Global magnitude of visual impairment caused by uncorrected refractive errors in 2004

Estimates of the prevalence of visual impairment caused by uncorrected refractive errors in 2004 have been determined at regional and global levels for people aged 5 years and over from recent published and unpublished surveys. The estimates were based on the prevalence of visual acuity of less than 6/18 in the better eye with the currently available refractive correction that could be improved to equal to or better than 6/18 by refraction or pinhole. A total of 153 million people (range of uncertainty: 123 million to 184 million) are estimated to be visually impaired from uncorrected refractive errors, of whom eight million are blind. This cause of visual impairment has been overlooked in previous estimates that were based on best-corrected vision. Combined with the 161 million people visually impaired estimated in 2002 according to best-corrected vision, 314 million people are visually impaired from all causes: uncorrected refractive errors become the main cause of low vision and the second cause of blindness. Uncorrected refractive errors can hamper performance at school, reduce employability and productivity, and generally impair quality of life. Yet the correction of refractive errors with appropriate spectacles is among the most cost-effective interventions in eye health care. The results presented in this paper help to unearth a formerly hidden problem of public health dimensions and promote policy development and implementation, programmatic decision-making and corrective interventions, as well as stimulate research.     

南宁市学龄前儿童视力及屈光度发育现况

了解南宁市学龄前儿童的视力、屈光度发育状况,为儿童眼病预防措施的制定提供依据.方法 采用整群随机抽样方法,选取南宁市3~6岁儿童2 304名,使用标准对数视力表进行视力检测,自然瞳孔下用SureSightTM手持式自动验光仪测定屈光状况.结果 2 304名学龄前儿童的眼视力≥1.0的比例为30.0%,视力不良的总检出率为7.2%.视力不良检出率随年龄增长而下降(P<0.05).视力不良检出率在近视儿童中最高,轻度远视儿童中最低(P<0.01).散光度≥0.75,≥1.50,≥2.50 D组学龄前儿童患视力不良的风险分别是散光度<0.75 D组的3.217,7.744和12.892倍.弱视检出率为2.78%.结论 学龄前儿童视力不良检出率高,且随年龄的增长而降低,随散光度增加而增高.应及时矫正学龄前儿童散光,以预防视力不良的发生.     

Global cost of child survival: estimates from country-level validation

Objective

To cross-validate the global cost of scaling up child survival interventions to achieve the fourth Millennium Development Goal (MDG4) as estimated by the World Health Organization (WHO) in 2007 by using the latest country-provided data and new assumptions.

Methods

After the main cost categories for each country were identified, validation questionnaires were sent to 32 countries with high child mortality. Publicly available estimates for disease incidence, intervention coverage, prices and resources for individual-level and programme-level activities were validated against local data. Nine updates to the 2007 WHO model were generated using revised assumptions. Finally, estimates were extrapolated to 75 countries and combined with cost estimates for immunization and malaria programmes and for programmes for the prevention of mother-to-child transmission of the human immunodeficiency virus (HIV).

Findings

Twenty-six countries responded. Adjustments were largest for system- and programme-level data and smallest for patient data. Country-level validation caused a 53% increase in original cost estimates (i.e. 9 billion 2004 United States dollars [US$]) for 26 countries owing to revised system and programme assumptions, especially surrounding community health worker costs. The additional effect of updated population figures was small; updated epidemiologic figures increased costs by US$ 4 billion (+15%). New unit prices in the 26 countries that provided data increased estimates by US$ 4.3 billion (+16%). Extrapolation to 75 countries increased the original price estimate by US$ 33 billion (+80%) for 2010–2015.

Conclusion

Country-level validation had a significant effect on the cost estimate. Price adaptations and programme-related assumptions contributed substantially. An additional 74 billion US$ 2005 (representing a 12% increase in total health expenditure) would be needed between 2010 and 2015. Given resource constraints, countries will need to prioritize health activities within their national resource envelope.     

The performance of methods for correcting measurement error in case-control studies

BACKGROUND: It is generally agreed that adjustment for measurement error (when feasible) can substantially increase the validity of epidemiologic analyses. Although a broad variety of methods for measurement error correction has been developed, application in practice is rare. One reason may be that little is known about the robustness of these methods against violations of their restrictive assumptions. METHODS: We carried out a simulation study to assess the performance of two error correction methods (a regression calibration method and a semiparametric approach) as compared with standard analyses without measurement error correction in case-control studies with internal validation data. Performance was assessed over a wide range of model parameters including varying degrees of violations of assumptions. RESULTS: In nearly all the settings assessed, the semiparametric estimate performed better than all alternatives under investigation. The regression calibration method is sensitive to violations of the assumptions of nondifferential error and small error variance. CONCLUSIONS: The semiparametric method is a very robust method to correct for measurement error in case-control studies, but lack of functional software hinders widespread use. If the assumptions for the regression calibration method are fulfilled, application of this method, originally developed for cohort studies, in case-control studies may be a useful alternative that is easy to implement.     

