Preparation of Corneal Donor Eyes Comparing 1% Versus 5% Povidone–Iodine

Evaluation of the Possible Influence of Povidone Iodine (PVI) Solution and Polyhexanide (PHMB) on Wound Healing in Corneal Epithelial Regeneration

This study investigates the possible toxic effects of the preoperative antiseptic substances povidone iodine (PVI) and polyhexanide (PHMB; Serasept® 2) on wound healing in ophthalmology. To assess this impact, human telomerase-immortalized corneal epithelial (hTCEpi) cells and human telomerase-immortalized conjunctival epithelial (hCjE) cells were exposed to 1% and 5% PVI or 0.04% PHMB for different periods to evaluate the cytotoxicity of these two antiseptics. Furthermore, the toxicity of these antiseptics was investigated in a human tissue-specific corneal epithelial construct and porcine eye culture model. The results reveal the high cytotoxicity of PVI and PHMB in the hTCEpi and hCjE in monolayer cell culture models, independent of the incubation time and concentration of these substances. However, after hTCEpi cell differentiation into a tissue-specific corneal epithelial construct, contact with these antiseptics for the relevant preoperative time did not alter cPARP1 or Ki67 expression. Furthermore, the wound-healing process in the porcine cornea was not significantly influenced after incubation with these antiseptics. In summary, corneal and conjunctival epithelial cell lines are very sensitive to PVI and PHMB, whereas no significant alterations were found in intact tissue-specific corneal epithelial constructs or porcine corneas. Therefore, we could not identify PVI and PHMB as reasons for postoperative eye irritation.

Povidone-Iodine Adverse Effects and Alternatives for Ocular Procedures

Purpose: Povidone-iodine (PVI), also known as Betadine, is a widely used antiseptic agent used in several fields of medicine. In ophthalmology, it is applied as a preoperative antiseptic to prevent infectious complications that can result from surgical procedures. PVI's safety and efficacy have been extensively studied and represented in the literature; however, the incidence of adverse effects has been reported in conjunction. The aim of this paper is to compile information regarding PVIs use, safety profile, adverse effects, and possible alternatives through a review of the existing literature. Methods: Literature was compiled utilizing the database PubMed and Google Scholar using specified keywords with a total of 86 reviewed articles, after excluding search results that did not meet the inclusion criteria. Results: While the allergic potential to PVI is a highly contested topic, there are several nonallergic adverse effects of PVI that should not be overlooked. These effects include chemical burn, cytotoxic effects, and general patient discomfort. In light of these adverse effects, alternatives to PVI may be considered. However, there has been little research identifying feasible alternatives in preoperative intraocular procedures. Alternatives including chlorhexidine, polyhexamethylene biguanide (polyhexanide), and octenidine were identified as potential substitutes for PVI. Conclusions: Further study is needed to provide robust evidence regarding the efficacy profiles of these alternatives in comparison with PVI and to demonstrate comparable tolerance to PVI in intraocular procedures.

Doctor I Have an Iodine Allergy

Ophthalmologists frequently face patients who refuse asepsis protocols involving povidone-iodine (PI) due to claims of an allergy to iodine. Such patients usually base this claim on previous reactions to shellfish consumption or to imaging procedures that used iodine-based contrast agents. Allergy to iodine, however, is biologically impossible, and iodine deficiency causes severe developmental problems, including mental retardation. Furthermore, shellfish allergy is due to tropomyosins in muscle tissue, and reactions to intravascular contrast dyes are due to hyperosmolar solutions; neither “allergy” is due to iodine. PI, which contains 9–12% iodine, is the preferred antiseptic for ophthalmic procedures. Experience shows that PI can be administered safely to patients claiming iodine allergy. True allergy to PI is rare and, if indicated, skin patch testing can be performed prior to surgery. Patients who react adversely to highly concentrated (5–10%) PI usually experience toxicity to the corneal and conjunctival epithelium after topical administration. Dilute (0.1–0.25%) PI kills microbes quicker than higher concentrations but for shorter periods of time because the total dose of iodine is smaller. Repeated administration (every 20–30 s) of dilute PI effectively kills microbes for as long as necessary with little risk of epithelial toxicity.

