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Paul Mitchell

Publications and source records attributed to Paul Mitchell.

At least 19 recordsLinked to original sources
PubMed2007

Heritability and shared environment estimates for myopia and associated ocular biometric traits: the Genes in Myopia (GEM) family study.

To examine the familial correlations, heritability (h(2)) and common environmental components (c(2)) of myopia and ocular biometric traits (all treated as continuous outcomes) in families collected through the Genes in Myopia (GEM) family study in Australia. A total of 132 pedigrees (723 participants) were recruited for this study. All individuals completed a risk factor questionnaire and underwent a detailed eye examination including spherical equivalent (SphE) and ocular biometric measurements of axial length (AL), anterior chamber depth (ACD) and corneal curvature (CC). Familial correlations were calculated and h(2) and c(2) were estimated using a variance component model that assumes a multivariate t distribution within each pedigree. Two definitions of common environments (c(2)) were considered: nuclear family (current) shared environment (Model 1) and sib-ship (childhood) shared environment (Model 2). Population ascertainment adjustment was performed using the Blue Mountains eye study dataset. The trends observed for familial correlations suggested that SphE is influenced by both environmental and genetic factors whereas AL, ACD and CC are predominantly genetically determined. This was largely confirmed by variance components modelling. Heritability estimates (adjusted for age, sex and years of education) from the best fitting ACE model (Model 2, childhood shared environment) were 0.50 +/- 0.05 for SphE, 0.73 +/- 0.04 for AL, 0.78 +/- 0.04 for ACD and 0.16 +/- 0.06 for CC. Childhood environmental effects were significant with c(2) estimated to be 0.33 +/- 0.04 for SphE, 0.06 +/- 0.03 for AL, 0.22 +/- 0.04 for ACD and 0.10 +/- 0.05 for CC. Age was associated with SphE, total years of education was associated with AL and sex was associated with all traits studied. We used a novel and conservative approach to account for and estimate common environmental effects by specifying either nuclear family or sib-ship environment when estimating heritability estimates and showed that all traits examined (SphE, AL, ACD and CC) are heritable, thus reflecting a genetic component. These traits therefore all represent candidates for quantitative trait linkage analyses.

Adult↗
PubMed2007

Ten-year incidence and progression of age-related maculopathy: the blue Mountains Eye Study.

PURPOSE: To assess the 10-year incidence of age-related maculopathy (ARM) in an older Australian cohort. DESIGN: Population-based cohort study. PARTICIPANTS: Three thousand six hundred fifty-four Blue Mountains Eye Study participants > or =49 years old were examined during 1992 through 1994; 2335 (75% of survivors) were reexamined after 5 years (1997-1999) and 1952 (76% of survivors) after 10 years (2002-2004). METHODS: The same graders performed retinal photographic grading in all examinations, using the Wisconsin Age-Related Maculopathy Grading System. Photographs of participants with ARM lesions at any of the examinations were subsequently regraded using a side-by-side comparison method. MAIN OUTCOME MEASURES: The diagnosis of incident late ARM was given if neovascular ARM or geographic atrophy was detected at either follow-up examination in persons free of these lesions at baseline. Incident early ARM was diagnosed if early ARM (soft indistinct or reticular drusen or combined soft distinct drusen and retinal pigment abnormality) was present in persons free of early and late ARM at baseline. Age-related maculopathy incidence was calculated using Kaplan-Meier methods to incorporate information from both 5- and 10-year examinations. Discrete logistic models were used to assess the risk of incident late ARM according to various baseline factors, including early ARM lesion characteristics. RESULTS: After excluding 72 late ARM cases present at baseline, 2395 of 3582 subjects at risk of late ARM (67%) were reexamined at either follow-up time point or both follow-up time points. Over the 10-year period, 72 of 2395 subjects (3.7%) developed late ARM and 266 of 2255 subjects (14.1%) developed early ARM. After age standardization to the Beaver Dam Eye Study population, our 10-year incidences of late and early ARM were 2.8% and 10.8%, respectively. Baseline age and early ARM lesion characteristics and severity were strong predictors of late ARM incidence. CONCLUSIONS: Long-term follow-up of this older population confirms that the risk of ARM progression is related strongly to the severity of early-stage lesions. The study provides evidence-based criteria for identifying persons at high risk of developing late ARM.

