Prevalence and causes of vision loss in Latin America and the Caribbean: 1990–2010

Colombian Ocular Diseases Epidemiology Study (CODES): Prevalence Incidence, and Sociodemographic Characterization of Vision Impairment (2015-2019), A Nationwide Study

PURPOSE

To describe the prevalence, incidence, and sociodemographic characterization of moderate to severe vision impairment (MSVI) and blindness in Colombia based on the National Health Registry Integrated Social Protection Information System (SISPRO) Database.

METHODS

We performed a nationwide population-based study using SISPRO and the International Classification of Diseases. Total and new cases were identified to calculate the prevalence and incidence per 100,000 inhabitants of MSVI and blindness between 2015 and 2019. Blindness was defined as a best-corrected visual acuity (BCVA) of less than 20/400 in the better-seeing eye. Meanwhile, MSVI is a BCVA from 20/70 to equal or better than 20/400 in the better-seeing eye. An ANOVA test was performed to identify age differences. A conditional autoregressive model was also employed to depict standardized morbidity rate maps.

RESULTS

From the 50 million inhabitants, the average prevalence and incidence of MSVI were 13.94 and 13.34 between 2015 and 2019, respectively, while for blindness, they were 4.03 and 3.53. Females accounted for most reported cases, and there was a notable shift towards individuals over 50 years (p < 0.001). Valle del Cauca was the region with the most cases reported and the greatest disease burden.

CONCLUSION

This is the first nationwide population-based study describing the prevalence, incidence, and sociodemographic characterization of blindness and MSVI in Colombia. In recent years, there has been an increased number of cases, prevalence, and incidence, with females over 50 particularly affected. This research provides insight into the country's vision impairment epidemiology landscape and contributes to formulating public health policies to improve eye health care.

Application of big data in ophthalmology

The advents of information technologies have led to the creation of ever-larger datasets. Also known as big data, these large datasets are characterized by its volume, variety, velocity, veracity, and value. More importantly, big data has the potential to expand traditional research capabilities, inform clinical practice based on real-world data, and improve the health system and service delivery. This review first identified the different sources of big data in ophthalmology, including electronic medical records, data registries, research consortia, administrative databases, and biobanks. Then, we provided an in-depth look at how big data analytics have been applied in ophthalmology for disease surveillance, and evaluation on disease associations, detection, management, and prognostication. Finally, we discussed the challenges involved in big data analytics, such as data suitability and quality, data security, and analytical methodologies.

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.

Governmental support for achieving "VISION 2020: the Right to Sight" in Iran: the cataract surgical rates

PURPOSE

The aim of this study was evaluate the effect of governmental support in the form of Health Transformation Plan (HTP) on increasing the cataract surgical rate.

METHODS

The number of cataract surgeries was collected from Iranian cataract surgery clinics during 2019. HTP was implemented in 2014. Forty-seven major and forty-five minor surgery centers were selected from all provinces. In each center, sampling was done from 2012, 2013, 2015, and 2016.

RESULTS

On average, 6202 and 7134 cataract surgery rate were performed before and after HTP, respectively. The cataract surgical rate rose by 15.03% after the HTP. After HTP, the proportion of cataract surgery increased by 21.32% in governmental centers and decreased by 17.56%, 24.45%, and 14.89% in private, insurance, and charity centers, respectively. The cataract surgical rate was 4093 and 6026 in the first economic quartile (the poorest), 3669 and 4595 in the second quartile, 5884 and 5928 in the third quartile, and 8427 and 9681 in the fourth quartile (the richest) before and after HTP, respectively. The highest growth in the cataract surgical rate was seen in the first quartile (47.24%) followed by the second (25.26%), fourth (14.88%), and third quartiles (0.74%).

CONCLUSION

The Health Transformation Plan has been successful in increasing the cataract surgical rate in the low-income group and identifying differences in the services as well as the economic groups within the population.

Reasons for delay in cataract surgery in patients with advanced cataracts during the COVID-19 pandemic

Purpose:

To analyze the reasons for delay in cataract surgery in patients with advanced cataracts during the COVID-19 pandemic.

