National survey of blindness and low vision in The Gambia: results

The Gambia Trachomatous Trichiasis Surveys: Results from Five Evaluation Units Confirm Attainment of Trachoma Elimination Thresholds

INTRODUCTION

Trichiasis is present when in-turned eyelashes touch the eyeball. It may result in permanent vision loss. Trachomatous trichiasis (TT) is caused by multiple rounds of inflammation associated with conjunctival Chlamydia trachomatis infection. Surveys have been designed to estimate the prevalence of TT in evaluation units (EUs) of trachoma-endemic countries in order to help develop appropriate programme-level plans. In this study, TT-only surveys were conducted in five EUs of The Gambia to determine whether further intensive programmatic action was required.

METHODS

Two-stage cluster sampling was used to select 27 villages per EU and ~25 households per village. Graders assessed the TT status of individuals aged ≥15 years in each selected household, including the presence or absence of conjunctival scarring in those with TT.

RESULTS

From February to March 2019, 11595 people aged ≥15 years were examined. A total of 34 cases of TT were identified. All five EUs had an age- and gender-adjusted prevalence of TT unknown to the health system <0.2%. Three of five EUs had a prevalence of 0.0%.

CONCLUSION

Using these and other previously collected data, in 2021, The Gambia was validated as having achieved national elimination of trachoma as a public health problem. Trachoma is still present in the population, but as its prevalence is low, it is unlikely that today's youth will experience the exposure to C. trachomatis required to precipitate TT. The Gambia demonstrates that with political will and consistent application of human and financial resources, trachoma can be eliminated as a public health problem.

The Gambia has eliminated trachoma as a public health problem: Challenges and successes

Trachoma is the leading infectious cause of blindness in the world and has been known to be a major public health problem in The Gambia for over 60 years. Nationwide blindness surveys, including trachoma, in 1986 and 1996 provided the foundation for a comprehensive plan to implement a trachoma elimination strategy. Impact and pre-validation surveillance surveys in 2011–13 demonstrated that active trachoma was below WHO threshold for elimination but trichiasis remained a public health problem. Trichiasis-only surveys in 2019 demonstrated that trichiasis was below WHO thresholds for elimination and in 2020 the Government of The Gambia completed and submitted its dossier for validation of elimination as a public health problem. Challenges that The Gambia faced on the pathway to elimination included effective use of data for decision making, poor trichiasis surgical outcomes, lack of access to antibiotic treatment for low prevalence districts, high attrition of ophthalmic nurses trained as trichiasis surgeons, unexpected active trachoma in madrassas, the misalignment of elimination of active trachoma and trichiasis, trichiasis in urban settings, and maintaining the quality of surgery post-elimination when trichiasis cases are rare. Elimination of trachoma does not end with the submission of an elimination dossier; The Gambia will need to sustain monitoring and support over the coming years.

The World Health Organization has validated that trachoma is no longer a public health problem in The Gambia as of April 2021. In this article, the authors summarize critical milestones achieved by The Gambia in its journey to elimination and the challenges to implementing the WHO-endorsed elimination strategy, including surgical management for people with trichiasis, antibiotics to all endemic communities, and uptake of face-washing practices and environmental improvements. In 1986, a national survey of blindness and low vision in The Gambia found that 17 per cent of blindness was caused by trachoma in the form of corneal opacity due to trichiasis. At this time, eye health services delivered by a trained eye health were limited to the Greater Banjul area, meaning people in remote locations were frequently left behind. This changed with the coordination of partners and donors strengthening the knowledge base of health workers on trachoma preventative measures and the capacity of ophthalmic nurses to deliver trichiasis surgical support to all trachoma-endemic communities. Final epidemiological surveys conducted in 2019 confirmed that there was sufficient evidence to show that elimination thresholds had been achieved all endemic areas prompting the formal submission of the country’s elimination dossier to the WHO.

Prevalence of blindness and distance vision impairment in the Gambia across three decades of eye health programming

BACKGROUND/AIMS

The 1986 Gambia National Eye Health Survey provided baseline data for a National Eye Health Programme. A second survey in 1996 evaluated changes in population eye health a decade later. We completed a third survey in 2019, to determine the current state of population eye health, considering service developments and demographic change.

METHODS

We estimated prevalence and causes of vision impairment (VI) in a nationally representative population-based sample of adults 35 years and older. We used multistage cluster random sampling to sample 10 800 adults 35 and above in 360 clusters of 30. We measured monocular distance visual acuity (uncorrected and with available correction) using Peek Acuity. Participants with either eye uncorrected or presenting (with available correction) acuity <6/12 were retested with pinhole and refraction, and dilated exams were completed on all eyes by ophthalmologists using a direct ophthalmoscope, slit lamp and 90 D lens.

RESULTS

We examined 9188 participants (response rate 83%). The 2013 census age-sex adjusted prevalence of blindness (presenting acuity<3/60 in better seeing eye) was 1.2% (95% CI 0.9 to 1.4) and of moderate or severe VI (MSVI,<6/18 to ≥3/60) was 8.9% (95% CI 9.1 to 9.7). Prevalence of all distance VI (<6/12) was 13.4% (12.4-14.4). Compared with 1996, the relative risk of blindness decreased (risk ratio 0.7, 95% CI 0.5 to 1.0) and MSVI increased (risk ratio 1.5, 95% CI 1.2 to 0.17).

CONCLUSION

Significant progress has been made to reduce blindness and increase access to eye health across the Gambia, with further work is needed to decrease the risk of MSVI.

Estimating Need for Glasses and Hearing Aids in The Gambia: Results from a National Survey and Comparison of Clinical Impairment and Self-Report Assessment Approaches

Few estimates are available of the need for assistive devices (ADs) in African settings. This study aimed to estimate population-level need for glasses and hearing aids in The Gambia based on (1) clinical impairment assessment, and (2) self-reported AD awareness, and explore the relationship between the two methods. The Gambia 2019 National Eye Health Survey is a nationally representative population-based sample of 9188 adults aged 35+ years. Participants underwent standardised clinical vision assessments including the need for glasses (distance and near). Approximately 25% of the sample underwent clinical assessment of hearing and hearing aid need. Data were also collected on self-reported awareness, need and access barriers to vision and hearing ADs. Overall, 5.6% of the study population needed distance glasses (95% CI 5.0-6.3), 45.9% (95% CI 44.2-47.5) needed near glasses and 25.5% (95% CI 22.2-29.2) needed hearing aids. Coverage for each AD was very low (<4%). The agreement between self-report and clinical impairment assessment for AD need was poor. In conclusion, there is high prevalence and very low coverage for distance glasses, near glasses and hearing aids in The Gambia. Self-report measures alone will not provide an accurate estimate of AD need.

The Gambia National Eye Health Survey 2019: survey protocol

Two national surveys of vision impairment and blindness were undertaken in The Gambia in 1986 and 1996. These provided data for the inception of The Gambia's National Eye Health Programme (NEHP) within the Ministry of Health and Social Welfare. There have been important developments in the eye health services provided by the NEHP in the last 20 years. At the same time, the population has also undergone major demographic changes that may have led to substantial changes in the burden of eye disease. We conducted a National Eye Health Survey of vision impairment, blindness and its comorbidities in adults in The Gambia in 2019. We examined a nationally representative population-based sample of adults 35 years and above to permit direct comparison with the data available from the previous surveys. Alongside a comprehensive vision and eye examination, the survey provides nationally representative data on important comorbidities in this population: diabetes, hypertension, obesity, hearing impairment, disability and mental health. Secondly, it estimates access to assistive technologies and eye health services. Thirdly, it is powered to allow a five-year follow up cohort study to measure the incidence and progression of eye disease.

