Review of recent surveys on blindness and visual impairment in Latin America

Risk Factors for Diabetic Retinopathy in Latin America (Mexico) and the World: A Systematic Review and Meta-Analysis

Diabetic retinopathy (DR) is one of the main complications of diabetes, and the management of the main control parameters explains only an 11% reduction in the risk of progressing to DR, leaving 89% to be explained by other factors or correlations between the usual factors that are currently unknown. The objective of this systematic review and meta-analysis is to evaluate the similarities and differences between the possible risk factors for developing DR when comparing the world to Latin American populations. The search was performed first for Latin American (LA) populations and a second search for non-Latin American (Non-LA) populations. Using the PRISMA guidelines, five articles were found to be relevant for each of the groups. The patients who had elevated systolic blood pressure (SBP) developed DR more frequently than the patients without retinopathy (Z = 2.1, p = 0.03), an effect measured in the population at a global level (GL), behavior that becomes not significant when the LA and non-LA populations are grouped separately; relevant to this is that the diagnosis of hypertension (HBP) grouped globally and stratified does not present a risk factor for DR (Z = 0.79, p = 0.42). This indicates that SBP is a risk factor for the world population and that, by separating it into different regions, the omission could cause it not to be considered a possible risk factor. In conclusion, the relationship between the increase in DR associated with the risk factors present in different populations, the limited research conducted in Latin America, and the cultural, social, economic, and genetic differences makes for a complex condition, which reflects the necessity of researching in a more integrated way.

National sex- and age-specific burden of blindness and vision impairment by cause in Mexico in 2019: a secondary analysis of the Global Burden of Disease Study 2019

Background

Reliable national estimations for blindness and vision impairment are fundamental to assessing their burden and developing public health policies. However, no comprehensive analysis is available for Mexico. Therefore, in this observational study we describe the national burden of blindness and vision loss by cause and severity during 2019.

Methods

Using public data from the Global Burden of Disease (GBD) study 2019, we present national prevalence and years lived with disability (YLDs) counts and crude and age-standardized rates (per 100,000 people) of total, severity- and cause-specific blindness and vision impairment with 95% uncertainty intervals (UIs) by sex and age group.

Findings

In Mexico, the burden of blindness and vision impairment was estimated at 11.01 million (95% UI, 9.25-13.11) prevalent cases and 384.96 thousand (259.57-544.24) YLDs during 2019. Uncorrected presbyopia caused the highest burden (6.06 million cases, 4.36-8.08), whereas severe vision loss and blindness affected 619.40 thousand (539.40-717.73) and 513.84 thousand (450.59-570.98) people, respectively. Near vision loss and refraction disorders caused 78.7% of the cases, whereas neonatal disorders and age-related macular degeneration were among the least frequent. Refraction disorders were the main cause of moderate and severe vision loss (61.44 and 35.43%), and cataracts were the second most frequent cause of blindness (26.73%). Females suffered an overall higher burden of blindness and vision impairment (54.99% and 52.85% of the total cases and YLDs), and people >50 years of age suffered the highest burden, with people between 70 and 74 years being the most affected.

Interpretation

Vision loss represents a public health problem in Mexico, with women and older people being the most affected. Although the causes of vision loss contribute differentially to the severity of visual impairment, most of the impairment is avoidable. Consequently, a concerted effort at different levels is needed to alleviate this burden.

Funding

This study received no funding.

Trends in the Prevalence of Blindness and Correlation With Health Status in Korean Adults: A 10-Year Nationwide Population-Based Study

BACKGROUND

Contemporary data on vision impairment form an important basis for public health policies. However, most data on the clinical epidemiology of blindness are limited by small sample sizes and focused not on systemic conditions but ophthalmic diseases only. In this study, we examined the ten-year trends of blindness prevalence and its correlation with systemic health status in Korean adults.

METHODS

This study investigated 10,000,000 participants randomly extracted from the entire Korean population (aged ≥ 20 years) who underwent a National Health Insurance Service health checkup between 2009 and 2018. Participants with blindness, defined as visual acuity in the better-seeing eye of ≤ 20/200, were identified. The prevalence of blindness was assessed, and the systemic health status was compared between participants with blindness and without blindness.

RESULTS

The mean prevalence of blindness was 0.473% (47,115 blindness cases) and tended to decrease over ten years (0.586% in 2009 and 0.348% in 2018; P < 0.001). The following factors were significantly associated with blindness: female sex, underweight (body mass index < 18.5), high serum creatinine (> 1.5 mg/dL), and bilateral hearing loss. In addition, except for those aged 30-39 and 40-49 years, high fasting glucose (≥ 126 mg/dL) and low hemoglobin (male: < 12 g/dL, female: < 10 g/dL) were significantly correlated with prevalent blindness.

CONCLUSION

Our ten-year Korean nationwide population-based study suggested a gradual decrease in the prevalence of blindness and its association with specific systemic health status. These conditions might be the cause or consequence of blindness and can be used as a reference for the prevention and/or rehabilitation of blindness to establish public health policies.

Prevalence and predictors of vision impairment among older adults in India: evidence from LASI, 2017-18

BACKGROUND

Older adults experience a natural decline in health, physical and cognitive functionality, and vision impairment (VI) is one among them and has become an increasing health concern worldwide. The present study assessed the association of chronic morbidities such as diabetes, hypertension, stroke, heart diseases and various socioeconomic factors with VI among older Indian adults.

METHODS

Data for this study were derived from the nationally-representative Longitudinal Ageing Study in India (LASI), wave-1 (2017-18). VI was assessed using the cut-off of visual acuity worse than 20/80, and additional analysis was carried out using the definition of VI with a cut-off of visual acuity worse than 20/63. Descriptive statistics along with cross-tabulation were presented in the study. Proportion test was used to evaluate the significance level for sex differentials in VI among older adults. Additionally, multivariable logistic regression analysis was conducted to explore the factors associated with VI among older adults.

RESULTS

About 33.8% of males and 40% of females suffered from VI in India (visual acuity worse than 20/80). Meghalaya (59.5%) had the highest prevalence for VI among older males followed by Arunachal Pradesh (58.4%) and Tripura (45.2%). Additionally, Arunachal Pradesh (77.4%) had the highest prevalence for VI among females followed by Meghalaya (68.8%) and Delhi (56.1%). Among the health factors, stroke [AOR: 1.20; CI: 1.03-1.53] and hypertension [AOR: 1.12; CI: 1.01-1.22] were the significant risk factors for VI among older adults. Additionally, being oldest old [AOR: 1.58; CI: 1.32-1.89] and divorced/separated/deserted/others [AOR: 1.42; CI: 1.08-1.87] were significantly associated with VI. Moreover, older adults with higher educational status [AOR: 0.42; CI: 0.34, 0.52], currently working [AOR: 0.77; CI: 0.67, 0.88], from urban areas [AOR: 0.86; CI: 0.76-0.98] and from western region [AOR: 0.55; CI: 0.48-0.64] had lower odds of VI in this study.

