Povidone iodine treatment is deleterious to human ocular surface conjunctival cells in culture

Photothermal and radiotherapy with alginate-coated gold nanoparticles for breast cancer treatment

Radiation therapy and phototherapy are commonly used cancer treatments that offer advantages such as a low risk of adverse effects and the ability to target cancer cells while sparing healthy tissue. A promising strategy for cancer treatment involves using nanoparticles (NPs) in combination with radiation and photothermal therapy to target cancer cells and improve treatment efficacy. The synthesis of gold NPs (AuNPs) for use in biomedical applications has traditionally involved toxic reducing agents. Here we harnessed dopamine (DA)-conjugated alginate (Alg) for the facile and green synthesis of Au NPs (Au@Alg-DA NPs). Alg-DA conjugate reduced Au ions, simultaneously stabilized the resulting AuNPs, and prevented aggregation, resulting in particles with a narrow size distribution and improved stability. Injectable Au@Alg-DA NPs significantly promoted ROS generation in 4T1 breast cancer cells when exposed to X-rays. In addition, their administration raised the temperature under a light excitation of 808 nm, thus helping to destroy cancer cells more effectively. Importantly, no substantial cytotoxicity was detected in our Au@Alg-DA NPs. Taken together, our work provides a promising route to obtain an injectable combined radio enhancer and photothermally active nanosystem for further potential clinic translation.

METHOD OF POVIDONE-IODINE APPLICATION AND ENDOPHTHALMITIS RISK

PURPOSE

To evaluate the proportion of patients developing endophthalmitis after intravitreal injection of anti-vascular endothelial growth factor agents according to the mode of povidone-iodine (PI) antisepsis.

METHODS

A retrospective review of the anti-vascular endothelial growth factor injections given in a 7-year period at a community-based retinal practice. Endophthalmitis was diagnosed to have occurred if an eye developed intraocular inflammation and was given antibiotics with or without supportive culture identification of an organism. As part of their habitual clinical practice, component physicians used 5% PI as two drops, one drop, or just a dot of PI administered with a cotton-tipped applicator to the site before injection.

RESULTS

There were 113,610 intravitreal injections administered and 23 cases were diagnosed with endophthalmitis over the 7-year period, for a rate of 1 case per 4,940 injections. The mode of PI antisepsis showed no significant relation to the rate of endophthalmitis ( P = 0.55, chi-square test). The proportion of endophthalmitis by physician demonstrated no significant difference ( P = 0.39, chi-square test).

CONCLUSION

The use of PI has been associated with decreased incidence of endophthalmitis, but the mode of application has not been standardized. The results of this study suggest that "more is not better" in PI antisepsis in endophthalmitis. Moreover, the toxicity of PI on the ocular surface is known to be dose-related.

Advances in Contact Lens Care Solutions: PVP-I Disinfectant and HAD Wetting Agents From Japan

ABSTRACT

Half of the individuals who wear contact lenses use reusable lenses that require proper care. Improper contact lens (CL) care and using inadequate disinfecting solutions can lead to lens contamination, CL-related microbial keratitis, and Acanthamoeba keratitis. Oxidative disinfecting solutions, such as hydrogen peroxide, show higher efficacy than multipurpose solutions. Povidone-iodine (PVP-I), an oxidative disinfectant used in ophthalmic surgery, has been proven to be safe and effective. The PVP-I system, a CL disinfecting solution developed in Japan, has demonstrated excellent antimicrobial and antiviral properties. Although CL discomfort does not have a risk of ocular disorders with poor visual prognosis, such as keratitis, CL discomfort can still lead to lens dropout and thus needs to be addressed. To mitigate CL discomfort, it is essential to use disinfecting solutions containing surfactants and wetting agents that improve wettability of the lens surface. A CL solution containing hyaluronic acid derivatives (HADs) as wetting agents that permanently adhere to the lens surface to improve wettability of the lens surface was developed in Japan. There is potential for HAD to be integrated into various solutions. This article reviews the efficacy of novel PVP-I-based disinfecting solution and HAD wetting agents.

In praise of povidone-iodine application in ophthalmology

Polyvinyl pyrrolidone or povidone-iodine (PVP-I) is a water-soluble complex formed by the combination of iodine and a water-soluble polymer, polyvinyl pyrrolidone. This complex exerts bactericidal, fungicidal, and virucidal action by gradually releasing free iodine at the site of application to react with pathogens. In ophthalmology, PVP-I is used as a disinfectant and antiseptic agent for preoperative preparation of the skin and mucous membranes and for treating contaminated wounds. PVP-I has been shown to reduce effectively the risk of endophthalmitis in various ocular procedures, including cataract surgery and intravitreal injections; however, it has also been used in the treatment of conjunctivitis, keratitis, and endophthalmitis, with promising results especially in low-resource situations. PVP-I has been associated with complications such as postoperative eye pain, persistent corneal epithelial defects, ocular inflammation, and an attendant risk of keratitis. In cases of poor PVP-I tolerance, applying PVP-I at lower concentrations or using alternative antiseptics such as chlorhexidine should be considered. We provide an update on the efficacy of PVP-I in the prophylaxis and treatment of conjunctivitis, keratitis, and endophthalmitis and a comprehensive analysis of the current literature regarding the use of PVP-I in the management of these ocular conditions. Also, PVP-I-related adverse effects and toxicities and its alternatives are discussed. The goal is to present a thorough evaluation of the available evidence and to offer practical recommendations for clinicians regarding the therapeutic usage of PVP-I in ophthalmology.