The Gambia National Eye Health Survey 2019: survey protocol

Two national surveys of vision impairment and blindness were undertaken in The Gambia in 1986 and 1996. These provided data for the inception of The Gambia's National Eye Health Programme (NEHP) within the Ministry of Health and Social Welfare. There have been important developments in the eye health services provided by the NEHP in the last 20 years. At the same time, the population has also undergone major demographic changes that may have led to substantial changes in the burden of eye disease. We conducted a National Eye Health Survey of vision impairment, blindness and its comorbidities in adults in The Gambia in 2019. We examined a nationally representative population-based sample of adults 35 years and above to permit direct comparison with the data available from the previous surveys. Alongside a comprehensive vision and eye examination, the survey provides nationally representative data on important comorbidities in this population: diabetes, hypertension, obesity, hearing impairment, disability and mental health. Secondly, it estimates access to assistive technologies and eye health services. Thirdly, it is powered to allow a five-year follow up cohort study to measure the incidence and progression of eye disease.

Prevalence And Associated Factors Of Visual Impairment Among School-Age Children In Bahir Dar City, Northwest Ethiopia

INTRODUCTION

Visual impairment (VI) is one of the major public health problems in the world. It is highly prevalent among children in sub-Saharan countries, including Ethiopia. Worldwide, the magnitude of VI among school-age children is 1%-10%. However, there was limited information regarding the prevalence and associated factors of VI among school-age children in the study area, which is essential to plan and implement appropriate interventions.

OBJECTIVE

The aim of this study was to determine the prevalence and associated factors of VI among school-age children livin g in Bahir Dar city, northwest Ethiopia.

METHODS

A community-based cross-sectional study was done on a sample of 632 school-age children selected by multistage sampling in Bahir Dar from April 30 to May 15, 2018. Data were collected through interviews and physical examinations. Face-to-face interviews were done with a pretested semistructured questionnaire. Physical examinations were done with visual acuity measures and assessment of ocular pathology by optometrists. Data were entered into Epi Info 7 and exported to and analyzed with SPSS 20. Binary logistic regression was fitted, and variables with P<0.05 in the multivariate model were considered statistically significant.

RESULTS

A total of 601 study subjects were included in this study, giving a response rate of 95.2%. The median age was 13 (IQR 11-16) years, and 303 (50.3%) were male. Prevalence of VI was 52 (8.7%, 95% CI 6.2%-10.7%). In multivariate analysis, prematurity [AOR 2.8 (95% CI 1.19-6.83)], admission to a neonatal intensive-care unit (AOR 5.5, 95% CI 2.01-15.15), having a parent with VI (AOR 1.8, 95% CI 0.13-0.97), watching television from <2 m (AOR 8.7, 95% CI 1.49-18.24), and mobile-phone exposure >4 hours per day (AOR 1.6, 95% CI 1.32-4.45) were factors significantly associated with VI.

CONCLUSION

The prevalence of VI among school-age children in Bahir Dar was significant. Premature birth, admission to a neonatal intensive-care unit, having a parent with VI, watching television from <2 m, and mobile exposure >4 hours per day were significantly associated.

Causes of Blindness among Syrian Refugees Living in Southeastern Turkey

Purpose: This study was conducted to evaluate the causes of blindness in Syrian refugees living in southeastern Turkey. Another aim was to help the authorities determine strategies for dealing with blindness.Methods: A detailed ophthalmologic examination, including visual acuity and intraocular pressure, of 253 Syrian refugee patients complaining of visual impairment was conducted between January 2016 and January 2018 at our hospital's outpatient clinic.Results: Of the 253 Syrian refugee patients who visited our outpatient clinic, 176 (69.6%) were female and 77 (30.4%) male. The mean age of the patients was 46.4 ± 20.8 years. 27.3% of the patients were blind (N = 69) and 5.9% of the patients had severe visual impairment (N = 15). The most common causes of blindness were cataract (N = 42, 60.8%), refractive error (N = 8, 11.6%), phthisis (N = 5, 7.3%) and corneal opacity (N = 5, 7.3%). The highest rate of blindness (21.3%) was observed in the subgroup of patients over 40 years of age.Conclusions: Our study showed that Syrian refugees living in southeastern Turkey have been affected by several causes of preventable blindness, although they had free access to public health services in the country. The possible reasons of this situation are difficulties associated with lack of knowledge regarding eye health services and challenges arising from organisational problems related to the delivery of health services. Providing regular eye disease screening programmes and rehabilitation services may be beneficial in preventing blindness in the refugee population.

Epidemiology of trachoma and its implications for implementing the "SAFE" strategy in Somali Region, Ethiopia: results of 14 population-based prevalence surveys

Purpose: Ethiopia is highly trachoma endemic. Baseline mapping was needed in Ethiopia’s Somali Region to guide elimination efforts.

Methods: Cross-sectional community-based surveys were conducted in 34 suspected trachoma-endemic woredas, grouped as 14 evaluation units (EUs), using a standardised mapping methodology developed for the Global Trachoma Mapping Project.

Results: In total, 53,467 individuals were enumerated. A total of 48,058 (89.9%) were present at the time of survey teams’ visits and consented to examination. The prevalence of trachomatous inflammation–follicular (TF) among children aged 1–9 years ranged from 4.1% in the EU covering Danot, Boh, and Geladin woredas in Doolo Subzone to 38.1% in the EU covering Kebribeyah and Hareshen woredas in Fafan Subzone (East). The trichiasis prevalence among adults aged over 15 years varied from 0.1% in the EU covering Afder, Bare, and Dolobay woredas in Afder Subzone (West) to 1.2% in the EU covering Awbere in Fafan Subzone (West).

Conclusion: Mass drug administration (MDA) with azithromycin is needed in 13 EUs (population 2,845,818). Two EUs (population 667,599) had TF prevalences in 1–9-year-olds of ≥30% and will require at least 5 years of MDA; 5 EUs (population 1,1193,032) had TF prevalences of 10–29.9% and need at least three years of MDA; 6 EUs (population 985,187) had TF prevalences of 5–9.9% and need at least one round of azithromycin distribution before re-survey. In all 13 of these EUs, implementation of facial cleanliness and environmental improvement measures is also needed. Surveys are still needed in the remaining 34 unmapped woredas of Somali Region.

Serology reflects a decline in the prevalence of trachoma in two regions of The Gambia

Trachoma is caused by Chlamydia trachomatis (Ct). It is targeted for global elimination as a public health problem. In 2014, a population-based cross-sectional study was performed in two previously trachoma-endemic areas of The Gambia. Participants of all ages from Lower River Region (LRR) (N = 1028) and Upper River Region (URR) (N = 840) underwent examination for trachoma and had blood collected for detection of antibodies against the Ct antigen Pgp3, by ELISA. Overall, 30 (1.6%) individuals had active trachoma; the prevalence in children aged 1-9 years was 3.4% (25/742) with no statistically significant difference in prevalence between the regions. There was a significant difference in overall seroprevalence by region: 26.2% in LRR and 17.1% in URR (p < 0.0001). In children 1-9 years old, seroprevalence was 4.4% in LRR and 3.9% in URR. Reversible catalytic models using information on age-specific seroprevalence demonstrated a decrease in the transmission of Ct infection in both regions, possibly reflecting the impact of improved access to water, health and sanitation as well as mass drug administration campaigns. Serological testing for antibodies to Ct antigens is potentially useful for trachoma programmes, but consideration should be given to the co-endemicity of sexually transmitted Ct infections.

Population-based prevalence survey of follicular trachoma and trachomatous trichiasis in the Casamance region of Senegal

Background

Trachoma, caused by ocular infection with Chlamydia trachomatis, is the leading infectious cause of blindness worldwide. We conducted the first population-based trachoma prevalence survey in the Casamance region of Senegal to enable the Senegalese National Eye Care Programme (NECP) to plan its trachoma control activities. The World Health Organization (WHO) guidelines state that any individual with trachomatous trichiasis (TT) should be offered surgery, but that surgery should be prioritised where the prevalence is >0.1%, and that districts and communities with a trachomatous inflammation, follicular (TF) prevalence of ≥10% in 1–9 year-olds should receive mass antibiotic treatment annually for a minimum of three years, along with hygiene promotion and environmental improvement, before re-assessing the prevalence to determine whether treatment can be discontinued (when TF prevalence in 1–9 year-olds falls <5%).

