of life in patients suffering from corneal blindness. TRIAL REGISTRATION: ClinicalTrials.gov NCT05870566. Registered on 22 May 2023.

[Corneal wound healing-Pharmacological treatment]. / Wundheilung der Kornea ­ Pharmakologische Therapie.

Physiological wound healing of the cornea is a complex process and involves numerous multifactorial tissue processes. A proper wound healing, especially without the formation of light-scattering scars, is essential to preserve the integrity and function of the cornea. Misdirected wound healing is of vast clinical relevance as it can lead to corneal fibrosis and the loss of optical transparency with subsequent reduction of visual acuity, up to blindness. In addition to the understanding of the pathophysiological mechanisms, the knowledge of therapeutic concepts and options for treating corneal wound healing disorders and fibrosis is essential to counteract a permanent damage of the cornea as early as possible. Nowadays, various pharmacological and surgical options are available for treatment. The decision, appropriate selection and indication for the optimal treatment depend primarily on the genesis and clinical appearance of the corneal wound, fibrosis or scar. The treatment of wound healing disorders ranges from the use of topical therapy and supportive measures up to tissue replacement procedures. As long as the mechanical stability of the cornea is intact and wound healing processes are still ongoing, a pharmacological modulation is reasonable, which is discussed in this article.

Anatomical and functional results after vitrectomy with conventional ILM peeling versus inverted ILM flap technique in large full-thickness macular holes.

BACKGROUND: Aim of the study was to compare success rate and functional outcome following pars plana vitrectomy (PPV) with conventional internal limiting membrane (ILM) peeling versus ILM flap technique for full-thickness idiopathic macular holes (FTMH). METHODS: Retrospective analysis of consecutive eyes with FTMH having undergone vitrectomy with sulfur hexafluoride (SF6) endotamponade 25% at the University Medical Center Rostock, Germany (2009-2020). Eyes were divided according to applied surgical technique (ILM peeling [group P] versus ILM flap [group F]). Inclusion criteria were macular hole base diameters (MH-BD) ≥ 400 µm plus axial length ≤ 26.0 mm. Each group was divided into two subgroups based on macular hole minimum linear diameter (MH-MLD): ≤ 400 µm and > 400 µm. Exclusion criteria were FTMH with MH-BD < 400 µm, trauma, myopia with axial length > 26.0 mm or macular schisis. Demographic, functional, and anatomical data were obtained pre- and postoperatively. Preoperative MH-BD and MH-MLD were measured using optical coherence tomography (OCT; Spectralis®, Heidelberg Engineering GmbH, Heidelberg, Germany). Main outcome parameter were: primary closure rate, best-corrected visual acuity (BCVA), and re-surgery rate. RESULTS: Overall 117 eyes of 117 patients with FTMH could be included, thereof 52 eyes underwent conventional ILM peeling (group P) and 65 additional ILM flap (group F) technique. Macular hole closure was achieved in 31 eyes (59.6%) in group P and in 59 eyes (90.8%) in group F (p < 0.001). Secondary PPV was required in 21 eyes (40.4%) in group P and in 6 eyes (9.2%) in group F. Postoperative BCVA at first follow-up in eyes with surgical closure showed no significant difference for both groups (MH-MLD ≤ 400 µm: p = 0.740); MH-MLD > 400 µm: p = 0.241). CONCLUSION: Anatomical results and surgical closure rate following ILM flap technique seems to be superior to conventional ILM peeling for treatment of FTMH.

PREVALENCE OF SARS-CoV-2 RNA AND ANTIBODY DETECTION, AND VACCINATION STATUS IN PATIENTS WITH OCULAR VASCULAR OCCLUSION.