CONCLUSION

This study identified higher rates of VI among those who are diagnosed with hypertension or stroke, currently unmarried, socioeconomically poorer, less educated and urban resident older people that can inform strategies to engage high risk groups. The findings also suggest that specific interventions that promote active aging are required for those who are socioeconomically disadvantaged as well as visually impaired.

Association of vision impairment and blindness with socioeconomic status in adults 50 years and older from Alto Amazonas, Peru

OBJECTIVE

To determine the relationship between socioeconomic status (SES) and visual impairment (VI) or blindness in the rural Peruvian Amazon, hypothesizing that higher SES would have a protective effect on the odds of VI or blindness.

METHODS

In this cross-sectional study of 16 rural communities in the Peruvian Amazon, consenting adults aged ≥ 50 years were recruited from ~30 randomly selected households per village. Each household was administered a questionnaire and had a SES score constructed using principal components analysis. Blindness and VI were determined using a ministry of health 3-meter visual acuity card.

RESULTS

Overall, 207 adults aged ≥ 50 were eligible; 146 (70.5%) completed visual acuity screening and answered the questionnaire. Of those 146 participants who completed presenting visual acuity screening, 57 (39.0%, 95% CI 30.2-47.1) were classified as visually impaired and 6 (4.1%, 95% CI 0.9-7.3) as blind. Belonging to the highest SES tercile had a protective effect on VI or blindness (OR 0.29, 95% CI 0.09 to 0.91, p = 0.034), with a linear trend across decreasing levels of SES (p = 0.019). This observed effect remained significant regardless of how SES groups were assigned.

CONCLUSION

Belonging to a higher SES group resulted in a lower odds of VI or blindness compared to those in the lowest SES group. The observation of a dose response provides confidence in the observed association, but causality remains unclear. Blindness prevention programs could maximize impact by designing activities that specifically target people with lower SES.

Visual outcome and complications of small-incision cataract surgery

BACKGROUND AND OBJECTIVES

Small-incision cataract surgery (SICS) is a commonly performed procedure in developing countries. It does not require expensive machines and can be safely done in high-volume centers also yielding good visual outcomes in the majority of patients. The objective of our study was to assess visual outcomes after SICS conducted at a tertiary care center in South Gujarat and also assessment of various complications responsible for poor visual outcomes.

MATERIALS AND METHODS

Three hundred and fifteen cataract patients were included in the study. An assessment of intraoperative and postoperative complications was done. Postoperative visual acuity assessment was done and compared with preoperative visual acuity of the patient and factors responsible for poor visual outcomes were assessed. A follow-up examination was done on days 1, 3, 7, 14, and 30.

RESULTS

The mean age group of patients was 59.3 years. Females were slightly more (53.3%) in number as compared to males. The most common surgical complication encountered were striate keratopathy (6.35%), followed by iris damage (5.71%), posterior capsular rent (PCR) with vitreous loss (3.14%), hypotony (0.63%), intraocular lens decentration (0.63%), surgery-induced astigmatism (0.63%), choroidal detachment (0.32%), endophthalmitis (0.32%), and hyphema (0.32%). About 95.87% of patients had vision better than 6/18. Complications associated with poor visual outcome (<6/18) were PCR, endophthalmitis, choroidal detachment, and surgical-induced astigmatism.

CONCLUSIONS

Although SICS can have a significant chance of complications, good visual outcomes can be attained in the majority of patients.

Prevalence, causes, and impact of self-reported vision impairment among older people in China: Findings from the China health and retirement longitudinal study

This article investigated the prevalence, causes, and impact of self-reported vision impairment among older people in China. A total of 12,910 participants aged ⩾50 years were included in this study from China Health and Retirement Longitudinal Study (CHARLS) over the periods of 2011, 2013, and 2015. All data were reported by participants via a self-reported questionnaire. Distance vision was assessed by asking if they could see the face of a person on the other side of the street. Near vision was assessed by asking if they could read ordinary newspaper. Depressive symptoms were evaluated by 10-item Center for Epidemiological Studies Depression Scale. The analysis method included the χ2 – square distribution test and multiple regression analysis. This article first found that prevalence of self-reported vision impairment was much higher in rural than in urban areas; in urban areas, females had a greater chance of being affected than males, and for both sexes, it increases with increasing age. Second, some factors found are significantly associated with increased vision impairment rates, include increasing age, female gender, rural residents, elementary-level education, unmarried individuals, and non-agricultural occupations. Third, the leading cause of vision impairment was a refractive error and the most common causes of vision impairment include cataracts and glaucoma. Fourth, vision impairment was significantly associated with falls and depressive symptoms and has a negative effect on the quality of life of older Chinese. The article concluded that older people with self-reported vision impairment were relatively low and it is majorly caused by refractive error. Older people with distance vision impairment and near vision impairment were more likely to report falls and depressive symptoms in the future. In line with these findings, a couple of policy recommendations for further research were made.

Correlation between genetic and environmental risk factors for age-related macular degeneration in Brazilian patients

PURPOSE

To analyze the correlations between age-related macular degeneration (AMD) and genetic and environmental risk factors for in a Brazilian population.

DESIGN

Cross-sectional study with a control group.

METHODS

We collected data on 236 participants 50 years of age or older (141 with AMD and 95 controls without the disease). Data was obtained using a questionnaire and included information on demographics, ocular and medical history, family history of AMD, lifestyle, and smoking and drinking habits. Genetic evaluations included direct sequencing for the LOC387715 (rs10490924) variant, as well as PCR and enzymatic digestion for the CFH Y402H (rs1061170) and HTRA1 (rs11200638) variants. We performed a risk assessment of environmental risk factors and genetic variants associated with AMD and determined correlations between AMD and the data collected using multiple linear regression analysis.