Methods

Local healthcare workers conducted a population-based household survey in four districts of the Bignona Department of Casamance region to estimate the prevalence of TF in 1–9 year-olds, and TT in ≥15 year-olds. Children’s facial cleanliness (ocular and/or nasal discharge, dirt on the face, flies on the face) was measured at time of examination. Risk factor questionnaires were completed at the household level.

Results

Sixty communities participated with a total censused population of 5580 individuals. The cluster-, age- and sex-adjusted estimated prevalence of TF in 1–9 year-olds was 2.5% (95% Confidence Interval (CI) 1.8–3.6) (38/1425) at the regional level and <5% in all districts, although the upper 95%CI exceeded 5% in all but one district. The prevalence of TT in those aged ≥15 years was estimated to be 1.4% (95%CI 1.0–1.9) (40/2744) at the regional level and >1% in all districts.

Conclusion

With a prevalence <5%, TF does not appear to be a significant public health problem in this region. However, TF monitoring and surveillance at sub-district level will be required to ensure that elimination targets are sustained and that TF does not re-emerge as a public health problem. TT surgery remains the priority for trachoma elimination efforts in the region, with an estimated 1819 TT surgeries to conduct.

Cross-Sectional Surveys of the Prevalence of Follicular Trachoma and Trichiasis in The Gambia: Has Elimination Been Reached?

Background

The Gambia’s National Eye Health Programme has made a concerted effort to reduce the prevalence of trachoma. The present study had two objectives. The first was to conduct surveillance following mass drug administrations to determine whether The Gambia has reached the World Health Organization’s (WHO) criteria for trachoma elimination, namely a prevalence of trachomatous inflammation—follicular (TF) of less than 5% in children aged 1 to 9 years. The second was to determine the prevalence of trichiasis (TT) cases unknown to the programme and evaluate whether these meet the WHO criteria of less than 0.1% in the total population.

Methodology/Principal Findings

Three cross-sectional surveys were conducted between 2011 and 2013 to determine the prevalence of TF and TT in each of nine surveillance zones. Each zone was of similar size, with a population of 60,000 to 90,000, once urban settlements were excluded. Trachoma grading was carried out according to the WHO’s simplified trachoma grading system. The prevalence of TF in children aged 1 to 9 years was less than 5% in each surveillance zone at each of the three surveys. The prevalence of TT cases varied by zone from 0 to 1.7% of adults greater than 14 years while the prevalence of TT cases unknown to the country’s National Eye Health Programme was estimated at 0.15% total population.

Conclusions/Significance

The Gambia has reached the elimination threshold for TF in children. Further work is needed to bring the number of unknown TT cases below the elimination threshold.

Trachoma, the world’s leading infectious cause of blindness, is caused by ocular infection with the bacterium Chlamydia trachomatis. The Gambia, situated in West Africa, has implemented all facets of the World Health Organization-recommended SAFE strategy for trachoma control including surgery to correct the in-turning of eyelashes (trichiasis), mass drug administration with antibiotics, promotion of facial hygiene and environmental improvements. In 2011, The Gambia’s National Eye Health Programme began three years of rolling surveys to determine the prevalence of trachoma in the country and to evaluate whether trachoma elimination has been reached. The results suggest the country has reached the elimination threshold for trachoma in children (less than 5% prevalence) but that more work needs to be done to reduce the prevalence of trichiasis in adults.

A Cross-Sectional Population-Based Survey of Trachoma among Migrant School Aged Children in Shanghai, China

We investigated the prevalence of clinical trachoma in 154,265 children aged 6 to 16 years in 206 Shanghai migrant schools. Clean water availability in school, each child's facial cleanliness, eyelids, corneas, and the presenting distance visual acuities were examined. Trachoma was clinically diagnosed in accordance with the World Health Organization simplified classification. Eyes diagnosed with trachoma were swabbed to test for ocular Chlamydia trachomatis infections (OCTI) with a rapid latex immunochromatographic test. Among 153,977 students, no blindness was found related to trachoma. Trachoma was diagnosed in 8029 children (5.2%). In 87 schools clinical trachoma prevalence was higher than 5%. OCTI was confirmed in 2073 of 6823 trachoma diagnosed children (30.4%). Clinical trachoma prevalence was higher among females than males (p < 0.001), but gender comparison showed no statistical difference in the prevalence of OCTI (p = 0.077). Age and clinical trachoma (r = -0.014; p < 0.001) or OCTI (r = -0.026; p = 0.031) prevalence were negatively correlated. Clinical trachoma was different in different districts and counties (p < 0.001). Trachoma warrants close attention in Shanghai migrant children because the condition remains endemic in some schools.

A review of African studies on central corneal thickness

Recently, there has been increasing interest in understanding central corneal thickness (CCT) measurements in various populations. This may be related to the influence of CCT in the diagnosis, classification and management of glaucoma. In addition, CCT measurements are also important for monitoring corneal diseases and contact lens wear, indicating the overall health of the cornea and assessing eligibility for refractive surgery. This article reviews studies that have reported CCT measurements in non-glaucomatous African sub-populations. The CCT measurements, gender associations and limitations of these studies are highlighted. The findings of these studies and their implications are discussed in relation to global studies reporting on CCT measurements.

Ocular morbidity among refugees in Southwest Ethiopia

BACKGROUND

Low vision and blindness are recognized as one of the major public health problems worldwide, especially in developing countries. The prevalence and cause of blindness and low vision vary from region to region, among different age and population groups in a country or geographical region. The objective of this study is thus to determine the causes of blindness and ocular morbidity among refugees in Southwest Ethiopia.

METHODS

A cross-sectional clinic based study was conducted on 1,054 refugees in Southwest Ethiopia. A basic anterior and posterior segment examination was done by ophthalmologists with Magnifying Loupe 2.5X and Direct Ophthalmoscope. Data were analyzed using SPSS version 16.0.

RESULTS

The most common causes of ocular morbidity identified were trachoma 547(21.2%), cataract 501(19.4%), refractive error 353(13.7%), conjunctivitis 240(9.3%), glaucoma 130(5.1%) and climatic droplet keratopathy 112(4.4%). The overall prevalence of blindness was 26.2% and the prevalence of childhood blindness was 0.7%. The prevalence was higher among females (16.9%) than males (9.3%) and age groups 60 years and above (15.9%) than other age groups (10.3%) (P<0.05). The overall prevalence of low vision was 25.8% and the prevalence of low vision in pediatric age group was 0.9%. The leading causes of blindness were cataract 112(40.6%), trachomatous corneal opacity 58(21.0%) and glaucoma 49(17.8%). The commonest cause of low vision was cataract 102(37.6%) followed by trachomatous corneal opacity 49(18.1%) and refractive error 35(12.9%).

CONCLUSIONS

There is a very high burden of blinding eye diseases among refugees. Integrated multidisciplinary intervention strategies for the prevention and control of blindness and low vision in the study settings should be initiated.

Mass administration of azithromycin and Streptococcus pneumoniae carriage: cross-sectional surveys in the Gambia

OBJECTIVE

To evaluate the effect of repeated mass drug administration (MDA) of azithromycin in the Gambia on the nasopharyngeal carriage of Streptococcus pneumoniae and on the emergence of antibiotic-resistant strains.