PURPOSE: To analyze the annual prevalence of ocular vascular occlusion in relation to COVID-19 infection and vaccination status in a prospective study. METHODS: All patients were examined for an active severe acute respiratory syndrome coronavirus 2 infection by RNA detection and for a previous infection by virus-specific antibody detection, and their vaccination status was documented. Data from pandemic year 2020 and previous years, before COVID-19 (2019, 2018, 2017), were retrospectively analyzed. RESULTS: In 2021, a total of 103 patients with the first diagnosis of ocular vascular occlusion were treated. Most frequent subdiagnoses were central retinal vein occlusion (20.4%), nonarteritic anterior ischemic optic neuropathy (18.4%), central retinal artery occlusion (13.6%), and branch retinal artery occlusion (12.6%). Thereof, only three patients (2.9%) presented with virus-specific severe acute respiratory syndrome coronavirus 2 antibodies, and none was PCR positive. Patients with preceded severe acute respiratory syndrome coronavirus 2 vaccination (59.2%) presented with comparable characteristics as unvaccinated patients with vascular occlusion regarding age, gender distribution, systemic risk factors, duration of symptoms, visual acuity, and the present subdiagnoses ( P > 0.05). The total number of cases in 2021 (103 cases) was comparable with the pandemic year 2020, at which no vaccination was available (114 cases), and to earlier years 2017, 2018, and 2019 without COVID-19 pandemic (100, 120, and 119 cases). Furthermore, we did not reveal any differences between pandemic and reference years regarding patients' characteristics ( P > 0.05). CONCLUSION: Our study did not reveal an increased annual prevalence of ocular vascular occlusions during COVID-19 pandemic years 2020 and 2021. Patients with previous COVID-19 vaccination did not present differences regarding the risk profile nor symptoms, compared with unvaccinated individuals.

Relevance of Laser Flare Photometry in Retinal Pathologies. / Relevanz der Laser-Flare-Photometrie bei retinalen Pathologien.

Laser flare photometry provides a non-invasive and objective measurement of the Tyndall effect in the anterior chamber. The laser flare value (measured in photon number per millisecond [pc/ms]) thus quantifies the extent of disruption to the blood-aqueous barrier and can be used in clinical applications to monitor uveitis therapy or to measure the postoperative degree of inflammation. Standardised performance must be observed during measurement. Publications of the last 35 years on laser flare photometry deal not only with the measurement procedure but also with its use in clinical practice for different ophthalmological pathologies. Likewise, various influencing factors have already been investigated and described that must be considered when measuring and evaluating laser flare values. The focus of this article is the relevance of laser flare photometry in retinal pathologies. In recently published studies, the level of objective tyndallometry in primary rhegmatogenous retinal detachment is shown to depend on lens status, symptom duration, and extent of retinal detachment. The greater is the area of the retina affected, the greater the disruption of the blood-aqueous barrier appears to be. Elevated laser flare values have also been considered as a predictor for the development of proliferative vitreoretinopathy (PVR). However, based on current knowledge, this assumption must be put into perspective. According to current data, objective tyndallometry can be used to monitor the progression of intraocular inflammation and to quantify the blood-aqueous barrier, and the values correlate with the extent and anatomical features, as well as the symptom duration in retinal detachment. Many influencing factors have already been identified. But further evaluation is desirable and needed. It is still unclear whether laser flare values can be used in the future as a predictor for sequelae such as PVR development.

Impact of implementation of polymerase chain reaction on diagnosis, treatment, and clinical course of Acanthamoeba keratitis.