Methods:

This was a prospective, cross-sectional, multicenter questionnaire study which included patients with mature cataract, nuclear sclerotic cataract grade IV, and cataracts with best corrected visual acuity (BCVA) <5/60, during the COVID-19 pandemic from December 2020 to April 2021. Reasons for delay in presentation to the hospital were analyzed.

Results:

One thousand four hundred seventy two patients were recruited with advanced cataracts. Absence of ophthalmic care nearby (44.2%), lack of awareness regarding elective surgeries (42.6%), lack of public transportation (37%), fear of contracting COVID-19 (23.4%), and waiting for outreach camps (20.4%) were found to be the reasons behind the delay in cataract surgery. 53.7% of the patients had worsening of defective vision and 55.3% of them had difficulty in carrying out activities of family living. 30.8% of the patients faced difficulty in commuting and 8.4% of the patients suffered a fall during this pandemic due to worsening of the visual acuity.

Conclusion:

The lockdown imposed during the pandemic has created a significant backlog of patients who are progressing to advanced cataracts due to lack of ophthalmic care nearby, lack of awareness regarding elective surgeries, lack of public transportation, and no outreach camps. Proactive measures to deal with this backlog are of utmost need to prevent blindness due to cataract.

Etiología de baja visión y ceguera en siete centros de referencia en Colombia entre los años 2012 a 2017

Introducción: la baja visión y la ceguera tienen alta prevalencia mundial, siendo categorías de discapacidad frecuentes en Colombia. Se requieren estudios que caractericen la etiología de las deficiencias visuales permanentes. Objetivo: Identificar y caracterizar las diferentes causas de baja visión y ceguera en siete centros de referencia para la población con discapacidad visual en Colombia, atendida entre los años 2012 a 2017 en seis ciudades capitales. Materiales y métodos: estudio retrospectivo, serie de casos, descriptivo y multicéntrico. Resultados: Se contó con una muestra de 879 registros de pacientes con discapacidad visual. El 70% (612/879) con baja visión y 30% (267/879) con ceguera. Para todos los grupos de edad es más prevalente la baja visión. La etiología más frecuente en pacientes con baja visión fue la degeneración macular asociada a la edad (DMAE) (24%, 144/612); en pacientes con ceguera fue el glaucoma (17%, 45/267). Discusión: Posiblemente en Colombia las causas de baja visión y ceguera van más allá de las cataratas, errores de refracción no corregidos y ceguera infecciosa. Conclusiones: las etiologías más frecuentes encontradas son condiciones oculares crónicas y diversas, que requieren intervenciones específicas para disminuir su prevalencia y prevenir casos de baja visión y ceguera.

Visual Impairment Prevalence, Causes, and Role of Healthcare Access: A Systematic Review and Meta-Analysis in Iran

Purpose

Healthcare access is one of the determinants of visual impairment (VI), as a public health problem. The objective of this study was to estimate VI prevalence, related causes, and its correlation with access to physicians in Iran.

Methods

: This systematic review and meta-analysis include observational studies published in Iran. PubMed, Web of Science, Scopus, Google Scholar, and local databases were systematically searched by using the MeSH headings. Data on the provincial distribution of physicians, as an index of access to healthcare, was retrieved. A random-effect meta-analysis was performed to assess.

Results

Eight articles were included. The pooled prevalence of blindness, low vision, and VI was 0.80% (95% CI: 0.61–0.99%), 2.92% (95% CI: 2.40–3.44%), and 5.57% (95% CI: 4.71–6.43%). Refractive errors were the most common causes of VI based on PVA with the pooled prevalence of 54.6% (95% CI: 43.4–65.8%). Based on BCVA, we found that the pooled prevalence of cataracts was 37.4% (95% CI: 29.5–45.3%) as the most common cause of VI. The results of metaregression showed that the greater number of general practitioners (GPs) (P value = 0.01) and pharmacists (P value = 0.024) per population were associated with a lower prevalence of blindness.

Conclusion

Some of the main causes of visual impairment in Iran are preventable. Access to healthcare services may lead to early diagnosis of preventable causes of VI. Further well-designed studies and national surveys should be conducted to provide accurate data from different regions of Iran.

