Pharmacokinetics of intravitreal antibiotics in endophthalmitis

Intraocular drugs: pharmacokinetic strategies and the influence on efficacy and durability

INTRODUCTION

The modern treatment of chorioretinal vascular diseases follows the recent development and rapid adoption of drugs that inhibit vascular endothelial growth factor (VEGF). All anti-VEGF drugs are delivered intravitreally, with clinical behavior, including efficacy, durability, and safety, largely determined by their pharmacokinetic properties.

AREAS COVERED

Properties of these new drugs include additional binding targets (placental growth factor (PlGF) and angiopoietin 2 (Ang 2)), binding affinity, potency, intravitreal half-life, and increased molar dose. A PubMed search for 'pharmacokinetics of anti-VEGF drugs' was performed from 2000 to 2023. Relevant studies were reviewed and referred to in the manuscript.

EXPERT OPINION

Early developers concentrated on improving efficacy, but since maximum efficacy with VEGF inhibition has been reached, development has pivoted to extending the duration of action. Durability strategies include inhibiting additional pathways (faricimab), increasing molar dose (abicipar, brolucizumab, faricimab, and aflibercept 8 mg), and prolonging the intravitreal half-life (abicipar and KSI-301). Recent phase 3 trials demonstrated modest improvements in durability, but failures that might be attributed to these strategies (conjugation and manufacturing processes) have occurred. Future drug development focuses on extending duration of action with implantable reservoirs (ranibizumab port delivery system), sustained release devices (tyrosine kinase inhibitors), and gene therapy.

Mathematical Models of Ocular Drug Delivery

Drug delivery is an important factor for the success of ocular drug treatment. However, several physical, biochemical, and flow-related barriers limit drug exposure of anterior and posterior ocular target tissues during drug treatment via topical, subconjunctival, intravitreal, or systemic routes. Mathematical models encompass various barriers so that their joint influence on pharmacokinetics (PKs) can be simulated in an integrated fashion. The models are useful in predicting PKs and even pharmacodynamics (PDs) of administered drugs thereby fostering development of new drug molecules and drug delivery systems. Furthermore, the models are potentially useful in interspecies translation and probing of disease effects on PKs. In this review article, we introduce current modeling methods (noncompartmental analyses, compartmental and physiologically based PK models, and finite element models) in ocular PKs and related drug delivery. The roles of top-down models and bottom-up simulations are discussed. Furthermore, we present some future challenges, such as modeling of intra-tissue distribution, prediction of drug responses, quantitative systems pharmacology, and possibilities of artificial intelligence.

Surgical approach to endophthalmitis: an overview

Endophthalmitis is one of the most severe ocular emergencies faced by ophthalmologists worldwide. Without prompt treatment significant visual loss is inevitable. With increased understanding of the science of endophthalmitis, recent studies have shown a clear role of early and more definitive surgery to achieve better visual and anatomic outcomes. Surgery in endophthalmitis encompasses a whole gamut of interventions. There are diagnostic procedures like anterior chamber tap and vitreous biopsy or therapeutic procedures like complete pars plana vitrectomy and retinal detachment repair. Current literature is deficient on a detailed description of the spectrum of surgical interventions in endophthalmitis. In the current communication, we summarize the studies based on various surgical interventions in endophthalmitis. We also elaborate in detail on each surgical maneuver, taking the reader through the nuances of each surgery via an exhaustive description and appropriate photos and surgical video clips.

Clinical outcomes and characterization of intraocular foreign body injuries from a Canadian centre: a 20-year retrospective study and literature review

OBJECTIVE

To analyse assessment and management patterns of intraocular foreign body (IOFB) injuries in an urban Canadian setting, providing valuable clinical insights to contextualize management.

METHODS

Single-surgeon retrospective chart review from January 2002 to January 2023 examining IOFB patient demographics, investigations, treatments, complications, and best-corrected visual acuity (BCVA).

RESULTS

This study evaluated IOFBs in 32 eyes from 31 patients (96.8% male). Sizes ranged from 1 to 12 mm; 28 (87.5%) were metallic and 15 (46.9%) were work-related injuries. For diagnosis, 19 patients (61.3%) underwent computed tomography (CT) imaging, and 8 (25.8%) received B-scans, with CT detecting IOFBs in 100% of cases and B-scan in 87.5%. At final follow-up, 17 eyes (53.1%) achieved BCVA ≥20/40, up from 7 (23.3%) initially. Presenting BCVA ≥20/200 was associated with a final BCVA ≥20/40 (P = 0.027). The IOFB was extracted in 27 eyes (84.4%), retained in 4 (12.5%), and 1 (3.1%) required enucleation. Intravitreal antibiotics were administered in 19 eyes (59.4%), resulting in one presumed case of drug toxicity. Complications were present in 30 eyes (93.8%), totalling 119 recorded overall, with 72 (60.5%) occurring within the first 24 hours. Traumatic cataracts were most common in 27 eyes (84.4%). Less-common complications included siderosis and retinal detachment with proliferative vitreoretinopathy, each occurring in one eye (3.1%). Four eyes (12.5%) developed secondary glaucoma, with 3 cases in retained or delayed extractions.

CONCLUSIONS

The IOFB characteristics and patient demographics are consistent with other regions. CT scans were the most effective investigation tool. Extended follow-up is recommended to monitor complications, particularly in retained or significantly delayed extractions.

Refractory Candida dubliniensis Retinitis in an Immunocompetent Patient

BACKGROUND

Fungal endophthalmitis is an intraocular infection that rarely develops in immunocompetent individuals.

CASE

A 35-year-old healthy, immunocompetent male presented with a 1-week history of pain and redness in the left eye. Visual acuity was 20/50. Dilated fundus examination revealed focal chorioretinitis in the posterior pole with associated vitritis, suspicious for a fungal etiology. He was started empirically on oral voriconazole and valacyclovir. A comprehensive systemic workup returned negative. Inflammation worsened and a diagnostic vitrectomy was performed which revealed Candida dubliniensis. The dose of oral voriconazole was increased, and intravitreal voriconazole and amphotericin B injections were added for refractory disease. Treatment response was gauged by fungal pillar height on optical coherence tomography. Eight months of oral voriconazole and 68 intravitreal antifungal injections were required to achieve complete regression and a final visual acuity of 20/20.

CONCLUSION

Candida dubliniensis endophthalmitis can affect immunocompetent individuals and require a prolonged treatment course.

[Surgical therapy and pathogen detection in endogenous endophthalmitis : Analysis of data from five German eye hospitals]

BACKGROUND

Endogenous endophthalmitis results from hematogenous spread of bacterial or fungal infection in severely diseased patients. Specific systemic and intraocular therapy is required. The basis for this treatment is causal pathogen detection in blood culture or vitreous sample. However, functional results are limited.

OBJECTIVE

The current article provides practical hints for surgical therapy and pathogen detection in patients with endogenous endophthalmitis.

METHODS

A retrospective analysis of anonymous data of 68 male and female patients from 2018-2023 from five ophthalmology clinics in Germany was performed.

RESULTS

Mean age of affected patients was 71.4 years (31-96 years). Surgical therapy included pars plana vitrectomy (ppV) and intravitreal injection (IVOM). In 44 of 68 patients (65%), 1-3 surgeries were performed, 4-6 surgeries were required in 14/68 (21%) of patients, and 10 or more surgeries were required in 4/68 patients (6%). Pathogen detection was possible in 34% of vitreous specimens and in 11% of anterior chamber samples. Mean initial visual acuity was logMAR 1.5. After treatment and a mean follow-up of 2.5 months, mean visual acuity was logMAR 1.3. Preanalytical methods for specimen collection like the Freiburg endophthalmitis set to optimize pathogen detection are presented.