PURPOSE: Acanthamoeba keratitis (AK) is a painful and possibly sight-threatening ocular infection. While the correct diagnosis and specific treatment in the early stages significantly improve the prognosis, the disease is often misdiagnosed and in clinical examination confused with other forms of keratitis. Polymerase chain reaction (PCR) for the detection of AK was first introduced in our institution in December 2013 to improve the timely diagnosis of AK. The aim of this study was to assess the impact of implementation of Acanthamoeba PCR on the diagnosis and treatment of the disease in a German tertiary referral center. PATIENTS AND METHODS: Patients treated for Acanthamoeba keratitis between 1st of January 1993 and 31st of December 2021 in the Department of Ophthalmology of the University Hospital Duesseldorf were identified retrospectively via in-house registries. Evaluated parameters include age, sex, initial diagnosis, method of correct diagnosis, duration of symptoms until correct diagnosis, contact lens use, visual acuity, and clinical findings as well as medical and surgical therapy by keratoplasty (pKP). In order to assess the impact of implementation of Acanthamoeba PCR, the cases were divided into two groups (before (pre-PCR group) and after PCR implementation (PCR group). RESULTS: Seventy-five patients with Acanthamoeba keratitis were included (69.3% female, median age 37 years). Eighty-four percent (63/75) of all patients were contact lens wearers. Until PCR was available, 58 patients with Acanthamoeba keratitis were diagnosed either clinically (n = 28), by histology (n = 21), culture (n = 6), or confocal microscopy (n = 2) with a median duration until diagnosis of 68 (18; 109) days. After PCR implementation, in 17 patients, the diagnosis was established with PCR in 94% (n = 16) and median duration until diagnosis was significantly shorter with 15 (10; 30.5) days. A longer duration until correct diagnosis correlated with a worse initial visual acuity (p = 0.0019, r = 0.363). The number of pKP performed was significantly lower in the PCR group (5/17; 29.4%) than in the pre-PCR group (35/58; 60.3%) (p = 0.025). CONCLUSIONS: The choice of diagnostic method and especially the application of PCR have a significant impact on the time to diagnosis and on the clinical findings at the time of confirmation of diagnosis and the need for penetrating keratoplasty. In contact lens-associated keratitis, the first crucial step is to take AK into consideration and perform a PCR test as timely confirmation of diagnosis of AK is imperative to prevent long-term ocular morbidity.

Argon cold atmospheric plasma eradicates pathogens in vitro that are commonly associated with canine bacterial keratitis.

Purpose: To investigate the antimicrobial effect of cold atmospheric plasma (CAP) on pathogens associated with canine bacterial keratitis. Materials and methods: Pseudomonas aeruginosa, Staphylococcus pseudintermedius, and Streptococcus canis strains, which were obtained from dogs with infectious keratitis, were subjected to testing. For each species, four isolates and a reference strain were cultivated on Columbia sheep blood agar and treated with the kiNPen Vet® plasma pen from Neoplas GmbH, Greifswald, Germany. Various continuous treatment durations (0.5, 2, and 5 min) were applied, along with a 0.5-min treatment repeated four times at short intervals. These treatments were conducted at distances of 3 and 18 mm between the agar surface and the pen. Results: CAP treatment reduced bacterial growth in all three species. The most effective treatment duration was 5 min at 3 mm distance, resulting in inhibition zones ranging from 19 to 22 mm for P. aeruginosa, 26-45 mm for S. pseudintermedius and an overall reduction of bacterial growth for Str. canis. Inhibition zones were smaller with decreasing treatment duration and larger distance. Treatment times of 30 s repeated four times and 2 min showed comparable results. Treatment with argon alone did not lead to visible reduction of bacterial growth. Conclusion: Argon cold atmospheric plasma demonstrated a potent in vitro antimicrobial effect on P. aeruginosa, S. pseudintermedius and Str. canis strains with the latter showing the highest sensitivity.

Retinal and Choroidal Ultra-Widefield OCT - Technology, Insights, and Clinical Relevance. / Retinale und choroidale Ultra-Weitwinkel-OCT ­ Technologie, Einblicke und klinische Bedeutung.

As one of the most state-of-the-art procedures for retinal and choroidal imaging, ultra-widefield optical coherence tomography (UWF-OCT) offers significant gains in terms of information pertaining to peripheral retinal lesions and their differential diagnoses. In particular, it enables the presence of minimal accumulations of subretinal fluid to be assessed in detail and then documented. It also enables choroidal expansion of choroidal lesions to be precisely measured. Similar to conventional OCT, its only limitations relate to patient compliance and opacities of the ocular media. While the pupil width is somewhat less important here, the quality of the images is nevertheless better with the patient under medication-induced mydriasis. Used in combination with UWF fundus photography, UWF-OCT is a helpful tool for assessing and monitoring peripheral retinal and choroidal lesions.

