Clinical Features and Treatment Outcomes of Carbapenem-Resistant Pseudomonas aeruginosa Keratitis.

Importance: Evaluation of the microbiological diagnostic profile of multidrug-resistant Pseudomonas aeruginosa keratitis and potential management with rose bengal-photodynamic antimicrobial therapy (RB-PDAT) is important. Objective: To document the disease progression of carbapenemase-resistant P aeruginosa keratitis after an artificial tear contamination outbreak. Design, Setting, and Participants: This retrospective observation case series included 9 patients 40 years or older who presented at Bascom Palmer Eye Institute and had positive test results for multidrug-resistant P aeruginosa keratitis between January 1, 2022, and October 31, 2023. Main Outcomes and Measures: Evaluation of type III secretion phenotype, carbapenemase-resistance genes blaGES and blaVIM susceptibility to antibiotics, and in vitro and in vivo outcomes of RB-PDAT against multidrug-resistant P aeruginosa keratitis. Results: Among the 9 patients included in the analysis (5 women and 4 men; mean [SD] age, 73.4 [14.0] years), all samples tested positive for exoU and carbapenemase-resistant blaVIM and blaGES genes. Additionally, isolates were resistant to carbapenems as indicated by minimum inhibitory concentration testing. In vitro efficacy of RB-PDAT indicated its potential application for treating recalcitrant cases. These cases highlight the rapid progression and challenging management of multidrug-resistant P aeruginosa. Two patients were treated with RB-PDAT as an adjuvant to antibiotic therapy and had improved visual outcomes. Conclusions and Relevance: This case series highlights the concerning progression in resistance and virulence of P aeruginosa and emphasizes the need to explore alternative therapies like RB-PDAT that have broad coverage and no known antibiotic resistance. The findings support further investigation into the potential effects of RB-PDAT for other multidrug-resistant microbes.

Oxidative Stress and Antioxidant-Based Interventional Medicine in Ophthalmology.

The different anatomical compartments of the eye are highly subjected to reactive oxygen species (ROS) generation due to internal factors, such as metabolic high oxygen consumption, as well as environmental factors, including UV light. An antioxidant defense system is endowed in the eye tissues to regulate ROS quantity and activity. When this homeostatic system is overwhelmed, oxidative stress occurs, causing cellular damage, chronic inflammation, and tissue degeneration. It also plays a significant role in the development and progression of various ocular diseases. Understanding the mechanisms underlying oxidative stress in ocular conditions is thus crucial for the development of effective prevention and treatment strategies. To track marketed products based on antioxidant substances as active ingredients, the databases of the European Medicines Agency and the U.S. Food and Drug Administration were consulted. Only a limited number of items were identified, which were either used as therapeutic treatment or during ocular surgery, including antioxidants, synthetical derivatives, or pro-drugs designed to enhance tissue permeation and activity. This review aims to provide an overview of the primary ocular pathologies associated with oxidative stress and of the available pharmacological interventions centered around antioxidant molecules. Such insights are essential for advancing the development of effective prevention and novel treatment approaches.

P12-A107†Porcine cornea ex vivo model as an alternative to human donor tissues for investigating new preservation conditions.