METHODS

This study involved villages that participated in a cluster randomized trial comparing the effect of one versus three azithromycin MDA rounds on the prevalence of trachoma. Only villages in which most children received 7-valent pneumococcal conjugate vaccine were included. Three cross-sectional surveys were performed in two villages that received three annual MDA rounds: the first immediately before the third MDA round and the second and third, 1 and 6 months, respectively, after the third MDA round. The third survey also covered six villages that had received one MDA round 30 months previously. Pneumococcal carriage was assessed using nasopharyngeal swabs and azithromycin resistance was detected using the Etest.

FINDINGS

The prevalence of pneumococcal carriage decreased from 43.4% to 19.2% between the first and second surveys (P < 0.001) but rebounded by the third survey (45.8%; P = 0.591). Being a carrier at the first survey was a risk factor for being a carrier at the second (odds ratio: 3.71; P <  0.001). At the third survey, the prevalence of carriage was similar after one and three MDA rounds (50.3% versus 45.8%, respectively; P = 0.170), as was the prevalence of azithromycin resistance (0.3% versus 0.9%, respectively; P = 0.340).

CONCLUSION

Three azithromycin MDA rounds did not increase the prevalence of nasopharyngeal carriage of azithromycin-resistant S. pneumoniae strains compared with one round.

Association between ocular bacterial carriage and follicular trachoma following mass azithromycin distribution in The Gambia

BACKGROUND

Trachoma, caused by ocular Chlamydia trachomatis infection, is the leading infectious cause of blindness, but its prevalence is now falling in many countries. As the prevalence falls, an increasing proportion of individuals with clinical signs of follicular trachoma (TF) is not infected with C. trachomatis. A recent study in Tanzania suggested that other bacteria may play a role in the persistence of these clinical signs.

METHODOLOGY/PRINCIPAL FINDINGS

We examined associations between clinical signs of TF and ocular colonization with four pathogens commonly found in the nasopharnyx, three years after the initiation of mass azithromycin distribution. Children aged 0 to 5 years were randomly selected from 16 Gambian communities. Both eyes of each child were examined and graded for trachoma according to the World Health Organization (WHO) simplified system. Two swabs were taken from the right eye: one swab was processed for polymerase chain reaction (PCR) using the Amplicor test for detection of C. trachomatis DNA and the second swab was processed by routine bacteriology to assay for the presence of viable Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus and Moraxella catarrhalis. Prevalence of TF was 6.2% (96/1538) while prevalence of ocular C. trachomatis infection was 1.0% (16/1538). After adjustment, increased odds of TF were observed in the presence of C. trachomatis (OR = 10.4, 95%CI 1.32-81.2, p = 0.03), S. pneumoniae (OR = 2.14, 95%CI 1.03-4.44, p = 0.04) and H. influenzae (OR = 4.72, 95% CI 1.53-14.5, p = 0.01).

CONCLUSIONS/SIGNIFICANCE

Clinical signs of TF can persist in communities even when ocular C. trachomatis infection has been controlled through mass azithromycin distribution. In these settings, TF may be associated with ocular colonization with bacteria commonly carried in the nasopharnyx. This may affect the interpretation of impact surveys and the determinations of thresholds for discontinuing mass drug administration.

Epidemiology of glaucoma in sub-saharan Africa: prevalence, incidence and risk factors

PURPOSE

The purpose of this study is to review the epidemiology of different types of glaucoma relevant to Sub-Saharan Africa (SSA) and to discuss the evidence regarding the risk factors for onset and progression of glaucoma, including risk factors for glaucoma blindness.

METHODS

Electronic databases (PubMed, MedLine, African Journals Online- AJOL) were searched using the full text, Medical Subject Headings (MeSH) terms, author(s) and title to identify publications since 1982 in the following areas: population-based glaucoma prevalence and incidence studies in SSA and in African-derived black populations outside Africa; population-based prevalence and incidence of blindness and visual impairment studies in SSA including rapid assessment methods, which elucidate the glaucoma-specific blindness prevalence; studies of risk factors for glaucoma; and publications that discussed public health approaches for the control of glaucoma in Africa.

RESULTS

Studies highlighted that glaucoma in SSA is a public health problem and predominantly open-angle glaucoma. It is the second-leading cause of blindness, has a high prevalence, an early onset and progresses more rapidly than in Caucasians. These factors are further compounded by poor awareness and low knowledge about glaucoma even by persons affected by the condition.

CONCLUSION

Glaucoma care needs to be given high priority in Vision 2020 programs in Africa. Many questions remain unanswered and there is a need for further research in glaucoma in SSA in all aspects especially epidemiology and clinical care and outcomes involving randomized controlled trials. Genetic and genome-wide association studies may aid identification of high-risk groups. Social sciences and qualitative studies, health economics and health systems research will also enhance public health approaches for the prevention of blindness due to glaucoma.

Etiology of visual impairment among ophthalmic patients at Federal Medical Center, Abeokuta, Nigeria

BACKGROUND

The Nigeria national blindness survey has documented region-specific prevalence and causes of visual impairment in the country. However, there is need for local studies to ascertain specific causes of visual impairment peculiar to each community, as this varies from one locality to another.

AIM

To determine the causes of blindness and low vision among patients presenting to the Eye Clinic, Federal Medical Center Abeokuta, Nigeria.

STUDY DESIGN

A retrospective study.

MATERIALS AND METHODS

Medical records of all patients seen at the Eye Clinic, Federal Medical Center, Abeokuta, Nigeria between January 2011 and December 2012 were reviewed.

RESULTS

Out of the 5,352 patients managed during the period, 474 (8.9%) were blind, 3,178 (59.4%) had low vision while 1,700 (31.7%) had "normal vision". The risk of visual impairment increased with age. The major causes of blindness were cataract (32.5%), glaucoma (20%) and age-related macular degeneration (12.8%), while the most common causes of low vision were uncorrected refractive errors (20.5%), cataract (17.6%) and glaucoma (14.8%).

CONCLUSION

Cataract, glaucoma and uncorrected refractive errors are the leading causes of visual impairment in Abeokuta, Nigeria. Public enlightenment coupled with prompt and effective management will reduce the burden of blindness in the country.

The Nakuru posterior segment eye disease study: methods and prevalence of blindness and visual impairment in Nakuru, Kenya

OBJECTIVES

To estimate the prevalence of blindness and visual impairment (VI) in adults aged ≥50 years in the Nakuru district of Kenya and to identify sociodemographic risk factors for these conditions. We also sought to validate the Rapid Assessment of Avoidable Blindness (RAAB) methodology.

PARTICIPANTS

There were 5010 subjects enumerated for this study. Of these, 4414 participants underwent examination, for a response rate of 88.1%.

DESIGN

Cross-sectional, population-based survey.

METHODS

Cluster random samplings with probability proportionate to size procedures were used to select a representative cross-sectional sample of adults aged ≥50 years. Each participant was interviewed, had distance visual acuity (VA) measured with reduced logarithm of the minimal angle of resolution tumbling-E chart, underwent autorefraction, and thereby had measurements of presenting, uncorrected, and best-corrected VA. All participants, regardless of vision, underwent detailed ophthalmic examinations including slit-lamp assessment and dilated retinal photographs.

MAIN OUTCOME MEASURES

Visual acuity of <6/12.

RESULTS

A representative sample of 4414 adults were enumerated (response rate, 88.1%). The prevalence of blindness (VA < 3/60 in better eye) was 1.6% (95% confidence interval [CI], 1.2-2.1%) and of VI, 0.4% (95% CI, 0.3-0.7%); 8.1% (95% CI, 7.2-9.2%); and 5.1% (95% CI, 4.3-6.1%) were severely (<6/60-3/60), moderately (<6/18-6/60), or mildly (<6/12-6/18) visually impaired, respectively. Being male, having less education, having Kalenjin tribal origin, and being ≥80 years old were associated with increased blindness prevalence. Prevalence estimates were comparable to a RAAB performed in the same area 2 years earlier.