Aged↗
PubMed2007

BMI and retinal vascular caliber in children.

OBJECTIVE: In adult populations, changes in retinal vascular caliber have been linked with obesity and metabolic syndrome. We examined the association of BMI and weight with retinal vascular caliber in children. RESEARCH METHODS AND PROCEDURES: This was a school-based, cross-sectional study of 768 children, 7 to 9 years old, randomly sampled from the Singapore Cohort Study of the Risk Factors for Myopia. Participants had digital retinal photographs. Retinal vascular caliber was measured using a computer-based program and combined to provide average calibers of arterioles and venules in that eye. Weight and height were measured using standardized protocol. These data were used to calculate BMI. RESULTS: In this population, the mean retinal arteriolar and venular calibers were 156.40 microm [95% confidence interval (CI), 155.44 to 157.36] and 225.43 microm (95% CI, 224.10 to 226.74) respectively. After controlling for age, gender, race, parental monthly income, axial length, birth weight, and birth length, each 3.1 kg/m2 (standard deviation) increase in BMI was associated with a 2.55-microm (95% CI, 1.21 to 3.89; p < 0.001) larger retinal venular caliber. In multivariable analysis, greater weight was also significantly associated with larger retinal venular caliber. BMI and weight were not associated with retinal arteriolar caliber. Height was not significantly associated with retinal arteriolar or venular caliber. DISCUSSION: Greater BMI and weight are associated with larger retinal venular caliber in healthy children.

Arterioles↗
PubMed2007

Astigmatism in 12-year-old Australian children: comparisons with a 6-year-old population.

PURPOSE: To study the distributions of refractive (RA), corneal (CA), and internal astigmatism (IA) in 12-year-old Australian children and to explore differences from previous findings in 6-year-old children. METHODS: Eligible year 7 students (2353/3144 [75.3%], median age, 12 years) from a random cluster sample of 21 high schools in Sydney, Australia, were examined by keratometry, cycloplegic autorefraction, and review of questionnaire data. RESULTS: Prevalence rates of RA, CA, and IA > or =1.0 D in right eyes were 6.7% (95% confidence interval [CI], 5.0-8.4), 26.6% (CI, 22.1-31.1), and 26.5% (CI, 22.9-30.0), respectively. RA was predominantly with-the-rule (WTR; 40.4%, CI, 32.6 to 48.2) and against-the-rule (ATR; 43.6%, CI, 35.7-51.5), CA was WTR (88.8%, CI, 86.3-91.3), and IA was ATR (90.2%, CI, 87.8-92.6). The girls had significantly greater CA and IA prevalence, with greater ATR astigmatism and lower oblique IA than did the boys. The European white-Australian children had lower CA prevalence than did the East Asian-Australian children and higher IA prevalence than did the South Asian-Australian children. Ethnic differences in RA prevalence were not significant, when adjusted for confounders. RA was more frequently ATR in European white than in other ethnic groups. Compensation between CA and IA reduced the magnitude of RA. Comparison with the data on 6-year-old children revealed minimal differences for all astigmatic components. CONCLUSIONS: There was a relatively low prevalence of RA, due to compensation between CA and IA. The minimal differences in all components of astigmatism between the two age cohorts suggest that astigmatism is stable between ages 6 and 12 years, although this conclusion needs to be confirmed in longitudinal studies.

Adolescent↗
PubMed2007

Measurement of retinal vascular caliber: issues and alternatives to using the arteriole to venule ratio.

