Causes and prevalence of visual impairment among adults in the United States.

OBJECTIVES: To estimate the cause-specific prevalence and distribution of blindness and low vision in the United States by age, race/ethnicity, and gender, and to estimate the change in these prevalence figures over the next 20 years. METHODS: Summary prevalence estimates of blindness (both according to the US definition of < or =6/60 [< or =20/200] best-corrected visual acuity in the better-seeing eye and the World Health Organization standard of < 6/120 [< 20/400]) and low vision (< 6/12 [< 20/40] best-corrected vision in the better-seeing eye) were prepared separately for black, Hispanic, and white persons in 5-year age intervals starting at 40 years. The estimated prevalences were based on recent population-based studies in the United States, Australia, and Europe. These estimates were applied to 2000 US Census data, and to projected US population figures for 2020, to estimate the number of Americans with visual impairment. Cause-specific prevalences of blindness and low vision were also estimated for the different racial/ethnic groups. RESULTS: Based on demographics from the 2000 US Census, an estimated 937 000 (0.78%) Americans older than 40 years were blind (US definition). An additional 2.4 million Americans (1.98%) had low vision. The leading cause of blindness among white persons was age-related macular degeneration (54.4% of the cases), while among black persons, cataract and glaucoma accounted for more than 60% of blindness. Cataract was the leading cause of low vision, responsible for approximately 50% of bilateral vision worse than 6/12 (20/40) among white, black, and Hispanic persons. The number of blind persons in the US is projected to increase by 70% to 1.6 million by 2020, with a similar rise projected for low vision. CONCLUSIONS: Blindness or low vision affects approximately 1 in 28 Americans older than 40 years. The specific causes of visual impairment, and especially blindness, vary greatly by race/ethnicity. The prevalence of visual disabilities will increase markedly during the next 20 years, owing largely to the aging of the US population.

Prevalence of cataract and pseudophakia/aphakia among adults in the United States.

OBJECTIVES:

To determine the prevalence of cataract and pseudophakia/aphakia in the United States and to project the expected change in these prevalence figures by 2020.

METHODS:

Summary prevalence estimates of cataract and of pseudophakia/aphakia were prepared separately for black, white, and Hispanic persons (for whom only cataract surgery data were available) in 5-year age intervals starting at 40 years for women and men. The estimates were based on a standardized definition of various types of cataract: cortical, greater than 25% of the lens involved; posterior subcapsular, present according to the grading system used in each study; and nuclear, greater than or equal to the penultimate grade in the system used. Data were collected from major population-based studies in the United States, and, where appropriate, Australia, Barbados, and Western Europe. The age-, gender-, and race/ethnicity-specific rates were applied to 2000 US Census data, and projected population figures for 2020, to obtain overall estimates.

RESULTS:

An estimated 20.5 million (17.2%) Americans older than 40 years have cataract in either eye, and 6.1 million (5.1%) have pseudophakia/aphakia. Women have a significantly (odds ratio = 1.37; 95% confidence interval, 1.26-1.50) higher age-adjusted prevalence of cataract than men in the United States. The total number of persons who have cataract is estimated to rise to 30.1 million by 2020; and for those who are expected to have pseudophakia/aphakia, to 9.5 million.

CONCLUSION:

The number of Americans affected by cataract and undergoing cataract surgery will dramatically increase over the next 20 years as the US population ages.

The prevalence of refractive errors among adults in the United States, Western Europe, and Australia.

OBJECTIVE:

To estimate the prevalence of refractive errors in persons 40 years and older.

METHODS:

Counts of persons with phakic eyes with and without spherical equivalent refractive error in the worse eye of +3 diopters (D) or greater, -1 D or less, and -5 D or less were obtained from population-based eye surveys in strata of gender, race/ethnicity, and 5-year age intervals. Pooled age-, gender-, and race/ethnicity-specific rates for each refractive error were applied to the corresponding stratum-specific US, Western European, and Australian populations (years 2000 and projected 2020).