CONCLUSIONS

This survey provides reliable estimates of blindness and VI prevalence in Nakuru. Older age and tribal origin were identified as predictors of these conditions. This survey validates the use of RAAB as a method of estimating blindness and VI prevalence.

Blindness and visual impairment in an urban West African population: the Tema Eye Survey

OBJECTIVE

To determine the prevalence, causes, and risk factors of blindness and visual impairment among persons aged 40 years or older residing in an urban West African location.

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

A total of 5603 participants residing in Tema, Ghana.

METHODS

Proportionate random cluster sampling was used to select participants aged 40 years or older living in the city of Tema. Presenting distance visual acuity (VA) was measured at 4 and 1 m using a reduced logarithm of the minimum angle of resolution tumbling E chart and then with trial frame based on autorefraction. A screening examination was performed in the field on all participants. Complete clinical examination by an ophthalmologist was performed on participants with best-corrected visual acuity (BCVA) <20/40 or failure of any screening test.

MAIN OUTCOME MEASURES

Age- and gender-specific prevalence, causes, and risk factors for blindness (VA of <20/400 in the better eye, World Health Organization definition) and visual impairment (VA of <20/40 in the better eye).

RESULTS

A total of 6806 eligible participants were identified, of whom 5603 (82.3%) participated in the study. The mean age (± standard deviation) of participants was 52.7 ± 1 0.9 years. The prevalence of visual impairment and blindness was 17.1% and 1.2%, respectively. After refraction and spectacle correction, the prevalence of visual impairment and blindness decreased to 6.7% and 0.75%, respectively, suggesting that refractive error is the major correctable cause of visual impairment and blindness in this population. Of 65 subjects with a VA <20/400, 22 (34%) were correctable with refraction, 21 to the level of visual impairment and 1 to normal. The remaining 43 patients (66%) had underlying pathology (cataract in 19, glaucoma in 9, nonglaucomatous optic neuropathy in 3, corneal opacities in 3, retinal disease in 3, and undetermined in 5) that prevented refractive correction. Increased age was a significant risk factor for blindness and visual impairment.

CONCLUSIONS

There is a high prevalence of blindness and visual impairment among those aged ≥ 40 years in Tema, Ghana, West Africa. Refractive error is a major cause of blindness and visual impairment in this population, followed by cataract, glaucoma, and corneal disease.

Prevalence and causes of blindness and visual impairment in sokoto state, Nigeria: baseline data for vision 2020: the right to sight eye care programme

Purpose:

To estimate the prevalence of low vision and blindness, identify the causes, and suggest policies for an effective eye care program based on 2005 data from Sokoto State, Nigeria.

Materials and Methods:

A stratified two-stage cluster sampling method was used to quantify the prevalence of blindness and the causes from 4 health zones in Sokoto State. Subjects were evaluated using a magnifying loupe, direct ophthalmoscope and torchlight. Data were collected based on the World Health Organization prevention of blindness coding for an eye examination. Prevalences with 95% confidence intervals (CI) were calculated and surgical coverage for causes of blindness was also analyzed.

Results:

The response rate was 91%. The prevalence of bilateral blindness was 1.9% (95% CI: 1.5–2.3%) ranging from 1.6% to 2.0% across the four health zones. The prevalence was 2.1% (95% CI: 1.6–2.6%) in males and 1.6% (95% CI: 1.1–2.1%) in females. The leading cause of bilateral blindness was cataract (51.6%), followed by uncorrected aphakia (20.9%) and glaucoma (11%). The prevalence of bilateral operable cataract was 1.9% (95% CI: 1.5–2.3%). The cataract surgical coverage (individuals with visual acuity <6/60) for the study was lower than the couching coverage (4.4% vs. 14.9%, respectively). Surgical coverage for trichiasis was 4.4%. The major barrier to cataract and glaucoma management was cost.

Conclusions:

The prevalence of blindness in Sokoto State is high yet the main causes are largely avoidable. Barriers can be reduced by appropriate health education regarding the eye care program and the provision of integrated, sustainable, affordable and equitable services.

Prevalence of blindness in people over 40 years in the volta region of ghana

SummaryIn 2001, we conducted a population-based cluster survey of the prevalence of blindness and glaucoma in three districts of the Volta region of Ghana, West Africa. A secondary purpose was to assess the presenting visual acuities of individuals who had undergone extracapsular cataract extraction with an intraocular lens implant (ECCE/IOL) and intracapsular cataract extraction (ICCE). The target population consisted of 2400 adults, aged 40 years and older, of whom, 2298 (95.7%) were examined. The prevalence of moderate to severe bilateral blindness was found to be 4.4 %. The main causes of blindness were cataract and glaucoma (53.9% and 20.6%, respectively). Eighty-one percent of the blind had preventable or treatable causes. Nine percent of the population >/=40 years needed cataract surgery in one or both eyes for vision </=6/18. The corrected prevalence of glaucoma in one or both eyes was 7.5%. There were 51 individuals who had undergone cataract surgery, all of whom had been operated in Ghana. Those who had ECCE/IOL surgery had a presenting visual acuity of 20/60 or better in 65% of eyes while those who had ICCE surgery achieved this level in only 30% of eyes [p=0.02].

Targeting CYP450 modulation to decrease the risk of induced cataract in the experimental model

Background:

Diabetes is one of the major causes of cataract. Some drugs prescribed for the treatment of diabetes are the modulators of CYP450, which may alter the risk of cataract.

Objective:

To study the effect of CYP450 modulation in galactosemic cataract.

Materials and Methods:

Male Sprague-Dawley suckling rats were allotted to four groups (n = 6), as follows: Group 1: Normal control, Group 2: Galactose control, Group 3: CYP450 inhibitor pretreated and Group 4: CYP450 inducer pretreated. Cataract was induced in animals of all groups except group 1 by feeding them galactose (50%), 21 days after parturition. From the eighteenth day of life, CYP450 inhibitor (nifedipine; 8.1 mg/kg) and CYP450 inducer (pioglitazone; 3.8 mg/kg) were given orally to groups 3 and 4, respectively. The maturation pattern of the cataract was observed by an operating microscope, every third day. Biochemical changes in the lenses of all groups, for example, CYP450 activity expressed as µM NADPH oxidized / unit time, alterations in the levels of total proteins, soluble proteins, and reduced glutathione (GSH) following the induction of cataract, were estimated.

Results:

The microscopic examination of the lenses indicated that CYP450 inhibitor pre-treatment delayed (fourteenth day) the occurrence of cataract, while CYP450 inducer pretreatment demonstrated an early (ninth day) cataract as compared to galactose control rats (twelfth day). A significant decrease and increase in CYP450 activity was observed with the CYP450 inhibitor and inducer pre-treatment, respectively. There was no alteration in the GSH level, but a significant increase in total and soluble protein was found in groups 3 and 4 as compared to group 2.

Conclusion:

CYP450 may have a role in the initiation of cataract without any effect on the maturation pattern, as revealed by the delayed occurrence of cataract with the CYP450 inhibitor and an early onset of cataract with the CYP450 inducer.