PURPOSE: Considering the growing shortage of corneal tissues for research, the present study aimed to develop and optimize a porcine cornea model with qualitative features comparable to those of human tissues. METHODS: A new decontamination procedure of porcine eye bulbs was set up and its efficacy as well as endothelial mortality were evaluated. Human corneas unsuitable for transplant and porcine corneas were then compared after storage under hypothermic (4-8°C, Eusol-C, AL.CHI.MI.A. S.R.L) or organ-culture (31-35°C, Tissue-C, AL.CHI.MI.A. S.R.L) storage conditions for 14 days. A new method, based on the semi-automatic analysis of Trypan-blue stained endothelial areas by Fiji software, was developed to quantify the whole endothelium viability. Corneas were assessed for central corneal thickness (CCT), corneal transparency, endothelial morphology, and endothelial cell density (ECD) at days 0, 7, and 14 of storage. Portions of lamellar tissues consisting of Descemet's membrane and endothelial cells were prepared for histological investigations. RESULTS: The new decontamination procedure of porcine eye bulbs resulted in 18% versus 89% ('no decontamination' control) of corneas still contaminated after 28 days of storage at 31°C. The decontamination protocol did not affect endothelium viability, as assessed by the new Fiji-based method. ECD (porcine: 3156 ± 144 cells/mm2; human: 2287 ± 152 cells/mm2), CCT (porcine: 1073 ± 151 µm; human: 581 ± 39 µm), transparency (porcine: 88.6 ± 11.0%; human: 76.3 ± 5.4%), and morphology score (porcine: 4.0 ± 0.0; human: 3.2 ± 0.4) measured in the porcine cornea at day 0 were significantly higher than in human corneas. Nonetheless, the qualitative parameters of porcine and human corneas showed comparable trends during the storage under hypothermic (4-8°C) and organ-culture (31-35°C) conditions for 14 days. CONCLUSION: The presented porcine cornea model represents a reliable and alternative model to human donor tissues for preliminary investigations and can be used for testing new media, substances, drugs, or preservation conditions and their impact on corneal tissue quality and safety. Furthermore, the quantitative method to assess whole endothelium mortality can be implemented at eye banks for the evaluation of corneas intended for transplantation.

P15-A112†Descemet's membrane endothelial keratoplasty (DMEK) graft preparation in porcine cornea.

PURPOSE: Descemet's membrane endothelial keratoplasty (DMEK) is a frequently used treatment option for patients with corneal endothelial dysfunction. The aim of this study was to set up a method to prepare porcine DMEK grafts and to simulate DMEK surgery in porcine eye bulbs in order to establish an ex-vivo-model for laboratory investigations on DMEK surgery conditions. METHODS: Ten (n=10) porcine eye bulbs from domestic pigs (Sus scrofa domestica), between 6 and 8 months old, were recovered at a local slaughterhouse, transported on ice and processed within 2 h after death. Porcine eye bulbs were decontaminated by immersion in 10 mL of 5% povidone-iodine and corneas were dissected under aseptic conditions, leaving approximately 2 mm of the scleral rim. DMEK grafts were prepared by means of mechanical stripping technique using specific surgical instruments for DMEK (Moria, France) on fresh corneas (n=2) and on corneas stored in Eusol-C (AL.CHI.MI.A. Srl, Italy) at 4°C for 7 days (n=4) and for 14 days (n=4). Endothelial cell (EC) density was compared before DMEK-preparation (specular and light microscopy on trypan blue stained tissues) and after DMEK-preparation (fluorescence microscopy on Calcein-AM stained tissues). DMEK graft injection was simulated in anterior chamber of fresh porcine eye bulbs. RESULTS: The porcine DMEK grafts preparation resulted to be more challenging compared to human DMEK grafts. Despite similarity between human and porcine corneas, porcine Descemet membrane (DM) firmly adheres to the underlying stroma. DMEK grafts preparation was not successful at day 0; DMEK preparation was possible by mechanical stripping technique on corneas stored in Eusol-C for 7 and 14 days obtaining naturally rolled endo-out porcine DMEK grafts. An EC mortality increase up to 20% was observed on DMEK graft compared to initial whole corneal tissue. DMEK roll injection was successfully simulated in anterior chamber of the porcine eye bulb. CONCLUSION: Naturally rolled DMEK endo-out grafts were successfully prepared by mechanical stripping technique on porcine corneal tissues stored in Eusol-C at 4°C (up to 14 days). DMEK Surgery including the tissue injection in anterior chamber could be simulated. Further studies will be performed to improve ex-vivo-porcine DMEK surgery model.

P14-A117†Assessment of performance and safety of corneal chamber hypothermic storage and PSS-L corneal rinsing in human and porcine corneas.