CONCLUSION

Severe inflammatory intraocular reactions in endogenous endophthalmitis necessitate a combination of ppV and repeated IVOM. In addition to providing a vitreous sample, ppV also serves to remove inflammatory fibrin membranes. Early pars plana vitrectomy with specific antibiotic or antifungal therapy should be sought in addition to the focus search and systemic therapy.

Emphasis on Nanostructured Lipid Carriers in the Ocular Delivery of Antibiotics

BACKGROUND

Drug distribution to the eye is still tricky because of the eye's intricate structure. Systemic delivery, as opposed to more traditional methods like eye drops and ointments, is more effective but higher doses can be harmful.

OBJECTIVE

The use of solid lipid nanoparticles (SLNPs) as a method of drug delivery has been the subject of research since the 1990s. Since SLNPs are derived from naturally occurring lipids, they pose no health risks to the user. To raise the eye's absorption of hydrophilic and lipophilic drugs, SLNs can promote corneal absorption and improve the ocular bioavailability of SLNPs.

METHODS

To address problems related to ocular drug delivery, many forms of nano formulation were developed. Some of the methods developed are, emulsification and ultra-sonication, high-speed stirring and ultra-sonication, thin layer hydration, adapted melt-emulsification, and ultrasonication techniques, hot o/w micro-emulsion techniques, etc. Results: Nanostructured lipid carriers are described in this review in terms of their ocular penetration mechanism, structural characteristic, manufacturing process, characterization, and advantages over other nanocarriers.

CONCLUSION

Recent developments in ocular formulations with nanostructured bases, such as surfacemodified attempts have been made to increase ocular bioavailability in both the anterior and posterior chambers by incorporating cationic chemicals into a wide variety of polymeric systems.

Susceptibility of Ocular Surface Bacteria to Various Antibiotic Agents in a Romanian Ophthalmology Clinic

Periodic assessment of bacterial contamination is necessary as it allows proper guidance in cases of eye infections through the use of appropriate antibiotics. Due to the extensive use of antibiotic treatment, many strains of the microbiota that cause infections are resistant to the usual ophthalmic antibiotics. The present study provides an updated assessment of the susceptibility of Gram-positive and Gram-negative bacteria found on the ocular surface to the most commonly used antibiotic agents in patients undergoing cataract surgery. A total of 993 patients were included in the study with ages between 44 and 98 years old. Conjunctival cultures were collected 7 days before cataract surgery. The response of Gram-positive and Gram-negative bacteria to various antibiotic classes, such as glycopeptides, cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, phenicols, tetracyclines, rifamycins, macrolides and penicillins, was assessed. From the tested antibiotics, vancomycin had 97.8% efficacy on Gram-positive bacteria. In the cephalosporin category, we observed a high level of resistance of the cefuroxime for both Gram-positive and negative bacteria. Antibiotics that have more than 90% efficacy on Gram-positive bacteria are meropenem, imipenem, netilmicin, amikacin and rifampicin. On Gram-negative bacteria, we found 100% efficacy of all tested fluoroquinolones, i.e., aminoglycosides (except for tobramycin), doxycycline, azithromycin, clarithromycin and chloramphenicol. The current study illustrates patterns of increased resistance in certain bacteria present on the ocular surface to some of the commonly used antibiotics in ophthalmological clinical practice. One such revealing example is cefuroxime, which has been highly used as an intracameral antibiotic for the prevention of bacterial endophthalmitis after cataract surgery.

Ocular Toxoplasmosis

INTRODUCTION

Ocular toxoplasmosis is the leading cause of posterior uveitis worldwide, affecting individuals acrossdifferent age groups. The key to reducing vision loss includes prompt diagnosis and treatment. However, despite the prevalence of ocular toxoplasmosis, there has been little consensus regarding its pathophysiology,clinical features, diagnosis, and especially management.

METHODS

The data sources were literature reviews, including Pub Med and Medline databases. Search terms included toxoplasmosis, retinitis, vasculitis, vitritis, uveitis alone or in combination with, serum, aqueous, vitreous eye, ocular and review.

RESULTS

In this review paper, we have sought to provide an overview of the pathophysiology, epidemiology, and clinical features of the disease, both based on current literature and our own clinical experience. We have also discussed the use of serology, ocular fluid, and ophthalmic investigations that could further facilitate the diagnosis of ocular toxoplasmosis.Different management strategies have been reported worldwide, including newer approaches such as local therapy.

CONCLUSION

A better understanding of critical aspects of ocular toxoplasmosis will hopefully lead to reduced morbidity, including blindness associated with this condition.

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.

High risk and low prevalence diseases: Endophthalmitis

INTRODUCTION

Endophthalmitis is a serious, vision-threatening condition that carries with it a high rate of morbidity.

OBJECTIVE

This review highlights the pearls and pitfalls of endophthalmitis, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Endophthalmitis is a vision-threatening emergency associated with infection and inflammation of vitreous and aqueous humor. Risk factors include ocular trauma or surgery, immunocompromised state, diabetes mellitus, and injection drug use. History and examination include visual changes, ocular pain, and inflammatory findings (e.g., hypopyon). Fever may be present. Diagnosis should be based on the clinical evaluation, though aqueous or vitreous culture performed by the ophthalmology specialist is recommended. Imaging including computed tomography, magnetic resonance imaging, and ultrasound may suggest the disease but cannot exclude the diagnosis. Management includes emergent ophthalmology consultation and evaluation. Treatment for all types of endophthalmitis is injection of intravitreal antibiotics with consideration of vitrectomy in severe cases. Systemic antimicrobials are recommended in specific types of endophthalmitis. Prompt recognition and diagnosis are key to optimizing favorable visual outcomes.

CONCLUSIONS

An understanding of endophthalmitis can assist emergency clinicians in diagnosing and managing this serious disease.

Endophthalmitis in Silicone Oil-Filled Eyes

Incidences of post pars plana vitrectomy (PPV) endophthalmitis vary between 0.02% and 0.13%, and infectious endophthalmitis in silicone oil-filled eyes is even rarer. We performed a literature review to describe the incidence, protective and predisposing factors, causative pathogens, management options, and prognosis of infectious endophthalmitis in silicone oil-filled eyes. Various studies have elucidated different aspects of this condition. Causative pathogens commonly include commensals. Traditional management involves the removal of silicone oil (SO), intravitreal antibiotics and then SO re-injection. Alternatively, injecting intravitreal antibiotics into silicone oil-filled eyes has also been reported. Visual prognoses are uniformly guarded. Due to the uncommon nature of this condition, studies are limited either by their retrospective design or by small sample sizes. However, observational studies, case series, and case reports can play an important role in rare conditions until larger studies are conducted. This comprehensive review aims to summarise the information available in the literature, to act as a good source for ophthalmologists looking for answers on this topic, and to suggest areas for future development.