Effect of Aqueous Extract of Embelica officinalis on Selenite Induced Cataract in Rats

Cataract is clouding of the eye lens that reduces the amount of incoming light and results in deteriorating vision. Blindness is thought to reach 75 million by 2020. Of these, unoperated cataract may be expected to account for at least 35 million. Thus, the burden of cataract is increasing remorselessly. Embelica officinalis is reported to have a very good antioxidant property and thus we hypothesized that it could be a good candidate in treatment of cataract. Hence, the aim of this study was to investigate the effect of aqueous extract of Embelica officinalis on selenite induced cataract in rats. For the purpose of this study, cataract was induced in young suckling (on the 10(th) day of life) albino wistar rats using sodium selenite (a single dose of sodium selenite; 20μM/kg; subcutaneously). After induction of cataract, the test drug (Embelica Officinalis) and the reference standard (ascorbic acid) were administered orally for 18 days. The progression or disappearance of cataract was observed with the help of an ophthalmoscope (OM-18, Takagi resolution 1.6). At the end of this study the alterations in the levels of total protein, soluble protein, reduced glutathione and malondialdehyde were estimated in the lens homogenate. Results showed that treatment with Embelica officinalis, as well as ascorbic acid, produced a significant decrease (p < 0.05) in malondialdehyde and a simultaneous increase in lens glutathione levels (p < 0.05). The malondialdehyde content was decreased by 48% in animals treated with Embelica officinalis. Similarly, lens glutathione was increased by 82.5% in animals treated with Embelica officinalis. There was also a significant (p < 0.05) increase in protein content (total protein = 59.36% and soluble protein = 105.78%) in animals treated with Embelica officinalis, indicating improvement in cataractogenic condition in the selenite induced cataract model. At the end of the treatment, disappearance of cataract was observed in test and standard treated animals. In conclusion, it could be said that aqueous extract of Embelica officinalis delayed the progression of cataract in sodium selenite induced cataractogenic rats.

National Registry for the Blind in Israel: Estimation of prevalence and incidence rates and causes of blindness

OBJECTIVE

To describe the population registered as blind in Israel and estimate the prevalence and incidence of blindness, by age, sex and the causes of blindness.

METHODS

Israel has maintained a Registry for the Blind since 1987. Patients are identified by ophthalmologists and registered if they have a visual acuity of < or = 0.05 (20/400) or a visual field of < 20 degrees radius in their better eye. The Registry consists of all eligible citizens living in Israel at the time of registration. This report includes prevalence data on 18,891 persons enrolled in the Registry from 1987-1999 and still alive and living in Israel in 1999, and incidence data on 2,511 persons newly registered in 1999. Data were collected on visual acuity and visual field loss, cause of blindness, and patient demographics.

RESULTS

In 1999, the estimated prevalence rate of blindness nationwide was 0.31% and the estimated incidence rate was 0.037%. The major causes of blindness in the complete Registry were age related macular degeneration (AMD) and glaucoma (14%), followed by diabetic retinopathy (11%), cataract and myopic maculopathy (10%), and optic atrophy (8.4%). The leading causes of newly diagnosed blindness were age-related macular degeneration (AMD) (20%), glaucoma (14%), diabetic retinopathy (12%), myopic maculopathy (11%), and optic atrophy and cataract (10%).

CONCLUSIONS

Israel has one of the few nationwide blindness registries in the world. The prevalence and incidence of blindness in Israel appear to be comparable to other western countries. Comparisons are difficult because of different definitions of blindness, age distributions, and the uniqueness of the Israeli Registry.

Visual impairment from age-related cataract among an indigenous African population

AIM

To determine the magnitude of visual impairment (VI) resulting from lens opacity/cataract among a rural population in southwestern Nigeria.

METHOD

A population-based cross-sectional survey using a multistage sampling method to select subjects >or=50 years. Participants with pinhole visual acuity of <or=6/18 in their better eye, exclusively from lens opacity/cataract, were further examined by an ophthalmologist. Their level of VI was categorised using the International Classification of Disease tenth revision and lens opacity was graded using the World Health Organization's cataract grading system.

RESULTS

From the enumerated population of 1200 subjects, 1031 subjects were examined. The prevalence of VI from cataract/lens opacity in the population studied was 11.9% (95% CI: 10.1-14.0) with a cataract blindness prevalence of 2.0% (95% CI: 1.3-3.0). The odds for VI increased with increasing age and female patients had 1.6 times the odds for cataract blindness than did male patients. Mixed cataract was the most prevalent of the visually disabling cataract. (3.9% (95% CI: 2.8-5.2)), whereas posterior subcapsular cataract was the least prevalent (2.5% (95% CI: 1.7-3.7)).

CONCLUSION

VI from cataract remains a public health problem in the Akinyele district of Nigeria. The need for a comprehensive cataract surgical service using the VISION 2020 model is necessary in the district if the burden from the backlog of visually disabling cataract is to be reduced.

The Nigerian national blindness and visual impairment survey: Rationale, objectives and detailed methodology

Background

Despite having the largest population in Africa, Nigeria has no accurate population based data to plan and evaluate eye care services. A national survey was undertaken to estimate the prevalence and determine the major causes of blindness and low vision. This paper presents the detailed methodology used during the survey.

Methods

A nationally representative sample of persons aged 40 years and above was selected. Children aged 10–15 years and individuals aged <10 or 16–39 years with visual impairment were also included if they lived in households with an eligible adult. All participants had their height, weight, and blood pressure measured followed by assessment of presenting visual acuity, refractokeratomery, A-scan ultrasonography, visual fields and best corrected visual acuity. Anterior and posterior segments of each eye were examined with a torch and direct ophthalmoscope. Participants with visual acuity of < = 6/12 in one or both eyes underwent detailed examination including applanation tonometry, dilated slit lamp biomicroscopy, lens grading and fundus photography. All those who had undergone cataract surgery were refracted and best corrected vision recorded. Causes of visual impairment by eye and for the individual were determined using a clinical algorithm recommended by the World Health Organization. In addition, 1 in 7 adults also underwent a complete work up as described for those with vision < = 6/12 for constructing a normative data base for Nigerians.

Discussion

The field work for the study was completed in 30 months over the period 2005–2007 and covered 305 clusters across the entire country. Concurrently persons 40+ years were examined to form a normative data base. Analysis of the data is currently underway.

Conclusion

The methodology used was robust and adequate to provide estimates on the prevalence and causes of blindness in Nigeria. The survey would also provide information on barriers to accessing services, quality of life of visually impaired individuals and also provide normative data for Nigerian eyes.

Prevalence and causes of blindness and low vision in southern Sudan

BACKGROUND

Blindness and low vision are thought to be common in southern Sudan. However, the magnitude and geographical distribution are largely unknown. We aimed to estimate the prevalence of blindness and low vision, identify the main causes of blindness and low vision, and estimate targets for blindness prevention programs in Mankien payam (district), southern Sudan.

METHODS AND FINDINGS

A cross-sectional survey of the population aged 5 y and above was conducted in May 2005 using a two-stage cluster random sampling with probability proportional to size. The Snellen E chart was used to test visual acuity, and participants also underwent basic eye examination. Vision status was defined using World Health Organization categories of visual impairment based on presenting visual acuity (VA). A total of 2,954 persons were enumerated and 2,499 (84.6%) examined. Prevalence of blindness (presenting VA of less than 3/60 in the better eye) was 4.1% (95% confidence interval [CI], 3.4-4.8); prevalence of low vision (presenting VA of at least 3/60 but less than 6/18 [corrected] in the better eye) was 7.7% (95% CI, 6.7-8.7); whereas prevalence of monocular visual impairment (presenting VA of at least 6/18 [corrected] in better eye and VA of less than 6/18 [corrected] in other eye) was 4.4% (95% CI, 3.6-5.3). The main causes of blindness were considered to be cataract (41.2%) and trachoma (35.3%), whereas low vision was mainly caused by trachoma (58.1%) and cataract (29.3%). It is estimated that in Mankien payam 1,154 persons aged 5 y and above (lower and upper bounds = 782-1,799) are blind, and 2,291 persons (lower and upper bounds = 1,820-2,898) have low vision.

CONCLUSIONS

Blindness is a serious public health problem in Mankien, and there is urgent need to implement comprehensive blindness prevention programs. Further surveys are essential to confirm these tragic findings and estimate prevalence of blindness and low vision in the entire region of southern Sudan in order to facilitate planning of VISION 2020 objectives.