RESULTS:

Six studies provided data from 29 281 persons. In the US, Western European, and Australian year 2000 populations 40 years or older, the estimated crude prevalence for hyperopia of +3 D or greater was 9.9%, 11.6%, and 5.8%, respectively (11.8 million, 21.6 million, and 0.47 million persons). For myopia of -1 D or less, the estimated crude prevalence was 25.4%, 26.6%, and 16.4% (30.4 million, 49.6 million, and 1.3 million persons), respectively, of whom 4.5%, 4.6%, and 2.8% (5.3 million, 8.5 million, and 0.23 million persons), respectively, had myopia of -5 D or less. Projected prevalence rates in 2020 were similar.

CONCLUSIONS:

Refractive errors affect approximately one third of persons 40 years or older in the United States and Western Europe, and one fifth of Australians in this age group.

Prevalence of open-angle glaucoma among adults in the United States.

OBJECTIVE:

To estimate the prevalence and distribution of open-angle glaucoma (OAG) in the United States by age, race/ethnicity, and gender.

METHODS:

Summary prevalence estimates of OAG were prepared separately for black, Hispanic, and white subjects in 5-year age intervals starting at 40 years. The estimated rates were based on a meta-analysis of recent population-based studies in the United States, Australia, and Europe. These rates were applied to 2000 US census data and to projected US population figures for 2020 to estimate the number of the US population with OAG.

RESULTS:

The overall prevalence of OAG in the US population 40 years and older is estimated to be 1.86% (95% confidence interval, 1.75%-1.96%), with 1.57 million white and 398 000 black persons affected. After applying race-, age-, and gender-specific rates to the US population as determined in the 2000 US census, we estimated that OAG affects 2.22 million US citizens. Owing to the rapidly aging population, the number with OAG will increase by 50% to 3.36 million in 2020. Black subjects had almost 3 times the age-adjusted prevalence of glaucoma than white subjects.

CONCLUSIONS:

Open-angle glaucoma affects more than 2 million individuals in the United States. Owing to the rapid aging of the US population, this number will increase to more than 3 million by 2020.

Quality of life and near vision impairment due to functional presbyopia among rural Chinese adults.

PURPOSE: To evaluate the impact of near-vision impairment on visual functioning and quality of life in a rural adult population in Shenyang, northern China. METHODS: A population-based, cross-sectional study was conducted among persons aged 40+ years, during which functional presbyopia (correctable presenting near vision < 20/50 [N8] at 40 cm) was assessed. Near-vision-related quality of life and spectacle usage questionnaires were administered by trained interviewers to determine the degree of self-rated difficulty with near tasks. RESULTS: A total of 1008 respondents (91.5% of 1102 eligible persons) were examined, and 776 (78%) of completed the questionnaires (mean age, 57.0 ± 10.2 years; 63.3% women). Near-vision spectacle wearers obtained their spectacles primarily from markets (74.5%) and optical shops (21.7%), and only 1.14% from eye clinics. Among 538 (69.3%) persons with functional presbyopia, self-rated overall (distance and near) vision was worse (P < 0.001) and difficulty with activities of daily living greater (P < 0.001) than among nonpresbyopes. Odds of reporting any difficulty with daily tasks remained higher (OR = 2.32; P < 0.001) for presbyopes after adjustment for age, sex, education and distance vision. Compared to persons without presbyopia, presbyopic persons were more likely to report diminished accomplishment due to vision (P = 0.01, adjusted for age, sex, education, and distance vision.) CONCLUSIONS: Difficulties with activities of daily living and resulting social impediments are common due to presbyopia in this setting. Most spectacle wearers with presbyopia in rural China obtain near correction from sources that do not provide comprehensive vision care.

Intraocular pressure, central corneal thickness, and glaucoma in chinese adults: the liwan eye study.

