Justin C. Sherwin

The Association between Time Spent Outdoors and Myopia in Children and Adolescents: A Systematic Review and Meta-analysis.

OBJECTIVE To summarize relevant evidence investigating the association between time spent outdoors and myopia in children and adolescents (up to 20 years). DESIGN Systematic review and meta-analysis. PARTICIPANTS Results from 7 cross-sectional studies were pooled in a meta-analysis. A further 16 studies (8 cross-sectional not meeting criteria for meta-analysis; 7 prospective cohort studies; 1 randomized, controlled trial [RCT]) were reported in the systematic review. METHODS The literature search included 4 databases (Medline, Embase, Web of Science, and Cochrane Central Register of Controlled Trials [CENTRAL]), and reference lists of retrieved studies. Estimates of association were pooled using random effects meta-analysis. We summarized data examining the association between time spent outdoors and prevalent myopia, incident myopia, and myopic progression. MAIN OUTCOME MEASURES Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for myopia for each additional hour spent outdoors per week from a meta-analysis. RESULTS The pooled OR for myopia indicated a 2% reduced odds of myopia per additional hour of time spent outdoors per week, after adjustment for covariates (OR, 0.981; 95% CI, 0.973-0.990; P<0.001; I(2), 44.3%). This is equivalent to an OR of 0.87 for an additional hour of time spent outdoors each day. Three prospective cohort studies provided estimates of risk of incident myopia according to time spent outdoors, adjusted for possible confounders, although estimates could not be pooled, and the quality of studies and length of follow-up times varied. Three studies (2 prospective cohort and 1 RCT) investigated time spent outdoors and myopic progression and found increasing time spent outdoors significantly reduced myopic progression. CONCLUSIONS The overall findings indicate that increasing time spent outdoors may be a simple strategy by which to reduce the risk of developing myopia and its progression in children and adolescents. Therefore, further RCTs are warranted to investigate the efficacy of increasing time outdoors as a possible intervention to prevent myopia and its progression.

Functional presbyopia in a rural Kenyan population: the unmet presbyopic need

Background:  Presbyopia is the most common reason for requiring spectacles in low‐income regions, although the unmet need for presbyopic spectacles in these regions is very high. The aim of this study was to estimate the prevalence of presbyopia, and the functional impairment and spectacle use among persons with presbyopia in a rural Kenyan population.

Epidemiology of vitamin A deficiency and xerophthalmia in at-risk populations

Vitamin A deficiency (VAD) is an important public health problem worldwide that contributes significantly to the global burden of disease. Vitamin A deficiency disorders include xerophthalmia and increased risk of infectious diseases, both of which increase risk of mortality. Xerophthalmia is also a leading cause of preventable blindness. Areas with highly prevalent VAD often share common dietary and other environmental exposures, including poverty, infectious diseases, limited development and poor availability of vitamin A containing food. Globally, the prevalence of VAD has been declining, which may be due to widespread vitamin A supplementation in conjunction with measles immunisation in at-risk populations. Recent meta-analyses confirm that provision of vitamin A to children aged between 6 months and 5 years confers a significant mortality benefit. Further preventative measures for VAD comprise improving availability of vitamin A containing food, including foods biofortified with vitamin A. Ensuring vitamin A is available in any form in adequate quantities remains problematic, especially in areas affected by environmental catastrophes and conflict, and other areas where access to vitamin A containing foods and healthcare interventions is limited. Hence, it remains essential that maternal and child health workers remain vigilant for VAD in nutritionally vulnerable populations.

Myopia is associated with lower Vitamin D status in young adults.