Prevalence and causes of visual impairment among older persons living in low-income old age homes in Durban, South Africa

BACKGROUND

Visual impairment (VI) increases with age and has been reported to be more prevalent among older adults living in old age homes than in the general population.

AIM

To determine the prevalence and causes of VI among older adults living in low-income old age homes in Durban, South Africa.

SETTING

This study was conducted at low-income old age homes in Durban.

METHODS

This cross-sectional study of 118 residents aged 60 years and older, collected socio-demographic data, presenting visual acuities (VAs) for each eye, and binocularly. Anterior segment eye examinations were conducted with a penlight torch and a portable slit-lamp, while posterior segment evaluation was conducted with direct and indirect ophthalmoscopy. Objective and subjective refractions were performed, and the best-corrected distance and near VAs were measured in each eye. VI was defined as presenting VA 6/18 and included moderate VI ( 6/18-6/60), severe VI ( 6/60 -3/60) and blindness ( 6/120).

RESULTS

The mean age of the participants was 73.3 years and included 80.5% females and 19.5% males. The prevalence of VI and blindness was 63.6%. Optical correction significantly reduced the prevalence of VI and blindness by 19.5% (p 0.05). The main causes of non-refractive VI and blindness were cataract (54.5%), posterior segment disorders (25.5%) and corneal opacities (20%).

CONCLUSION

The prevalence of VI and blindness is high among residents in low-income old age homes living in Durban. Refractive correction and surgical cataract intervention can significantly reduce the burden of VI and blindness among the elderly residents.

Cataract blindness in Hungary

AIM

To estimate the prevalence of blindness and visual impairment resulting from cataract in the population aged ≥50y in Hungary, and to assess the cataract surgical services.

METHODS

A rapid assessment of avoidable blindness (RAAB) was conducted. A total of 3523 eligible people were randomly selected and examined. Each participant underwent surgery for cataract was interviewed with regard to the year, place, and costs of the surgery. Participants with obvious cataract were asked why they had not yet undergone surgery (barriers to surgery).

RESULTS

An estimated 12 514 people were bilaterally blind; the visual acuity (VA) in 19 293 people was <6/60, and the VA in 73 962 people was <6/18 in the better eye due to cataract. An estimated 77 933 eyes are blind; 98 067 eyes had a VA of <6/60, and an estimated 277 493 eyes had a VA of <6/18 due to cataract. Almost all cataract surgeries were conducted in government hospitals. The age- and sex-adjusted cataract surgical coverage with VA<3/60 in eyes was 90.0%. The rate of good visual outcome after surgery was 79.5%. Ocular comorbidity was the main cause of poor outcome (78.1%), followed by late complications (such as posterior capsule opacification) (17.2%), inadequate optical correction (3.1%), and surgical complications (1.6%). The main barrier to surgery in people with bilateral cataract and VA of <6/60 was 'need not felt'.

CONCLUSION

The prevalence of visual impairment resulting from cataract is slightly higher than expected. The quality of the cataract surgical service seems adequate in Hungary. However, the number of cataract operations per year should continue to increase due to the increasing patient demands and the aging population.

How to improve Iranians' vision health: on the national policy of preventing Iranians' blindness

AIM

To review vision health situation of Iranian community, analyze its determinants, and discuss the adopted improvement strategies by the Iran Ministry of Health and Medical Education (MOHME).

METHODS

This was a rapid situation analysis with a qualitative approach in three parts of recognition, orientation and implementation. The data were gathered via review of upstream documents, national and international experiences, and experts and stakeholders' opinions.

RESULTS

Eradicating trachoma, increasing human resources, increasing educational and research centers and promotion of ophthalmic technologies were important achievements in the field of vision health in Iran. Through these achievements, it seemed that the pattern of causes of blindness and low vision was similar to that of the developed countries. However, the review of Iranians' vision health indicators showed that a considerable percent of the blindness and low vision was avoidable through a national program demanding 3 types of interventions in social determinants of health (SDH), community education, and increasing the access to health care services by integrating the necessary services in primary health care system.

CONCLUSION

Managing the issue requires attentions from a national committee for preventing blindness with participation of all stakeholders, implementing a national survey on vision health, preparation of the primary level health centers including employment and education of community health workers (Behvarzes), optometrists and general practitioners, fair distribution of specialized human resources and establishing at least one specialized center in each province for referring patients from the primary levels.