The effect of ocular rinse volume on surface irritation after povidone-iodine preparation for intravitreal injections: a randomized controlled trial

PURPOSE

To evaluate whether the volume of wash out rinse after povidone iodine (PI) application for intravitreal injections (IVI) affects patients' ocular surface irritation.

METHODS

This was a prospective, single-masked, randomized-controlled trial consisting of 142 subjects. A total of 51, 45, and 46 patients received 3-mL, 10-mL, and 15-mL of ocular rinse respectively. Reductions in the Ocular Surface Disease Index (OSDI) and the Standardized Patient Evaluation of Eye Dryness II (SPEED II) surveys, conducted before and at 24-72 h post-injection, were analyzed.

RESULTS

There was no statistical difference in objective dry eye findings of Schirmer test (p-value = 0.788), tear break-up time (p-value = 0.403), Oxford fluorescein grade (p-value = 0.424) between the study groups prior to injections. Dry eye symptoms as measured by reductions in the OSDI and SPEEDII scores were not different between the study groups (p-value = 0.0690 and 0.6227, respectively).

CONCLUSION

There is no difference in patients' ocular surface irritation between 3-mL, 10-mL, and 15-mL post injection rinse. Given the large number of IVIs performed, modification of practice patterns based on these findings could lead to significant reduction in global cost burden for IVIs.

Randomized Controlled Study of Cooled vs Room-Temperature Artificial Tears for Reducing Ocular Surface Irritation After Intravitreal Injection

Purpose: To evaluate the efficacy of cooled vs room-temperature artificial tears in reducing ocular discomfort after intravitreal injections (IVIs). Methods: Patients receiving a standard intravitreal injection in the retina clinic who met the eligibility criteria and provided informed consented were enrolled in the study. Patients were randomized to the cooled tears or room-temperature tears intervention group. Both groups rated their ocular discomfort following IVI after cooled or room-temperature tears were administered. Results: The cooled group comprised 48 patients and the room-temperature group, 61 patients. There was no significant difference in the reduction of ocular discomfort between the cooled vs room-temperature artificial tears groups (P = .387). In addition, there was a similar level of reduction in ocular discomfort after either intervention (P = .681) regardless of whether or not the patients routinely used artificial tears after previous IVIs. Conclusions: Cooled tears provided no additional benefit in reducing ocular discomfort post-IVI compared with room-temperature tears. Baseline tear use after an IVI may have no true benefit other than a potential placebo effect, recall bias, or both.

Cell death and barrier disruption by clinically used iodine concentrations

Povidone-iodine (PVP-I) inactivates a broad range of pathogens. Despite its widespread use over decades, the safety of PVP-I remains controversial. Its extended use in the current SARS-CoV-2 virus pandemic urges the need to clarify safety features of PVP-I on a cellular level. Our investigation in epithelial, mesothelial, endothelial, and innate immune cells revealed that the toxicity of PVP-I is caused by diatomic iodine (I2), which is rapidly released from PVP-I to fuel organic halogenation with fast first-order kinetics. Eukaryotic toxicity manifests at below clinically used concentrations with a threshold of 0.1% PVP-I (wt/vol), equalling 1 mM of total available I2 Above this threshold, membrane disruption, loss of mitochondrial membrane potential, and abolition of oxidative phosphorylation induce a rapid form of cell death we propose to term iodoptosis. Furthermore, PVP-I attacks lipid rafts, leading to the failure of tight junctions and thereby compromising the barrier functions of surface-lining cells. Thus, the therapeutic window of PVP-I is considerably narrower than commonly believed. Our findings urge the reappraisal of PVP-I in clinical practice to avert unwarranted toxicity whilst safeguarding its benefits.