PURPOSE: The arteriole to venule ratio (AVR) is widely used in studies of the associations of retinal microvascular disease with systemic and ocular outcomes. This is a discussion of the limitations of AVR; a comparison of its predictive information with that of its components, arteriolar and venular caliber; and a description of a suggested alternative method of modeling arteriolar and venular calibers directly. METHODS: Data from the population-based Blue Mountains Eye Study were used to compare the predictive information in models using AVR with models using arteriolar and venular calibers directly. Determination was made of how the apparent relationship between vessel caliber and two systemic outcomes (blood pressure [BP] and white blood cell count [WBC]) was influenced by the choice of regression model. These findings were interpreted with reference to the known biological relationship among vessel calibers, BP, and WBC. RESULTS: Models using arteriolar and venular calibers directly had more predictive information than models using AVR. The apparent relationship of vessel caliber to BP and WBC differed substantially, depending on the model chosen. For example, after adjustment for age, sex, and other covariates, decreasing venular caliber was associated with higher systolic BP when modeled separately, but was associated with lower systolic BP when modeled simultaneously with arteriolar caliber. CONCLUSIONS: The findings suggest AVR provides less information with regards to predicting systemic outcomes than its two components. Modeling arteriolar and venular calibers separately could be biased by confounding, while modeling both simultaneously appears to provide unbiased, biologically plausible results. The use of this approach is recommended in future research relating retinal vascular caliber to systemic or ocular outcomes.

Aged↗
PubMed2006

Retinal vein occlusion and vascular mortality: pooled data analysis of 2 population-based cohorts.

PURPOSE: To assess the association of retinal vein occlusion (RVO) with cardiovascular and cerebrovascular mortality. DESIGN: Pooled data from 2 population-based cohort studies. PARTICIPANTS: At baseline, the Beaver Dam Eye Study (BDES) examined 4926 persons aged 43 to 86 years (from 1988-1990) and the Blue Mountains Eye Study (BMES) examined 3654 persons aged 49 to 97 years (from 1992 to 1994). METHODS: Retinal vein occlusion was assessed from retinal photographs. Vascular deaths were determined using either death certificates (BDES) or the Australian National Death Index (BMES). Cox regression analysis was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). MAIN OUTCOME MEASURE: Vascular (cardiovascular and cerebrovascular) mortality was determined. RESULTS: Of 8384 baseline participants, 96 (1.14%) had RVO at baseline (BDES, n = 38; BMES, n = 58). Over 12 years, 1312 (15.7%) died of cardiovascular-related conditions and 341 (4.1%) died of cerebrovascular-related conditions. Age-standardized vascular mortality rates were 26.0% and 5.3%, respectively, in persons with RVO and 17.1% and 4.5%, respectively, in those without RVO. After adjusting for age, gender, body mass index, hypertension, diabetes, smoking, glaucoma, and study site, RVO was not associated with cardiovascular-related mortality (HR, 1.2; 95% CI, 0.8-1.8) or cerebrovascular-related mortality (HR, 0.9; 95% CI, 0.4-2.1) among participants of all ages. However, in persons aged less than 70 years, baseline RVO was associated with higher cardiovascular mortality (combined BDES and BMES: HR, 2.5; 95% CI, 1.2-5.2; BDES: HR, 2.5; 95% CI, 0.9-6.9; BMES: HR, 2.1; 95% CI, 0.7-6.8). CONCLUSIONS: Retinal vein occlusion in persons aged 43 to 69 years may signal a doubling of the risk of cardiovascular mortality.

Adult↗
PubMed2006

Association between circulating white blood cell count and long-term incidence of age-related macular degeneration: the Blue Mountains Eye Study.

