The prevalence and causes of visual impairment among the male homeless population of Montreal, Canada.

CLINICAL RELEVANCE: Homeless populations have lower health indicators, including in eye care. Few data exist on the levels and causes of visual impairment in Canadian homeless populations, and none in Montreal. BACKGROUND: This study aims to characterise the causes and levels of visual impairment, as well as eye care services utilisation among the Montreal homeless. METHODS: Using random sampling, five homeless shelters were selected. In each shelter, 20 participants were randomly selected. After obtaining informed consent, participants completed an ocular examination, which included: presenting visual acuity (pinhole as needed), intraocular pressure, confrontation visual field, dilated fundus examination, post-dilation autorefraction and questionnaire on social determinants of health. RESULTS: A total of 95 participants were examined, of which 97.9% were male. The median age was 49 years old (interquartile range 38-56.5). The age-adjusted prevalence of visual impairment (presenting visual acuity <6/12) was 23.6% (95% CI 15.1-32.9) compared to 6.0% in the Canadian population (Z = 77.9, p < 0.0001). With pinhole correction, the prevalence of visual impairment dropped to 5.8% (95% CI 1.7-11.8). Prevalence was 8.2% (95% CI 3.7-15.9) for cataracts, 11.4% (95% CI 5.9-19.7) for glaucoma or suspects and 4.7% (95% CI 1.7-11.9) for diabetic retinopathy. Lastly, 18.9% of participants had an ocular examination within the last year compared to 41.4% in Canada (Z = -4.5, p < 0.0001) and 13.7% had never had a comprehensive eye examination. CONCLUSIONS: This sample population shows a prevalence of visual impairment which is four times that of the general Canadian population, with highly prevalent uncorrected refractive error, while accessing primary eye care twice less often.

The sociodemographic characteristics and social determinants of visual impairment in a homeless population in the Montreal area.

OBJECTIVE: Homelessness is a serious social and public health concern in Canada. Individuals experiencing homelessness face numerous health problems and barriers in accessing health services. Visual impairment can exacerbate the lower quality of life experienced by people who are homeless, but its incidence among this population has been poorly documented in the literature. Our study aimed to describe health and sociodemographic characteristics and determine their association with visual impairment, ocular pathology and uncorrected refractive errors in a homeless population in Montreal, Canada. METHODS: This cross-sectional study was conducted between May 2019 and September 2020 in eight homeless shelters selected using a stratified random sampling approach on the island of Montreal. An eye examination was performed on all participants, who were also administered a survey on social determinants of health. Descriptive analysis was used to analyze survey data, and logistic regression was used for each of the three study outcomes. RESULTS: A total of 124 individuals experiencing homelessness (93 men, 31 women) were recruited. Participants were mostly Caucasian (> 70%) with an average age of 48 years (standard deviation = 13 years). Our sample reported a high level of education (68% had a high school diploma or higher), a high level of health insurance coverage (77%), social assistance benefits (71%), and social support (over 50%). There was a high prevalence of chronic conditions including diabetes (14%), hypertension (25%), and HIV/AIDS (3%). Results from eye examinations showed a high prevalence of visual impairment (22%), ocular pathology (23%), and uncorrected refractive error (75%). Age was statistically significantly associated with each outcome variable. CONCLUSION: Despite a high level of social and health support, individuals experiencing homelessness in Montreal, Canada, experience high levels of chronic conditions and visual impairment. Our study highlights the unmet need for eye healthcare among homeless populations, and that eye health can be a unique entry point for intervening with homeless populations.