The Role of Silicone Oil in the Surgical Management of Endophthalmitis: A Systematic Review

(1) Background: We aimed to systematically review the current literature to evaluate if in patients with postoperative endophthalmitis treated with pars plana vitrectomy, silicone oil tamponade could provide a useful contribution to the control and eradication of infection and if it could influence anatomical recovery and functional outcome. (2) Randomized controlled trials, cross-sectional studies, case series, and case reports published in the English language in peer-reviewed journals were included. No restriction was placed based on the study location. We used medical subject headings (MeSH) and text words. We searched MEDLINE (OVID and PubMed), Google Scholar, ISI Web of Science (Thom-on-Reuters), and the Cochrane Library (Wiley) from January 1995 to the present. To ensure literature saturation, we scanned the reference lists of included studies or relevant reviews identified through the search. Risk of Bias was assessed using the Newcastle-Ottawa scale for longitudinal studies and Cochrane risk-of-bias tool for randomized trials. (3) Results: abstracts of 75 articles were selected for full-text reading; after full-text reading, 44 articles were taken into consideration in the systematic review. 5 out of 7 in vitro experimental studies demonstrated antimicrobial activity against different species of bacteria and fungi. The use of SO as endotamponade associated with PPV led to better visual acuity and a lower rate of retinal detachment and the need for additional surgery. (4) Conclusions: Silicone oil reduces the risk of postoperative retinal detachment, especially in case of undetected retinal breaks, produces compartmentalization of the eye, may lead to early visual recovery, allows laser photocoagulation, prevents severe postoperative hypotony and has antimicrobic activity due to an inhibitory effect for several species of pathogens. Concerns regarding possible toxic effects on the retina and optic disc, compartmentalization and impaired washout of pathogen toxins have been reported. It may also influence intravitreal antibiotic distribution and clearance.

Anti-Infective Treatment and Resistance Is Rarely Problematic with Eye Infections

The treatment of eye infections is very different than treating other body infections that require systemic anti-infectives. Endophthalmitis, keratitis, conjunctivitis, and other ocular infections are treated with direct injection and with topical drops directly to the infection site. There are no anti-infective susceptibility standards to interpret treatment success, but the systemic standards can be used to guide ocular therapy if the concentration of anti-infective in the ocular tissue is assumed to be higher than the concentration in the blood serum. This Perspective describes: (1) eye infections, (2) diagnostics of eye infections, (3) anti-infective treatment of eye infections, (4) anti-infective resistance of ocular pathogens, and (5) alternative anti-infective delivery and therapy. The data, based on years of clinical and laboratory research, support the premise that ocular infections are less problematic if etiologic agents are laboratory-diagnosed and if prompt, potent, anti-infective therapy is applied. Anti-infective susceptibility should be monitored to assure continued therapeutic success and the possibility of new-found resistance. New delivery systems and therapies may be helpful to better treat future ocular infections.

Endophthalmitis Caused by Curtobacterium pusillum Following Open Globe Injury

Purpose: To report the first case of <i>Curtobacterium</i> endophthalmitis within 6 hours after open globe injury, with extensive phlebitis and secondary subretinal neovascularization. Case summary: A 53-year-old man with hypersensitivity to beta-lactam antibiotics was admitted due to visual disturbance in the left eye experienced while working in a rural area. Fundus examination was impossible due to a full-layer corneal laceration and traumatic cataract in the left eye. B-scan ultrasonography and orbital computed tomography showed no shadowing of retained intraocular foreign bodies. After a corneal scraping smear, primary closure, lensectomy, and vitrectomy were performed. Organic material was observed in a focal area of pale macula, accompanied by extensive retinal phlebitis in the mid-periphery. After diagnosing acute bacterial endophthalmitis, intravitreal vancomycin and dexamethasone were injected. <i>Curtobacterium pusillum</i> was cultured on an automated microbial identification system. Intravenous vancomycin and oral clarithromycin were administered for 2 weeks. After 3 months, endophthalmitis had not recurred, and the visual acuity reached 20/100. However, subretinal neovascularization was newly detected under the damaged macula. No complications of neovascularization were observed until 6 months after primary closure. Conclusions: <i>Curtobacterium pusillum</i> can induce acute endophthalmitis through direct penetration in cases of ocular trauma, and may be accompanied by extensive phlebitis and secondary subretinal neovascularization. In cases of open globe injury sustained in rural areas, acute endophthalmitis caused by a rare Gram-positive bacillus, such as <i>Curtobacterium</i> species, should be considered.

A non-invasive nanoparticle-based sustained dual-drug delivery system as an eyedrop for endophthalmitis

Endophthalmitis is an infectious disease that affects the entire eye spreading to the internal retinal layers and the vitreous and causes severe sight-threatening conditions. Current treatment strategies rely on intraocular injections of antibiotics that are invasive, may lead to procedural complications and, ultimately, blindness. In this study, we developed a non-invasive strategy as an eyedrop containing nanoparticle-based dual-drug delivery system in which the hydrophobic poly-L-lactide core was loaded with azithromycin or triamcinolone acetonide, and the hydrophilic shell was made of chitosan. The developed nanoparticles were ~200-250 nm in size, spherical in shape, moderately hydrophilic, lysozyme tolerant, cytocompatible, and hemocompatible. Application of these chitosan-coated nanoparticles as eye drops to C57BL/6 mice showed higher bioavailability in choroid and retina when compared to the uncoated nanoparticles. The delivery system showed sustained release of drug for 300 h and exhibited antimicrobial effects against Gram-positive and Gram-negative bacteria and anti-inflammatory effects on activated microglial cells. Interestingly, the combination of the nanoparticles loaded with azithromycin and the nanoparticles loaded with triamcinolone acetonide acted synergistically as compared to either of the nanoparticles/drugs alone. Overall, the developed dual-drug delivery system is non-invasive, has antimicrobial and anti-inflammatory effects, and shows potential as an eye drop formulation against endophthalmitis.

Does Endogenous Endophthalmitis Need a More Aggressive Treatment?

Topic: To focus on endogenous endophthalmitis management, particularly etiology-based medical and surgical therapy.Methods: Literature search of published studies from July 1990 to February 2019 on endogenous endophthalmitis available on PubMed was made without any language constraints.Results: A total of 78 articles were retrieved from 728 initially analyzed and 62 studies were included. Although the superiority of vitrectomy over tap and inject techniques is controversial, the most recent publications favor an early surgical approach for endogenous endophthalmitis. Vitrectomy is useful in severe cases complicated by marked vitreous opacity, retinal detachment, poor initial visual acuity, and more virulent pathogens. Oral or intravenous antibiotics are also necessary to treat systemic infection. Vitrectomy is superior to blood cultures in diagnosing the etiology of infection.Conclusions: Endogenous endophthalmitis is an important cause of visual acuity impairment. Prompt treatment with appropriate use of pharmacological or surgical therapy is mandatory to preserve visual function.Abbreviations: IOP: intra-ocular pressure; AIDS: acquired immune deficiency syndrome; EVS: endophthalmitis vitrectomy study; CEVE: complete and early vitrectomy for endophthalmitis.

Endophthalmitis management study. Report #1. Protocol

To date, the Endophthalmitis Vitrectomy Study (EVS) has remained the hallmark of evidence-based management of acute bacterial endophthalmitis after cataract surgery with an intraocular lens. In the last quarter-century since its publication, several studies have reported that the microbiological spectrum of endophthalmitis is not the same across the world; there is emerging antibiotic resistance of gram-negative microorganisms to the EVS recommended antibiotics; there are newer molecules that could cross the blood-retinal barrier; the advances in vitreous surgery have become safer than before, and there are newer methods of microbiological evaluation. One of the often-mentioned drawbacks of the EVS was not recruiting grossly infected eyes with poor visibility of the iris and vitreous. Keeping these factors in mind, a new prospective multi-centered randomized study, the Endophthalmitis Management Study (EMS), is designed. The EMS will recruit all post-cataract surgery endophthalmitis patients irrespective of severity (including suspected fungal infection); the EMS will use quantifiable inflammatory score instead of the presenting vision to allocate for surgery, randomize the eyes to two different combinations of intravitreal antibiotics and use the newer microbiological diagnostic techniques. We believe the EMS findings will complement the EVS recommendations.