Inflammatory processes are implicated in the development and progression of age-related macular degeneration (AMD). However, there are limited data on longitudinal associations between systemic markers of inflammation and AMD. The authors examined the prospective relation between the circulating white blood cell (WBC) count and early and late AMD in a population-based cohort of 3,654 participants, aged 49-97 years, in the Blue Mountains region, Australia. The main outcome of interest was the 10-year incidence of early and late AMD among individuals free from corresponding disease at the baseline (1992-1994). An elevated baseline WBC count was associated with early AMD incidence, independent of smoking and other major confounders. The multivariable relative risk comparing tertile 3 of WBC count (>6.7 x 10(9) cells/liter) with tertile 1 (</=5.5 x 10(9) cells/liter) was 1.85 (95% confidence interval: 1.33, 2.58). The association between WBC count and early AMD was present consistently in analyses of different early AMD lesions, including incident pigmentary abnormalities and soft indistinct/reticular drusen. Moreover, this association persisted in subgroup analyses by gender and smoking. An elevated WBC count at baseline was not consistently associated with late AMD incidence. This study provides population-based evidence supporting a longitudinal association between the circulating WBC count, a widely available marker of inflammation, and incidence of early AMD.

Aged↗
PubMed2006

Prevalence and associations of enhanced retinal arteriolar light reflex: a new look at an old sign.

PURPOSE: To assess the prevalence, associated risk factors and prognosis (mortality) of the enhanced retinal arteriolar light reflex sign in an older Australian population. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Three thousand six hundred fifty-four participants (82.4% response) ages >/=49 years from Australia's Blue Mountains region. METHODS: Retinal photographs of participants were graded for presence and severity of the enhanced arteriolar light reflex sign by comparison with standard photographs. Associations with systemic factors (subject-specific) and ocular variables (eye-specific) were assessed by logistic regression. Mortality data were obtained using the Australian National Death Index. Hazard ratios were calculated using Cox regression. MAIN OUTCOME MEASURES: Prevalence of enhanced arteriolar light reflex and associations with demographic variables (age, gender), blood pressure, blood parameters, health risk behaviors, cataract, retinal vessel wall signs, retinopathy, and 10-year incident mortality. RESULTS: The enhanced arteriolar light reflex sign was found in 1053 participants (31.7%, including 28.8% graded as mild and 2.9% as marked). Prevalence decreased with age (36.0%, 37.7%, 28.0%, and 18.8% for age groups < 60, 60-69, 70-79 and > or = 80 years, respectively, P(trend)<0.0001); odds ratio (OR) 0.78; and 95% confidence interval (CI) 0.72 to 0.85 per decade. Persons with cataract were less likely to have mildly enhanced light reflex (OR, 0.74; CI 0.64-0.87). After multivariate adjustment, mildly enhanced light reflex was significantly associated with serum glucose (OR 1.11 per SD increase), total cholesterol (OR 1.11), low-density lipoprotein (OR 1.55), triglycerides (OR 1.11), platelets (OR 0.89), and body mass index (OR 1.12). Markedly enhanced light reflex was significantly associated with mean arterial blood pressure (OR 1.24), heavy alcohol consumption (OR 2.66, > or = 40 grams alcohol per day), and serum glucose (OR 1.16). Strong associations were demonstrated between presence of mildly enhanced light reflex and either arteriovenous nicking (OR 3.12) or retinopathy (OR 1.96). There was no association between mildly or markedly enhanced light reflex and either all-cause or vascular mortality. CONCLUSIONS: In this older population, the enhanced retinal arteriolar light reflex sign was a relatively common finding. Although some associations of this sign with vascular risk factors were found, only a marked level of enhanced light reflex was correlated with elevated blood pressure, but not with poor survival.

Aged↗
PubMed2006

Pain and falls in older people.

Pain and falling both affect substantial segments of the older population. Despite the presence of several plausible mechanisms for pain to contribute to falling, very few studies have investigated this relationship in older people. If pain is a falls risk factor, this represents a potentially important point of intervention for falls prevention. Falls are a major cause of disability and loss of independent living status in older people. We examined the relationship between pain, pain-related interference with activities and falls in a cross-sectional analysis of 3509 people aged 49 years or more in two postal code areas in New South Wales, Australia (the Blue Mountains Eye Study). We found that subjects reporting pain with moderate to severe level of pain-related interference with activities were more likely to report any falls or multiple falls in the past 12 months than subjects not reporting pain (adjusted prevalence ratios 1.42, p=0.0001 and 1.62, p=0.0156, respectively). We also found a significant trend in the association indicating an increasing likelihood of self-reported falls associated with increasing level of pain-related interference with activities. The association was stronger for multiple falls than for any falls. Excluding subjects with recent fractures did not alter the findings. Given the high prevalence and public health importance of both conditions, further investigation of this association in prospective studies is recommended.