RESULTS

Of the 141 AMD cases, 99 (70%) had advanced AMD in at least one eye (57% neovascular AMD and 13% geographic atrophy), and 42 (30%) had not-advanced AMD. Family history of AMD (OR: 6.58; 95% CI: 1.94-22.31), presence of cardiovascular disease (CVD) (OR: 2.39; 95% CI: 1.08-5.28), low physical activity level (OR: 1.39; 95% CI: 0.82-2.37), and high serum cholesterol (OR: 1.49; 95% CI: 0.84-2.65) were associated with an increased risk for AMD. There was a significant association between CVD and incidence of advanced AMD (OR: 2.29; 95% CI 0.81-6.44). The OR for the risk allele of the LOC387715 gene, the CFH gene and the HTRA1 gene were 2.21 (95% CI: 1.47-3.35), 2.27 (95% CI: 1.52-3.37), and 2.76 (95% CI: 1.89-4.03), respectively. In the stepwise multiple linear regression analyses, the HTRA1 and CFH risk alleles, family history of AMD, the LOC387715 risk allele, and CVD were associated with an increased risk of AMD for a total of 25.6% contribution to the AMD phenotype.

CONCLUSIONS

The analysis correlating environmental and genetic risk factors such as family history of AMD, and CVD and the variants of HTRA1, CFH, and LOC387715 genes showed an expressive contribution for the development of AMD among this admixed population.

Prevalence of blindness and its determinants in Bangladeshi adult population: results from a national cross-sectional survey

OBJECTIVE

The objective of this study was to determine the prevalence of blindness and its determinants in Bangladeshi adult population.

STUDY DESIGN

A cross-sectional population-based survey conducted at household level with national representation. Samples were drawn from the 2011 national census frame using a multistage stratified cluster sampling method.

SETTING AND PARTICIPANTS

The survey was done in urban and rural areas in 2013 using a probability proportionate to size sampling approach to locate participants from 72 primary sampling units. One man or one woman aged ≥40 years was randomly selected from their households to recruit 7200. In addition to sociodemographic data, information on medication for hypertension and diabetes was obtained. Blood pressure and capillary blood glucose were measured. Eyelids, cornea, lens, and retina were examined in addition to visual acuity and refraction testing.

PRIMARY OUTCOME MEASURES

The following definition was used to categorise subjects having (1) blindness: visual acuity <3/60, (2) low vision: ≥3/60 to <6/60 and (3) normal vision: ≥6/12 after best correction.

RESULTS

We could recruit 6391 (88.8%) people among whom 2955 (46.2%) were men. Among them, 1922 (30.1%) were from urban and 4469 (69.9%) were from rural areas. The mean age was 54.3 (SD 11.2) years. The age-standardised prevalence, after best correction, of blindness and low vision was 1.0% (95% CI 0.5% to 1.4%) and 12.1% (95% CI 10.5% to 13.8%), respectively. Multivariable logistic regression indicated that cataract, age-related macular degeneration and diabetic retinopathy were significantly associated with low vision and blindness after adjustment for age and sex. Population attributable risk of cataract for low vision and blindness was 79.6%.

CONCLUSIONS

Low vision and blindness are common problems in those aged 40 years or older. Extensive screening and eye care services are necessary for wider coverage engaging all tiers of the healthcare system especially focusing on cataract.

Primary glaucomas in adults: Epidemiology and public health-A review

Glaucoma is a mixed group of optic neuropathies that lead to irreversible visual field loss and blindness if left untreated. It is estimated that 3.5% of the global population aged 40 to 80 years have any glaucoma, being the primary open-angle and the primary angle-closure glaucoma the most prevalent forms. Although the age-standardised prevalence of blindness caused by glaucoma has decreased substantially over the last decades, population growth and ageing impose many challenges in preventing glaucoma-related morbidities on a global level. In addition, difficulties in diagnoses and treatment, along with its chronic and irreversible nature, urge the development and implementation of innovative approaches in confronting the disease. This manuscript reviews recent literature related to the epidemiology of primary glaucomas in adults, the risk factors attributed to the development of the disease, and discuss challenges and potential solutions from a public health perspective.

A global genetic epidemiological review of pseudoexfoliation syndrome

Pseudoexfoliation (PXF) syndrome is an important public health concern requiring individual population level analysis. Disease prevalence differs by geographic location and ethnicity, and has environmental, demographic, genetic, and molecular risk factors have been demonstrated. Epidemiological factors that have been associated with PXF include age, sex, environmental factors, and diet. Genetic and molecular components have also been identified that are associated with PXF. Underserved populations are often understudied within scientific research, including research about eye disease such as PXF, contributing to the persistence of health disparities within these populations. In each population, PXF needs may be different, and by having research that identifies individual population needs about PXF, the resources in that population can be more efficiently utilized. Otherwise, PXF intervention and care management based only on the broadest level of understanding may continue to exacerbate health disparities in populations disproportionally burdened by PXF.

Cataract as a Cause of Blindness and Vision Impairment in Latin America: Progress Made and Challenges Beyond 2020

PURPOSE

To provide an update of cataract as a cause of vision loss in Latin America and to analyze sex inequalities in cataract surgical coverage (CSC) and effective CSC (eCSC) in the region.

DESIGN

Population-based systematic review with longitudinal comparisons.

METHODS

The Latin American and Caribbean Health Sciences Literature (LILACS) and PubMed databased were searched for population-based studies reporting cataract blindness, surgical coverage, and outcomes published between January 2014 and December 2019. Information on the number of surgeries performed from the 2014-2016 period was obtained from ministries of health and was used for calculation of the cataract surgical rate (CSR). Sources such as Rapid Assessment of Avoidable Blindness (RAAB) and Rapid Assessment of Cataract Surgical Services data were reanalyzed to calculate sex inequality in CSC and eCSC by subtracting the rate in women from the rate in men.

RESULTS

Cataract was the cause of 29.8%-77.6% of cases of blindness in the included studies; the CSR improved in 10 countries. The CSC pinhole visual acuity of 3/60 varied from 24.1% in Peru to 97.1% in Argentina, and the median absolute gender inequality CSC pinhole visual acuity 3/60 was -0.7%. The eCSC pinhole visual acuity 3/60 varied from 14.8% in Guatemala to 92.1% in Argentina, and the median absolute gender inequality eCSC pinhole visual acuity 3/60 was -0.8%.

CONCLUSIONS

Cataract remains a leading cause of blindness in Latin America. Coverage is suboptimal, and surgical results are also below target levels in many countries. Incentives for a better distribution of human resources, adequate training of ophthalmologists, and the inclusion of vision services in universal health care coverage could reduce the burden of cataract in Latin America.

Causes of vision loss at China's largest blind school during a period of significant economic growth: 2008-2016

PURPOSE

To investigate the different causes of vision loss and school-based treatment regimens at Quanzhou Blind School (QBS), China's largest blind school, in 2008 and 2016.

METHODS

In 2008, 144 students received comprehensive eye examinations along with a complete family and ophthalmic history; in 2016, 125 students were examined. Vision loss was categorized into visual impairment and blindness classifications based on WHO guidelines. The etiologies of impairment and blindness in 2008 were compared to those in 2016 using the Fisher exact test. The prevalence and type of visual aids were also analyzed during this period.