Epidemiology of Aspergillus species causing keratitis in Mexico

BACKGROUND

The incidence of fungal keratitis has increased in recent years. While the epidemiology and clinical roles of various Candida and Fusarium species have been relatively well-identified in infections of the eye, data regarding keratitis caused by Aspergillus species are scant. Accurate and rapid diagnosis is important for successful management of this infection.

OBJECTIVES

To present the first molecular epidemiological data from Mexico during a 4-year period of cases admitted with Aspergillus keratitis to a tertiary care eye institution in Mexico City.

PATIENTS/METHODS

A total of 25 cases of keratitis were included in the study. Aspergillus isolates were identified by sequencing the calmodulin gene. Antifungal susceptibility was tested according to CLSI.

RESULTS

The aetiological agents belonged to Aspergillus flavus (n = 13), Aspergillus effusus (n = 1), Aspergillus tamarii (n = 4), Aspergillus sydowii (n = 1), Aspergillus protuberus (n = 3) and Aspergillus terreus (n = 3). All strains had low minimum inhibitory concentrations (MICs) of itraconazole and voriconazole (VCZ). Amphotericin B and natamycin showed moderate elevated MICs.

CONCLUSIONS

Early diagnosis and application of topical VCZ 1% were associated with good outcome. Monitoring of local epidemiological data plays an important role in clinical practice.

Prevalence and causes of vision loss in Latin America and the Caribbean in 2015: magnitude, temporal trends and projections

OBJECTIVE

To estimate the prevalence and causes of blindness and vision impairment for distance and near in Latin America and the Caribbean (LAC) in 2015 and to forecast trends to 2020.

METHODS

A meta-analysis from a global systematic review of 283 cross-sectional, population-representative studies from published and unpublished sources from 1980 to 2014 in the Global Vision Database included 17 published and 6 unpublished studies from LAC.

RESULTS

In 2015, across LAC, age-standardised prevalence was 0.38% in all ages and 1.56% in those over age 50 for blindness; 2.06% in all ages and 7.86% in those over age 50 for moderate and severe vision impairment (MSVI); 1.89% in all ages and 6.93% in those over age 50 for mild vision impairment and 39.59% in all ages and 45.27% in those over 50 for near vision impairment (NVI). In 2015, 117.86 million persons were vision impaired; of those 2.34 million blind, 12.46 million with MSVI, 11.34 million mildly impaired and 91.72 million had NVI. Cataract is the most common cause of blindness. Undercorrected refractive-error is the most common cause of vision impairment.

CONCLUSIONS

These prevalence estimates indicate that one in five persons across LAC had some degree of vision loss in 2015. We predict that from 2015 to 2020, the absolute numbers of persons with vision loss will increase by 12% to 132.33 million, while the all-age age-standardised prevalence will decrease for blindness by 15% and for other distance vision impairment by 8%. All countries need epidemiologic research to establish accurate national estimates and trends. Universal eye health services must be included in universal health coverage reforms to address disparities, fragmentation and segmentation of healthcare.

Health system dynamics analysis of eyecare services in Trinidad and Tobago and progress towards Vision 2020 Goals

Avoidable blindness is an important global public health concern. This study aimed to assess Trinidad and Tobago's progress towards achieving the Pan American Health Organization, 'Strategic Framework for Vision 2020: The Right to Sight-Caribbean Region,' indicators through comprehensive review of the eyecare system, in order to facilitate health system priority setting. We administered structured surveys to six stakeholder groups, including eyecare providers, patients and older adult participants in the National Eye Survey of Trinidad and Tobago. We reviewed reports, registers and policy documents, and used a health system dynamics framework to synthesize data. In 2014, the population of 1.3 million were served by a pluralistic eyecare system, which had achieved 14 out of 27 Strategic Framework indicators. The Government provided free primary, secondary and emergency eyecare services, through 108 health centres and 5 hospitals (0.26 ophthalmologists and 1.32 ophthalmologists-in-training per 50 000 population). Private sector optometrists (4.37 per 50 000 population), and ophthalmologists (0.93 per 50 000 population) provided 80% of all eyecare. Only 19.3% of the adult population had private health insurance, revealing significant out-of-pocket expenditure. We identified potential weaknesses in the eyecare system where investment might reduce avoidable blindness. These included a need for more ophthalmic equipment and maintenance in the public sector, national screening programmes for diabetic retinopathy, retinopathy of prematurity and neonatal eye defects, and pathways to ensure timely and equitable access to subspecialized surgery. Eyecare for older adults was responsible for an estimated 9.5% (US$22.6 million) of annual health expenditure. This study used the health system dynamics framework and new data to identify priorities for eyecare system strengthening. We recommend this approach for exploring potential health system barriers to addressing avoidable blindness, and other important public health problems.