Accidental Falls↗
PubMed2006

Positive association between plasma fibrinogen level and incident hypertension among men: population-based cohort study.

Elevated plasma fibrinogen is implicated in cardiovascular disease. However, it is not clear whether fibrinogen levels predict the development of hypertension. We examined the relationship between plasma fibrinogen level and hypertension in a population-based cohort study of 3654 participants (mean age: 61.5 years; range: 49 to 84 years) at the baseline examination (1992-1994) in the Blue Mountains region, west of Sydney, Australia, who were examined 5 years (1997-1999) later. Main outcomes of interest were prevalent hypertension (systolic blood pressure >or=140 mm Hg, diastolic blood pressure >or=90 mm Hg, or a combination of self-reported hypertension diagnosis and use of antihypertensive medications) at baseline (n=2212/3180) and 5-year incidence of hypertension among baseline normotensive individuals (n=361/637). Elevated plasma fibrinogen level was positively associated with prevalent hypertension both among men and women and positively associated with 5-year incident hypertension among men, independent of several cardiovascular risk factors. Multivariable odds ratio (95% CI) of 5-year incident hypertension comparing tertile 3 of plasma fibrinogen (>or=3.9 g/L) with tertile 1 (<or=3.2 g/L) was 1.95 (1.03 to 3.68; P trend=0.040). This prospective association, however, was not observed in women (odds ratio; 95% CI) comparing tertile 3 versus tertile 1 of plasma fibrinogen (1.00; 0.54 to 1.86; P trend=0.986). Subgroup analyses stratified by smoking, body mass index, diabetes, and blood pressure categories supported this male gender-specific pattern of association. These data provide prospective epidemiological evidence of an essential link between plasma fibrinogen level and incident hypertension among men but not among women, a finding consistent with that observed in the Atherosclerosis Risk in Communities Study.

Aged↗
PubMed2006

Cataract surgery and the 10-year incidence of age-related maculopathy: the Blue Mountains Eye Study.

PURPOSE: To assess the long-term (10-year) risk of late age-related maculopathy (ARM) in eyes that had previously undergone cataract surgery (before the baseline examination). DESIGN: Population-based cohort study. PARTICIPANTS: In the Blue Mountains Eye Study (BMES) cohort, 2335 of 3654 baseline participants > or =49 years old (75% of survivors) were reexamined after 5 years and 1952 (76% of survivors) were reexamined after 10 years. METHODS: At the baseline examination, nonphakic (aphakic or pseudophakic) eyes were identified at slit-lamp examination and confirmed at lens photographic grading. Side-by-side grading of baseline and follow-up stereoretinal photographs was performed using the Wisconsin ARM grading system. Eye-specific data were analyzed using Kaplan-Meier estimates and generalized estimating equation models, adjusting for correlation between the 2 eyes. MAIN OUTCOME MEASURES: Incident late ARM was defined if either neovascular ARM or geographic atrophy developed in eyes without either lesion at baseline. RESULTS: After excluding eyes with either late ARM lesion at baseline or that had missing photographs at either examination, 4763 eyes were considered at risk of incident late ARM, including 132 eyes that had cataract surgery before the baseline examination. Late ARM developed in 10 of 132 nonphakic eyes (7.6%) compared to 96 of 4631 phakic eyes (2.1%). After adjusting for baseline age, gender, smoking, and presence of early ARM lesions, nonphakic (cataract surgical) eyes had a 3-fold risk of developing late-stage ARM (odds ratio [OR], 3.3; 95% confidence interval [CI], 1.1-9.9) or neovascular ARM (OR, 3.4; 95% CI, 1.1-10.9) compared to phakic eyes. CONCLUSIONS: Our findings support the hypothesis that the long-term risk of developing late ARM is higher in cataract surgical eyes, consistent with findings from the Beaver Dam Eye Study.