RESULTS

The leading cause of visual impairment significantly shifted from corneal scarring in 2008 to retinopathy of prematurity (ROP) in 2016 (P = 0.020). Congenital cataracts remained the leading cause of blindness in 2008 and 2016. In 2016 there was a significant increase in the use of visual aids, with 63.2% of students using them in 2016 compared to 8.3% in 2008 (P = 0.0001).

CONCLUSIONS

Between 2008 and 2016, the leading cause of visual impairment shifted from corneal scarring to ROP, while congenital cataracts remained the leading cause of blindness.

Rapid assessment of avoidable blindness and diabetic retinopathy in individuals aged 50 years or older in Costa Rica

In the present study, we examined the causes and the prevalence of avoidable blindness and visual impairment, as well as the prevalence of diabetic retinopathy in individuals aged ≥50 years in Costa Rica, in order to provide baseline data for the initial planning and monitoring of ongoing blindness intervention programs. The assessment was based on the standardized methodology of the Rapid Assessment of Avoidable Blindness and Diabetic Retinopathy, a population-based survey for blindness and visual impairment. From 3,255 eligible subjects, 76.6% were examined. The adjusted prevalence of bilateral blindness [presenting visual acuity (VA) in the better eye of less than 3/60] was 1.7% (95% confidence interval, 1.2%–2.2%), with avoidable causes (treatable and preventable) accounting for 68.8% of cases. The main causes of blindness were cataract (52.1%), glaucoma (6.3%), and diabetic retinopathy (6.3%); these data were similar to those for other neighboring countries. Cataract surgical coverage (CSC) in the survey area was estimated as 88.9% for individuals with blindness (VA, <3/60), 76.6% for those with a VA of <6/60, and 60.3% for those with a VA of <6/18. The most common barriers against cataract surgery in individuals with a best-corrected VA of ≤6/60 included “need not felt” (48.8%) and “fear” (14.6%). Among individuals with a past history of cataract surgery, only 57.1% showed a “good” or “very good” outcome (VA, ≥6/18). Finally, 23.5% individuals with known or newly diagnosed diabetes showed retinopathy and/or maculopathy, with 6.2% exhibiting sight-threatening diabetic retinopathy (proliferative retinopathy, referable maculopathy, or both). Our findings indicate the need to overcome barriers against surgery for cataract, which is the main cause of avoidable blindness, to increase CSC, and to improve surgical outcomes. Moreover, improved methods for diabetic retinopathy screening can ensure prompt identification of patients with a risk of blindness. Glaucoma screening is also necessary for areas with a high prevalence.

Effect of Timing of Initial Cataract Surgery, Compliance to Amblyopia Therapy on Outcomes of Secondary Intraocular Lens Implantation in Chinese Children: A Retrospective Case Series

Purpose

As a secondary analysis, we reassess the association of initial congenital cataract surgery times, compliance to amblyopia therapy, and visual outcomes for a long-term follow-up in a secondary IOL implantation.

Methods

Retrospective review of records of all infants with congenital cataracts who underwent secondary IOL implantation in the Eye and ENT Hospital of Fudan University from January 1, 2001, to December 31, 2007, and the minimum follow-up period was 5 years. Multiple regression analysis was used and the possible confounding factors were also analyzed to assess the effect on visual outcome.

Results

A total of 110 patients (male: 59.1%) were included. The median (min-max) age at cataract extraction and IOL implantation was 7.5 (3.0-15.0) and 35.0 (22.0-184.0) months, respectively, and the average follow-up period was 99.3 ± 23.6 months. The median (min-max) BCVA at final follow-up was 0.20 (0.01-1.00). Compliance to amblyopia therapy was none, poor, and good in 21.8%, 24.5%, and 53.6%, respectively. Postoperative BCVA [logMAR, median (min-max) 0.70 (0.00-2.00)] linearly decreased with increasing cataract extraction time (per month) (β = 0.04, 95% CI: 0.03-0.06, p < 0.0001) in multivariable models with laterality and compliance to amblyopia therapy adjusted. Good compliance to amblyopia therapy was associated with better BCVA (logMAR) at last follow-up (β = -0.40, 95% CI = -0.53 to -0.27, p < 0.0001) with laterality, opacity type, and extraction time adjusted.

Conclusions

For Chinese infants with congenital cataract, an earlier primary congenital cataract surgery at an age of 3 to 15 months is associated with a better visual outcome. Good compliance to amblyopia therapy was also significant to visual outcome.

Prevalence and causes of low vision and blindness in an elderly population in Nepal: the Bhaktapur retina study

BACKGROUND

This study aims to explore the prevalence and causes of low vision and blindness focused on retinal disease in a population above 60 years in Nepal.

METHODS

Two thousand one hundred subjects were enrolled in a population-based cross-sectional study. History, presenting and best corrected visual acuity after subjective refraction, anterior and posterior segment examinations was obtained in detail.

RESULTS

Among the total subjects, 1860 (88.57%) had complete information. Age varies from 60 to 95 (mean age: 69.64 ± 7.31) years. Low vision and blindness in both eyes at presentation was found in 984 (52.90%, 95% confidence interval (CI): 50.60-55.19) and 36 (1.94%, 95% CI: 1.35-2.66) subjects respectively. After best correction, bilateral low vision and blindness was found in 426 (22.92%, 95% CI: 21.01-24.88), and 30 (1.61%, 95% CI: 0.10-2.30) subjects respectively. As compared to 60-69 years old, risk of visual impairment was four times higher (95% CI:3.26-5.58) in the 70-79 year olds and 14 times higher (95% CI: 9.72-19.73) in the age group 80 years and above. Major causes of bilateral low vision were cataract (68.07%), followed by retinal disorders (28.64%), and for blindness; retinal disorders (46.66%), followed by cataract (43.33%). Illiteracy was significantly associated with visual impairment.

CONCLUSION

Among the elderly population, prevalence of visual impairment was high. Refractive error, cataract and retinal disorders were the major cause of low vision. Screening the population at the age 60 years and above, focused on cataract and posterior segment diseases, providing glasses and timely referral can help reduce visual impairment.

Vision loss in Indigenous peoples of the world: a systematic review protocol

REVIEW OBJECTIVE/QUESTION

The objectives of this review are.

Long-term efficiency of cataract surgery with hydrophilic acrylic Ioflex intraocular lens

OBJECTIVE

To evaluate the efficiency of long-term cataract surgery using low-cost intraocular lens implantation in community campaigns.

METHODS

Fifty-eight randomly selected patients were evaluated four years after phacoemulsification and Ioflex intraocular lens implantation. Causes of low visual acuity related to the intraocular lens were evaluated, and treatment costs were calculated.