Determination of the retinal toxicity of intravitreal colistin in rabbit eyes

PURPOSE

To determine the possible adverse effects and safe dose range of intravitreal colistin, an antibiotic, after its intravitreal application.

METHODS

Twenty eyes of 20 adult male and female New Zealand white rabbits were selected. Various concentrations of colistin were prepared. In each rabbit, 0.1 mL of colistin solution or saline solution was injected intravitreally into the right eye. Electroretinographic recordings were taken before and 2 weeks after injection. Histopathological examination was made using a light microscope following enucleation and fixation procedures. In histopathologic cross-sections, the differences between drug-injected eyes and control eyes were evaluated.

RESULTS

Electroretinographic examination showed a decrease of 30% as a significant value in the a and b wave amplitudes of the rabbits that injected 400 µg/0.1 ml and higher concentrations. Histological examination revealed histiocytic infiltration, histiocytic vacuoles, inflammation, and retinal degeneration in rabbit eyes given 400 µg/0.1 ml, 800 µg/0.1 ml, and 1.6 mg/0.1 ml concentrations of colistin.

CONCLUSION

Based on our findings, the safe concentration of colistin is 0.2 mg/0.1 ml. Administration of 0.4 mg/0.1 ml was associated with cataract development, electrophysiological depression, and pathological changes in retinal layers.

Speciation and Antibiotic Susceptibilities of Coagulase Negative Staphylococci Isolated from Ocular Infections

Coagulase-negative staphylococci (CoNS) are frequently occurring ocular opportunistic pathogens that are not easily identifiable to the species level. The goal of this study was to speciate CoNS and document antibiotic susceptibilities from cases of endophthalmitis (n = 50), keratitis (n = 50), and conjunctivitis/blepharitis (n = 50) for empiric therapy. All 150 isolates of CoNS were speciated using (1) API Staph (biochemical system), (2) Biolog GEN III Microplates (phenotypic substrate system), and (3) DNA sequencing of the sodA gene. Disk diffusion antibiotic susceptibilities for topical and intravitreal treatment were determined based on serum standards. CoNS identification to the species level by all three methods indicated that S. epidermidis was the predominant species of CoNS isolated from cases of endophthalmitis (84-90%), keratitis (80-86%), and conjunctivitis/blepharitis (62-68%). Identifications indicated different distributions of CoNS species among endophthalmitis (6), keratitis (10), and conjunctivitis/blepharitis (13). Antibiotic susceptibility profiles support empiric treatment of endophthalmitis with vancomycin, and keratitis treatment with cefazolin or vancomycin. There was no clear antibiotic choice for conjunctivitis/blepharitis. S. epidermidis was the most frequently found CoNS ocular pathogen, and infection by other CoNS appears to be less specific and random. Antibiotic resistance does not appear to be a serious problem associated with CoNS.

Intravitreal moxifloxacin injections in acute post-cataract surgery endophthalmitis: Efficacy and safety

Purpose

The aim of this study was to evaluate the efficacy and safety of intravitreal moxifloxacin injections in the treatment of acute post-cataract surgery endophthalmitis with visual acuity equal to or greater than hand movements.

Methods

Fifty two patients with post-cataract surgery endophthalmitis who presented within 6 weeks with visual acuity equal to or greater than hand movements received two intravitreal moxifloxacin injections 48 h apart. Patients with prior history of ocular disease or treatment were excluded. Patients were followed up to 3 months either for resolution of endophthalmitis or worsening of disease. Number of patients who achieved visual acuity equal to or better than 20/40 and 20/200 at the third-month follow-up visit were compared with the number of patients at presentation, using Chi-square test. In addition, pretreatment LogMAR visual acuity at the time of presentation was compared with posttreatment visual acuity at end of third month using paired t test.

Results

Fifty (96.15%) patients showed complete resolution of endophthalmitis while three patients required vitrectomy. Forty-one (78.85%) and 49 (94.23%) patients achieved visual acuity equal to or better than 20/40 and 20/200, respectively, at the third-month follow-up visit as compared to eight (15.38%) and 13 (25%) patients, respectively, at presentation (P < 0.05). In addition, mean LogMAR visual acuity at the time of presentation was 0.755 which improved to 0.307 at the third-month follow-up visit (P < 0.05). None of the patients developed hypersensitivity reactions to intravitreal moxifloxacin.

Conclusion

Intravitreal moxifloxacin injections showed promising results in acute post-cataract surgery endophthalmitis.

Clinical presentations, microbiology and management outcomes of culture-proven endogenous endophthalmitis in India

Purpose:

To report the clinical presentation, microbiology, and management outcome of endogenous endophthalmitis in Indian patients.

Methods:

Retrospective chart review of culture-positive (vitreous/urine/blood) endogenous endophthalmitis cases treated in tertiary eye care facility in India was done.

Results:

The study included 173 eyes of 117 patients. Mean patient age was 25.41 ± 20.46 years (median 24 years). Pre-disposing systemic illness could not be elicited in 79 (67.63%) patients. Commonest predisposing systemic condition in patients where it could be detected (n = 79) was pyrexia of unknown origin (25/79 = 32.0%). Following treatment, 45 out of 173 (26.0%) eyes regained vision of ≥20/400. Commonest isolated organism from vitreous was Streptococcus pneumoniae (36 eyes, 20.8%) and fungi were isolated in 24 (13.8%) eyes, the commonest being Candida spp. (8/24, 33.33%). Favorable functional outcome was seen in 26% eyes and favorable anatomic outcome in 43% eyes. Those with an underlying systemic illness were older (P = 0.02), had greater urine culture positivity (P = 0.003), lesser vitreous culture positivity (0.001), greater gram negative etiology (P = 0.0006), and greater fungal etiology (P = 0.01) as compared to those cases without underlying systemic illness.

Conclusion:

Endogenous endophthalmitis in India often presents in young immunocompetent individuals without any underlying systemic illness and with negative blood or urine microbiologic work up. Underlying systemic illness leads to greater gram-negative and fungal etiology. Overall visual outcome is poor inspite of prompt management.

Intravenous administration of Penicillin results in therapeutic intravitreal levels in chronic postoperative endophthalmitis

IMPORTANCE

The role of systemic antibiotics in the treatment of bacterial endophthalmitis remains controversial. While penicillin is a highly effective antibiotic against bacteria that frequently cause endophthalmitis, the ability of systemically administered Penicillin G to penetrate into the vitreous at adequate therapeutic concentrations has not been studied. Its role in the treatment of endophthalmitis, particularly for bacteria for which it is the antibiotic of choice, therefore remains unknown.

OBJECTIVE

We sought to determine whether intravenous administration of Penicillin G leads to adequate therapeutic concentrations in the vitreous for the treatment of bacterial endophthalmitis.

DESIGN AND SETTING

This study was conducted in an ambulatory setting, at the Ottawa Hospital Eye Institute, a university-affiliated tertiary care center, where a 77-year old gentleman with chronic post-cataract surgery Actinomyces neuii endophathalmitis was treated with intravenous Penicillin G (4 × 106 units every 4 h) and intravitreal ampicillin (5000μg/0.1 m1).

MAIN OUTCOMES AND MEASURES

Intravitreal concentration of Penicillin G and ampicillin were obtained at the time of intraocular lens removal, measured by high-performance liquid chromatography.

RESULTS

The intravitreal concentration of penicillin and ampicillin was 3.5μg/ml and 0.3μg/ml, respectively. Both the concentration of penicillin and ampicillin were within the level of detection of their respective assays (penicillin 0.06-5μg/ml, ampicillin 0.12-2.5μg/ml).