Prevalence and causes of blindness and visual impairment in Muyuka: a rural health district in South West Province, Cameroon

AIM

To estimate the prevalence and causes of blindness and visual impairment in the population aged 40 years and over in Muyuka, a rural district in the South West Province of Cameroon.

METHODS

A multistage cluster random sampling methodology was used to select 20 clusters of 100 people each. In each cluster households were randomly selected and all eligible people had their visual acuity (VA) measured by an ophthalmic nurse. Those with VA <6/18 were examined by an ophthalmologist.

RESULTS

1787 people were examined (response rate 89.3%). The prevalence of binocular blindness was 1.6% (95% CI: 0.8% to 2.4%), 2.2% (1.% to 3.1%) for binocular severe visual impairment, and 6.4% (5.0% to 7.8%) for binocular visual impairment. Cataract was the main cause of blindness (62.1%), severe visual impairment (65.0%), and visual impairment (40.0%). Refractive error was an important cause of severe visual impairment (15.0%) and visual impairment (22.5%). The cataract surgical coverage for people was 55% at the <3/60 level and 33% at the <6/60 level. 64.3% of eyes operated for cataract had poor visual outcome (presenting VA<6/60).

CONCLUSIONS

Strategies should be developed to make cataract services affordable and accessible to the population in the rural areas. There is an urgent need to improve the outcome of cataract surgery. Refractive error services should be provided at the community level.

Temporal cytokine gene expression patterns in subjects with trachoma identify distinct conjunctival responses associated with infection

Ocular chlamydial disease is clinically diagnosed by the appearance of characteristic inflammatory changes and development of lymphoid follicles in the conjunctiva. Nucleic acid amplification tests and relatively non-invasive methods of sampling the conjunctival surface can be used to quantify the expression of chlamydial and host genes. Using quantitative real-time polymerase chain reaction to detect the presence of Chlamydia trachomatis (CT) 16S rRNA and human interleukin (IL)-1beta, IL-10, IL-12p40, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha transcripts we examined the immune response at the conjunctival surface in a cohort of children living in a trachoma-endemic village in The Gambia. Elevated cytokine transcript levels were associated with the presence of CT 16S rRNA. Subclinical infection (CT infection without clinical signs of disease) elicited an immune response that is proinflammatory in nature, with elevations in the transcription of IL-1beta, IFN-gamma and IL-12p40. Clinically apparent infections were associated with the elevation of mRNA for the multi-functional cytokine TNF-alpha (fibrotic, type 1 inflammatory and regulatory) and the counter regulatory cytokine, IL-10, in addition to the other proinflammatory cytokines. A positive correlation between IFN-gamma transcript levels and the amount of CT 16S rRNA expressed in conjunctiva was found.

Causes of blindness and the results of cataract surgical intervention in the Micronesian islands: a retrospective study

Since 1983, we have delivered eye care to inhabitants of the Micronesia islands a total of 18 times over an 18-year period. Approximately 14,000 islanders were examined. We diagnosed a total of 1226 blind eyes and 1231 eyes with low vision. Unoperated cataract (n = 765, 62.4%) was the leading cause of blindness in our data, and 611 cataract operations were performed. The preoperative visual acuity of the patients who underwent cataract surgery was less than 20/200. Visual acuity improved in 588 cases (96.2%) after the surgery. Sight-threatening complications occurred in 1.1% (7) of the eyes after the surgery, which is comparable to the rate in developed countries. Corneal opacity secondary to infection (11.2%) was the second leading cause of blindness in our data. Diabetic retinopathy (9.9%) was a cause of low vision in our data, and the number of eyes diagnosed with diabetic retinopathy in each district increased over the years. Glaucoma was the cause of blindness in 1.9% of the blind eyes, although the percentage may actually have been higher because visual loss was assessed only by reduced visual acuity. The demand for correcting refractive errors that caused a visual acuity of less than 20/60, was evident throughout the region. The majority of blind individuals in this study were suffering from operable cataract and good results were obtained with cataract surgery in this region. Further training of local medical staff would significantly improve eye care services in Micronesia.

Current problems of perinatal Chlamydia trachomatis infections

Chlamydia trachomatis has been recognized as a pathogen of trachoma, nongonococcal urethritis, salpingitis, endocervicitis, pelvic inflammatory disease, inclusion conjunctivitis of neonates, follicular conjunctivitis of adults, infantile pneumonia and associated conditions. Chlamydial infections during pregnancy may also cause a variety of perinatal complications. Different antigenic strains of C. trachomatis from endocervical, nasopharyngeal and conjunctival origins have been associated with different clinical conditions. Control programs emphasizing early diagnosis, targeted screening, and effective treatment will lead to an eventual decline in the incidence of perinatal chlamydial infection. This review focuses on current problems of perinatal C. trachomatis infections in the aspects of microbiological and immunological pathogenesis.

Trachoma

Trachoma is the most common infectious cause of blindness. It is caused by ocular serovars of Chlamydia trachomatis. Transmission is favoured in poor communities, where crowding is common and access to water and sanitation inadequate. Repeated reinfection over many years causes dense scarring of the upper eyelid. The resultant inversion of the lashes abrades the eyeball, and the abrasion leads to corneal opacification and visual impairment. The host immune response is probably at least partly the cause of this process. The "SAFE" strategy is used for the control of trachoma: surgery for in-turned lashes, antibiotics for active disease, facial cleanliness, and environmental improvement. The demonstration that a single oral dose of the antibiotic azithromycin is as effective as 6 weeks of topical tetracycline was an important advance in trachoma control. By means of the SAFE strategy, WHO and its partners aim to eliminate trachoma as a public-health problem by the year 2020.

Blindness: how to assess numbers and causes?

BACKGROUND

Traditionally, blindness surveys have modelled themselves on the "gold standard" of a census and examination of a whole population. Blindness, however, is a relatively rare condition even in badly affected communities; hence, large sample sizes are required to gain adequate estimates of prevalence, particularly by cause.

METHODS

Three assessments of blindness prevalence and aetiology in the same communities are reported. One involved asking individuals questions concerning their visual status during a census (perceived visual status, PVD), one involved examination of all ostensibly visually disabled people presenting to a central point within each community (examination of the visually disabled, EVD), and the final assessment involved a gold standard examination of the whole population (whole community examination, WCE).

RESULTS

In a population of 8139 the blindness prevalence was 2.7% PVS, 3.6% EVD, and 3.1% WCE. Attributed causes of blindness were not representative in the PVS except for cataract. The END yielded cause specific estimates not far from those found at WE except for a relative under-representation of glaucoma and optic atrophy.

CONCLUSION

Since cataract is, by a significant margin, the most common cause of blindness in the world such a simple method as asking individuals if they are blind and what they believe to be the cause may yield adequate estimates of the problem for planning eye care strategies for this condition. Alternatively, an ophthalmologist visiting villages and examining allcomers for visual disability may provide reasonably accurate cause specific prevalence estimates without the expense of a major blindness survey.

Paediatric cataract blindness in the developing world: surgical techniques and intraocular lenses in the new millennium

Paediatric cataract blindness presents an enormous problem to developing countries in terms of human morbidity, economic loss, and social burden. Managing cataracts in children remains a challenge: treatment is often difficult, tedious, and requires a dedicated team effort. To assure the best long term outcome for cataract blind children, appropriate paediatric surgical techniques need to be defined and adopted by ophthalmic surgeons of developing countries. The high cost of operative equipment and the uneven world distribution of ophthalmologists, paediatricians, and anaesthetists create unique challenges. This review focuses on issues related to paediatric cataract management that are appropriate and suitable for ophthalmic surgeons in the developing world. Practical guidelines and recommendations have also been provided for ophthalmic surgeons and health planners dealing with childhood cataract management in the developing world.

Survey of glaucoma in an eye clinic in Ghana, West Africa

PURPOSE

To report the various types of glaucoma among West African patients presenting to an eye clinic in Ghana.