RESULTS

The mean age of patients was 72±10.2 years. Four years after surgery, 25 eyes (43.0%) had decreased visual acuity related to the intraocular lens: posterior capsule opacification was noted in 24 eyes (41.3%), and intraocular lens opacification was noted in one eye (1.7%). The total cost of the post-surgical complication treatments represented 6.3% of the initial budget of the entire surgical patient group.

CONCLUSIONS

The efficiency of cataract surgery with low-cost Ioflex intraocular lens implantation was significantly reduced in a long-term follow-up study because postoperative complications related to intraocular lenses emerged at higher rates than when the gold-standard treatment was used.

Field Testing Project to Pilot World Health Organization Eye Health Indicators in Latin America

PURPOSE

To develop and implement mechanisms to collect, report, and assess the World Health Organization (WHO) core eye health indicators in Chile, Honduras, Mexico, Peru, and Uruguay.

METHODS

Simple templates for a situational analysis (of data collection and reporting processes), a national data collection strategy, and a national work plan to implement the core eye health indicators were developed. Public and private sector representatives from the ministries of health (MOHs), national vision committees, and national societies of ophthalmology of each country used these tools with 2013 baseline data to improve their data collection processes and collected 2015 data. Final analysis and cross-validation were performed using intraocular lens sales data and last observation carried forward imputation.

RESULTS

Study tools were effectively implemented in all five countries and resulted in improved intersectoral stakeholder collaboration and communications, which improved the data collection and reporting processes. More complete and accurate data were reported by 2015 compared to the 2013 baseline.

CONCLUSIONS

Multisectoral stakeholders, including national professional societies and national vision committees, should collaborate with MOHs to improve the quality of data that are reported to WHO. This study involved these stakeholders in the data collection processes to better understand the realities of indicator implementation, better manage their expectations, and improve data quality. WHO Member States across the globe can feasibly adapt the study tools and methodologies to strengthen their data collection processes. Overall, the reliability and validity of the indicators is hampered with limitations that prevent fully accurate data from being collected.

Educational Differences in Health Among Middle-Aged and Older Adults in Brazil and Mexico

OBJECTIVE

This study examines educational differences in health conditions among middle-aged and older adults in Brazil and Mexico.

METHOD

Cross-sectional data from the 2013 Brazilian National Health Survey and the 2012 Mexican National Health and Nutrition Survey were used in the analyses. We used multivariate Poisson regressions to examine the relationship between educational level and prevalence of common health conditions (obesity, abdominal obesity, diabetes, hypertension, heart disease, and hearing and visual impairments).

RESULTS

Socioeconomic and sex inequalities persist in both countries. In general, low levels of education were associated with higher risk for having health conditions. However, men of lower education had a smaller risk of abdominal obesity and hypertension.

DISCUSSION

Brazil and Mexico have expanded public health actions aimed at improving health behaviors, diagnosis, and access to treatment of chronic conditions. However, important social disparities remain. Improving lifestyle behaviors, such as physical activity and dietary habits, could benefit both countries.

Refractive error study in young subjects: results from a rural area in Paraguay

AIM

To evaluate the distribution of refractive error in young subjects in a rural area of Paraguay in the context of an international cooperation campaign for the prevention of blindness.

METHODS

A sample of 1466 young subjects (ranging from 3 to 22 years old), with a mean age of 11.21±3.63 years old, were examined to assess their distance visual acuity (VA) and refractive error. The first screening examination performed by trained volunteers, included visual acuity testing, autokeratometry and non-cycloplegic autorefraction. Inclusion criteria for a second complete cycloplegic eye examination by an optometrist were VA <20/25 (0.10 logMAR or 0.8 decimal) and/or corneal astigmatism ≥1.50 D.

RESULTS

An uncorrected distance VA of 0 logMAR (1.0 decimal) was found in 89.2% of children. VA <20/25 and/or corneal astigmatism ≥1.50 D was found in 3.9% of children (n=57), with a prevalence of hyperopia of 5.2% (0.2% of the total) in this specific group. Furthermore, myopia (spherical equivalent ≤-0.5 D) was found in 37.7% of the refracted children (0.5% of the total). The prevalence of refractive astigmatism (cylinder ≤-1.50 D) was 15.8% (0.6% of the total). Visual impairment (VI) (0.05≤VA≤0.3) was found in 12/114 (0.4%) of the refracted eyes. Main causes for VI were refractive error (58%), retinal problems (17%, 2/12), albinism (17%, 2/12) and unknown (8%, 1/12).

CONCLUSION

A low prevalence of refractive error has been found in this rural area of Paraguay, with higher prevalence of myopia than of hyperopia.

The prevalence and causes of visual impairment and blindness among older adults in the city of Lodz, Poland

To investigate the prevalence and causes of visual impairment and blindness in a sample of Polish older adults. The study was designed in a cross-sectional and observational manner. Data concerning the vision status were assessed in 2214 eyes from 1107 subjects of European Caucasian origin; most of whom live in the city of Lodz, in central Poland. Visual impairment was defined as distance visual acuity <20/40 in the worse-seeing eye. Low vision was defined as best-corrected visual acuity (BCVA) <20/40 but >20/200 in better-seeing eye, and blindness was defined as BCVA ≤20/200 in both eyes (United States criteria). Visual impairment was found in 27.5% subjects in the worse-seeing eye. Multiple regression analysis showed that increasing age (OR 0.98, 95% CI 0.97-0.99) and female gender (OR 1.47, 95% CI 1.11-1.93) were independent risk factors. No association was found between visual impairment and socioeconomic status of subjects. Noncorrectable visual impairment was found in 7.0% of subjects, including 5.2% of subjects with unilateral and 1.8% of subjects with bilateral visual impairment. Low vision and blindness accounted for 1.3% and 0.5%, respectively, and were only associated with older age (OR 1.05, 95% CI 1.02-1.10). Retinal diseases represented the major cause of noncorrectable visual impairment and accounted for more than half of causes of blindness. Provision of appropriate refractive correction improves visual acuity in 75% subjects presenting with visual impairment. Retinal diseases are a major cause of noncorrectable visual impairment and blindness in this older population.

The first rapid assessment of avoidable blindness (RAAB) in Thailand

BACKGROUND

The majority of vision loss is preventable or treatable. Population surveys are crucial for planning, implementation, and monitoring policies and interventions to eliminate avoidable blindness and visual impairments. This is the first rapid assessment of avoidable blindness (RAAB) study in Thailand.