Schwann Cells Promote Myogenic Differentiation of Myoblasts and Adipogenic Mesenchymal Stromal Cells on Poly-ɛ-Caprolactone-Collagen I-Nanofibers.

For the purpose of skeletal muscle tissue engineering, different cell types have been investigated regarding their myogenic differentiation potential, including co-cultured myoblasts and adipogenic mesenchymal stromal cells (Mb/ADSC). As neural cells enhance synaptic junction formation, the aim of this study was to co-culture Schwann cells (SCs) with Mb/ADSC on biocompatible electrospun aligned poly-ε-polycaprolacton (PCL)-collagen I-nanofibers. It was hypothesized that SCs, as part of the peripheral nervous system, promote the myogenic differentiation of Mb/ADSC co-cultures. Mb/ADSC were compared to Mb/ADSC/SC regarding their capacity for myogenic differentiation via immunofluorescent staining and gene expression of myogenic markers. Mb/ADSC/SC showed more myotubes after 28 days of differentiation (p ≤ 0.05). After 28 days of differentiation on electrospun aligned PCL-collagen I-nanofibers, gene expression of myosin heavy chains (MYH2) and myogenin (MYOG) was upregulated in Mb/ADSC/SC compared to Mb/ADSC (p ≤ 0.01 and p ≤ 0.05, respectively). Immunofluorescent staining for MHC showed highly aligned multinucleated cells as possible myotube formation in Mb/ADSC/SC. In conclusion, SCs promote myogenic differentiation of Mb/ADSC. The co-culture of primary Mb/ADSC/SC on PCL-collagen I-nanofibers serves as a physiological model for skeletal muscle tissue engineering, applicable to future clinical applications.

Electrospun PCL Scaffolds as Drug Carrier for Corneal Wound Dressing Using Layer-by-Layer Coating of Hyaluronic Acid and Heparin.

Due to its ability to reduce scarring and inflammation, human amniotic membrane is a widely used graft for wound dressings after corneal surgery. To overcome donor dependency and biological variances in the donor tissue, artificial nanofibrous grafts acting as drug carrier systems are promising substitutes. Electrospun nanofibrous scaffolds seem to be an appropriate approach as they offer the properties of permeable scaffolds with a high specific surface, the latter one depending on the fiber diameter. Electrospun scaffolds with fiber diameter of 35 nm, 113 nm, 167 nm and 549 nm were manufactured and coated by the layer-by-layer (LbL) technology with either hyaluronic acid or heparin for enhanced regeneration of corneal tissue after surgery. Studies on drug loading capacity and release kinetics defined a lower limit for nanofibrous scaffolds for effective drug loading. Additionally, scaffold characteristics and resulting mechanical properties from the application-oriented characterization of suture pullout from suture retention tests were examined. Finally, scaffolds consisting of nanofibers with a mean fiber diameter of 113 nm were identified as the best-performing scaffolds, concerning drug loading efficiency and resistance against suture pullout.

Examining the Transmission of Visible Light through Electrospun Nanofibrous PCL Scaffolds for Corneal Tissue Engineering.

The transparency of nanofibrous scaffolds is of highest interest for potential applications like corneal wound dressings in corneal tissue engineering. In this study, we provide a detailed analysis of light transmission through electrospun polycaprolactone (PCL) scaffolds. PCL scaffolds were produced via electrospinning, with fiber diameters in the range from (35 ± 13) nm to (167 ± 35) nm. Light transmission measurements were conducted using UV-vis spectroscopy in the range of visible light and analyzed with respect to the influence of scaffold thickness, fiber diameter, and surrounding medium. Contour plots were compiled for a straightforward access to light transmission values for arbitrary scaffold thicknesses. Depending on the fiber diameter, transmission values between 15% and 75% were observed for scaffold thicknesses of 10 µm. With a decreasing fiber diameter, light transmission could be improved, as well as with matching refractive indices of fiber material and medium. For corneal tissue engineering, scaffolds should be designed as thin as possible and fabricated from polymers with a matching refractive index to that of the human cornea. Concerning fiber diameter, smaller fiber diameters should be favored for maximizing graft transparency. Finally, a novel, semi-empirical formulation of light transmission through nanofibrous scaffolds is presented.