Aged↗
PubMed2006

Sensory and cognitive association in older persons: findings from an older Australian population.

BACKGROUND: Explanations for associations found between sensory and cognitive function remain unclear. OBJECTIVE: To assess in an older Australian population: (1) the correlation between sensory and cognitive function across groups with a narrow age range; (2) any independent association between sensory and cognitive impairment. METHODS: We examined 3,509 non-institutionalised residents aged 50+ years in the second cross-sectional survey of the Blue Mountains Eye Study (1997-2000). Visual impairment was defined for best-corrected visual acuity (VA) < 6/12 in the better eye, moderate to severe hearing loss for hearing threshold > 40 dB (better ear), and likely cognitive impairment for Mini-Mental State Examination (MMSE) < 24 points. RESULTS: We found likely cognitive impairment in 3.3%, vision impairment in 2.7% and moderate to severe hearing loss in 10.5% of this population. Correlation between VA or hearing threshold and MMSE score increased with age. After adjusting for age, weak but significant correlation was evident in the normal ageing sample between vision and MMSE (r = 0.12 with vision items included and r = 0.11 with vision items excluded, both p < 0.0001), and between hearing thresholds and MMSE (r = -0.12, p < 0.0001). After adjusting for age, sex, education and history of stroke, persons with vision impairment had a lower mean MMSE score than those with normal vision, regardless of whether vision-related items were included (27.1 vs. 28.6, p < 0.001) or excluded (19.8 vs. 21.0, p < 0.001). Similarly, persons with moderate to severe hearing loss had a lower mean MMSE score than those without hearing loss (28.1 vs. 28.7, p < 0.001). Persons with likely cognitive impairment also had lower mean VA and higher mean hearing threshold than those without, after adjustment. CONCLUSIONS: We have documented an age-related correlation between sensory and cognitive function in a normal ageing sample. The association between sensory impairment and likely cognitive impairment remained significant after excluding vision-related MMSE items and adjusting for confounding factors. Our data suggest that age-related decline and the effect of visual impairment on the measurement of cognition only partly explain the association between sensory and cognitive impairments in older persons.

Age Factors↗
PubMed2006

Relation of age-related macular degeneration and cognitive impairment in an older population.

BACKGROUND: The aetiology of age-related macular degeneration (AMD) and cognitive impairment is poorly understood. A link between cognitive impairment and AMD has been proposed although only a weak association was found in population-based studies. PURPOSE: To assess cross-sectional associations between AMD and cognitive impairment in an older Australian population. METHODS: The Blue Mountains Eye Study examined 3,509 persons aged 49+ years during 1997-2000. AMD lesions were assessed from retinal photographs using the Wisconsin System. Mini-mental state examination (MMSE), demographics, lifestyle factors and medical history were collected at interview. MMSE score was categorised as high-normal (28-30), low-normal (24-27) and impaired (< 24). A modified MMSE excluded five vision related items and was dichotomised as normal (18-22) and impaired (0-17). Logistic regression was used to assess associations after adjusting for age, sex, visual impairment, stroke, current smoking status, hypertension, alcohol consumption and post-high-school qualification. RESULTS: Prevalence rates for late and early AMD were 1.5% (n = 50) and 8.3% (n = 273), respectively. Cognitive impairment was present in 18.0% in persons with late AMD and 8.4% with early AMD, compared to 2.6% in persons without AMD. After multivariate adjustment, late AMD was associated with low normal MMSE (odds ratio (OR): 2.2, 95% confidence interval (CI): 1.1-5.0) and cognitive impairment (OR: 3.7, CI: 1.3-10.6). Using the modified MMSE, the multivariate association between late AMD and cognitive impairment remained (OR: 2.2, CI: 1.0-5.0). No significant association was found between cognitive impairment and early AMD. CONCLUSIONS: We found a significant, cross-sectional association between late AMD and cognitive impairment in a sample of older Australians that appeared to be independent of visual impairment. The association was weaker but remained significant after excluding vision-related items from the MMSE.

