Aerosol generation through pars plana vitrectomy.

PURPOSE: To assess whether pars plana vitrectomy (PPV) is an aerosol-generating procedure (AGP) in an ex vivo experimental model. METHODS: In this ex vivo study on 10 porcine eyes, optical particle counter was used to measure particles ≤10 µm using cumulative mode in the six in-built channels: 0.3 µm, 0.5 µm, 1 µm, 2.5 µm, 5 µm and 10 µm aerosols during PPV. Two parts of the study were as follows: (1) to assess the pre-experimental baseline aerosol count in the theatre environment where there are dynamic changes in temperature and humidity and (2) to measure aerosol generation with 23-gauge and 25-gauge set-up. For each porcine eye, five measurements were taken for each consecutive step in the experiment including pre-PPV, during PPV, fluid-air exchange (FAX) and venting using a flute with 23-gauge set-up and a chimney with 25-gauge set-up. Therefore, a total of 200 measurements were recorded. RESULTS: With 23-gauge and 25-gauge PPV, there was no significant difference in aerosol generation in all six channels comparing pre-PPV versus PPV or pre-PPV versus FAX. Venting using flute with 23-gauge PPV showed significant reduction of aerosol ≤1 µm. Air venting using chimney with 25-gauge set-up showed no significant difference in aerosol of ≤1 µm. For cumulative aerosol counts of all particles measuring ≤5 µm, compared with pre-PPV, PPV or FAX, flute venting in 23-gauge set-up showed significant reduction unlike the same comparison for chimney venting in 25-gauge set-up. CONCLUSION: PPV and its associate steps do not generate aerosols ≤10 µm with 23-gauge and 25-gauge set-ups.

Ocular Manifestations of Emerging Flaviviruses and the Blood-Retinal Barrier.

Despite flaviviruses remaining the leading cause of systemic human infections worldwide, ocular manifestations of these mosquito-transmitted viruses are considered relatively uncommon in part due to under-reporting. However, recent outbreaks of Zika virus (ZIKV) implicated in causing multiple ocular abnormalities, such as conjunctivitis, retinal hemorrhages, chorioretinal atrophy, posterior uveitis, optic neuritis, and maculopathies, has rejuvenated a significant interest in understanding the pathogenesis of flaviviruses, including ZIKV, in the eye. In this review, first, we summarize the current knowledge of the major flaviviruses (Dengue, West Nile, Yellow Fever, and Japanese Encephalitis) reported to cause ocular manifestations in humans with emphasis on recent ZIKV outbreaks. Second, being an immune privilege organ, the eye is protected from systemic infections by the presence of blood-retinal barriers (BRB). Hence, we discuss how flaviviruses modulate retinal innate response and breach the protective BRB to cause ocular or retinal pathology. Finally, we describe recently identified infection signatures of ZIKV and discuss whether these system biology-predicted genes or signaling pathways (e.g., cellular metabolism) could contribute to the pathogenesis of ocular manifestations and assist in the development of ocular antiviral therapies against ZIKV and other flaviviruses.

Eye banking and corneal transplantation communicable adverse incidents: current status and project NOTIFY.

PURPOSE: Evidence of the transmission of disease via donor ocular tissue has been demonstrated for adenocarcinoma, rabies, hepatitis B virus, cytomegalovirus, herpes simplex virus, Creutzfeldt-Jakob disease, and a variety of bacterial and fungal infections. METHODS: Although there is no evidence to date of disease transmission for HIV infection, syphilis, hepatitis C, hepatitis A, tuberculosis, HTLV-1 and -2 infection, active leprosy, active typhoid, smallpox, and active malaria, these entities remain contraindications for transplantation for all eye banks nationally and internationally. The potential sources of contamination include infected donors, during the process of removing tissue from cadaveric donors, the processing environment, and contaminated supplies and reagents used during processing. The transmissions of Herpes simplex virus and HSV via corneal graft have been shown to be responsible for primary graft failure. HSV-1 may also be an important cause of PFG. RESULTS: The long latency period of some diseases, the emergence of new infectious disease, and the reemergence of others emphasize the need for long-term record maintenance and effective tracing capabilities. CONCLUSIONS: The standardization of definitions for adverse events and reactions will be necessary to support the prevention and transmission of disease. International classification of a unique identification system for donors will be increasingly important for vigilance and traceability in cross-national exportation of human cells, tissues, and cellular- and tissue-based products. Opportunities for continuous improvement exist as does the need for constant vigilance and surveillance.