CONCLUSION AND RELEVANCE

This study shows that intravenous Penicillin G administered every four-hours allows for adequate intravitreal concentrations of penicillin. Future studies are required to determine if the results of this study translate into improved clinical outcomes.

Exogenous Fungal Endophthalmitis: Clues to Aspergillus Aetiology with a Pharmacological Perspective

Exogenous fungal endophthalmitis (EXFE) represents a rare complication after penetrating ocular trauma of previously unresolved keratitis or iatrogenic infections, following intraocular surgery such as cataract surgery. The usual latency period between intraocular inoculation and presentation of symptoms from fungal endophthalmitis is several weeks to months as delayed-onset endophthalmitis. Aspergillus spp., is the most common causative mould pathogen implicated in this ocular infection and early diagnosis and prompt antimicrobial treatment, concomitantly in most cases with expert surgical attention, reduce unfavorable complications and increase the possibility of eye function preservation. Topical, intravitreal and systemic antifungal molecules are the mainstay of a medical approach to the disease and azoles, polyenes and in particular cases echinocandins are the pharmacological classes most commonly used in clinical practice. This review discusses pharmacokinetics and pharmacodynamic of antifungal agents in their principal modes of administration with a focus on their ability to achieve high drug concentration in the vitreous and ocular tissues.

A Case of Bilateral Endogenous Candida dubliniensis Endophthalmitis Treated with Aggressive Local and Systemic Therapy

Candida dubliniensis is an emerging pathogen implicated in a variety of infections in immunocompromised hosts. A 79-year-old male with autoimmune pancytopenia on chronic oral steroid therapy was admitted for suspected sepsis and started on empirical antibiotics and micafungin. He developed floaters and decreased vision while on this regimen and was diagnosed with bilateral candida endophthalmitis. Blood cultures grew C. dubliniensis.Intravenous therapy was switched to voriconazole and amphotericin B. He also received aggressive intravitreal antifungal therapy consisting of 100 μg/0.1 mL voriconazole (4 OD, 3 OS) and 5 μg/0.1 mL amphotericin B (3 OD, 1 OS) over 2 weeks that resulted in local control of infection. The right eye developed a retinal detachment 1 month after initial presentation that was repaired by 25-gauge pars plana vitrectomy, scleral buckle, laser and silicone oil. At the 15-month follow-up exam, subsequent to silicone oil removal, membrane peel and cataract surgery, OD visual acuity had improved to 20/80. OS was phakic and 20/25. Aggressive intravitreal antifungal therapy combined with intravenous therapy may control endophthalmitis and avoid the risks associated with pars plana vitrectomy during acute infection.

Antimicrobial guide to posterior segment infections

PURPOSE

This review article is meant to serve as a reference guide and to assist the treating physician in making an appropriate selection and duration of an antimicrobial agent.

METHODS

Literature review.

RESULTS

Infections of the posterior segment require prompt medical or surgical therapy to reduce the risk of permanent vision loss. While numerous options exist to treat these infections, doses and alternative therapies, especially with contraindications for first-line therapy, are often elusive. Antimicrobial agents to treat posterior segment infections can be administered via various routes, including topical, intravitreal, intravenous, and oral.

CONCLUSIONS

Although there are many excellent review articles on the management of endophthalmitis, we take the opportunity in this review to comprehensively summarize the appropriate antimicrobial regimen of both common and rare infectious etiologies of the posterior segment, using evidence from clinical trials and large case series.

Vitrectomy combined with intravitreal antifungal therapy for posttraumatic fungal endophthalmitis in eastern China

Background

To evaluate the effect and prognostic factors of vitrectomy combined with intravitreal antifungal therapy for posttraumatic fungal endophthalmitis in Eastern China.

Methods

We retrospectively reviewed the medical records of patients who developed fungal endophthalmitis after penetrating ocular trauma at an ophthalmic center in Eastern China. All patients underwent vitrectomy and intravitreal injection of antifungal drugs.

Results

Thirty-five patients (35 eyes) were included. Twelve eyes suffered plant trauma, 17 eyes metal trauma, and 6 eyes other trauma. The culture results for all 35 eyes showed filamentous fungi, including Aspergillus in 26 eyes (74.3%). Twenty-three eyes underwent vitrectomy once and 12 eyes were treated twice. Four eyes were iridectomized because of a fungal lesion behind the iris. Fungal endophthalmitis was effectively controlled in 33 eyes (94.3%), whereas 2 eyes were ultimately enucleated. Visual acuity was significantly better after treatment than before treatment (P = 0.0006). According to the preoperative vision, the affected eyes were divided into two groups: group 1A (light perception) and group 1B (better than light perception). The final visual acuity in group 1B was significantly better than that in group 1A (P = 0.0289).

Conclusions

Vitrectomy combined with intravitreal antifungal therapy is an effective treatment for posttraumatic fungal endophthalmitis. Preoperative visual acuity is a significant factor affecting the prognosis of visual acuity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-020-01703-7.

A case report of fulminant endophthalmitis caused by Streptococcus dysgalactiae in a patient with traumatic corneal laceration

BACKGROUND

To report a case of enucleation caused by Streptococcus dysgalactiae endophthalmitis after traumatic corneal laceration.

CASE PRESENTATION

A 69-year-old man with history of retinal detachment treated with vitrectomy and subsequent cataract surgery presented with traumatic corneal laceration while cutting grass. Appropriate repair of corneal laceration and intravitreal antibiotics (vancomycin, ceftazidime) injection was performed. S. dysgalactiae which was sensitive to the conventional antibiotics (Ampicillin, Ceftriaxone, Levofloxacin, etc.) detected by aqueous culture. One day following primary closure, the patient developed a complete hypopyon and vitreous membranes. Despite vigorous systemic and intravitreal antibiotics administration with vitrectomy, endophthalmitis was not controlled and patient's ocular pain was increased. The vitreous culture was also positive for S. dysgalactiae. Finally, total enucleation was performed 9 days after trauma due to fulminant endophthalmitis with severe scleritis.

CONCLUSION

Progression of traumatic endophthalmitis associated with S. dysgalactiae can be fulminant. Sufficient warning to patient about enucleation and intensive care is needed in the case of this infection.

Pharmacological Advances in the Treatment of Age-related Macular Degeneration

Age-related macular degeneration is an acquired degenerative disease that is responsible for severe loss of vision in elderly people. There are two types: dry age-related macular degeneration and wet age-related macular degeneration. Its treatment has been improved and tries to be tailored in the future. The aim of this review is to summarize the pharmacological advances in the treatment of age-related macular degeneration. Regarding dry AMD, there is no effective treatment to reduce its progression. However, some molecules such as lampalizumab and eculizumab were under investigation, although they have shown low efficacy. Herein, in an attempt to prevent dry AMD progression, the most important studies suggested increasing the antioxidants intake and quitting the smoke habit. On the other hand, wet AMD has more developed treatment. Nowadays, the gold standard treatment is anti-VEGF injections. However, more effective molecules are currently under investigation. There are different molecules under research for dry AMD and wet AMD. This fact could help us treat our patients with more effective and lasting drugs but more clinical trials and safety studies are required in order to achieve an optimal treatment.

Management of Endophthalmitis with and without Topical Antibiotics: A Case-Control Study

PURPOSE

The aim of this study was to compare the management outcome of endophthalmitis with and without the use of topical antibiotics.

METHODS

A retrospective comparative chart review of 2 cohorts of endophthalmitis (other than those associated with open-globe injury, keratitis, or wound site infection), one managed with topical antibiotics (TA group) and one without (NTA group), was performed.

