Evaluation of Retinal Function and Pathology After Intravitreal Injection of Povidone-Iodine and Polyvinyl Alcohol-Iodine in Rabbits

Electroretinographic Evaluations Using Skin Electrode of Eyes with Bleb-Related Endophthalmitis Following Vitrectomy with 0.025% Povidone Iodine Irrigation

Purpose

To determine whether 0.025% povidone-iodine (0.025% PI) in the irrigation solution during vitrectomy for endophthalmitis is safe.

Methods

Two cases of bleb-associated endophthalmitis were treated with vitrectomy using 0.025% PI in the irrigation solution. The RETevel electroretinographic (ERG) system with skin electrodes was used to assess the physiology of the retina pre- and postoperatively.

Case

Case 1 was a 46-year-old man who had atopic keratoconjunctivitis and underwent trabeculectomy with the creation of a bleb after there was a rise in the intraocular pressure. One month postoperatively, a mild filtering bleb-associated endophthalmitis developed, and the eye was treated with intravitreal and subconjunctival injections of vancomycin (VCM) and ceftazidime (CAZ). After three days, the fundus was not visible and B-mode echography showed an area of high brightness in the retina. Vitrectomy with irrigation with VCM and CAZ, and 0.025% PI was performed successfully. Pre- and postoperative ERGs showed an improvement in both the a- and b-wave amplitudes and the b/a ratio was stable at 2.0. Case 2 was a 63-year-old man who had undergone trabeculectomy for glaucoma. Five years later, the eye developed blebitis which was treated with topical and subconjunctival injections of VCM and CAZ. Three days later, vitreous opacities appeared and a high brightness area was seen in the B-mode echographic images. Vitrectomy with VCM and CAZ, and 0.025% PI irrigation was successfully performed. Comparisons of the pre- and postoperative ERGs found that the a- and b- wave amplitudes of the ERGs increased and the b/a ratio was stable at approximately 1.5.

Conclusion

Vitrectomy with 0.025% PI irrigation is safe and ERG recordings with skin electrodes can be used to evaluate the pre- and postoperative retinal physiology safely.

ACUTE ATYPICAL ENDOPHTHALMITIS FOLLOWING INTRAVITREAL SUSTAINED-RELEASE DEXAMETHASONE IMPLANT: A CASE SERIES

PURPOSE

To present three cases of acute endophthalmitis following intravitreal sustained-release dexamethasone (Ozurdex) with atypical presentation and to discuss the management of these patients.

METHODS

A retrospective case series of three patients with endophthalmitis following intravitreal sustained-release dexamethasone (Ozurdex) implantation who presented between July 2020 and August 2020.

RESULTS

Two of three patients who were treated with topical steroid and antibiotic therapy alone showed favorable outcomes and were managed without the need for intravitreal antibiotics or implant removal. One patient who showed initial response to topical therapy subsequently required pars plana vitrectomy, implant removal, and a single empirical dose of intravitreal antibiotics and antifungal agent due to persistent inflammation.

CONCLUSION

Postintravitreal Ozurdex endophthalmitis, although a rare entity, can present with atypical features of a painless white eye and a delayed onset intraocular inflammation. Although all cases of endophthalmitis should be treated as infective until proven otherwise, it is fair to consider a trial of conservative treatment with topical steroids and antibiotics initially with close monitoring. In cases with poor response to topical therapy, pars planar vitrectomy and implant removal should be strongly considered.

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.

ALTERNATIVE INTRAVITREAL ANTIBIOTICS: A Systematic Review for Consideration in Recalcitrant or Resistant Endophthalmitis

PURPOSE

To organize, categorize, and create a quick reference guide for the use of intravitreal antibiotic alternatives to the standard combination of vancomycin and ceftazidime for the treatment of endophthalmitis.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. The authors searched for all available information regarding intravitreal antibiotics in the last 21 years. Manuscripts were selected according to relevance, level of information, and the available data regarding intravitreal dose, potential adverse effects, bacterial coverage, and relevant pharmacokinetic information.