Updates on the Epidemiology of Age-Related Macular Degeneration

This meta-analysis reports on current estimates of the prevalence of age-related macular degeneration (AMD) based on a review of recent meta-analyses and literature research. Within an age of 45-85 years, global prevalences of any AMD, early AMD, and late AMD were 8.7% [95% credible interval (CrI), 4.3‒17.4], 8.0% (95% CrI, 4.0‒15.5), and 0.4% (95% CrI, 0.2-0.8). Early AMD was more common in individuals of European ancestry (11.2%) than in Asians (6.8%), whereas prevalence of late AMD did not differ significantly. AMD of any type was less common in individuals of African ancestry. The number of individuals with AMD was estimated to be 196 million (95% CrI, 140‒261) in 2020 and 288 million (95% CrI, 205‒399) in 2040. The worldwide number of persons blind (presenting visual acuity < 3/60) or with moderate to severe vision impairment (MSVI; presenting visual acuity < 6/18 to 3/60 inclusive) due to macular disease in 2010 was 2.1 million [95% uncertainty interval (UI), 1.9‒2.7] individuals out of 32.4 million individuals blind and 6.0 million (95% UI, 5.2‒8.1) persons out of 191 million people with MSVI. Age-standardized prevalence of macular diseases as cause of blindness in adults aged 50+ years worldwide decreased from 0.2% (95% UI, 0.2‒0.2) in 1990 to 0.1% (95% UI, 0.1‒0.2) in 2010; as cause for MSVI, it remained mostly unchanged (1990: 0.4%; 95% UI, 0.3‒0.5; 2010: 0.4%; 95% UI, 0.4‒0.6), with no significant sex difference. In 2015, AMD was the fourth most common cause of blindness globally (in approximately 5.8% of blind individuals) and third most common cause for MSVI (3.9%). These data show the globally increasing importance of AMD.

The National Eye Survey of Trinidad and Tobago (NESTT): Rationale, Objectives and Methodology

PURPOSE

This paper describes the rationale, study design and procedures of the National Eye Survey of Trinidad and Tobago (NESTT). The main objective of this survey is to obtain prevalence estimates of vision impairment and blindness for planning and policy development.

METHODS

A population-based, cross-sectional survey was undertaken using random multistage cluster sampling, with probability-proportionate-to-size methods. Eligible participants aged 5 years and older were sampled from the non-institutional population in each of 120 cluster segments. Presenting distance and near visual acuity were screened in their communities. People aged 40 years and older, and selected younger people, were invited for comprehensive clinic assessment. The interview included information on potential risk factors for vision loss, associated costs and quality of life. The examination included measurement of anthropometrics, blood glucose, refraction, ocular biometry, corneal hysteresis, and detailed assessment of the anterior and posterior segments, with photography and optical coherence tomography imaging. Adult participants were invited to donate saliva samples for DNA extraction and storage.

RESULTS

The fieldwork was conducted over 13 months in 2013-2014. A representative sample of 10,651 individuals in 3410 households within 120 cluster segments identified 9913 people who were eligible for recruitment.

CONCLUSION

The study methodology was robust and adequate to provide the first population-based estimates of the prevalence and causes of visual impairment and blindness in Trinidad and Tobago. Information was also gathered on risk factors, costs and quality of life associated with vision loss, and on normal ocular parameters for the population aged 40 years and older.