PURPOSE: To prove the safety and performance of the hypothermic corneal storage medium Corneal Chamber, containing Eusol-C solution (AL.CHI.MI.A. S.r.l.) and of the rinsing solution PSS-L (AL.CHI.MI.A. S.r.l.) in support to the new CE certification process in accordance to the EU 2017/745 Medical Device Regulation METHODS: Fifteen (n=15) human donor corneas unsuitable for transplantation and n=11 porcine corneas were evaluated for the following quality parameters: ECD, HEX%, CV%, endothelial morphology, endothelial mortality and transparency at day 0 and after 14±1 days (day 14) of storage in Corneal Chamber at 2-8°C. Then, corneas were rinsed in PSS-L for 1' at room temperature (RT) and the same parameters were assessed Post Rinsing (Day 14PR). In order to evaluate the antimicrobial carryover after the corneal storage in Corneal Chamber(14 days at 4°C), gentamicin sulphate was quantified in human and porcine corneas homogenates by UHPLC. RESULTS: Human and porcine corneas stored in Corneal Chamber at 2-8°C for 14 days showed a good overall quality of the tissue according to quality parameters evaluated. In particular, mean ECD, HEX% and CV% did not show statistically significant changes at the end of storage and endothelial mortality increased of 3.1±3.3% in human corneas and 7.8±3.5% in porcine corneas. Slight variations in endothelial morphology score and corneal transparency were observed. Rinsing with PSS-L did not negatively affect the quality parameters evaluated before and after rinsing and gentamicin sulfate residues were completely removed. CONCLUSION: The storage of corneal tissues in Corneal Chamber at 2-8°C for 14 days and the corneal rinse with 30 ml of PSS-L at RT for 1 min are safe and effective procedures allowing the preservation of the corneal quality parameters including ECD, endothelial mortality, endothelial morphology, HEX%, CV%, and corneal transparency and the elimination of gentamicin sulfate from the tissues before transplantation.

P20-A129†An innovative wound healing method reveals a donor and post-mortem time-dependent regeneration of corneal epithelium.

PURPOSE: The aim of this study was to establish and optimize a new and reproducible epithelial wound healing model on human corneas. This assay was used to study the kinetics of epithelial regeneration following a chemical injury. METHODS: Thirty (n=30) human corneas unsuitable for transplant were used for the experiments. Corneas were cultured in Storagix medium (FBOV) at 31°C. Epithelial integrity before the beginning of the experiments (pre-wound) was assessed using the vital dyes trypan blue (TB, TB-S 0.25%, AL.CHI.MI.A. srl) and sodium fluorescein (Fluo). 1-heptanol soaked paper disks (6 mm) were applied in the centre of the corneas for 1' to trigger a chemical damage at the epithelial layer. Afterwards, sodium fluorescein and TB stainings were repeated to quantify the damaged area and to monitor healing progression. The damaged area (mm2) was calculated for each time point with Fiji software. Wound healing rate (HR, mm2/die) was calculated for both Fluo (HRF) and TB (HRTB) measurements using the previously described formula:Arithmetical averages (HRFAVG and HRTBAVG) of HRs were calculated and correlated by Pearson correlation coefficient with the following donor's parameters: age, sex, post-mortem time (PMT, time between death and tissue procurement), stromal defects, septicaemia, body temperature, diabetes. RESULTS: The execution of the heptanol wounding is highly reproducible, as highlighted by Fluo and TB staining. The average time for full recovery from wounding was 3,8 ± 0,41 days for Fluo and 3,5 ± 0,63 days for TB. Fluo and TB stainings are interchangeable as they significantly correlate (Pearson correlation coefficient = 0.630; p>0.05). A negative linear correlation was observed between HR and PMT (HRFAVG: corrected R2: 0.243, p = 0.003; HRTBAVG: corrected R2: 0,132, p = 0.028), but not with the other donors' parameters. CONCLUSION: Our wound/healing model might be of great interest for studies of epithelial regeneration kinetics and validation of drugs for the treatment of ocular defects. The inverse correlation between PMT and HR provides valuable insights for scientists investigating the regenerative properties of the corneal epithelium, as well as for eye bank personnel aiming to preserve the regenerative potential of corneal epithelium.