Review, analysis, and education of antiseptic related ocular injury in the surgical settings

Preoperative skin antiseptic preparation is the gold standard for prevention of surgical infection. However, improper use of antiseptics may lead to severe ocular damage. Currently, the most common surgical antiseptics can be divided into aqueous-based and alcohol-based disinfectants, with chlorhexidine and iodine/iodophors being the two major components. Chlorhexidine has a persistent antimicrobial effect and is resistant to neutralization by blood or organic products in surgical wounds. Nevertheless, due to its toxicity to the ears, meninges, and eyes, application of chlorhexidine should be prohibited in these surgical fields. Iodine/iodophor is better tolerated by the ocular surface and is the recommended antiseptic for ophthalmic or head and neck surgeries close to the periocular area. Alcohol is less pricey and has a rapid antiseptic effect, though its desiccating effect and flammability restrict the use in mucosal or laser surgeries. The single or combined use of these antiseptics may inadvertently induce severe ocular damage, especially during time-consuming head and neck surgeries with prone, hyperextension, or lateral tilt positions, or surgeries under general anesthesia. Apart from the choice of antiseptics, appropriate selection and attachment of bio-occlusive dressings are key to avoiding antiseptic-related ocular injuries. In this review, we provided a comprehensive summary of the characteristics of antiseptics used in surgical settings and the possible mechanisms and outcomes of antiseptic-related ocular injuries. The prevention, diagnosis, and acute management of these complications were also discussed.

Translational and Regulatory Challenges of Corneal Endothelial Cell Therapy: A Global Perspective

Cell therapies are emerging as a unique class of clinical therapeutics in medicine. In 2015, Holoclar (ex vivo expanded autologous human corneal epithelial cells containing stem cells) gained the regulatory approval for treating limbal stem cell deficiency after chemical eye burn. This has set a precedent in ophthalmology and in medicine, reinforcing the therapeutic promise of cell therapy. However, to generalize and commercialize cell therapies on a global scale, stringent translational and regulatory requirements need to be fulfilled at both local and international levels. Over the past decade, the Singapore group has taken significant steps in developing human corneal endothelial cell (HCEnC) therapy for treating corneal endothelial diseases, which are currently the leading indication for corneal transplantation in many countries. Successful development of HCEnC therapy may serve as a novel solution to the current global shortage of donor corneas. Based on the experience in Singapore, this review aims to provide a global perspective on the translational and regulatory challenges for bench-to-bedside translation of cell therapy. Specifically, we discussed about the characterization of the critical quality attributes (CQA), the challenges that can affect the CQA, and the variations in the regulatory framework embedded within different regions, including Singapore, Europe, and the United States. Impact statement Functional corneal endothelium is critical to normal vision. Corneal endothelial disease-secondary to trauma, surgery, or pathology-represents an important cause of visual impairment and blindness in both developed and developing countries. Currently, corneal transplantation serves as the current gold standard for treating visually significant corneal endothelial diseases, although limited by the shortage of donor corneas. Over the past decade, human corneal endothelial cell therapy has emerged as a promising treatment option for treating corneal endothelial diseases. To allow widespread application of this therapy, significant regulatory challenges will need to be systematically overcome.

The use of povidone-iodine in ophthalmology

PURPOSE OF REVIEW

Povidone-iodine (PVI) is a disinfectant and antiseptic agent used for preoperative preparation of the skin and mucous membranes, as well as for the treatment of contaminated wounds. Currently regimens for prophylaxis against postsurgical endophthalmitis are being modified, including a total withdrawal of antibiotics in intravitreal injections. The aim of this study was to evaluate the use of PVI in ophthalmology.

RECENT FINDINGS

As a result of its broad spectrum of microbicidal activity, PVI is routinely used in ophthalmic surgery. However, various protocols are applied worldwide and within different procedures. Additional indications include prophylaxis against ophthalmia neonatorum, acute conjunctivitis, adenoviral conjunctivitis, bacterial keratitis or corneal ulcer, endophthalmitis, giant fornix syndrome, and antimicrobial prophylaxis in patients with Boston type I keratoprosthesis.