Number of People Blind or Visually Impaired by Glaucoma Worldwide and in World Regions 1990 - 2010: A Meta-Analysis

Objective

To assess the number of individuals visually impaired or blind due to glaucoma and to examine regional differences and temporal changes in this parameter for the period from 1990 to 2012.

Methods

As part of the Global Burden of Diseases (GBD) Study 2010, we performed a systematic literature review for the period from 1980 to 2012. We primarily identified 14,908 relevant manuscripts, out of which 243 high-quality, population-based studies remained after review by an expert panel that involved application of selection criteria that dwelt on population representativeness and clarity of visual acuity methods used. Sixty-six specified the proportion attributable to glaucoma. The software tool DisMod-MR (Disease Modeling–Metaregression) of the GBD was used to calculate fraction of vision impairment due to glaucoma.

Results

In 2010, 2.1 million (95% Uncertainty Interval (UI):1.9,2.6) people were blind, and 4.2 (95% UI:3.7,5.8) million were visually impaired due to glaucoma. Glaucoma caused worldwide 6.6% (95% UI:5.9,7.9) of all blindness in 2010 and 2.2% (95% UI:2.0,2.8) of all moderate and severe visual impairment (MSVI). These figures were lower in regions with younger populations (<5% in South Asia) than in high-income regions with relatively old populations (>10%). From 1990 to 2010, the number of blind or visually impaired due to glaucoma increased by 0.8 million (95%UI:0.7, 1.1) or 62% and by 2.3 million (95%UI:2.1,3.5) or 83%, respectively. Percentage of global blindness caused by glaucoma increased between 1990 and 2010 from 4.4% (4.0,5.1) to 6.6%. Age-standardized prevalence of glaucoma related blindness and MSVI did not differ markedly between world regions nor between women.

Significance

By 2010, one out of 15 blind people was blind due to glaucoma, and one of 45 visually impaired people was visually impaired, highlighting the increasing global burden of glaucoma.

Visual Impairment among Older Adults in a Rural Community in Eastern China

Purpose. To determine the prevalence, causes, and associations of visual impairment (VI) among participants aged 60 years or older in a rural community in China. Methods. A community-based survey was undertaken in a rural town located in Eastern China and 4579 people aged 60 years or older participated in the study. Presenting visual acuity was assessed using a Snellen chart with tumbling-E optotypes and anterior segment was examined using a slit-lamp. VI was defined as presenting VA <6/18 and it included moderate VI (<6/18 to 6/60) and blindness (<6/60). Results. The prevalence of VI was 5.4% (95% confidence interval [CI] 4.7–6.0). In multivariate analysis, the presence of VI was positively associated with increasing age (odds ratio [OR] = 1.12, 95% CI 1.10–1.16, per year increase), female gender (OR = 2.33, 95% CI 1.53–3.55), the presence of hypertension (OR = 1.31, 95% CI 1.001–1.85), living alone (OR = 1.52, 95% CI 1.08–2.62), and increased sleeping hours (OR = 1.10, 95% CI 1.001–1.22). Drinking 3 or more glasses of green tea per day was inversely associated with VI (OR = 0.79, 95% CI 0.63–0.98). Conclusion. VI was less prevalent in this community compared with previous report in other areas in China.

Burden of serious fungal infections in Mexico

Serious fungal infections (SFIs) could be more frequent than are recognised. Estimates of the incidence and prevalence of SFIs are essential in order to identify public health problems. We estimated the rates of SFIs in Mexico, following a methodology similar to that used in prior studies. We obtained information about the general population and populations at risk. A systematic literature search was undertaken to identify epidemiological reports of SFIs in Mexico. When Mexican reports were unavailable, we based our estimates on international literature. The most prevalent SFIs in Mexico are recurrent vulvovaginal candidiasis (5999 per 100,000) followed by allergic bronchopulmonary aspergillosis (60 per 100,000), chronic pulmonary aspergillosis (15.9 per 100,000), fungal keratitis (10.4 per 100,000), invasive candidiasis (8.6 per 100,000) and SFIs in HIV (8.2 per 100,000); coccidioidomycosis (7.6 per 100,000), IA (4.56 per 100,000). These correspond to 2,749,159 people affected in any year (2.45% of the population), probably >10,000 deaths and 7000 blind eyes. SFIs affect immunocompromised and healthy populations. Most are associated with high morbidity and mortality rates. Validation of these estimates with epidemiological studies is required. The burdens indicate that an urgent need to improve medical skills, surveillance, diagnosis, and management of SFIs exists.