RESULTS

The authors included 164 of 1810 manuscripts. The antibiotics were classified according to their class into fluoroquinolones, cephalosporins, glycopeptide and lipopeptide, penicillins and beta-lactams, tetracyclines, and miscellaneous. The authors also included information regarding intravitreal adjuvants for the treatment of endophthalmitis and one ocular antiseptic.

CONCLUSION

The treatment of infectious endophthalmitis is a therapeutic challenge. The current review summarizes the properties of possible intravitreal antibiotic alternatives that should be considered in cases of suboptimal response to initial treatment.

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.

Vitrectomy using 0.025% povidone-iodine irrigation for treating post-traumatic endophthalmitis due to intraocular foreign bodies: Two case reports

Traumatic eye injury-related endophthalmitis is a serious traumatic complication that threatens the vision of many patients worldwide. Herein, we present two cases of traumatic endophthalmitis that underwent 0.025% povidone-iodine treatment and hoped to introduce the bactericidal effect of 0.025% povidone-iodine in balanced salt solution PLUS (0.025% PI-BSS PLUS) and its use in vitrectomy for traumatic endophthalmitis. The 0.025% PI-BSS PLUS solution is bactericidal and nontoxic when used as an irrigation solution in pars plana vitrectomy. The two cases of traumatic endophthalmitis were resolved by pars plana vitrectomy using 0.025% PI-BSS PLUS.

Safety Measures for Maintaining Low Endophthalmitis Rate after Intravitreal Anti-Vascular Endothelial Growth Factor Injection before and during the COVID-19 Pandemic

During the COVID-19 pandemic, intravitreal injections are performed with patients wearing masks. The risk of endophthalmitis after intravitreal injection is reported to increase due to an influx of exhaled air containing oral bacteria from the upper part of the mask onto the ocular surface. We retrospectively investigated the incidence of endophthalmitis when intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections were performed using the same infection control measures before and during the pandemic. Vitreoretinal specialists performed intravitreal injections of anti-VEGF agents in the outpatient room of a university hospital. Infection control measures before and during the pandemic included covering the patient’s eye with adhesive face drape and irrigating the ocular surface with 0.25% povidone-iodine before draping, and immediately before and after injection. Before the COVID-19 pandemic (February 2016 to December 2019), one case of endophthalmitis occurred among 31,173 injections performed (0.0032%; 95% confidence interval (CI), 0.000008–0.017872%). During the COVID-19 pandemic (January 2020 to August 2021), one case of endophthalmitis occurred among 14,725 injections performed (0.0068%; 95% CI, 0.000017–0.037832%). There was no significant difference between the two periods (Fisher’s exact test: p = 0.5387). Even during the COVID-19 pandemic, very low incidence of endophthalmitis after intravitreal injection can be maintained by implementing basic infection prophylactic measures, including face draping and 0.25% povidone-iodine irrigation, established before COVID-19 pandemic.

Cataract Surgery by Intraoperative Surface Irrigation with 0.25% Povidone-Iodine

Postoperative endophthalmitis after cataract surgery is typically caused by the patient's own conjunctival normal bacterial flora. A three-step approach is recommended to prevent endophthalmitis: (1) "border control" to prevent microorganisms from entering the eye by disinfecting the ocular surface is the most important measure; (2) bacteria that have gained access into the anterior chamber are reduced by irrigation; (3) bacteria remaining in the anterior chamber and vitreous at the end of surgery are controlled by antibacterial drugs. We have devised a method, "the Shimada technique", for irrigating the ocular surface with povidone-iodine, a disinfectant with potent microbicidal effect and established effective and safe concentrations for eye tissues. Povidone-iodine exhibits a bactericidal effect for a wide concentration range of 0.005-10%, but 0.1% povidone-iodine has the highest activity and requires the shortest time of only 15 s to achieve microbicidal effect. When used to irrigate the ocular surface every 20-30 s during cataract surgery, 0.25% povidone-iodine is conceivably diluted to around 0.1%. Irrigation with 0.25% povidone-iodine during cataract surgery significantly reduced bacteria contamination rate in the anterior chamber compared with saline (p = 0.0017) without causing corneal endothelial damage.