Aged↗
PubMed2006

Factors associated with a previous diagnosis of strabismus in a population-based sample of 12-year-old Australian children.

PURPOSE: To describe the prevalence of strabismus and factors associated with its diagnosis in a representative sample of older Australian children. DESIGN: Cross-sectional, population-based study. METHODS: A representative stratified random cluster sample of 2353 children (aged 12 years) attending 21 secondary schools in Sydney, Australia was examined in 2004 to 2005 (response 75.3%). Cover testing was performed at near (30 cm) and distance (6 m); cycloplegic autorefraction, visual acuity, and stereoacuity were assessed. Previous strabismus diagnosis was obtained from parental questionnaires. RESULTS: Strabismus was evident in 64 children (2.7%); 21 (33%) had esotropia, 27 (42%) had exotropia, and 16 (25%) had microstrabismus. There were no gender (P = .2) or ethnicity (P = .6) associations. Previous diagnosis by an eye practitioner was noted in 27 (42%). This was related to hyperopia (P = .04), esotropia (P = .001), and amblyopia (P = .001). CONCLUSIONS: Strabismus was relatively infrequent in this Australian childhood sample. Its diagnosis was strongly related to presence of esotropia, hyperopia, and amblyopia.

Child↗
PubMed2006

Refractive error and patterns of spectacle use in 12-year-old Australian children.

PURPOSE: To document the prevalence of visual impairment resulting from refractive error and to describe patterns of spectacle use in a representative sample of 12-year-old Australian school children. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Two thousand three hundred fifty-three predominantly 12-year-old children examined from 2004 through 2005. METHODS: Logarithm of the minimum angle of resolution (logMAR) visual acuity (VA) was measured unaided and with spectacles if worn. Subjective refraction, cycloplegic autorefraction (with cyclopentolate), and detailed dilated fundus examination were performed. MAIN OUTCOME MEASURES: Myopia was defined as spherical equivalent (SE) refraction < or =-0.50 diopters (D), hyperopia as SE refraction > or =2.0 D, and astigmatism as cylinder > or =1.0 D. Uncorrected visual impairment was defined using unaided VA, and presenting visual impairment was defined using spectacle-corrected VA, if worn. Visual impairment was defined as VA <20/40 (<40 logMAR letters) for both better and worse eyes. Spectacle need was defined as uncorrected visual impairment in the better eye, improving by at least 2 lines with refraction, and undercorrection as presenting impairment in the better eye, improving by at least 2 lines with refraction. RESULTS: Uncorrected and presenting visual impairment in at least 1 eye because of refractive error was found in 10.4% and 3.7%, respectively. Spectacle use was reported by 448 children (19.0%); 204 (46.3%) had myopia, 48 (10.9%) had hyperopia, and 96 (21.8%) had astigmatism in at least 1 eye; 38.3% had no significant refractive error in either eye. Eight children were in need of spectacles and 37 children (8.3% of spectacle users) were undercorrected. Nonrefractive spectacle users were more likely to report eyestrain and headache or to have had learning difficulty at school (P<0.0001). CONCLUSIONS: This study documents a relatively low prevalence of undercorrected refractive error in a population of Australian children. Nonrefractive prescription of spectacles is common.

Adolescent↗
PubMed2006

Age-related macular degeneration and risk for stroke.