METHODS

A cross-sectional study of a population in Thailand age 50 years old or over aimed to assess the prevalence and causes of blindness and visual impairments. Using the Thailand National Census 2010 as the sampling frame, a stratified four-stage cluster sampling based on a probability proportional to size was conducted in 176 enumeration areas from 11 provinces. Participants received comprehensive eye examination by ophthalmologists.

RESULTS

The age and sex adjusted prevalence of blindness (presenting visual acuity (VA) <20/400), severe visual impairment (VA <20/200 but ≥20/400), and moderate visual impairment (VA <20/70 but ≥20/200) were 0.6% (95% CI: 0.5-0.8), 1.3% (95% CI: 1.0-1.6), 12.6% (95% CI: 10.8-14.5). There was no significant difference among the four regions of Thailand. Cataract was the main cause of vision loss accounted for 69.7% of blindness. Cataract surgical coverage in persons was 95.1% for cut off VA of 20/400. Refractive errors, diabetic retinopathy, glaucoma, and corneal opacities were responsible for 6.0%, 5.1%, 4.0%, and 2.0% of blindness respectively.

CONCLUSION

Thailand is on track to achieve the goal of VISION 2020. However, there is still much room for improvement. Policy refinements and innovative interventions are recommended to alleviate blindness and visual impairments especially regarding the backlog of blinding cataract, management of non-communicative, chronic, age-related eye diseases such as glaucoma, age-related macular degeneration, and diabetic retinopathy, prevention of childhood blindness, and establishment of a robust eye health information system.

Blindness Registers as Epidemiological Tools for Public Health Planning: A Case Study in Belize

For public eye health programs, blindness registers can be an important tool for informing service planning. This study examines how the Belize Council for the Visually Impaired (BCVI) used its blindness register data to drive several public health interventions. Cross-sectional analysis was performed for all active registrants (n=1194) to determine the distribution of causes of registration according to age, sex, and geographical district. Cataract was the leading cause of registration (39.6%), followed by glaucoma (20.8%), diabetic retinopathy (10.2%), and childhood blindness (9.4%). The distribution of the causes of registration was fairly similar between men and women and across the various districts. However, in Stann Creek, whose population is largely of African descent, glaucoma exceeded cataract. For most causes, the majority of registrants were registered at age 50 or older. Follow-up was conducted four years later. Several interventions had been initiated, most notably bolstering cataract surgical services and creating screening programs for glaucoma and diabetic retinopathy. The register itself was also improved to maximize its utility for future use. While standardized surveys may be the most appropriate method of estimating population-based measures such as prevalence or incidence, the blindness register is still a valuable source of data for public health planning.

Blindness and Visual Impairment among Adults in a Tertiary Eye Clinic, in Osogbo S W Nigeria

Background:

To plan and implement appropriate management of patients with blindness and visual impairment (VI) requires the knowledge of the common presenting causes.

Aim:

The aim of the following study is to determine the common causes of VI in adults and develop a template for eye care delivery.

Materials and Methods:

A retrospective descriptive analysis of subjects aged 17 years and above who attended LAUTECH Teaching Hospital eye clinic between October 2012 and March 2013. Information on demographic data, visual acuity, anterior and posterior segment examinations, and refraction were obtained from patients’ records. Statistical Package for the Social Sciences version 16. 2, USA was used for descriptive analysis. Chi-square, P values and confidence intervals (CI) were derived for statistical significance.

Results:

A total of 617 cases were reviewed including 306/617 (49.6%) males and 311/617 (50.4%) females. The frequently occurring age-groups were the 51-60 year 120/617 (19.4%) and the 61-70 year 115/617 (18.6%). The common causes of blindness and VI were cataract 225/617 (36.5%, CI: 32.7-40.3), glaucoma 124/617 (20.1%, CI: 16.93-23.25), refractive errors 119/617 (19.3%, CI: 16.17-22.4); trauma and cornea opacities 14/617 (6.1%) each. Refractive error 6/176 (3.4%) was a significant cause of blindness in this study. χ² = 33.68, P < 0.001. More females presented with refractive errors 79/311 (66.4%), while more males presented with trauma 32/306 (78.0%). χ² = 186.47, P < 0.001.

Conclusions:

The common causes of VI are avoidable. Planning for best practice methods, purchase of equipment/instruments, consumables, drugs, and manpower development is required. Establishment of low-cost cataract surgical and refractive services could reduce their incidence.

The cataract situation in Latin America: barriers to cataract surgery

PURPOSE

To provide an update of cataract data and barriers to cataract surgery in Latin America.

DESIGN

Review and longitudinal study.

METHODS

Cataract surgery rates and other related indicators that have been reported to the VISION 2020 Latin America program since 2005 were reviewed. PubMed was searched for publications concerning regional epidemiologic studies related to cataract, cataract surgery, barriers, outcomes, and cataract prevalence between January 2012 and October 2013 to obtain the most up-to-date data from 19 countries.

RESULTS

The weighted mean regional cataract surgery rate has increased by an impressive 70% since 2005, from 1562 to 2672 cataract surgeries per 1 million inhabitants. The weighted mean number of ophthalmologists per 1 million inhabitants in the region is approximately 62. Cataract surgery coverage varies widely in Latin America, from a meager 15% in El Salvador to a more satisfactory 77% in Uruguay. Five recent surveys indicate that lack of awareness of cataract and the surgery treatment option as well as the cost of the surgery are the main barriers to cataract surgery.

CONCLUSIONS

In spite of the increasing rates of cataract surgery and the more-than-adequate number of ophthalmologists in Latin America, it is not known how many ophthalmologists actually perform surgery. Coverage remains less than satisfactory across the region. Barriers to cataract surgery hinder the efforts of eye care programming. More comprehensive eye care programs and training centers are needed so that they can focus on reaching the underserved and unaware communities, increase surgery output and uptake, and improve outcomes.

Prevalence and risk factors of visual impairment and blindness in Korea: the Fourth Korea National Health and Nutrition Examination Survey in 2008-2010

PURPOSE

To describe the age, gender specific prevalence and risk factors of visual impairment and blindness in Korea.

METHODS

From 2008 to 2010, a total 14 924 randomly selected national representative participants of the Korea National Health and Nutrition Examination Survey underwent additional ophthalmologic examinations by the Korean Ophthalmologic Society. Best Corrected Distance Visual Acuity was measured using an international standard vision chart based on Snellen scale (Jin's vision chart). Independent risk factors for visual impairment were investigated using multivariate logistic regression analysis.

RESULTS

The overall prevalence of visual impairment (≤20/40) of adults 40 years and older was 4.1% (95% CI, 3.6-4.6) based on the better seeing eye. The overall prevalence of blindness (≤20/200) for adults 40 years and older was 0.2% (95% CI, 0.1-0.3). Risk indicators of visual impairment were increasing age, low education status, living in rural area, being unemployed, being without spouse and the absence of private health insurance. The visually impaired were more likely to have eye diseases compared with the normal subjects, and they were less likely to utilize eye care.