Prevalence of positive microbiology results from donor cornea tissue in different methods of corneal transplantation.

PURPOSE: To evaluate the prevalence of positive microbiology results (culture and/or Gram stain) in donor cornea tissue with newer transplant methods and to assess if the results subsequently correlate with higher incidence of clinical infection. METHODS: A retrospective review of the microbiology records of 569 consecutive corneal transplants from July 2006 through July 2010 was performed to evaluate positive microbiology results in routine evaluation of cornea donor tissue. RESULTS: Microbiologic results were available for 544 of 569 transplants. The remaining 25 cases did not have specimens submitted for microbiologic analysis. In cases with results available, 46 (8.5%) positive reports occurred. In 10 of the 46 cases, Gram stain results were positive with subsequent negative cultures. Analysis revealed that the prevalence of positive results was 6 in 137 (4.4%), 14 in 127 (11.0%), and 26 in 271 (9.6%) for femtosecond laser-enabled keratoplasty, Descemet stripping automated endothelial keratoplasty, and conventional penetrating keratoplasty, respectively; 9 femtosecond deep anterior lamellar keratoplasty had no positive results. There was no significant relationship between the types of transplant procedures and the occurrence of positive microbiologic results (P = 0.08). The overall incidence of clinical infection was found to be 0.4% (2 of 569); however, only 1 case (1 of 569 or 0.2%), which was a Candida albicans infection after Descemet stripping automated endothelial keratoplasty, was attributable to the donor. Of 25 cases in which microbiology studies were not performed, none developed a clinical infection. CONCLUSIONS: Prevalence of positive microbiologic results and subsequent infections do not appear to be increased with the method of donor handling used for newer techniques for keratoplasty.

Human ocular infection with Dirofilaria repens (Railliet and Henry, 1911) in an area endemic for canine dirofilariasis.

Dirofilaria repens, which is usually found in canine subcutaneous tissues, is the main causative agent of human dirofilariasis in the Old Word. However, a relationship between animal and human cases of dirofilariasis caused by D. repens in a given area has never been demonstrated. The uneven distribution of D. repens in provinces in Sicily, Italy represented the foundation for this study. We report a human case of ocular infection with D. repens from Trapani Province, where canine dirofilariasis is endemic. The nematode was morphologically and molecularly identified and surgical removal of the parasite was documented. The relationship between the prevalence of D. repens in dogs and the occurrence of human cases of ocular dirofilariasis is discussed on the basis of a review of the historical literature.

Infectious disease risk factors of corneal graft donors.

OBJECTIVE: To determine how donor health status affects the risk of infection after corneal transplant. METHODS: An adverse reaction surveillance registry was used to conduct a matched case-control study among transplanted donor corneas from January 1, 1994, to December 31, 2003. Cases comprised 162 reports of endophthalmitis after penetrating keratoplasty including 121 with microbial recovery, of which 59 had concordant donor and recipient microbial isolates. Two controls were matched to each case by surgery date. Conditional logistic regression estimated adjusted odds ratios with 95% confidence intervals according to the premortem status of decedent donors. RESULTS: Postkeratoplasty endophthalmitis was associated with recent hospitalization (odds ratio, 2.84; 95% confidence interval, 1.61-4.98) and fatal cancer (odds ratio, 2.46; 95% confidence interval, 1.53-3.97) among donors. Endophthalmitis appeared more likely with tissues transplanted longer than 5 days after donation (odds ratio, 1.55; 95% confidence interval, 1.02-2.35). The prevalence of concordant microbial isolates from donors and recipients was greater among fungal endophthalmitis than among bacterial endophthalmitis (P < .001). CONCLUSIONS: Corneal grafts with eye tissue obtained from donors dying in the hospital or with cancer may have an increased risk of postsurgical endophthalmitis, possibly due to donor-to-host microbial transmission. Together with donor screening and processing, improvements in microbiological control may reduce infection associated with corneal transplant.