SUMMARY

Despite the introduction of new antiseptics in surgery, PVI is still the preeminent antiseptic measure in ophthalmology. Its use is economically reasonable. There have been no reports of resistance to PVI or anaphylaxis with topical ophthalmic use. Furthermore, it does not induce resistance or cross-grztance to antibiotics. With these advantages the range of indications for topical use of antibiotics might decrease, with PVI as the sole perioperative antiseptic measure. Additional studies are required to assess the optimal timing, concentration and exposure time within different ophthalmic procedures.

Systemic Fungal Infections in Donors for Corneal Transplantation

PURPOSE

To determine the prevalence of postkeratoplasty fungal infection when corneal tissue from donors with a recent medical history of oral thrush or respiratory, urine, wound, sputum, bronchial, tracheal, or throat culture positive for fungus is identified before recovery and after decontamination of the corneal tissue with 5% povidone-iodine flush to the donors' eyes during recovery.

METHODS

This is a prospective analysis of corneas from 42 donors with a documented medical history of fungus or positive fungal culture, which were recovered between January 2010 and November 2010. Standard aseptic swab of the donors' corneas before and after application of 5% povidone-iodine solution was performed. Culture results were analyzed in relationship to the donors' medical history and potential posttransplantation infections.

RESULTS

Eighty-four eyes from 42 patients were swabbed for cultures during the study period. Seven eyes (8.3%) were positive for fungal growth before treatment with 5% povidone-iodine, whereas there were no positive fungal cultures after treatment (P = 0.007). Fifty-four corneas from this study group were used for corneal transplantation. There were no cases of fungal infection in any postkeratoplasty eyes transplanted from this study group.

CONCLUSIONS

In this small study, the overall prevalence of fungal infections after corneal transplantation using corneal donor tissue from donors with a fungal-positive medical history is low. Corneal fungal contamination in donors with a history of fungal infection or a positive fungal culture can be significantly reduced with a 5% povidone-iodine flush.

Obtaining corneal tissue for keratoplasty

Cornea transplant is the most common tissue transplant in the world. In Spain, tissue donation activities depend upon transplant coordinator activities and the well-known Spanish model for organ and tissue donation. Tissue donor detection system and tissue donor evaluation is performed mainly by transplant coordinators using the Spanish model on donation. The evaluation of a potential tissue donor from detection until recovery is based on an exhaustive review of the medical and social history, physical examination, family interview to determine will of the deceased, and a laboratory screening test. Corneal acceptance criteria for transplantation have a wider spectrum than other tissues, as donors with active malignancies and infections are accepted for kearatoplasty in most tissue banks. Corneal evaluation during the whole process is performed to ensure the safety of the donor and the recipient, as well as an effective transplant. Last step before processing, corneal recovery, must be performed under standard operating procedures and in a correct environment.

Effects of Disinfectants on Larval Development of Ascaris suum Eggs

The objective of this study was to evaluate the effects of several different commercial disinfectants on the embryogenic development of Ascaris suum eggs. A 1-ml aliquot of each disinfectant was mixed with approximately 40,000 decorticated or intact A. suum eggs in sterile tubes. After each treatment time (at 0.5, 1, 5, 10, 30, and 60 min), disinfectants were washed away, and egg suspensions were incubated at 25˚C in distilled water for development of larvae inside. At 3 weeks of incubation after exposure, ethanol, methanol, and chlorohexidin treatments did not affect the larval development of A. suum eggs, regardless of their concentration and treatment time. Among disinfectants tested in this study, 3% cresol, 0.2% sodium hypochlorite and 0.02% sodium hypochlorite delayed but not inactivated the embryonation of decorticated eggs at 3 weeks of incubation, because at 6 weeks of incubation, undeveloped eggs completed embryonation regardless of exposure time, except for 10% povidone iodine. When the albumin layer of A. suum eggs remained intact, however, even the 10% povidone iodine solution took at least 5 min to reasonably inactivate most eggs, but never completely kill them with even 60 min of exposure. This study demonstrated that the treatment of A. suum eggs with many commercially available disinfectants does not affect the embryonation. Although some disinfectants may delay or stop the embryonation of A. suum eggs, they can hardly kill them completely.