RESULTS

The study included a total of 270 eyes of 270 patients. Of these, 169 eyes were in the TA group and 101 were in the NTA group. Post-cataract surgery was the most common etiology, accounting for 81.06 and 78.2% of cases, respectively (p = 0.57). A favorable functional outcome at the last visit was seen in 37.5 and 39.6% of eyes (p = 0.73), and a favorable anatomic outcome was noted in 61.2 and 49.5% of eyes (p = 0.06), respectively. The median follow-up was 3.5 and 9 months, respectively (p < 0.0001). Susceptibilities to the common antibiotics used (vancomycin, ceftazidime, and amikacin) were comparable, with the exception of imipenem, for which the susceptibility noted was 95 and 66%, respectively (p = 0.01). Culture positivity in the TA group was seen in 72 out of 169 eyes (42.6%), while in the NTA group it was seen in 98 out of 101 eyes (97.02%; p < 0.0001).

CONCLUSION

Topical antibiotics do not give any added advantage in the management of endophthalmitis otherwise being treated with intravitreal antibiotics and standard vitrectomy techniques.

Drug Delivery to the Posterior Segment of the Eye: Biopharmaceutic and Pharmacokinetic Considerations

The treatment of the posterior-segment ocular diseases, such as age-related eye diseases (AMD) or diabetic retinopathy (DR), present a challenge for ophthalmologists due to the complex anatomy and physiology of the eye. This specialized organ is composed of various static and dynamic barriers that restrict drug delivery into the target site of action. Despite numerous efforts, effective intraocular drug delivery remains unresolved and, therefore, it is highly desirable to improve the current treatments of diseases affecting the posterior cavity. This review article gives an overview of pharmacokinetic and biopharmaceutics aspects for the most commonly-used ocular administration routes (intravitreal, topical, systemic, and periocular), including information of the absorption, distribution, and elimination, as well as the benefits and limitations of each one. This article also encompasses different conventional and novel drug delivery systems designed and developed to improve drug pharmacokinetics intended for the posterior ocular segment treatment.

Antibiotics and antifungals in silicone oil

Background

Antimicrobials may be injected into silicone oil-filled eyes with endophthalmitis, but the interaction with oil is unclear. The purpose of the experiment is to determine whether vancomycin, amikacin, and amphotericin B mix with silicone oil.

Methods

Using the relative proportions of the human eye, 4 ml of 1000 centistokes silicone oil was centrifuged with 0.1 ml of vancomycin 1 mg/0.1 ml, amikacin 0.4 mg/0.1 ml, or amphotericin B 5 µg/0.1 ml in vitro and eluted. The aqueous was immediately analyzed with a liquid chromatographer/mass spectrometer and after 24 h.

Results

Within 24 h, a mean of 26.9 μmol/L of vancomycin, 0 nmol/L of amikacin, and 0 nmol/L of amphotericin B were recovered. When the concentrations of amikacin and amphotericin B were increased 100-fold, 0 nmol/L of amikacin and 75.7 µmol/L of amphotericin B were recovered.

Conclusions

Vancomycin and amphotericin B partially mixed with the silicone oil. Amikacin was not recovered from the antibiotic–silicone oil mixture.

Metastatic Klebsiella pneumoniae Invasive Liver Abscess Syndrome in Denver, Colorado

BACKGROUND

Klebsiella pneumoniae has gained recognition for its association with invasive liver abscess syndrome (ILAS). ILAS is associated with a hypervirulent strain of K pneumoniae and can impact immunocompetent as well as immunocompromised patients.

CASE REPORT

A 42-year-old Hispanic male with no significant past medical history was admitted with complaints of subjective fevers and worsening fatigue. The patient was found to have multiple septic pulmonary emboli, a prostate abscess, a seminal vesicle abscess, bilateral frontoparietal and left temporal infarcts thought to be due to septic emboli, pyelonephritis, endophthalmitis, and hepatic abscesses. Cultures grew K pneumoniae that was determined to be the hypervirulent strain associated with ILAS. The patient was treated for a total of 71 days, including ceftriaxone and multiple intravitreal injections with ceftazidime.

CONCLUSION

Notably, this case report details a disease state new to Colorado. Pharmacists are able to assist in the care of ILAS with antibiotic selection, considering sites of infection and encouraging appropriate consultation of specialized care teams.

Comparison of intravitreal antifungal 100 μg voriconazole and 5 μg amphotericin B in experimental <em>Aspergillus flavus</em> endophthalmitis model in rabbits

BACKGROUND Fungal endophthalmitis is a sight-threatening disease associated with high morbidity and Aspergillus sp. is the most common causes. Voriconazole (VCZ) and Amphotericin B (AmB) are the most used antifungal drugs, while head-to-head comparison for in vivo intravitreal efficacy is still unknown. This study was aimed to compare the efficacy of both agents against Aspergillus flavus.  METHODS A randomized, masked, controlled-experimental study was conducted on 15 albino New Zealand white rabbits. Endophthalmitis was induced by intravitreal inoculation of Aspergillus flavus. Intravitreal injection was given 24 hours post-inoculation, the rabbits were divided into three groups; 100 μg/0.1 ml VCZ intravitreal injection, 5 μg/0.1 ml AmB, and control. Clinical evaluation of corneal opacity, aqueous cells and flare, and vitreous opacity using Yang’s method of quantification were performed at day 1, 3, 5, 7, and 10 after treatment. Mycology quantitative analysis and histopathological examination were performed at the final evaluation.  RESULTS Clinical evaluation showed improvement of inflammation in the VCZ and AmB treatment groups (Δ score −2.1 [2.8] and −1.0 [3.2]) compared with the control group (Δ score 0.8 [3.1]). Although the VCZ group demonstrated a better clinical response with less inflammation and relatively intact retina structures in the histopathology result. Number of fungal colony was significantly less in AmB group (CFU/0.1 ml, p < 0.05).  CONCLUSIONS Favorable clinical improvement was shown in VCZ group compared to AmB group. Intravitreal VCZ showed a better clinical response tendency for Aspergillus flavus-induced endophthalmitis in rabbits.

Toxicities of and inflammatory responses to moxifloxacin, cefuroxime, and vancomycin on retinal vascular cells

Prophylactic intracameral injection of antibiotics is commonly used to prevent endophthalmitis after cataract surgery. However, devastating visual complications have been reported including hemorrhagic occlusive retinal vasculitis (HORV).To determine the toxic and inflammatory effects of moxifloxacin, cefuroxime, and vancomycin on human retinal vascular cells, human retinal vascular endothelial cells (RVEC) and pericytes were exposed to three antibiotics, and the adverse effects were assessed by membrane damage, loss of intrinsic esterase activity, kinetic cell viability, and inflammatory cytokine secretion. Their retinal toxicity was examined by live/dead assays after an intravitreal injection of the three antibiotics into mice eyes. In vascular cells in culture, membrane damage and loss of esterase activity were induced after exposure to the three antibiotics. The toxic effects were most obvious after moxifloxacin (RVEC, ≥125 μg/mL; pericytes, ≥1000 μg/mL) at 24 h. Cefuroxime also reduced esterase activity and the membrane integrity of vascular cells but were less toxic than moxifloxacin. Kinetic cell viability testing showed that 500 μg/mL of moxifloxacin exposure induced significant decrease (29%) in the viability as early as 1 h. When the inflammatory effects of the antibiotics were examined, a significant induction of IL-8 was observed especially by RVECs after exposure to cefuroxime or vancomycin which was exacerbated by L-alanyl-γ-D-glutamyl-meso-diaminopimelic acid (Tri-DAP), a NOD1 ligand. Intravitreal injections in mice showed that cefuroxime and vancomycin caused retinal and vascular toxicity extending to the inner nuclear layers. Collectively, moxifloxacin causes immediate damage to retinal vascular cells in vitro, while cefuroxime and vancomycin induced significant inflammatory effects on vascular endothelial cells and caused retinal toxicity. Surgeons need to be cautious of the toxicity when antibiotics are used prophylactically especially by intravitreal administration.