PURPOSE: To describe the distribution of central corneal thickness (CCT), intraocular pressure (IOP), and their determinants and association with glaucoma in Chinese adults.DESIGN: Population-based cross-sectional study.METHODS: Chinese adults aged 50 years and older were identified using cluster random sampling in Liwan District, Guangzhou. CCT (both optical [OCCT] and ultrasound [UCCT]), intraocular pressure (by Tonopen, IOP), refractive error (by autorefractor, RE), radius of corneal curvature (RCC), axial length (AL), and body mass index (BMI) were measured, and history of hypertension and diabetes (DM) was collected by questionnaire. Right eye data were analyzed.RESULTS: The mean values of OCCT, UCCT, and IOP were 512 ± 29.0 μm, 542 ± 31.4 μm, and 15.2 ± 3.1 mm Hg, respectively. In multiple regression models, CCT declined with age (P < .001) and increased with greater RCC (P < .001) and DM (P = .037). IOP was positively associated with greater CCT (P < .001), BMI (P < .001), and hypertension (P < .001). All 25 persons with open-angle glaucoma had IOP <21 mm Hg. CCT did not differ significantly between persons with and without open- or closed-angle glaucoma. Among 65 persons with ocular hypertension (IOP >97.5th percentile), CCT (555 ± 29 μm) was significantly (P = .01) higher than for normal persons.CONCLUSIONS: The distributions of CCT and IOP in this study are similar to that for other Chinese populations, though IOP was lower than for European populations, possibly due to lower BMI and blood pressure. Glaucoma with IOP <21 mm Hg is common in this population. We found no association between glaucoma and CCT, though power (0.3) for this analysis was low.

Proprioceptive acuity predicts muscle co-contraction of the tibalis anterior and gastrocnemius medialis in older adults’ dynamic postural control

Older adults use a different muscle strategy to cope with postural instability, in which they ‘co-contract’ the muscles around the ankle joint. It has been suggested that this is a compensatory response to age-related proprioceptive decline however this view has never been assessed directly. The current study investigated the association between proprioceptive acuity and muscle co-contraction in older adults. We compared muscle activity, by recording surface EMG from the bilateral tibalis anterior and gastrocnemius medialis muscles, in young (aged 18-34) and older adults (aged 65-82) during postural assessment on a fixed and sway-referenced surface at age-equivalent levels of sway. We performed correlations between muscle activity and proprioceptive acuity, which was assessed using an active contralateral matching task. Despite successfully inducing similar levels of sway in the two age groups, older adults still showed higher muscle co-contraction. A stepwise regression analysis showed that proprioceptive acuity measured using variable error was the best predictor of muscle co-contraction in older adults. However, despite suggestions from previous research, proprioceptive error and muscle co-contraction were negatively correlated in older adults, suggesting that better proprioceptive acuity predicts more co-contraction. Overall, these results suggest that although muscle co-contraction may be an age-specific strategy used by older adults, it is not to compensate for age-related proprioceptive deficits.

Root caries development in older adults- a prospective cohort study

Objectives: To identify factors associated with root caries development during a two year period in a population of independently living older adults. Methods: A prospective cohort study was carried out with 334 independently living volunteers aged 65 and older. At baseline (t0), each participant completed a questionnaire which recorded age, gender, medical history, fluoride exposure, oral and denture hygiene practices, smoking and alcohol consumption, diet information, and socio economic information. Clinical examinations were performed and stimulated saliva samples were collected. Patients were reviewed 12(t1) and 24(t2) months later to determine the root caries increment. Results: 307 adults were assessed at t1 and 280 were assessed at t2 with 83.8% of participants examined at 24 months. Incidence of root caries in this cohort was 17.4% at t1 and 21.6% at t2. The mean root caries increment was 0.43 (SD 1.45) surfaces at t1 and 0.70 (SD 1.86) surfaces at t2. Age >70 years, completing education at primary level, poor oral hygiene, xerostomia, coronal decay at baseline, higher root caries index at baseline and number of exposed root surfaces showed a statistically significant association (P < 0.05) with root caries development. Conclusion: Root caries is a substantive dental health problem for our older population. Root caries prevention strategies should be targeted at older adults who have poor plaque control and high levels of caries experience. In particular patients with xerostomia should be targeted with preventive measures.