屈光相对安全儿童青少年裸眼视力生长曲线研究

目的 分析3～18岁屈光相对安全范围儿童青少年裸眼视力分布,为研制不同年龄段儿童青少年裸眼视力的生长曲线和参考值范围、制定视力异常转诊界值提供参考.方法 通过整群抽样的方法,选取上海市9146名3～18岁儿童青少年进行裸眼视力、散瞳验光、裂隙灯等眼科检查,采用LMS法拟合屈光相对安全范围儿童青少年裸眼视力的百分位数和生...     

学龄前视力低常儿童屈光状况分析

目的分析3~6岁视力低常儿童的屈光状态分布,探讨不同屈光类型与弱视发生的关系。方法本文采用描述性研究,收集2014-2018年1 644名(3 288眼)3~6岁视力低常儿童,并进行视力检查和阿托品散瞳后验光检查。分析不同年龄段屈光状态、屈光参差分布、散光分布及弱视发生状况。结果各年龄组视力低常儿童屈光类型均以远视为主,在远视类型中又以复性远视散光比例最高,为60.04%。随年龄增长远视比例降低,近视比例明显上升。屈光参差发生率为14.05%,其发生率随年龄增加逐渐降低(χ^2=37.31,P<0.01)。屈光参差程度越高,高屈光参差患者发生率相对越低(χ^2=79.181,P<0.01)。各年龄组散光程度及散光轴向分布之间的差异有统计学意义(χ^2=95.919、150.79,P<0.01)。弱视的发生率为12.77%,双眼等效球镜度差值≥1D时容易引起屈光参差性弱视,并且弱视发生率随屈光参差程度增加而升高(χ^2=379.15,P<0.01)。结论学龄前视力低常儿童的屈光状态分布以远视为主,远视性屈光不正、散光、屈光参差等屈光异常更容易引起弱视的发生。     

Screening of primary school children for refractive error in South-South Nigeria

Background

Vision screening study in primary school children has not been done in Bayelsa State, South-South Nigeria. This study was therefore conducted to screen primary school children for refractive error in Bayelsa State and use the data to plan for an effective school Eye Health Program.

Methods

A cross sectional study on screening for refractive error in school children was carried out in Yenagoa Local Government Area of Bayelsa State in June 2009. A multistage sampling technique was used to select the study population (pupils aged 5–15 years). Visual acuity for each eye was assessed by an Ophthalmic nurse and Optometrist outside the classroom, at 6 meters distance. Those with visual acuity of 6/9 or less were presented with a pinhole and the test repeated. Improvement of visual acuity with pinhole was considered refractive error. Funduscopy was done inside a poorly lit classroom. Data was analyzed with EPI INFO version 6.

Results

A total of 1,242 (658 females and 584 males) Pupils were examined. About 97.7% of eyes had normal vision of 6/6 while 49 out of 56 eyes, with visual acuity of 6/9 or less, improved with pinhole. Twenty seven pupils had refractive error, giving a prevalence of 2.2%. Refractive error involved both eyes in 22 pupils (81.5%) with the 8–10 years age range having the highest proportion (40.7%) of cases followed by 11–13 years age range (37.0%).

Conclusion

The prevalence of refractive error in school children in Bayelsa State, South-South Nigeria was low.     

Quantitative assessment of color vision impairment in workers exposed to toluene

Color vision was examined by the Lanthony-D-15 desaturated test in two groups of workers occupationally exposed to toluene and in a control group. Biological parameters of toluene exposure were analyzed: toluene in air and in venous blood, orthocresol, and hippuric acid in urine after workshift. The first exposed group, Group E₁, comprised 41 workers (toluene exposure ranged from 11.30 to 49.30 ppm), and the second exposed group, Group E₂, comprised 32 workers (toluene exposure ranged from 66.00 to 250.00 ppm). The nonexposed group, Group NE, comprised 83 subjects. Each group was divided into two subgroups; alcohol consumers and nonconsumers. Color vision loss was expressed as a color confusion index (CCI) and as age and alcohol intake-adjusted color confusion index (AACCI). Significantly higher values of CCI and AACCI (both P < 0.0001) in Group E₂ in comparison to Group NE, and significantly higher CCI (P < 0.0001) and AACCI (P < 0.05) values in Group E₂ in comparison to Group E₁ were established. The significant difference in CCI value between alcohol consumers and nonconsumers was established only in Group NE (P < 0.05). In Group NE significant correlation was found between CCI value as a dependent and age and alcohol intake as independent cofactors (R² = 0.45; P = 0.0000). In Group E₂ significant correlation was established between CCI as a dependent factor and age, toluene in air, and alcohol intake (R² = 0.72; P = 0.0001), or between CCI as dependent and age, toluene in blood and alcohol intake as independent cofactors (R² = 0.68; P = 0.0002). In Group E₁ significant correlation was established only between CCI and age (P < 0.005). In Group E_2, AACCI value significantly correlated with toluene in air (P < 0.0001), toluene in blood (r < 0.0005), orthocresol (P < 0.005) and hippuric acid (P < 0.005) in urine after workshift. There were no differences between smokers and nonsmokers in CCI values in the examined groups. Results of this study indicate that toluene in exposed workers can impair color vision. The role of alcohol intake and age influence on color vision loss cannot be ignored in such workers. Am. J. Ind. Med. 33:297–304, 1998. © 1998 Wiley-Liss, Inc.     