Contamination of disposable tonometer prisms during tonometry.

AIM: Due to the theoretical possibility of prion transmission in applanation tonometry, many ophthalmological units in the United Kingdom now use disposable tonometer prisms. We have investigated the potential for bacterial and viral transmission from the health practitioner to the patient via disposable prisms. METHODS: All staff who perform applanation tonometry at the Sussex Eye Hospital (SEH) received a questionnaire to evaluate if the applanating face of the prism is touched during tonometry and the ease of use of the disposable prism compared to the reusable prisms that were previously used. We then cultured prisms handled by a random sample of staff members for common bacteria. Finally, we constructed a model to investigate the possibility of interpatient adenoviral transmission via disposable tonometer prisms. RESULTS: The questionnaire revealed that almost 50% of the staff admit to touching the applanating face of the tonometer prism prior to applanation. Cultures of the prisms grew a range of bacteria including Staphylococcus epidermidis, Staphylococcus aureus, and Bacillus species. The viral model suggested that adenovirus could be transmitted by applanation tonometry. CONCLUSION: The use of disposable prisms for applanation tonometry may reduce the risk of prion transmission but is not bacteriologically or virologically aseptic. This is a potential infection risk to patients.

Microbial contamination of immersion biometry ultrasound equipment.

PURPOSE: To investigate the prevalence of microorganisms on ultrasound biometry equipment and cleaning habits. DESIGN: Observational case series. PARTICIPANTS: Thirty-four university-based and private ophthalmology clinics. METHODS: In a prospective multicenter study, clinics representative of every region of the country sampled their fixed immersion biometry equipment (i.e., ultrasound probe, immersion shell, and infusion tubing) for bacteria and fungi. Assessment of the cleaning habits for this equipment was conducted by way of a standard questionnaire that included type of fluid and delivery method, frequency of fluid change, method of cleaning the probe and shell, and frequency of tubing change and/or cleaning. MAIN OUTCOME MEASURES: Frequency (prevalence), descriptive statistics, and type of microorganisms. RESULTS: Eighteen samples (53% [18/34]) grew organisms from either the probe/shell or tubing. Positive cultures were found in 32% (11/34) of the immersion shell/probes and in 31% (10/32) of the infusion tubing samples. The bacteria most commonly cultured from both probe/shell and tubing was coagulase-negative Staphylococcus, whereas Penicillium species was the most commonly cultured fungus (exclusively from the probe/shell). Overall, fungi (Penicillium and Alternaria species) were cultured in 12% of the probe/shell samples. Only 14% of the study sites adequately disinfected the probe/shell according to Centers for Disease Control and Prevention (CDC) guidelines, which recommend a 5-minute soak in antiseptic. CONCLUSIONS: The bacteria and fungi that colonize biometry equipment are not being adequately eliminated by the cleaning/disinfecting techniques employed in most ophthalmology clinics. These results also may apply to contact biometry, pachymetry, and tonometry equipment as well. Clinicians should follow the CDC recommendations for disinfecting instruments that come in contact with the eye, and the infusion tubing should be changed after each patient.

[Unconventional transmissible agents]. / Agents transmissibles non conventionnels.

Ophthalmologists must take into account the possible emergence of unconventional transmissible agents in their daily practice. Official recommendations have been circulated; however, their routine application remains difficult, with technical and financial considerations limiting factors in the use of an ideal of one disposable medical device per patient. This review describes how these recommendations are followed and tries to provide insights into improving daily practice with these unconventional transmissible agents.

[Transmission of conventional agents during outpatient care]. / Transmission des agents conventionnels en consultation.

Outpatient care bring together in a single location a large number of patients potentially bearing conventional infectious agents (virus, bacteria, fungi, parasites). This report details the germs potentially involved. We emphasize adenovirus epidemic keratoconjunctivitis, which is particularly prevalent in ophthalmology outpatient care. We analyze the modes of contamination and the means to prevent iatrogenic infections.