BACKGROUND: Age-related macular degeneration (AMD) affects 7 million persons 40 years of age and older in the United States. Risk factors for the disease are similar to those for stroke. OBJECTIVE: To determine what relationship, if any, exists between AMD and incident clinical stroke. DESIGN: Prospective cohort study. SETTING: The population-based Atherosclerosis Risk in Communities Study, which was conducted in Minnesota, Maryland, Mississippi, and North Carolina. PATIENTS: 10 405 persons between 49 and 73 years of age who had no history of stroke or coronary heart disease. MEASUREMENTS: Participants had retinal photographs taken between 1993 and 1995. A standardized protocol was used to evaluate the photographs for the presence of drusen and other signs of AMD. Incident stroke events were identified and validated by reviewing case records. RESULTS: There were 498 early-stage and 10 late-stage cases of AMD in the cohort (n = 508). Over a 10-year period, 241 persons had an incident stroke event. After adjusting for age, sex, ethnicity, and site, the authors found that persons with early-stage AMD had a higher cumulative incidence of stroke than those without the disease (4.08% vs. 2.14%). The presence of early-stage AMD was associated with a higher adjusted risk for stroke (hazard ratio, 1.87 [95% CI, 1.21 to 2.88]). Further adjustment for systolic blood pressure, diabetes, cigarette smoking, and use of antihypertensive medications did not substantially alter this association (hazard ratio, 1.85 [CI, 1.19 to 2.87]). The authors found that the association between early-stage AMD and stroke varied by study site and patient ethnicity. Multivariable-adjusted hazard ratios were 3.15 and 1.07 in samples of white patients in Minnesota and Maryland, respectively; 3.77 in a sample of African-American patients in Mississippi; and 0.33 in a sample of mostly white patients (91%) in North Carolina. No site included sufficient numbers of both African-American and white patients to determine whether ethnicity contributed to the observed differences by study site. LIMITATIONS: There were few cases of late-stage AMD, and the cohort assembly method prohibited full understanding of variation by ethnicity and site. CONCLUSION: Middle-aged persons with signs of early-stage AMD have a higher risk for stroke independent of traditional stroke risk factors.

Aged↗
PubMed2006

Retinal vessel signs and 10-year incident age-related maculopathy: the Blue Mountains Eye Study.

OBJECTIVE: To examine whether retinal vessel signs are independent predictors of the long-term development of age-related maculopathy (ARM). DESIGN: Prospective population-based cohort study. PARTICIPANTS: Blue Mountains Eye Study participants aged > or =49 years (n = 3654) were examined during 1992 through 1994; 2335 (75% of survivors) were reexamined after 5 years and 1952 (76% of survivors) were reexamined after 10 years. METHODS: Baseline focal arteriolar narrowing and arteriovenous (AV) nicking were assessed and vessel calibers were measured from retinal photographs. A side-by-side grading method was used to assess ARM incidence. Eye-specific data were analyzed using generalized estimating equation models, adjusting for age, gender, smoking, and blood pressure. MAIN OUTCOME MEASURES: Incident early ARM (soft indistinct or reticular drusen or combined soft distinct drusen and retinal pigment abnormality) was defined in eyes free of both early and late ARM at baseline. Incident late ARM (either geographic atrophy or neovascular macular degeneration) was defined in eyes free of these 2 lesions at baseline. RESULTS: Over a 10-year period, incident late ARM developed in 106/4745 eyes at risk of late ARM (2.2%). Eyes with mild (2.7%) or severe (4.6 %) AV nicking were more likely to develop late ARM than eyes without this sign (1.5%). The adjusted odds ratio (OR) was 1.4, 95% confidence interval (CI) 0.8 to 2.4 for mild and OR 2.6, 95% CI 1.2 to 5.5 for severe AV nicking. Eyes with focal narrowing were also more likely to develop late ARM (7.6% vs. 1.8%), adjusted OR 2.2, 95% CI 1.1 to 4.1. Incident early ARM developed in 398/4490 eyes at risk of early ARM (8.9%). Severe AV nicking, but not focal arteriolar narrowing, was associated with an increased long-term risk of early ARM (13.6% vs. 8.2%; OR 1.5; 95% CI 1.0-2.3). Neither arteriolar nor venular caliber was significantly associated with the incidence of either early or late ARM. CONCLUSIONS: These 10-year incidence data confirm our previous observation that structural retinal arteriolar changes may either contribute to ARM progression or share common pathologic pathways with ARM, independent of traditional vascular risk factors.

Aged↗