Alpha-2 agonists for sedation of mechanically ventilated adults in intensive care units: a systematic review

BACKGROUND: Care of critically ill patients in intensive care units (ICUs) often requires potentially invasive or uncomfortable procedures, such as mechanical ventilation (MV). Sedation can alleviate pain and discomfort, provide protection from stressful or harmful events, prevent anxiety and promote sleep. Various sedative agents are available for use in ICUs. In the UK, the most commonly used sedatives are propofol (Diprivan(®), AstraZeneca), benzodiazepines [e.g. midazolam (Hypnovel(®), Roche) and lorazepam (Ativan(®), Pfizer)] and alpha-2 adrenergic receptor agonists [e.g. dexmedetomidine (Dexdor(®), Orion Corporation) and clonidine (Catapres(®), Boehringer Ingelheim)]. Sedative agents vary in onset/duration of effects and in their side effects. The pattern of sedation of alpha-2 agonists is quite different from that of other sedatives in that patients can be aroused readily and their cognitive performance on psychometric tests is usually preserved. Moreover, respiratory depression is less frequent after alpha-2 agonists than after other sedative agents.

OBJECTIVES: To conduct a systematic review to evaluate the comparative effects of alpha-2 agonists (dexmedetomidine and clonidine) and propofol or benzodiazepines (midazolam and lorazepam) in mechanically ventilated adults admitted to ICUs.

DATA SOURCES: We searched major electronic databases (e.g. MEDLINE without revisions, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE and Cochrane Central Register of Controlled Trials) from 1999 to 2014.

METHODS: Evidence was considered from randomised controlled trials (RCTs) comparing dexmedetomidine with clonidine or dexmedetomidine or clonidine with propofol or benzodiazepines such as midazolam, lorazepam and diazepam (Diazemuls(®), Actavis UK Limited). Primary outcomes included mortality, duration of MV, length of ICU stay and adverse events. One reviewer extracted data and assessed the risk of bias of included trials. A second reviewer cross-checked all the data extracted. Random-effects meta-analyses were used for data synthesis.

RESULTS: Eighteen RCTs (2489 adult patients) were included. One trial at unclear risk of bias compared dexmedetomidine with clonidine and found that target sedation was achieved in a higher number of patients treated with dexmedetomidine with lesser need for additional sedation. The remaining 17 trials compared dexmedetomidine with propofol or benzodiazepines (midazolam or lorazepam). Trials varied considerably with regard to clinical population, type of comparators, dose of sedative agents, outcome measures and length of follow-up. Overall, risk of bias was generally high or unclear. In particular, few trials blinded outcome assessors. Compared with propofol or benzodiazepines (midazolam or lorazepam), dexmedetomidine had no significant effects on mortality [risk ratio (RR) 1.03, 95% confidence interval (CI) 0.85 to 1.24, I (2) = 0%; p = 0.78]. Length of ICU stay (mean difference -1.26 days, 95% CI -1.96 to -0.55 days, I (2) = 31%; p = 0.0004) and time to extubation (mean difference -1.85 days, 95% CI -2.61 to -1.09 days, I (2) = 0%; p < 0.00001) were significantly shorter among patients who received dexmedetomidine. No difference in time to target sedation range was observed between sedative interventions (I (2) = 0%; p = 0.14). Dexmedetomidine was associated with a higher risk of bradycardia (RR 1.88, 95% CI 1.28 to 2.77, I (2) = 46%; p = 0.001).

LIMITATIONS: Trials varied considerably with regard to participants, type of comparators, dose of sedative agents, outcome measures and length of follow-up. Overall, risk of bias was generally high or unclear. In particular, few trials blinded assessors.

CONCLUSIONS: Evidence on the use of clonidine in ICUs is very limited. Dexmedetomidine may be effective in reducing ICU length of stay and time to extubation in critically ill ICU patients. Risk of bradycardia but not of overall mortality is higher among patients treated with dexmedetomidine. Well-designed RCTs are needed to assess the use of clonidine in ICUs and identify subgroups of patients that are more likely to benefit from the use of dexmedetomidine.