Optimization of polycaprolactone - based nanofiber matrices for the cultivation of corneal endothelial cells.

Posterior lamellar transplantation of the eye' s cornea (DSAEK, DMEK) currently is the gold standard for treating patients with corneal endothelial cell and back surface pathologies resulting in functional impairment. An artificial biomimetic graft carrying human corneal endothelium could minimize the dependency on human donor corneas giving access to this vision-restoring surgery to large numbers of patients, thus reducing current long waiting lists. In this study, four groups of electrospun nanofibrous scaffolds were compared: polycaprolactone (PCL), PCL/collagen, PCL/gelatin and PCL/chitosan. Each of the scaffolds were tissue-engineered with human corneal endothelial cells (HCEC-B4G12) and analyzed with regard to their potential application as artificial posterior lamellar grafts. Staining with ZO-1 and Na+/K+-ATPase antibodies revealed intact cell functionalities. It could be shown, that blending leads to decreasing contact angle, whereby a heterogeneous blend morphology could be revealed. Scaffold cytocompatibility could be confirmed for all groups via live/dead staining, whereby a significant higher cell viability could be observed for the collagen and gelatine blended matrices with 97 ± 3% and 98 ± 2% living cells respectively. TEM images show the superficial anchoring of the HCECs onto the scaffolds. This work emphasizes the benefit of blended PCL nanofibrous scaffolds for corneal endothelial keratoplasty.

Biomechanical assessment of healthy and keratoconic corneas (with/without crosslinking) using dynamic ultrahigh-speed Scheimpflug technology and the relevance of the parameter (A1L-A2L).

AIMS: To examine corneal biomechanics in healthy and keratoconic eyes, with or without crosslinking obtained by ultrahigh-speed Scheimpflug measurements (Corvis ST). METHODS: One hundred and seventeen eyes were studied in three groups: group 1 (n=39) contained keratoconic eyes without crosslinking. Group 2 (CXL; n=28) comprised keratoconic eyes after crosslinking. These were compared with a control group (n=50 matched healthy eyes). In addition, 10 keratoconus patients, before and after CXL treatment, respectively, were examined. RESULTS: The novel parameter A1L-A2L demonstrated highly significant differences between crosslinked corneas and untreated keratoconic or healthy corneas. Velocity during second applanation (A2V) and deformation amplitude (DA) were significantly increased in crosslinked keratoconic eyes both compared with untreated keratoconic eyes and with healthy controls. Radius at highest curvature also was significant among all groups. Inward applanation length (A1L) was significantly increased in controls, whereas outward applanation length (A2L) was significantly reduced in crosslinked keratoconic eyes compared with both other groups. The follow-up analysis revealed statistically significant changes in pachymetry and intraocular pressure and showed tendencies towards significance in applanation times 1 and 2 and in DA. CONCLUSIONS: Both A2V and A2L are viable parameters to discriminate healthy from keratoconic but also crosslinked from non-crosslinked keratoconic corneas. The difference of A1L-A2L could reliably discriminate crosslinked from non-crosslinked and healthy corneas. Follow-up examination in a small cohort allows distinction between crosslinked and untreated keratoconus in follow-up examinations. The difference of A1L-A2L could reliably discriminate crosslinked from non-crosslinked and healthy corneas. Measurements of corneal deformation using dynamic ultrahigh-speed Scheimpflug technology are reproducible and provide useful information about keratoconus assessment and biomechanics. Therefore, the Corvis ST seems to provide useful technology to monitor therapeutic success of crosslinking treatment.