PURPOSE To investigate the association between serum vitamin D levels and myopia in young adults. METHODS A total of 946 individuals participating in the 20-year follow-up of the Western Australian Pregnancy Cohort (Raine) Study were included in this study. Ethnicity, parental myopia, and education status were ascertained by self-reported questionnaire. A comprehensive ophthalmic examination was performed, including postcycloplegic autorefraction and conjunctival UV autofluorescence photography. Serum 25-hydroxyvitamin D₃ (25(OH)D₃) concentrations were determined using mass spectrometry. The association between serum 25(OH)D₃ concentrations and prevalent myopia was determined using multivariable logistic regression. Myopia was defined as mean spherical equivalent ≤ -0.5 diopters. RESULTS Of the 946 participants, 221 (23.4%) had myopia (n = 725 nonmyopic). Myopic subjects had lower serum 25(OH)D₃ concentrations compared to nonmyopic participants (median 67.6 vs. 72.5 nmol, P = 0.003). In univariable analysis, lower serum 25(OH)D₃ concentration was associated with higher risk of having myopia (odds ratio [OR] for <50 vs. ≥50 nmol/L: 2.63; confidence interval [95% CI] 1.71-4.05; P < 0.001). This association persisted after adjustment for potential confounders, including age, sex, ethnicity, parental myopia, education status, and ocular sun-exposure biomarker score (adjusted OR 2.07; 95% CI 1.29-3.32; P = 0.002). CONCLUSIONS Myopic participants had significantly lower 25(OH)D₃ concentrations. The prevalence of myopia was significantly higher in individuals with vitamin D deficiency compared to the individuals with sufficient levels. Longitudinal studies are warranted to investigate whether higher serum 25(OH)D₃ concentration is protective against myopia or whether it is acting as a proxy for some other biologically effective consequence of sun exposure.

Risk factors for mortality in Clostridium difficile infection in the general hospital population: a systematic review

BACKGROUND Clostridium difficile infection (CDI) is one of the most important healthcare-associated infections, causing considerable mortality. Numerous severity scores have been proposed to identify patients with CDI at risk of mortality, but a systematic review of the evidence upon which these are based has never been published. Such a review could permit future development of scores that better predict mortality. AIM A systematic review of the published literature investigating clinically useful risk markers for mortality in CDI. METHODS We searched MEDLINE 1950 to present, Web of Science with conference proceedings 1899 to present and BIOSIS Citation Index 1969 to present using PubMed and Web of Knowledge. Potential risk markers that had been evaluated by at least four studies were extracted. FINDINGS Twenty-six studies, of 1617 initially identified, met inclusion criteria. The majority were retrospective cohort studies, mostly based in the USA. Older age, higher white blood cell count (WBC), higher creatinine level, lower albumin levels and, to a lesser extent, corticosteroid use were most frequently associated with mortality. Presence of fever, haemoglobin/haematocrit level, diarrhoea severity, presence of renal disease, diabetes, cancer, or nasogastric tube use did not appear to be associated with mortality. CONCLUSION Our results support the use of age, WBC, serum creatinine, serum albumin level and possibly pre-existing corticosteroid use as potentially useful risk markers for mortality in CDI. Our results do not support the use of fever, haemoglobin/haematocrit, diarrhoea severity and several comorbidities as useful risk markers, raising questions about their inclusion in CDI severity scores.

Myopia in Young Adults Is Inversely Related to an Objective Marker of Ocular Sun Exposure: The Western Australian Raine Cohort Study

PURPOSE To determine the association between ocular sun exposure measured by conjunctival ultraviolet (UV) autofluorescence and myopic refractive error in young adults. DESIGN Cross-sectional study. METHODS setting: Population-based cohort in Western Australia. study population: Total of 1344 mostly white subjects aged 19-22 years in the Western Australian Pregnancy Cohort (Raine) Eye Health Study. observation procedures: Cycloplegic autorefraction, conjunctival ultraviolet autofluorescence photography, participant questionnaire. main outcome measures: Prevalence of myopic refractive error (spherical equivalent less than -0.50 diopters) and area of conjunctival ultraviolet autofluorescence in mm(2). RESULTS There was an inverse relationship between myopic refractive error and ocular sun exposure, with more than double the prevalence of myopia in the lowest quartile of conjunctival autofluorescence than the highest quartile (33.0% vs 15.6%). Median area of autofluorescence was significantly lower in myopic than in nonmyopic subjects (31.9 mm(2) vs 47.9 mm(2), P < .001). These differences remained significant after adjustment for age, sex, parental history of myopia, and subject level of education. The use of corrective lenses did not explain the lower conjunctival autofluorescence observed in myopic subjects. CONCLUSIONS In this young adult population, myopic refractive error was inversely associated with objectively measured ocular sun exposure, even after adjustment for potential confounders. This further supports the inverse association between outdoor activity and myopia.

The association between pterygium and conjunctival ultraviolet autofluorescence: The Norfolk Island Eye Study

Purpose:  To investigate the association between conjunctival ultraviolet autofluorescence (UVAF), a biomarker of ocular ultraviolet radiation (UVR) exposure, and prevalent pterygium.