METHODS

A complete evaluation was performed in 198 consecutive Ghanaian glaucoma patients. Main outcome measures included intraocular pressure, visual acuity, gonioscopy findings, visual field, and total number of glaucoma medications.

RESULTS

The most common form of glaucoma was primary open-angle glaucoma (44.2%). Open-angle glaucoma suspects also comprised a large percentage of the group (30.5%). Chronic angle-closure glaucoma was diagnosed in 6.6% of the patients.

CONCLUSIONS

Primary open-angle glaucoma is the most common form of glaucoma being treated in this outpatient eye clinic in Ghana. Chronic angle-closure glaucoma was the second most common form of glaucoma in this series and was usually undiagnosed due to a lack of gonioscopic evaluation. Gonioscopy is an important diagnostic tool that should be promoted to guide more effective glaucoma treatment in this region. Pseudoexfoliation and pseudoexfoliation-associated glaucoma were not seen in this population.

A survey of visual impairment in children attending the Royal Blind School, Edinburgh using the WHO childhood visual impairment database

PURPOSE

To assess the aetiology and changing patterns of childhood blindness in one school for the blind in the UK and to assess the use of the World Health Organisation Prevention of Blindness (WHO/PBL) methodology and reporting form in a developed country.

METHODS

One hundred and seven children in one school for the blind and visually impaired in Edinburgh were examined using the WHO/PBL childhood blindness assessment form.

RESULTS

Of the 107 children examined, 87 (81%) were blind or severely visually impaired (corrected visual acuity of <6/60 (20/200) in the better eye). Perinatal related blindness (40%), hereditary disease (26%) and developmental factors (26%) formed the three largest aetiological categories.

CONCLUSION

The pattern of childhood blindness seen in this study was similar to reports from other developed countries. The WHO/PBL reporting form allows detailed comparisons between countries and over time. Additional fields for more detailed reporting of cerebral visual impairment and associated handicaps would increase the usefulness of the WHO/PBL form for population-based studies and for use in developed countries.

Visual loss in urban and rural chronic glaucoma patients in Ghana

The visual acuity of newly diagnosed glaucoma patients in a rural and an urban area were compared in a hospital-based cross-sectional study in Ghana. Age at presentation was strikingly higher in the rural group due to local factors which result in a difference-in-age structure of the rural and urban population. The crude relative frequency of bilateral blindness was significantly higher for rural than urban. However, with age adjusted relative frequencies for bilateral blindness there was no significant difference between rural and urban patients. There was significant difference between them for those aged 51-71 when blindness in one or both eyes were considered together. There was more consistent blindness in the rural community: the difference was attributed to local factors such as better access to eye care in the urban group.

Blindness in Africa: present situation and future needs

AIM

To review the prevalence and causes of blindness in sub-Saharan Africa, the existing services and limitations, and the Vision 2020 goals for the future.

METHODS

Methodologically sound population based surveys published in the past 20 years are reviewed and results for prevalence and causes of blindness are tabulated. The current resources and needs according to recent publications and international working groups are described.

CONCLUSIONS

Blindness prevalence rates vary widely but the evidence suggests that approximately 1% of Africans are blind. The major cause is cataract; trachoma and glaucoma are also important causes of blindness. The bulk of blindness in the region is preventable or curable. Efforts should focus on eye problems which are universally present and for which there are cost effective remedies, such as cataract and refractive problems and on those problems which occur focally and can be prevented by primary healthcare measures, such as trachoma, onchocerciasis, and vitamin A deficiency. Major development of staffing levels, infrastructure, and community programmes will be necessary to achieve Vision 2020 goals.

Assessment of trachoma prevalence in a mobile population in Central Australia

Trachoma is reported to be hyperendemic in Australia. This study was conducted in a desert area of Central Australia to implement and evaluate the WHO SAFE strategy to control trachoma. The aim of the study was to obtain baseline trachoma prevalence data and to determine whether a single annual visit is adequate for a treatment program targeting households with active cases in a highly mobile population. All registered residents of two Aboriginal communities were eligible for examination. Four visits over the course of 13 months were made to the communities for ocular examinations of residents present at the time of the visit. Examination, diagnosis, and grading of trachoma followed WHO guidelines. The overall examination rate was 75%, refusal rate was <1%, but approximately 50% of community residents were absent during the examination period. Prevalence varied on each visit, but the overall prevalence of active trachoma was 49% over the 13-month period. Children less than 10 years of age had the highest prevalence of active trachoma (79%), over the course of the 13 months, yet the prevalence at any one visit was approximately 60%. Trachomatous scarring was present in 23% of the population. These results suggest that many cases of active trachoma may be missed if a prevalence survey is conducted at only one point in time. Multiple examinations should be conducted to adequately establish prevalence in the population. Antibiotic treatment and health promotion campaigns need to be developed in consideration of local community dynamics.

Results of cataract surgery in young children in east Africa

BACKGROUND

Cataract is the leading cause of blindness in children in east Africa. The results of surgery are poor, partly because of inadequate correction of aphakia.

METHODS

A retrospective survey of 118 eyes in 71 children with bilateral cataract. All eyes had implantation of an IOL at the time of cataract surgery. The average age at surgery was 3.5 years. 28 patients(39%) were less than 2 years old at the time of surgery on their first eye.

RESULTS

Preoperatively, 75.4% of eyes and 76.1% of patients were blind. A follow up of at least 3 months was available in 91 (77.1%) eyes. In these eyes, 44% had a latest corrected vision of 6/18 or better and 91.2% had a latest corrected vision of 6/60 or better. Eyes with zonular cataract, and eyes operated after the age of 2 years were more likely to obtain a vision of 6/18 or better. 3.3% of eyes and 1.8% of patients had an acuity of less than 3/60. Nystagmus was present in 42.3% of patients before surgery. In those patients followed up for a minimum of 6 months, 10.2% still had nystagmus. The most frequent complication was severe fibrinous uveitis, which occurred in 36 (30.5%) eyes. 62 (52.5%) eyes had a posterior capsulotomy at the time of cataract extraction. Of the remaining 56 eyes, 20 (35.7%) had so far required a posterior capsulotomy. The leading cause of poor visual outcome was amblyopia. Two patients developed severe complications related to the intraocular lens.

CONCLUSIONS

Insertion of a lens implant at the time of cataract extraction appears to be well tolerated in the short term, and may offer significant advantages in an African setting.

Gender and blindness: a meta-analysis of population-based prevalence surveys

BACKGROUND

Many individual surveys of blindness have reported slightly higher rates of blindness for women. In order to gain a continent-by-continent and global sense of the burden of blindness by sex we conducted a meta-analysis of published, population-based surveys of blindness.

METHOD

Published reports were collected using a predetermined search protocol involving commercial electronic databases, hand-searching of references and direct contact with researchers. Studies were included that were population-based, included clinical examination and had a minimum sample size of 1000. The studies were critically appraised to determine methodological rigour. Data were analysed using the Cochrane Collaboration Review Manager.

RESULTS

The overall odds ratio (age-adjusted) of blind women to men is 1.43 (95% CI 1.33-1.53), ranging from 1.39 (95% CI 1.20-1.61) in Africa, 1.41 (95% CI 1.29-1.54) in Asia, and 1.63 (95% CI 1.30-2.05) in industrialised countries. There was good homogeneity of findings from Africa, Asia, and the industrialised countries. Globally, women bear excess blindness compared to men. In these surveys, overall, women account for 64.5% of all blind people. The excess of blindness in women was marked among the elderly and not due only to differential life expectancy.

CONCLUSION

The excess burden of blindness among women is likely due to a number of factors, which are different in industrialised countries compared to developing countries. Particular attention to gender differences in blindness is needed in the creation of targets for blindness reduction and in the development of interventions.