[Cold Plasma to Treat Therapy-Refractive Corneal Ulcers]. / Kaltplasma zur Behandlung therapierefraktärer Hornhautulzera.

BACKGROUND: The integrity of the ocular surface and the transparency of the cornea is crucial to obtain a good visual acuity - a requirement to actively participate in both social and professional environments. The homeostasis of the ocular surface is constantly endangered by microbes and by intrinsic factors with negative influence on wound healing. Furthermore, widespread use of contact lenses obtain a risk of corneal infection even resulting in corneal perforation and loss of the eye. Current therapies include topical and systemic antibiotics and antimycotics, often applied in an in-ward setting. PATIENTS/MATERIALS AND METHODS: Some microbes can be therapy-resistent or -refractory and therefore cause a deterioration of the clinical aspect. In this study, the effects of cold plasma treatment of corneal ulcers on reduction of microbial load in vitro, in tissue ex vivo and in a therapy-refractory ulcer. RESULTS: In vitro, ex vivo and in the patient microbial load could be reduced or the clinical findings improved. CONCLUSIONS: Plasma medicine and its disinfective properties could open a novel approach to treat microbial infections of the cornea. The can result in reduced treatment times, a faster demission of the patients and overall in a reduction of health care costs.

Argon Cold Plasma-A Novel Tool to Treat Therapy-resistant Corneal Infections.

PURPOSE: To test whether therapy-resistant corneal infections can be successfully treated with argon cold plasma to reduce or eliminate pathogen microorganisms without affecting corneal cell viability. DESIGN: First-in-human case series and experimental study. METHODS: Cold plasma effects on viability of primary human corneal limbal epithelial cells were studied using exposure times from 0.5 to 10 minutes (metabolic activity, oxidative stress, apoptosis). Disinfective potential of cold plasma was tested against common pathogens (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans) on culture medium and evaluated by counting colony-forming units and optical density measurements, as well as against S aureus in a human cornea infection model. Additionally, in a first-in-human trial 4 patients with therapy-resistant corneal ulcers were treated to evaluate the clinical potential of cold plasma. RESULTS: Cells treated for 0.5-5 minutes completely recovered within 24 hours without changes in morphology; only 10-minute treatment impaired the cells permanently. No evident oxidative stress, apoptosis, or damage to the corneal structure could be found. All pathogens were susceptible to cold plasma treatments, with different levels of sensitivity. The condition of all 4 patients significantly improved after cold plasma treatment combined with antibiotic therapy. CONCLUSIONS: Our results indicate that argon cold plasma treatment reduces or eliminates common pathogens without impairing corneal epithelial cells in vitro, ex vivo, and in direct application on patients' eyes. We conclude that argon cold plasma therapy offers a potential supplement or alternative therapy for therapy-resistant corneal infections. A larger, comparative study is necessary to further confirm these findings.

[Novel concepts for treatment of the corneal endothelium with nanoparticles]. / Neuartige Konzepte zur Behandlung des Hornhautendothels mittels Nanopartikel.

BACKGROUND: The number of corneal transplantations has increased in Germany in recent years. One reason is an earlier time point of surgery due to less invasive posterior lamellar grafting techniques. To date, penetrating and lamellar corneal transplantations are the only established therapeutic options to treat corneal diseases resulting from endothelial cell pathologies. AIM: This review article provides an insight into nanoparticle-related translational strategies to improve or to avoid corneal transplantation. RESULTS: Nanoparticle-based strategies for optimization of the corneal endothelium have different fields of application: 1. during donor cornea cultivation in culture medium, 2. for single cell injection therapies and 3. to treat the patients' own endothelium in an effort to avoid transplantation. CONCLUSION: Several translational concepts exist to improve or to avoid grafting of a donor cornea. The coming decade will provide established alternatives to conventional corneal transplantation.