CONCLUSION

The prevalence of visual impairment was demonstrated to be higher while that of blindness was similar to previous population studies in Asia or U.S. Sociodemographic disparities are present in the prevalence of visual impairment and more targeted efforts are needed to promote vision screening in high risk groups.

Prevalence and outcomes of cataract surgery in adult rural Chinese populations of the Bai nationality in Dali: the Yunnan minority eye study

PURPOSE

To investigate the prevalence and visual acuity (VA) outcomes of cataract surgery in adults of the Bai Nationality populations in rural China.

METHODS

We conducted a population-based cross-sectional survey (from randomly selected block groups) of Chinese Bai Nationality aged ≥50 years in southwestern China. Presenting visual acuity (PVA), best corrected visual acuity (BCVA) were recorded and a detailed eye examination was carried out. For all aphakic and pseudophakic subjects identified, information on the date, setting, type, and complications of cataract surgery were recorded. In eyes with VA <20/63, the principal cause of visual impairment was identified.

RESULTS

Of 2133 (77.8% of 2742) subjects, 99 people (129 eyes) had undergone cataract surgery. The prevalence of cataract surgery was 4.6%. Surgical coverage among those with PVA <20/200 in both eyes because of cataract was 52.8%. Unoperated cataract was associated with older age. The main barrier to cataract surgery was lack of awareness and knowledge, cost, and fear. Among the 129 cataract-operated eyes, 22.5% had PVA of ≥20/32, 25.6% had PVA of 20/40 to 20/63, 23.3% had PVA <20/63 to 20/200, and 28.7% had PVA<20/200. With BCVA, the percentages were 42.6%, 23.3%, 10.9%, and 23.3%, respectively. Aphakia (odds ratio [OR], 8.49; P<0.001) and no education (OR, 10.18; P = 0.001) or less education (OR, 6.49; P = 0.014) were significantly associated with postoperative visual impairment defined by PVA, while aphakia (OR, 8.49; P<0.001) and female gender (OR, 4.19; P = 0.004) were significantly associated with postoperative visual impairment by BCVA. The main causes of postoperative visual impairment were refractive error, retinal disorders and glaucoma.

CONCLUSIONS

Half of those with bilateral visual impairment or blindness because of cataract remain in need of cataract surgery in Bai population. Surgical uptake and visual outcomes should be further improved in the future.

Elimination of avoidable blindness due to cataract: where do we prioritize and how should we monitor this decade?

Background:

In the final push toward the elimination of avoidable blindness, cataract occupies a position of eminence for the success of the Right to Sight initiative.

Aims:

Review existing situation and assess what monitoring indicators may be useful to chart progress towards attaining the goals of Vision 2020.

Settings and Design:

Review of published papers from low and middle income countries since 2000.

Materials and Methods:

Published population-based data on prevalence of cataract blindness/visual impairment were accessed and prevalence of cataract blindness/visual impairment computed, where not reported. Data on prevalence of cataract blindness, cataract surgical coverage at different visual acuity cut offs, surgical outcomes, and prevalence of cataract surgery were analyzed. Scatter plots were used to look at relationships of some variables, with Human Development Index (HDI) rank. Available data on Cataract Surgical Rate (CSR) was plotted against prevalence of cataract surgery reported from surveys.

Results:

Worse HDI Ranks were associated with higher prevalence of cataract blindness. Most studies showed that a significant proportion of the blind were covered by surgery, while a fifth showed that a significant proportion, were operated before they went blind. A good visual outcome after surgery was positively correlated with higher surgical coverage. CSR was positively correlated with cataract surgical coverage.

Conclusions:

Cataract surgical coverage is increasing in most countries at vision <3/60 and visual outcomes after cataract surgery are improving. Establishing population-based surveillance of cataract surgical need and performance is a strong monitoring tool and will help program planners immensely.

The Politics of Avoidable Blindness in Latin America—Surgery, Solidarity, and Solutions: The Case of Misión Milagro

Avoidable blindness, especially when caused by cataracts, is a disease primarily of the economically disadvantaged sectors of the population. With a focus on Latin America and the Caribbean, this paper focuses on the program Misión Milagro within its historical, political, and economic contexts. This initiative, led by the governments of Cuba and Venezuela, covers close to 35 countries across Latin America, the Caribbean, Asia, and Africa. It is well-known throughout Latin America as close to 2 million patients have undergone free screening, corrective surgery, and rehabilitation since its inception in 2004. Misión Milagro shows that implementation of a massive initiative to curb avoidable blindness caused by cataracts in a relatively short time is feasible. The program is also built upon a unique model of international cooperation, which stresses social objectives and solidarity rather than hegemonic international initiatives built on commercial relationships. It also provides elements that could be applied to other public health issues of global or national relevance, not only to other low-middle-income countries, but also to high-income countries such as Canada.

Activation of JNK signaling mediates connective tissue growth factor expression and scar formation in corneal wound healing

Connective Tissue Growth Factor (CTGF) and Transforming growth factor-β1 (TGF-β1) are key growth factors in regulating corneal scarring. Although CTGF was induced by TGF-β1 and mediated many of fibroproliferative effects of TGF-β1, the signaling pathway for CTGF production in corneal scarring remains to be clarified. In the present study, we firstly investigated the effects of c-Jun N-terminal kinase (JNK) on CTGF expression induce by TGF-β1 in Telomerase-immortalized human cornea stroma fibroblasts (THSF). Then, we created penetrating corneal wound model and determined the effect of JNK in the pathogenesis of corneal scarring. TGF-β1 activated MAPK pathways in THSF cells. JNK inhibitor significantly inhibited CTGF, fibronectin and collagen I expression induced by TGF-β1 in THSF. In corneal wound healing, the JNK inhibitor significantly inhibited CTGF expression, markedly improved the architecture of corneal stroma and reduced corneal scar formation, but did not have a measurable impact on corneal wound healing in vivo. Our results indicate that JNK mediates the expression of CTGF and corneal scarring in corneal wound healing, and might be considered as specific targets of drug therapy for corneal scarring.

Evaluation of dry eye signs and symptoms in patients with systemic sclerosis

BACKGROUND

One of the most frequent ocular features of systemic sclerosis (SSc) is dry eye disease (DED), which has been identified to occur in 37-79% of patients. Although several studies have found weak or no correlations between symptoms and signs of dry eye, symptoms are often the motivation for seeking eye care, and are therefore a critical outcome measure when assessing treatment effect. The aim of this study is to evaluate the impact of symptoms of dry eye on vision-related quality of life in patients with systemic sclerosis, and to investigate the relation between clinical tests and symptoms of dry eye in these patients.