Ocular Biodistribution Studies using Molecular Imaging

Classical methodologies used in ocular pharmacokinetics studies have difficulties to obtain information about topical and intraocular distribution and clearance of drugs and formulations. This is associated with multiple factors related to ophthalmic physiology, as well as the complexity and invasiveness intrinsic to the sampling. Molecular imaging is a new diagnostic discipline for in vivo imaging, which is emerging and spreading rapidly. Recent developments in molecular imaging techniques, such as positron emission tomography (PET), single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI), allow obtaining reliable pharmacokinetic data, which can be translated into improving the permanence of the ophthalmic drugs in its action site, leading to dosage optimisation. They can be used to study either topical or intraocular administration. With these techniques it is possible to obtain real-time visualisation, localisation, characterisation and quantification of the compounds after their administration, all in a reliable, safe and non-invasive way. None of these novel techniques presents simultaneously high sensitivity and specificity, but it is possible to study biological procedures with the information provided when the techniques are combined. With the results obtained, it is possible to assume that molecular imaging techniques are postulated as a resource with great potential for the research and development of new drugs and ophthalmic delivery systems.

INTRAVITREAL THERAPY OF ENDOGENOUS ENDOPHTALMITIS DUE TO UROSEPSIS - A CASE REPORT

A case report of 58-year-old man with endogenous endophtalmitis due to urosepsis and bronchitis. Patient was hospitalized in Department of Internal Medicine another hospital. He was sent to consiliar examination to our Ophtalmology Department with worsening vision and pain in left eye one day after onset. The diagnose endogenous endophtalmitis was set. Visual aquity was a hand movement on the first visit. Intravitreal therapy was realized promptly that day, a combination of two antibiotic drugs (ceftazidim 2mg/ 0.1 ml a vankomycin 1 mg/ 0.1 ml) and antifungal agent (amfotericin B 10 &#956;g/ 0.1 ml). This therapy was applicated 3x totally, in two weeks. Humour from anterior chamber was taken during first intravitreal application and was negative. Blood culture was positive for staphylococcus aureus. Intravenous treatment with antibiotics (gentamycin 240 mg i.v. á 24hours a amoxicilin with clavulan acid 1.2 g i.v. á 8 hod) was set for two weeks then continued antibiotic (ciprofloxacin 500 mg á 12 hours) and antifungal therapy (itrakonazol 100 mg á 12 hod) per os two months. Visual aquity of the left eye was 20/100 after four weeks and 20/40 after two months. We would like to highlight advantage of multidisciplinary co-operation.

Intracameral cefuroxime in combined pars plana vitrectomy and phacoemulsification: a study of safety

Background

Postoperative endophthalmitis is a severe complication after intraocular surgery. The aim of this pilot study was to investigate the safety of intracameral cefuroxime in combined vitrectomy and phacoemulsification for cataract and various vitreoretinal disease.

Methods

The charts of 152 patients who underwent combined phacoemulsification, intraocular lens implant and pars plana vitrectomy were reviewed. The final tamponade was chosen among fluid, air, gas or silicone oil, based on the requirement of each single case. Patients were operated on by four different surgeons. At the end of surgery, 1 mg/0.1 mL of intracameral cefuroxime (Aprokam) was administered.

Results

The mean follow-up was 6.26±7.78 months (range 1–12). No retinal complication, such as retinal infarction or hemorrhages were observed. No acute macular serous detachment and no new intraretinal cysts were noted, in those patients who received optical coherence tomography within the fifth day after surgery. No endophthalmitis was recorded.

Conclusion

Intracameral cefuroxime, at the end of combined phacoemulsification and pars plana vitrectomy, is safe as it has no toxicity on the retina and maybe could be considered effective in endophthalmitis prevention. Due to the relatively small number of patients, further studies are advisable.

Summary statement

The standard dose of intracameral cefuroxime at the end of combined phacoemulsification and pars plana vitrectomy has no toxic effects on the retina. This paper/The abstract of this paper was presented at the European Vitreo Retinal Society Conference 2017 as a conference talk with interim findings. The poster’s abstract was not published.

Precision Intravitreal Chemotherapy for Localized Vitreous Seeding of Retinoblastoma

Purpose

To describe and evaluate the effectivity of a novel precision intravitreal injection technique for select cases of localized vitreous seeding in retinoblastoma.

Methods

Patients with localized vitreous seeds from retinoblastoma received intravitreal chemotherapy via a precision injection technique (P-IVitC) intended to optimize local delivery of melphalan to target seeds. The needle was inserted trans-pars plana and chemotherapy deposited within 3 mm of the target seed(s) under indirect ophthalmoscopic guidance. Without subsequent globe manipulation, the head was then positioned to promote gravity-dependent settling of chemotherapy.

Results

There were 8 eyes of 8 patients treated with P-IVitC for active vitreous seeds following adequate solid tumor control with intravenous chemotherapy (n = 3, 38%) or intra-arterial chemotherapy (n = 5, 63%). Viable vitreous seeds were primarily solitary spheres (n = 6, 75%) and measured an average of 2.7 mm in diameter. Vitreous seed resolution (n = 8, 100%) was noted after a mean of 2.6 injections (median 2; range 1-3) of 20 μg melphalan. There was no recurrence at a mean follow-up of 10.0 months. Only 1 eye had an associated complication (focal retinal pigment epithelial mottling, n = 1, 13%).

Conclusions

With direct delivery of chemotherapy to within 3-4 mm of vitreous seed activity, P-IVitC provided complete control of localized vitreous seeds with minimal toxicity.

Postsurgical Cataract Prophylaxis With Intravitreal "Triamcinolone-Moxifloxacin" May Not Be Optimal For Preventing Endophthalmitis

PURPOSE

Intravitreal injections of antibiotics and anti-inflammatories are used by some cataract surgeons for surgical prophylaxis. To support this prophylaxis, intravitreal triamcinolone-moxifloxacin (TM) and triamcinolone-moxifloxacin-vancomycin (TMV) were tested for preventing Staphylococcus aureus (SA) endophthalmitis in rabbits.

METHODS

Trademark formulations of TM (15/1 mg/mL) and TMV (15/1/10 mg/mL) were intravitreally injected into seven groups of eight rabbits each (A-G). Before intravitreal injection, the vitreous was first challenged with clinical SA endophthalmitis isolates (5,000 colony-forming unit) with varying minimum inhibitory concentrations (MICs in μg/mL) to moxifloxacin (denoted by the MIC at the end of each group listed): A) TMV-10, B) TM-10, C) Saline-10, D) TM-2, E) Saline-2, F) TM-0.032, and G) Saline-0.032. After 24 hr, the rabbit eyes were graded for clinical endophthalmitis and cultured for viable SA.

RESULTS

Rabbits treated with TMV and challenged by SA with a moxifloxacin MIC of 10 μg/mL did not present with endophthalmitis (0/8, no eyes with endophthalmitis). For SA with moxifloxacin MICs of 10.0 and 2.0 μg/mL, TM did not prevent endophthalmitis (16/16, 100% of eyes with endophthalmitis). For SA with a moxifloxacin MIC of 0.032 μg/mL, endophthalmitis was prevented with TM (0/8, no eyes with endophthalmitis). All saline-treated eyes developed endophthalmitis (23/23, 100% of eyes with endophthalmitis).