STUDY REGISTRATION: This study is registered as PROSPERO CRD42014014101.

FUNDING: The National Institute for Health Research Health Technology Assessment programme. The Health Services Research Unit is core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates.

Impaired orthostatic blood pressure recovery and cognitive performance at two-year follow up in older adults: The Irish Longitudinal Study on Ageing

Background: Prospective investigations of the association between impaired orthostatic blood pressure (BP) regulation and cognitive decline in older adults are limited, and findings to-date have been mixed. The aim of this study was to determine whether impaired recovery of orthostatic BP was associated with change in cognitive function over a 2-year period, in a population based sample of community dwelling older adults. 

Methods: Data from the first two waves of the Irish Longitudinal Study on Ageing were analysed. Orthostatic BP was measured during a lying to standing orthostatic stress protocol at wave 1 using beat-to-beat digital plethysmography, and impaired recovery of BP at 40 s post stand was investigated. Cognitive function was assessed at wave 1 and wave 2 (2 years later) using the Mini-Mental State Exam (MMSE), verbal fluency and word recall tasks. 

Results: After adjustment for measured, potential confounders, and multiple imputation for missing data, the change in the number of errors between waves on the MMSE was 10 % higher [IRR (95 % CI) = 1.10 (0.96, 1.26)] in those with impaired recovery at 40 s. However, this was not statistically significant (p = 0.17). Impaired BP recovery was not associated with change in performance on any of the other cognitive measures. 

Conclusions: There was no clear evidence for an association between impaired recovery of orthostatic BP and change in cognition over a 2-year period in this nationally representative cohort of older adults. Longer follow-up and more detailed cognitive testing would be advantageous to further investigate the relationship between orthostatic BP and cognitive decline.

Increasing fruit and vegetable intake has no effect on retinal vessel caliber in adults at high risk of developing cardiovascular disease

BACKGROUND AND AIM: Retinal vessel abnormalities are associated with cardiovascular disease (CVD) risk. To date, there are no trials investigating the effect of dietary factors on the retinal microvasculature. This study examined the dose response effect of fruit and vegetable (FV) intake on retinal vessel caliber in overweight adults at high CVD risk.

METHODS AND RESULTS: Following a 4 week washout period, participants were randomized to consume either 2 or 4 or 7 portions of FV daily for 12 weeks. Retinal vessel caliber was measured at baseline and post-intervention. A total of 62 participants completed the study. Self-reported FV intake indicated good compliance with the intervention, with serum concentrations of zeaxanthin and lutein increasing significantly across the groups in a dose-dependent manner (P for trend < 0.05). There were no significant changes in body composition, 24-h ambulatory blood pressure or fasting blood lipid profiles in response to the FV intervention. Increasing age was a significant determinant of wider retinal venules (P = 0.004) whereas baseline systolic blood pressure was a significant determinant of narrower retinal arterioles (P = 0.03). Overall, there was no evidence of any short-term dose-response effect of FV intake on retinal vessel caliber (CRAE (P = 0.92) or CRVE (P = 0.42)).

CONCLUSIONS: This study demonstrated no effect of increasing FV intake on retinal vessel caliber in overweight adults at high risk of developing primary CVD.

Biomarker responses to folic acid intervention in healthy adults: a meta-analysis of randomized controlled trials

BACKGROUND: The task of revising dietary folate recommendations for optimal health is complicated by a lack of data quantifying the biomarker response that reliably reflects a given folate intake.

OBJECTIVE: We conducted a dose-response meta-analysis in healthy adults to quantify the typical response of recognized folate biomarkers to a change in folic acid intake.

DESIGN: Electronic and bibliographic searches identified 19 randomized controlled trials that supplemented with folic acid and measured folate biomarkers before and after the intervention in apparently healthy adults aged ≥18 y. For each biomarker response, the regression coefficient (β) for individual studies and the overall pooled β were calculated by using random-effects meta-analysis.