METHODS

In this cross-sectional study, 45 consecutive patients with SSc were enrolled. For evaluation of the symptoms the "Ocular Surface Disease Index (OSDI)" questionnaire was applied to all patients. After that, all individuals were submitted to a full ophthalmic examination, including the following tests: tear break-up time, Schirmer I, rose bengal staining. Patients were then grouped into dry eye and non-dry eye groups with regard to the diagnosis of dry eye. Mann-Whitney test was used to compare continuous variables, whereas the Fisher exact test was used to compare categorical data between groups. Spearman's correlation test was used to analyze the correlations between clinical tests and OSDI scores. P values <0.05 were considered significant.

RESULTS

Dry eye disease was diagnosed in 22 patients (48.9%). Other ocular surface abnormalities found were: blepharitis (40% of the patients), pterygium (15.6%), pinguecula (82.2%), and superficial punctate keratitis (26.7%). Among the 45 patients, 29 patients (64.4%) had symptoms of ocular surface disease. The mean OSDI score was 26.8 ± 25.8 (SD). There were no statistically significant differences in OSDI scores between DED and non-DED patients. No substantive correlations were found between OSDI scores and TBUT, Schirmer I, or rose bengal staining score, and none of the observed correlations reached statistical significance.

CONCLUSION

Symptoms of dry eye have a moderate impact on vision-related quality of life in patients with systemic sclerosis and do not correlate well with clinical findings.

The global burden of cataract

PURPOSE OF REVIEW

To review the previous year's literature related to prevalence of blindness in general, blindness due to cataract, cataract surgical coverage (CSC) and cataract surgical rates (CSRs).

RECENT FINDINGS

Cataracts are the major cause of blindness and visual impairment in developing countries and contributes to more than 90% of the total disability adjusted life years. This review shows that coverage continues to be a problem in many countries, especially for the female population, those residing in rural areas and those who are illiterate. Although CSR is an indicator of the availability and acceptability of services, for measuring the impact of the program, we should look at combining CSR with CSC. This strategy would also enable us achieve our goal of eliminating avoidable blindness due to cataracts by the year 2020.

SUMMARY

Cataracts still continue- to be a major cause of blindness globally and with the rapidly aging population, it is a challenge to tackle. We need to plan a comprehensive strategy addressing issues related to availability, affordability, accessibility and acceptability of eye-care services.

Causes of blindness and visual impairment in Latin America

We review what is known in each country of the Latin American region with regards to blindness and visual impairment and make some comparisons to Hispanic populations in the United States. Prevalence of blindness varied from 1.1% in Argentina to 4.1% in Guatemala in people 50 years of age and older, with the major cause being cataract. Diabetic retinopathy and glaucoma are starting to make serious inroads, although epidemiological data are limited, and age-related macular degeneration is now a concern in some populations. Infectious diseases such as trachoma and onchocerciasis are quickly diminishing. Although progress has been made, retinopathy of prematurity remains the major cause of childhood blindness. If VISION 2020 is to succeed, many more epidemiological studies will be needed to set priorities, although some can be of the Rapid Assessment of Avoidable Blindness design. Developing the infrastructure for screening and treatment of ophthalmic disease in Latin America continues to be a challenge.

Prevalence of the refractive errors by age and gender: the Mashhad eye study of Iran

BACKGROUND

Refractive errors are a common eye problem. Considering the low number of population-based studies in Iran in this regard, we decided to determine the prevalence rates of myopia and hyperopia in a population in Mashhad, Iran.

DESIGN

Cross-sectional population-based study.

PARTICIPANTS

Random cluster sampling. Of 4453 selected individuals from the urban population of Mashhad, 70.4% participated.

METHODS

Refractive error was determined using manifest (age > 15 years) and cycloplegic refraction (age ≤ 15 years). Myopia was defined as a spherical equivalent of -0.5 diopter or worse. An spherical equivalent of +0.5 diopter or worse for non-cycloplegic refraction and an spherical equivalent of +2 diopter or worse for cycloplegic refraction was used to define hyperopia.

MAIN OUTCOME MEASURES

Prevalence of refractive errors.

RESULTS

The prevalence of myopia and hyperopia in individuals ≤ 15 years old was 3.64% (95% CI: 2.19-5.09) and 27.4% (95% CI: 23.72-31.09), respectively. The same measurements for subjects > 15 years of age was 22.36% (95% CI: 20.06-24.66) and 34.21% (95% CI: 31.57-36.85), respectively. Myopia was found to increase with age in individuals ≤ 15 years and decrease with age in individuals > 15 years of age. The rate of hyperopia showed a significant increase with age in individuals > 15 years. The prevalence of astigmatism was 25.64% (95% CI: 23.76-27.51).

CONCLUSIONS

In children and the elderly, hyperopia is the most prevalent refractive error. After hyperopia, astigmatism is also of importance in older ages. Age is the most important demographic factor associated with different types of refractive errors.

Protective effects and mechanism of tetramethylpyrazine against lens opacification induced by sodium selenite in rats

Tetramethylpyrazine (TMP), extracted from the Chinese herbal medicine Ligusticum wallichii franchat (chuan xiong in Chinese), is a potent anti-free radical and calcium antagonist. Correspondingly, two important hypotheses in the causation of cataracts are free radical toxicity and calcium ion overload. In this study we investigated the effect of TMP on lens opacification induced by sodium selenite in rats, addressing the potential of TMP eye drops to prevent and treat cataracts. Results showed that the extent of lens opacification in the untreated Normal Control group (NC group) was significantly less than that of selenite-injected untreated rats (MC group) on days 3, 5, 7 and 10 (p < 0.001), while TMP treated selenite-injected rats (TMP group) had less lens opacification than the MC group on days 3, 5, 7 and 10 (p < 0.05). Compared with the NC group, the MC group had significantly decreased activity of super-oxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) and significantly elevated malondialdehyde (MDA) and calcium ion content (p < 0.001). Compared with the MC group, the activity of (SOD), (GSH-PX) and (CAT) were significantly higher while (MDA) and calcium ion levels were significantly lower in the TMP group at all time points (p < 0.01). The findings demonstrate that the selenite-induced cataract rat models were successfully built and the TMP eye drops can delay lens opacification induced by sodium selenite in rats. The mechanism by which TMP preserves lens transparency from selenite treated animals is associated with the lenses' ability to maintain normal levels of activity of SOD, GSH-PX and CAT and normal concentrations of MDA and calcium ion.