CONCLUSIONS

Intravitreal monotherapy with TM did not provide consistent prevention of SA endophthalmitis, whereas intravitreal TMV successfully prevented endophthalmitis because of SA with elevated MIC values to moxifloxacin. Cataract surgeons need to be aware that vancomycin seems to be essential for intravitreal prophylaxis to cover moxifloxacin resistance.

Analysis of pharmaceuticals and small molecules in aqueous humor

Aqueous humor (AH) is a transparent fluid found in the anterior chamber of the eye. The circulating AH nourishes the cornea and lens and removes the metabolic waste moving through the ocular chambers and drains from the eye to the venous blood. Analysis of drugs in AH is necessary to evaluate their pharmacokinetics parameters, which may be crucial to avoid potential adverse effects. Analysis of endogenous components of AH may help to understand its physiology as well as changes evoked by pathological situation. This review describes analytical methods used for determination of pharmaceuticals and small endogenous molecules in AH, focusing on sample preparation procedures and analytical techniques. Studies on human and animal samples are included. After inspection and filtering of records found in PubMed about 100 research papers were selected to review. In these articles AH samples of human and rabbit origin were studied most often. Sample evaporation and reconstitution in smaller solvent volume was the most popular method for analyte pre-concentration. Acetonitrile, methanol or mixture of both solvents were used most often for protein precipitation.

Review of Intraocular Pharmacokinetics of Anti-Infectives Commonly Used in the Treatment of Infectious Endophthalmitis

Although intravitreal administration of anti-infectives represents the standard treatment for infectious endophthalmitis, the knowledge about their pharmacokinetics is still limited. In this review, we aimed to summarise the factors influencing the pharmacokinetics of the anti-infective agents. We have conducted a comprehensive review of the preclinical pharmacokinetic parameters obtained in different studies of intravitreal injections of anti-infectives performed on animals, mainly rabbits. The two aspects with the biggest influence on pharmacokinetics are the distribution in the vitreous humour and the elimination through the posterior segment. The distribution can be affected by the molecular weight of the drug, the convection flow of the vitreous, the condition of the vitreous humour depending on the age of the patient, the possible interactions between the drug and the components of the vitreous, and the presence of vitrectomy. Meanwhile, the elimination includes the metabolism of the drug, the clearance via the anterior and posterior routes, and the possible inflammation of the eye resulting from the disease. Understanding the pharmacokinetics of the anti-infectives used in clinical practice is essential for a correct application. The information provided in this review could offer guidance for selecting the best therapeutic option according to the characteristics of the drugs.

A Review of Antimicrobial Therapy for Infectious Uveitis of the Posterior Segment

Treatment of infectious posterior uveitis represents a therapeutic challenge for ophthalmologists. The eye is a privileged site, maintained by blood ocular barriers, which limits penetration of systemic antimicrobials into the posterior segment. In addition, topical and subconjunctival therapies are incapable of producing sufficient drug concentrations, intraocularly. Posterior infectious uveitis can be caused by bacteria, virus, fungi, or protozoa. Mode of treatment varies greatly based on the infectious etiology. Certain drugs have advantages over others in the treatment of infectious uveitis. Topical and systemic therapies are often employed in the treatment of ocular infection, yet the route of treatment can have limitations based on penetration, concentration, and duration. The introduction of intravitreal antimicrobial therapy has advanced the management of intraocular infections. Being able to bypass blood-ocular barriers allows high drug concentrations to be delivered directly to the posterior segment with minimal systemic absorption. However, because the difference between the therapeutic and the toxic doses of some antimicrobial drugs falls within a narrow concentration range, intravitreal therapy could be associated with ocular toxicity risks. In many cases of infectious uveitis, combination of intravitreal and systemic therapies are necessary. In this comprehensive review, the authors aimed at reviewing clinically relevant data regarding intraocular and systemic antimicrobial therapy for posterior segment infectious uveitis. The review also discussed the evolving trends in intraocular treatment, and elaborated on antibiotic pharmacokinetics and pharmacodynamics, efficacy, and adverse effects.

The Susceptibility of Bacterial Endophthalmitis Isolates to Vancomycin, Ceftazidime, and Amikacin: a 23 Year-Review

PURPOSE

To investigate the in vitro susceptibility of Gram-positive and Gram-negative endophthalmitis bacterial isolates to vancomycin, amikacin, and ceftazidime over a 23-year period.

DESIGN

Retrospective non-comparative laboratory case series.

SUBJECTS

Endophthalmitis patients that were culture positive for bacteria.

METHODS

Laboratory records of bacteria isolated from endophthalmitis specimens collected from January 1^st 1993 to December 31^st 2015 were reviewed for incidence and standard susceptibility testing.

MAIN OUTCOME MEASURES

The in vitro susceptibilities of bacteria cultured from endophthalmitis to vancomycin (VAN), amikacin (AMK), and ceftazidime (CEF).

RESULTS

Patients with endophthalmitis were culture positive for bacteria in 665 cases.. Coagulase negative Staphylococci (CoNS) were the most common bacteria (54.6%), followed by Streptococci (Strep) species (20.8%), Staphylococcus aureus (SA) (10.2%), other Gram-positive (other-GP) bacteria (7.4%) and Gram-negative (GN) bacteria (7.1%). All Gram-positive organisms were susceptible to VAN, with the exception of 2 isolates. The in vitro susceptibilities of bacteria to AMK were: CoNS (95.3%), SA (75.0%), Strep (8.0%), GN (95.7%), and other-GP (81.1%). The in vitro susceptibilities of bacteria to CEF were: CoNS (58.5%), SA (54.4%), Strep (84.1%), GN (93.6.%), and other-GP (52.8%). There was no difference between AMK (95.7%) and CEF (93.6%) for GN coverage. AMK provided better coverage than CEF for CoNS, SA, and other-GP bacteria respectively (p<0.05, Fisher's exact), however, CEF appeared to provide better coverage (p<0.001, Fisher's exact) for Strep than AMK.

CONCLUSIONS

Based on standard in vitro susceptibility testing, vancomycin remains an optimal antibiotic choice for the treatment of Gram-positive endophthalmitis. AMK and CEF appear to provide equal GN coverage, but AMK appears to provide better coverage for CoNS, SA, and other-GP, but not Strep.

Pharmacokinetic aspects of retinal drug delivery

Drug delivery to the posterior eye segment is an important challenge in ophthalmology, because many diseases affect the retina and choroid leading to impaired vision or blindness. Currently, intravitreal injections are the method of choice to administer drugs to the retina, but this approach is applicable only in selected cases (e.g. anti-VEGF antibodies and soluble receptors). There are two basic approaches that can be adopted to improve retinal drug delivery: prolonged and/or retina targeted delivery of intravitreal drugs and use of other routes of drug administration, such as periocular, suprachoroidal, sub-retinal, systemic, or topical. Properties of the administration route, drug and delivery system determine the efficacy and safety of these approaches. Pharmacokinetic and pharmacodynamic factors determine the required dosing rates and doses that are needed for drug action. In addition, tolerability factors limit the use of many materials in ocular drug delivery. This review article provides a critical discussion of retinal drug delivery, particularly from the pharmacokinetic point of view. This article does not include an extensive review of drug delivery technologies, because they have already been reviewed several times recently. Instead, we aim to provide a systematic and quantitative view on the pharmacokinetic factors in drug delivery to the posterior eye segment. This review is based on the literature and unpublished data from the authors' laboratory.