Rose Bengal Photodynamic Antimicrobial Therapy: A Review of the Intermediate-Term Clinical and Surgical Outcomes.

PURPOSE: To evaluate the intermediate-term clinical outcomes of Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT) for infectious keratitis; secondarily, to evaluate the surgical outcomes of individuals who underwent optical keratoplasty after RB-PDAT. DESIGN: Retrospective cohort study. METHOD: A retrospective chart review was performed of 31 eyes from 30 consecutive individuals with infectious keratitis refractory to standard medical therapy who underwent RB-PDAT at the Bascom Palmer Eye Institute between January 2016 and July 2020. Data collected included demographics, risk factors for infectious keratitis, microbiological diagnosis, best spectacle-corrected visual acuity (BCVA), clinical outcomes after RB-PDAT, and complication rates post-keratoplasty. RB-PDAT was performed as described in previous studies. Graft survival was evaluated using Kaplan-Meier curves with log-ranks in individuals who underwent keratoplasty after RB-PDAT. RESULTS: The mean age of the study population was 53 ± 18.0 years. In all, 70% were female; 53.3% self-identified as non-Hispanic White and 43.3% as Hispanic. Mean follow-up time was 28.0 ± 14.4 months. Risk factors included contact lens use (80.6%), history of infectious keratitis (19.3%), and ocular surface disease (16.1%). Cultures were positive for Acanthamoeba (51.6%), Fusarium (12.9%), and Pseudomonas (6.5%). Of the individuals with Acanthamoeba infection, 22.5% were treated with concomitant Miltefosine. Clinical resolution was achieved in 77.4% of patients on average 2.72 ± 1.85 months after RB-PDAT, with 22.5% requiring therapeutic penetrating keratoplasties and 54.8% subsequently requiring optical penetrating keratoplasties. At 2 years, the overall probability of graft survival was 78.7%, and the graft failure rate was 21.3%. CONCLUSION: RB-PDAT is a potential adjunct therapy for infectious keratitis that may reduce the need for a therapeutic penetrating keratoplasty. Patients who undergo keratoplasty after RB-PDAT may have a higher probability of graft survival at 1 year postoperatively.

19†Killing efficacy of a new hypothermic corneal storage medium Kerasave at 4°C against nine micro- organisms frequently found in donor corneas.

PURPOSE: The aim of the present study was to determine the killing efficacy of Kerasave (AL.CHI.MI.A Srl), a corneal cold storage medium provided with antimycotic tablet against nine contaminants associated corneal infections. METHODS: The killing efficacy of Kerasave was determined after 0, 3 and 14 days of incubation at 4°C in Kerasave after inocumation of the medium with 10(5)-10(6) (CFU) of Candida albicans (CA), Fusarium solani (FS), Aspergillus brasiliensis (AB), Staphylococcus aureus (SA), Enterococcus faecalis (EF), Bacillus subtilis spizizenii (BS), Pseudomonas aeruginosa (PA), Enterobacter cloacae (EC) and Klebsiella pneumoniae (KP). Log10 reductions at different time intervals were determined by the serial dilution plating technique. RESULTS: After 3 days, Kerasave induced the highest log10decrease in the concentrations of KP, PA, CA and EC. The 2 log10 decrease was observed for SA and EF. The lowest log10 decrease was observed in BS, AB and FS concentrations. After 14 days, the microbial count of CA, FS, SA, EF, PA and EC further decreased CONCLUSIONS: Corneal cold storage medium Kerasave effectively reduced the microbial concentration of almost all tested mciroorganisms after 3 days and represents a valuable tool to control the microbial contamination of human donor corneas intended for trasnplantation.

18†A porcine cornea and lamellar tissue model to investigate effects of storage conditions on corneal preservation.