Population-based assessment of visual impairment among ethnic Dai adults in a rural community in China

Dai ethnicity is one of the major Chinese ethnic minorities with a population of about 1.2 million. We aimed to determine the prevalence and potential causes of visual impairment (VI) among ethnic Dai adults aged 50 years or older in a rural community in China. A population-based survey including 2163 ethnic Dai people (80.5%) was undertaken using a random cluster sampling strategy. The detailed eye examination was performed after pupil dilation by trained study ophthalmologists and optometrists. Presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) was measured using the Early Treatment Diabetic Retinopathy Study logMAR chart and VI was defined as a VA of less than 20/63 in the better-seeing eye. The overall prevalence of presenting blindness and low vision was 3.0% (95% CI, 2.3-3.7) and 13.3% (95% CI, 11.9-14.8), respectively. The prevalence estimates were reduced to 2.1% (95% CI, 1.5-2.8) and 6.7% (95% CI, 5.7-7.8) when BCVA was considered. Men were more likely to be affected by low vision but less likely to be blind compared with women. Cataract accounted for 62.7% of presenting low vision and 68.8% of presenting blindness, respectively. In conclusion, VI was a significant health concern in Dai Chinese in China.

Thyroid function and age-related macular degeneration: a prospective population-based cohort study--the Rotterdam Study

BACKGROUND

In animal models, lack of thyroid hormone is associated with cone photoreceptor preservation, while administration of high doses of active thyroid hormone leads to deterioration. The association between thyroid function and age-related macular degeneration (AMD) has not been investigated in the general population.

METHODS

Participants of age ≥ 55 years from the Rotterdam Study with thyroid-stimulating hormone (TSH) and/or free thyroxine (FT4) measurements and AMD assessment were included. We conducted age- and sex-adjusted Cox proportional hazards models to explore the association of TSH or FT4 with AMD, in the full range and in those with TSH (0.4-4.0 mIU/L) and/or FT4 in normal range (11-25 pmol/L). Cox proportional hazards models were performed for the association of TSH or FT4 with retinal pigment alterations (RPA), as an early marker of retinal changes. Multivariable models additionally included cardiovascular risk factors and thyroid peroxidase antibodies positivity. We also performed stratification by age and sex. A bidirectional look-up in genome-wide association study (GWAS) data for thyroid parameters and AMD was performed. Single nucleotide polymorphisms (SNPs) that are significantly associated with both phenotypes were identified.

RESULTS

We included 5,573 participants with a median follow-up of 6.9 years (interquartile range 4.4-10.8 years). During follow-up 805 people developed AMD. TSH levels were not associated with increased risk of AMD. Within normal range of FT4, participants in the highest FT4 quintile had a 1.34-fold increased risk of developing AMD, compared to individuals in the middle group (95% confidence interval [CI] 1.07-1.66). Higher FT4 values in the full range were associated with a higher risk of AMD (hazard ratio 1.04, CI, 1.01-1.06 per 1 pmol/L increase). Higher FT4 levels were similarly associated with a higher risk of RPA. Restricting analyses to euthyroid individuals, additional multivariable models, and stratification did not change estimates. We found a SNP (rs943080) in the VEGF-A gene, associated with AMD, to be significant in the TSH GWAS (P = 1.2 x 10(-4)). Adding this SNP to multivariable models did not change estimates.

CONCLUSIONS

Higher FT4 values are associated with increased risk of AMD - even in euthyroid individuals - and increased risk of RPA. Our data suggest an important role of thyroid hormone in pathways leading to AMD.

Photo-damage, photo-protection and age-related macular degeneration

The course of Age-related Macular Degeneration (AMD) is described as the effect of light (400–580 nm) on various molecular targets in photoreceptors and the retinal pigment epithelium (RPE). Photo-damage is followed by inflammation, increasing oxidative stress and, probably, unveiling new photosensitive molecules.