Tumor Volume in Radical Prostatectomy Specimens Assessed by Digital Image Analysis Software Correlates With Other Prognostic Factors

PURPOSE Digital image analysis software to review histopathology specimens is advancing uropathology by objectivity and reproducibility. Subjective pathologist assessed prostate tumor volume calculations correlate with known prognostic factors at radical prostatectomy. We ascertained whether image analysis software calculations of prostate tumor volume correlate with such prognostic factors, particularly positive surgical margins. MATERIALS AND METHODS Prostate tumor volume was calculated using digital image analysis software in 851 sequential radical prostatectomy specimens. Results were correlated with clinicopathological data by logistic regression. RESULTS Median prostate tumor volume was 2.2 cc (IQR 0.9-3.8). Median peripheral and transition zone tumor volume was 1.9 and 0.6 cc, respectively. Transition zone tumors were noted in 236 specimens (27.8%) and positive surgical margins occurred in 244 (28.7%). Tumors with extensive positive surgical margins had larger image analysis software assessed prostate tumor volume (p = 0.029) and peripheral zone volume (p = 0.007) than those with only focal positive surgical margins. On univariate analysis positive surgical margin tumors were larger and had seminal vesicle invasion, extraprostatic extension, perineural invasion and higher preoperative prostate specific antigen than those without positive surgical margins (each p <0.001). A linear relationship existed between image analysis software determined prostate tumor volume, and increasing tumor stage, Gleason score and prostate specific antigen (p for trend <0.001). On multivariate analysis tumor volume and tumor volume as a percent of prostate volume predicted positive surgical margins. CONCLUSIONS Prostate tumor volume determined objectively by image analysis software correlates with positive surgical margins, as do prognostic variables such as extraprostatic extension, seminal vesicle invasion, perineural invasion, peripheral zone volume and Gleason score greater than 7. Objective digital image analysis software assessment appears to be a valid form to determine prostate tumor volume at radical prostatectomy. It is a useful adjunct to other histopathological analyses.

The EPIC-Norfolk Eye Study: rationale, methods and a cross-sectional analysis of visual impairment in a population-based cohort

Objectives To summarise the methods of the European Prospective Investigation of Cancer (EPIC)-Norfolk Eye Study, and to present data on the prevalence of visual impairment and associations with visual impairment in the participants. Design A population-based cross-sectional study nested within an on-going prospective cohort study (EPIC). Setting East England population (the city of Norwich and its surrounding small towns and rural areas). Participants A total of 8623 participants aged 48–92 years attended the Eye Study and underwent assessment of visual acuity, autorefraction, biometry, tonometry, corneal biomechanical measures, scanning laser polarimetry, confocal scanning laser ophthalmoscopy, fundal photography and automated perimetry. Outcome measures Visual impairment was defined according to the WHO classification and the UK driving standard, and was based on presenting visual acuity. Summary measures of other ophthalmic measurements are also presented. Results The prevalence (95% CI) of WHO-defined moderate-to-severe visual impairment and blindness was 0.74% (0.55% to 0.92%). The prevalence (95% CI) of presenting visual acuity worse than the UK driving standard was 5.87% (5.38% to 6.37%). Older age was significantly associated with visual impairment or blindness (p<0.001). Presenting visual acuity worse than UK driving standard was associated with older age (p<0.001), female sex (p=0.005) and lower educational level (p=0.022). Conclusions The prevalence of blindness and visual impairment in this selected population was low. Visual impairment was more likely in older participants, women and those with a lower educational level.

Blindness and visual impairment due to uncorrected refractive error in sub-Saharan Africa: review of recent population-based studies

Aim The authors aimed to review published data on uncorrected refractive error (URE) as a cause of blindness and visual impairment in adults aged ≥40 years in sub-Saharan Africa (SSA). Methods Data were extracted from population-based prevalence surveys measuring presenting visual acuity (PVA). Results from 11 surveys performed in 10 countries in SSA, encompassing 39 458 people aged ≥40 years and older, are presented. Results The prevalence of blindness (PVA<3/60 in better eye) ranged from 1.1% in an urban district of Cameroon to 7.9% in a rural district in Ethiopia. More than half of studies (6/11) reported no blindness due to URE. The proportion of moderate visual impairment (PVA ≤6/60 and >6/18) due to URE ranged from 12.3% to 57.1%. Excluding two studies that included uncorrected aphakia as part of URE, the highest proportion of blindness and severe visual impairment due to uncorrected aphakia was found in Gambia (15.2%) and Nigeria (15.8%), respectively. Conclusion Although URE is a leading cause of visual impairment, it does not represent a major cause of blindness in SSA.