BACKGROUND: Globally, more than 12 million people are awaiting corneal transplantation and cornea donor reduction has been observed since the outbreak of the COVID-19 pandemic, negatively influencing the availability of human corneas for research purposes as well. Therefore, the exploitation of ex vivo animal models in this field is of great value.The present study aimed at the development of a novel experimental model of porcine cornea ex vivo and lamellar tissue preparation to investigate the effects of storage conditions on corneal preservation. METHODS: Twelve fresh porcine eye bulbs were disinfected by immersion in 10 mL of 5% povidone-iodine under orbital mixing for 5 minutes at room temperature. The corneoscleral rims were dissected, and stored in Tissue-C (Alchimia S.r.l., n=6) at 31°C and in Eusol-C (Alchimia S.r.l., n=6) at 4°C up to 14 days.The evaluation of Endothelial Cell Density (ECD) and endothelial mortality was performed using vital dye Trypan Blue staining (TB-S, Alchimia S.r.l.). Digital 1X pictures of TB-stained corneal endothelium were acquired and percentage of stained area was quantified using FIJI ImageJ software. ECD and endothelial mortality were determined at 0, 3, 7 and 14 days.Medium turbidity detected by naked eye was considered as proof of tissue contamination.Additionally, non-vital staining of the endothelium with Alizarin Red (AR) was performed and the endothelial morphology was investigated at Day 14 in both whole corneas and dissected endothelial lamellae. RESULTS: The contamination rate of porcine corneas corresponded to <10% and 0% in Tissue-C and Eusol-C after 14 days, respectively.Porcine corneas stored in Tissue-C and Eusol-C showed <10% and <20% mortality in Tissue-C and Eusol-C respectively at the end of storage.Preliminary ECD determination (range 3700-4100 cells/mm2) at Day 0 aligned with data present in the literature (Meltendorf et al., Graefe's Arch Clin Exp Ophthalmol, 2007).Whole cornea and dissected lamellae stained with TB and AR showed comparable endothelial morphology after incubation in Tissue-C and Eusol-C for 14 days. The lamellar tissue allowed endothelium morphology analysis at higher magnification compared to whole cornea. CONCLUSION: The presented ex vivo porcine model allows evaluation of the performance and safety of storage conditions. Future perspectives of this method will be the extension of the porcine corneas storage up to 28 days.

25†Simulation of eye surgery in porcine eye globes and evaluation of retinal cytotoxicity.

PURPOSE: To simulate pars plana vitrectomy in porcine eyes ex-vivo using intraoperative devices and to evaluate viability of retinal cells. METHODS: 25 enucleated porcine eyes were divided in following groups Group A) No surgery control: Group B) Sham surgery; Group C) Cytotoxic control; Group D) Surgery with residues; Group E) Surgery with minimal residues. The retina was extracted from each eye bulb and the cell viability was determined by MTT assay. The in vitro cytotoxicity of each used compounds was tested on ARPE-19 cells. RESULTS: No cytotoxicity was detected in retinal samples in groups A, B and E. Samples from eye bulbs that had undergone surgery with minimal removal of residues (group D) and cytotoxic controls (group C) showed high retinal cytotoxicity. The simulation of vitrectomy indicated that the combined use of compounds does not affect retinal cells viability if all the compounds are properly removed, whereas the cytotoxicity detected in group D may suggest that the presence and accumulation of the residues of the compounds used intraoperatively could negatively impact retinal viability. CONCLUSIONS: The present study demonstrate the crucial role of an optimal removal of the intraoperative devices used in eye surgery to ensure safety to the patient.

Performance of New Hypothermic Corneal Storage Media With an Antimycotic Tablet in Comparison to Traditional Hypothermic Media During Simulated Eye Bank Processing.