Immunocytochemical characterization of ex vivo cultured conjunctival explants; marker validation for the identification of squamous epithelial cells and goblet cells

Tissue-engineered products are at the cutting edge of innovation considering their potential to functionally and structurally repair various tissue defects when the body's own regenerative capacity is exhausted. At the ocular surface, the wound healing response to extensive conjunctival damage results in tissue repair with structural alterations or permanent scar formation rather than regeneration of the physiological conjunctiva. Conjunctival tissue engineering therefore represents a promising therapeutic option to reconstruct the ocular surface in severe cicatrizing pathologies. During the rapid race to be a pioneer, it seems that one of the fundamental steps of tissue engineering has been neglected; a proper cellular characterization of the tissue-engineered equivalents, both morphologically and functionally. Currently, no consensus has been reached on an identification strategy and/or markers for the characterization of cultured squamous epithelial and goblet cells. This study therefore evaluated the accuracy of promising markers to identify differentiated conjunctival-derived cells in human primary explant cultures through immunocytochemistry, including keratins (i.e., K7, K13, and K19) and mucins (i.e., MUC1, MUC5AC, and PAS-positivity). Comparison of the in vivo and in vitro cellular profiles revealed that the widely used goblet cell marker K7 does not function adequately in an in vitro setting. The other investigated markers offer a powerful tool to distinguish cultured squamous epithelial cells (i.e., MUC1 and K13), goblet cells (i.e., MUC5AC and PAS-staining), and conjunctival-derived cells in general (i.e., K19). In conclusion, this study emphasizes the power alongside potential pitfalls of conjunctival markers to assess the clinical safety and efficacy of conjunctival tissue-engineered products.

Biocompatibility and Mechanical Properties of Carboxymethyl Chitosan Hydrogels

Hydrogels have the properties of solid substances and are useful for medicine, e.g., in systems for the controlled release of drugs or as wound dressings. They isolate the wound from the external environment and constitute a barrier to microorganisms while still being permeable to oxygen. In the current study, hydrogels were formed from concentrated aqueous solutions of carboxymethyl chitosan (CMCS) via electron beam irradiation, with the presence of a crosslinking agent: poly(ethylene glycol)diacrylate. The aim of the study was to compare the properties and action of biopolymer CMCS hydrogels with commercial ones and to select the best compositions for future research towards wound-dressing applications. The elasticity of the gel depended on the component concentrations and the irradiation dose employed to form the hydrogel. Young's modulus for the tested hydrogels was higher than for the control material. The Live/Dead test performed on human fibroblasts confirmed that the analyzed hydrogels are not cytotoxic, and for some concentrations, they cause a slight increase in the number of cells compared to the control. The biocompatibility studies carried out on laboratory rats showed no adverse effect of hydrogels on animal tissues, confirming their biocompatibility and suggesting that CMCS hydrogels could be considered as wound-healing dressings in the future. Ionizing radiation was proven to be a suitable tool for CMCS hydrogel synthesis and could be of use in wound-healing therapy, as it may simultaneously sterilize the product.

Low-concentration povidone-iodine for the prevention of intraocular infections in ophthalmic surgery

PURPOSE OF REVIEW

Endophthamitis following intraocular surgery is rare using current antiseptic techniques, such as single application of 5% povidone-iodine to the ocular surface and adjuvant topical or intracameral antibiotics. Challenges remain, however, including increased multidrug-resistant bacterial endophthalmitis, increased fungal endophthalmitis, and the low but nonzero endophthalmitis rate attributable to the typical bacteria that colonize the ocular surface.

RECENT FINDINGS

Povidone-iodine has a wide spectrum of activity, including activity against novel pathogens, such as SARS-CoV-2. Povidone-iodine alternatives, such as hypochlorous acid can have significantly less efficacy in vitro against endophthalmitis isolates. Repetitive application of dilute povidone-iodine has an excellent safety profile and strong evidence base for efficacy.

SUMMARY

Povidone-iodine is widely available, inexpensive, and commonly used by ophthalmologists. The repetitive application of dilute povidone-iodine is a well studied, well tolerated, and efficacious way to transiently sterilize the ocular surface during intraocular surgery. Additional benefits include activity against multidrug-resistant bacteria, fungi, and lack of inducible resistance.

Characterisation of Gel-Forming Mucins Produced In Vivo and In Ex Vivo Conjunctival Explant Cultures

One key element to the health of the ocular surface encompasses the presence of gel-forming mucins in the pre-ocular tear film. Conjunctival goblet cells are specialized epithelial cells that secrete mucins necessary for tear film stability and general homeostasis. Their dysfunction can be linked to a range of ocular surface inflammation disorders and chronic injuries. To obtain new perspectives and angles to tackle mucin deficiency, the need for an accurate evaluation of their presence and corresponding mucin secretion in ex vivo conjunctival cultures has become a requisite. In vitro, goblet cells show a significant decrease in the production and secretion of gel-forming mucins, accompanied by signs of dedifferentiation or transdifferentiation. Explant cultures on laminin-treated CLP-PEG hydrogels can, however, support the production of gel-forming mucins. Together, we challenge the current paradigm to evaluate the presence of cultured goblet cells solely based on their general mucin (MUC) content through imaging analyses, showing the need for additional techniques to assess the functionality of goblet cells. In addition, we broadened the gel-forming mucin profile of in vivo goblet cells with MUC5B and MUC6, while MUC2 and MUC6 is added to the profile of cultured goblet cells.