Subclinical impairment of colour vision among workers exposed to styrene.

The effects of exposure to styrene were studied among 60 men aged 20 to 56 (mean 29.5) employed in shipbuilding. Exposure was due to the handling of glass reinforced polyester materials. The study was cross sectional and the workers were compared with a control group matched for age, social and occupational state, and ethnic origin. During the study, the mean atmospheric exposure to styrene was 24.3 ppm. Mean urinary elimination was 230 mg/g creatinine for mandelic acid and 57.4 mg/g creatinine for phenylglyoxylic acid. The Farnsworth 100 hue test showed no significant differences between the exposed and control groups for error scores. A significant difference was found, however, for the number of subjects with errors axis in the red-green, or blue-yellow ranges, or both, which was larger among the exposed workers (32/60 v 20/60 for the controls (p < 0.05)). Psychometric tests were also conducted, using the World Health Organisation (WHO) neurobehavioural core test battery. Of the seven tests it included, anomalies were only found for the aiming test. These results suggest that exposure to moderate styrene concentrations of the order of 25 ppm can lead to impairment of colour vision.     

Subclinical impairment of colour vision among workers exposed to styrene.

The effects of exposure to styrene were studied among 60 men aged 20 to 56 (mean 29.5) employed in shipbuilding. Exposure was due to the handling of glass reinforced polyester materials. The study was cross sectional and the workers were compared with a control group matched for age, social and occupational state, and ethnic origin. During the study, the mean atmospheric exposure to styrene was 24.3 ppm. Mean urinary elimination was 230 mg/g creatinine for mandelic acid and 57.4 mg/g creatinine for phenylglyoxylic acid. The Farnsworth 100 hue test showed no significant differences between the exposed and control groups for error scores. A significant difference was found, however, for the number of subjects with errors axis in the red-green, or blue-yellow ranges, or both, which was larger among the exposed workers (32/60 v 20/60 for the controls (p < 0.05)). Psychometric tests were also conducted, using the World Health Organisation (WHO) neurobehavioural core test battery. Of the seven tests it included, anomalies were only found for the aiming test. These results suggest that exposure to moderate styrene concentrations of the order of 25 ppm can lead to impairment of colour vision.     

Aetiology of childhood vision impairment, metropolitan Atlanta, 1991-93

Data from the population-based Metropolitan Atlanta Developmental Disabilities Surveillance Program (MADDSP) were used to describe the underlying causes of vision impairment (VI; corrected visual acuity in the better eye of 20/70 or worse) in young children (n = 228) in metropolitan Atlanta in 1991-93. Children with VI were identified through record review at multiple educational and medical sources. Children were categorised as having isolated VI or multiple disabilities (i.e. VI plus one or more of four additional developmental disabilities) and as having low vision (visual acuity 20/70-20/400) or blindness (visual acuity worse than 20/400). Medical conditions abstracted from MADDSP sources were reviewed to determine the probable aetiology of a child's VI. Aetiologies were assigned to one of three developmental time periods: prenatal, perinatal, or postnatal. Prenatal aetiologies were identified in 43% of the children; 38% of the prenatal aetiologies were genetic. Perinatal aetiologies were found in 27% of the children. Postnatal aetiologies were rare. Prenatal aetiologies were more common in children with isolated VI; perinatal and postnatal aetiologies were more common in children with multiple disabilities. Children with prenatal aetiologies tended to have less severe vision loss than did children with perinatal or postnatal aetiologies. The distribution varied by birthweight, but did not differ significantly by sex or race.     

莫廷视力筛查仪对264例婴幼儿视力屈光参数纵向监测的结果分析

目的 通过纵向跟踪婴幼儿的视觉发育状况,分析婴幼儿视觉发育规律及其影响因素,以指导婴幼儿眼保健工作,预防学龄期低视力的发生。方法 采用莫廷视力筛查仪对本院儿保门诊264例0~24个月婴幼儿进行视力纵向监测分析,详细记录球镜度、柱镜度数值及视觉发育相关影响因素。结果 视力监测结果显示:球镜度的值、柱镜度的绝对值随年龄的增长逐渐变小(趋于0),视力越接近正常范围。结论 婴幼儿视觉的发育在2岁内呈动态变化趋势,早期的眼保健指导和相应的干预措施可以使婴幼儿视力的发育沿着遗传优势所决定的轨道发展。