PURPOSE: To compare the performance of Kerasave (AL.CHI.MI.A. S.R.L., Ponte San Nicolò, Italy) containing 2.5 µg/mL of amphotericin B and Optisol-GS (Bausch & Lomb, Bridgewater, NJ) cold corneal storage media on donor corneas during routine eye bank procedures. METHODS: Forty-four paired donor corneas were preserved after swab sample collection and povidone-iodine decontamination. Right and left corneas were immersed in Kerasave and Optisol-GS, respectively, and stored at 4°C before the initial evaluation. Paired corneas were assigned to processing subgroups for penetrating keratoplasty (n = 20), Descemet stripping automated endothelial keratoplasty (n = 14), or Descemet membrane endothelial keratoplasty (n = 10). Endothelial cell density, central corneal thickness, slit-lamp examination, and endothelial cell damage were assessed at different intervals. Sterility testing was performed on media samples. RESULTS: At the initial evaluation, after 25.6 ± 3.2 hours of storage, the mean central corneal thickness of all corneas in Kerasave (n = 22) was greater than those in Optisol-GS (n = 22) (571 ± 12 µm vs. 526 ± 10 µm, respectively; P = 0.006). All other metrics were comparable between Kerasave and Optisol-GS in processing subgroups at all time intervals. Corneal swabs were positive in 90% of corneas before decontamination with povidone-iodine. At the initial evaluation, fungal contamination was detected in 24% and 19% of Kerasave and Optisol-GS, respectively. At the final evaluation, no fungi was detected in Kerasave and 1 Optisol-GS sample was positive (P = 0.999). CONCLUSIONS: Metrics of corneas stored in Kerasave and Optisol-GS were comparable. Kerasave might be considered an antifungal-possessing alternative to Optisol-GS.

H-Content Is Not Predictive of Perfluorocarbon Ocular Endotamponade Cytotoxicity in Vitro.

In recent years, cases of retinal toxicity occurred in some European, Middle Eastern, and South American countries following the use of perfluorocarbon liquids (PFCLs) on vitreoretinal surgeries owing to impurities in the product. Moreover, Spanish ophthalmologists reported several toxic cases on the use of perfluoro-n-octane Ala Octa (Alamedics, Dornstadt, Germany), raising the necessity of reviewing the current validated methods used for assessing the safety of PFCLs. We proved that in samples of PFCLs contaminated on purpose with impurities previously detected in Ala Octa devices, the determination of the so-called H-content using a 1H NMR quantitative assay implemented with the electronic reference to access in vivo concentrations 2 technology failed to demonstrate a correlation between the H-content and in vitro cytotoxicity test in ARPE-19 and BALB 3T3 cell lines. Therefore, direct information on the safety of PFCLs was provided only by the cytotoxicity test in vitro validated according to ISO 10993-5, and the H-content was not predictive of perfluorocarbon ocular endotamponade cytotoxicity in vitro.

Residual antibiotics in decontaminated human cardiovascular tissues intended for transplantation and risk of falsely negative microbiological analyses.

We investigated the presence of antibiotics in cryopreserved cardiovascular tissues and cryopreservation media, after tissue decontamination with antibiotic cocktails, and the impact of antibiotic residues on standard tissue bank microbiological analyses. Sixteen cardiovascular tissues were decontaminated with bank-prepared cocktails and cryopreserved by two different tissue banks according to their standard operating procedures. Before and after decontamination, samples underwent microbiological analysis by standard tissue bank methods. Cryopreserved samples were tested again with and without the removal of antibiotic residues using a RESEP tube, after thawing. Presence of antibiotics in tissue homogenates and processing liquids was determined by a modified agar diffusion test. All cryopreserved tissue homogenates and cryopreservation media induced important inhibition zones on both Staphylococcus aureus- and Pseudomonas aeruginosa-seeded plates, immediately after thawing and at the end of the sterility test. The RESEP tube treatment markedly reduced or totally eliminated the antimicrobial activity of tested tissues and media. Based on standard tissue bank analysis, 50% of tissues were found positive for bacteria and/or fungi, before decontamination and 2 out of 16 tested samples (13%) still contained microorganisms after decontamination. After thawing, none of the 16 cryopreserved samples resulted positive with direct inoculum method. When the same samples were tested after removal of antibiotic residues, 8 out of 16 (50%) were contaminated. Antibiotic residues present in tissue allografts and processing liquids after decontamination may mask microbial contamination during microbiological analysis performed with standard tissue bank methods, thus resulting in false negatives.