RESULTS: Folate biomarkers (serum/plasma and red blood cell folate) increased in response to folic acid in a dose-response manner only up to an intake of 400 μg/d. Calculation of the overall pooled β for studies in the range of 50 to 400 μg/d indicated that a doubling of folic acid intake resulted in an increase in serum/plasma folate by 63% (71% for microbiological assay; 61% for nonmicrobiological assay) and red blood cell folate by 31% (irrespective of whether microbiological or other assay was used). Studies that used the microbiological assay indicated lower heterogeneity compared with studies using nonmicrobiological assays for determining serum/plasma (I(2) = 13.5% compared with I(2) = 77.2%) and red blood cell (I(2) = 45.9% compared with I(2) = 70.2%) folate.

CONCLUSIONS: Studies administering >400 μg folic acid/d show no dose-response relation and thus will not yield meaningful results for consideration when generating dietary folate recommendations. The calculated folate biomarker response to a given folic acid intake may be more robust with the use of a microbiological assay rather than alternative methods for blood folate measurement.

A Wii Bit of Fun: A Novel Platform to Deliver Effective Balance Training to Older Adults

BACKGROUND: Falls and fall-related injuries are symptomatic of an aging population. This study aimed to design, develop, and deliver a novel method of balance training, using an interactive game-based system to promote engagement, with the inclusion of older adults at both high and low risk of experiencing a fall.

STUDY DESIGN: Eighty-two older adults (65 years of age and older) were recruited from sheltered accommodation and local activity groups. Forty volunteers were randomly selected and received 5 weeks of balance game training (5 males, 35 females; mean, 77.18 ± 6.59 years), whereas the remaining control participants recorded levels of physical activity (20 males, 22 females; mean, 76.62 ± 7.28 years). The effect of balance game training was measured on levels of functional balance and balance confidence in individuals with and without quantifiable balance impairments.

RESULTS: Balance game training had a significant effect on levels of functional balance and balance confidence (P < 0.05). This was further demonstrated in participants who were deemed at high risk of falls. The overall pattern of results suggests the training program is effective and suitable for individuals at all levels of ability and may therefore play a role in reducing the risk of falls.

CONCLUSIONS: Commercial hardware can be modified to deliver engaging methods of effective balance assessment and training for the older population.

Risk indicators associated with root decay in independently living older adults

Objective: To determine the risk indicators associated with root caries experience in a cohort of independently living older adults in Ireland.
Methods: The data reported in the present study were obtained from a prospective longitudinal study conducted on the risk factors associated with root caries incidence in a cohort of independently living older adults (n=334). Each subject underwent an oral examination, performed by a single calibrated examiner, to determine the root caries index and other clinical variables. Questionnaires were used to collect data on oral hygiene habits, diet, smoking and alcohol habits and education level. A regression analysis with the outcome variable of root caries experience (no/yes) was conducted.
Results: A total of 334 older adults with a mean age of 69.1 years were examined. 53.3% had at least one filled or decayed root surface. The median root caries index was 3.13 (IQR 0.00, 13.92). The results from the multivariate regression analysis indicated that individuals with poor plaque control (OR 9.59, 95%CI 3.84-24.00), xerostomia (OR 18.49, 95%CI 2.00-172.80), two or more teeth with coronal decay (OR 4.50, 95% CI 2.02-10.02) and 37 or more exposed root surfaces (OR 5.48, 95% CI 2.49-12.01) were more likely to have been affected by root caries.
Conclusions: The prevalence of root caries was high in this cohort. This study suggests a correlation between root caries and the variables poor plaque control, xerostomia, coronal decay (≥2 teeth affected) and exposed root surfaces (≥37). The significance of these risk indicators and the resulting prediction model should be further evaluated in a prospective study of root caries incidence.
Clinical Significance: Identification of risk indicators for root caries in independently living older adults would facilitate dental practitioners to identify those who would benefit most from interventions aimed at prevention.