RéSUMé: OBJECTIF: L'itinérance est un problème social et de santé publique important au Canada. Les personnes en situation d'itinérance font face à plusieurs problèmes de santé et d'accès aux soins de santé. La déficience visuelle est un problème de santé moins documenté chez cette population, mais qui peut grandement nuire à la qualité de vie. Notre étude visait à décrire les caractéristiques sanitaires et socio-démographiques et à déterminer leur association avec la déficience visuelle, les pathologies oculaires et les erreurs de réfraction non corrigée, dans une population d'itinérants à Montréal, au Canada. MéTHODOLOGIE: Une étude transversale a été réalisée entre mai 2019 et septembre 2020 auprès de 8 refuges pour itinérants à Montréal, sélectionnés par échantillonnage aléatoire stratifié. Les participants ont tous reçu un examen de la santé oculo-visuelle et il leur a été administré un questionnaire sur les déterminants sociaux de la santé. Une analyse descriptive a été utilisée pour analyser les données de l'enquête et une régression logistique a été utilisée pour chacun des trois variables dépendantes. RéSULTATS: Au total, 124 itinérants (93 hommes, 31 femmes) ont participé à l'étude. Les participants étaient caucasiens (>70 %) avec un âge moyen de 48 ans (±13 ans). Notre échantillon a déclaré un niveau d'éducation élevé (68 % avaient un diplôme d'études secondaires ou plus), un niveau élevé de couverture d'assurance maladie (77 %), d'aide sociale (71 %) et de soutien social (plus de 50 %). La prévalence des maladies chroniques était importante, notamment le diabète (14 %), l'hypertension (25 %) et le VIH/sida (3 %). Il y avait aussi une prévalence élevée de déficience visuelle (22 %), de pathologies oculaires (23 %) et d'erreurs réfractives non corrigées (75 %). L'âge était significativement associé à chacune des 3 variables dépendantes. CONCLUSION: Malgré un niveau élevé de soutien social et de santé, les itinérants de Montréal font face à un niveau élevé de maladies chroniques et de déficience visuelle. Notre étude met en évidence le niveau élevé des besoins non comblés en matière de soins de santé oculaire parmi les populations itinérantes, et le fait que la santé oculaire peut être un point d'entrée unique pour intervenir auprès de ces populations.

Development of support based on chitosan and cellulose nanocrystals for the immobilization of anti-Shiga toxin 2B antibody.

This work describes the development of membrane based on chitosan (CHI), cellulose nanocrystals (CNCs), and glycerol (GLY), and optimization of the formulation for immobilization of monoclonal anti-Shiga toxin 2B antibody (mAnti-stx2B-Ab) for E. coli O157:H7 detection. The effect of CHI deacetylation degree & viscosity, CNCs and GLY concentrations on Anti-stx2B-Ab immobilization efficiency was evaluated. Fractional factorial and Box-Behnken designs were applied to screen the effects of compounds interactions and optimize their concentrations for detection of Anti-stx2B-Ab. The results demonstrated that the use of 0.6 % (w/v) CNCs improved significantly the Anti-stx2B-Ab immobilization and the level of signal detection. The detection limit of Escherichia coli O157:H7 by developed optimized membrane is 1 log CFU/mL. The time needed for detection of E. coli O157:H7 was only 4 h of enrichment compared to 24 h with conventional methods. The developed immobilization support has potential for future pathogen detection in food and biomedical samples.

Effect of the optimized selective enrichment medium on the expression of the p60 protein used as Listeria monocytogenes antigen in specific sandwich ELISA.

This paper presents the effects of the composition of different media (i.e., Tryptic soy broth (TSB), Brain heart infusion (BHI), Listeria enrichment broth (LEB), Fraser broth (FB) and University of Vermont medium (UVM)) on the detection of a short peptide fragment PepD specific to the p60 protein (p60) of L. monocytogenes by a monoclonal antibody (anti-PepD mAb). Expression of the p60 obtained was demonstrated to be proportional to the cellular growth of Listeria monocytogenes regardless of the tested growth medium. However, the early growth of L. monocytogenes and the expression of the p60 were negatively affected by the presence of selective agents present in LEB, FB and UVM. Among those three selective enrichment media commonly used for L. monocytogenes, LEB allowed a better expression of L. monocytogenes p60 after an incubation period of 18 h. Optimization of the LEB revealed that the dextrose concentration was the critical factor for improving the expression of p60 and promotes the early expression of p60. Moreover, an optimal dextrose concentration of 0.5% (w/v) in LEB, coupled with anti-PepD mAb immobilized to solid support, reduced the detection of p60 from 18 h to 9 h for an initial concentration of L. monocytogenes of 108 CFU/ml.