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1.  Risk factors for open-angle glaucoma in Nigeria: results from the Nigeria National Blindness and Visual Impairment Survey 
BMC Ophthalmology  2016;16:78.
Background
The glaucoma-specific blindness prevalence in Nigeria (0.7 %, 95 % CI 0.6–0.9 %) among those aged ≥40 years is one of the highest ever reported. This study determined the risk factors for open-angle glaucoma (OAG) in adults examined in the Nigeria National Blindness and Visual Impairment Survey.
Methods
A nationally representative sample of 13,591 people aged ≥40 years in 305 clusters in Nigeria were examined (response rate 90.4 %) between January 2005 to June 2007. Everyone had logMAR visual acuity measurement, Frequency Doubling Technology (FDT) visual field testing, autorefraction, A-scan biometry and optic disc assessment. Full ocular examination (n = 6397), included Goldmann applanation tonometry. Values for defining glaucoma using International Society of Geographical and Epidemiological Ophthalmology criteria were derived from the study population. Disc images were graded by Moorfields Eye Hospital Reading Centre. Socio-demographic factors (age, gender, ethnicity, literacy and place of residence), ocular parameters (intraocular pressure [IOP], axial length and mean ocular perfusion pressure [MOPP]) and systemic parameters (blood pressure, blood glucose and body mass index [BMI]) were assessed for association with OAG.
Results
Thirteen thousand eighty-one (96 %) of 13,591 participants had vertical cup:disc ratio measured in at least one eye. 682 eyes of 462 participants were classified as OAG, with 12,738 controls. In univariate analyses the following were associated with OAG: increasing age, male gender, Igbo and Yoruba ethnic groups, illiteracy, longer axial length, higher IOP, lower MOPP, greater severity of hypertension and low BMI (underweight). In multivariate analysis, increasing age (odds ratio [OR] 1.04, 95 % CI 1.03–1.05), higher IOP (OR 1.22, 95 % CI 1.18–1.25) and Igbo ethnicity (OR 1.73, 95 % CI 1.18–2.56) were independent risk factors for OAG.
Conclusion
Case detection strategies for OAG should be improved for those aged ≥40 years and for ethnic groups most at risk as a public health intervention.
doi:10.1186/s12886-016-0264-7
PMCID: PMC4895902  PMID: 27267038
Open-angle glaucoma; Risk factors; Ethnicity; Nigeria
2.  So let me find my way, whatever it will cost me, rather than leaving myself in darkness: experiences of glaucoma in Nigeria 
Global Health Action  2016;9:10.3402/gha.v9.31886.
Background
Blindness from glaucoma is associated with socio-economic deprivation, presumed to reflect poor access to care and poor adherence to treatment.
Objectives
To determine why people with glaucoma are presenting late for treatment and to understand access to glaucoma care. Additionally, we sought to identify what patients and the community know, do and think about the condition and why the poor are the most affected with glaucoma blindness.
Design
Study participants were from four communities and two hospitals in Abuja-FCT and Kaduna State, Nigeria. A total of 120 participants were involved, including 8 focus group discussions, 7 in-depth interviews with blind/visually impaired glaucoma patients, 5 rapid direct observation visits with these patients and 13 exit interviews of glaucoma patients in the hospital. The data were analysed using content analysis, interpreting participant experiences in terms of three key steps conceptualised as important in the care pathway: what it takes to know glaucoma, to reach a diagnosis and to access continued care.
Results
This article presents multiple narratives of accessing and maintaining glaucoma care and how people manage and cope with the disease. People may be presenting late due to structural barriers, which include lack of knowledge and awareness about glaucoma and not finding an appropriately equipped health care facility. What keeps glaucoma patients within the care pathway are a good hospital experience; a support structure involving family, counselling and shared patients’ experiences; and an informed choice of treatment, as well as agency. The high cost of purchasing care is a major factor for patients dropping out of treatment.
Conclusion
The findings suggest the need to address economic and social structural drivers as glaucoma presents another case study to demonstrate that poverty is a strong driver for blindness. There is also a need for clear glaucoma care pathways with early case finding in the community, two-way referral/feedback systems, well-equipped glaucoma care hospitals and better eye health care financing.
doi:10.3402/gha.v9.31886
PMCID: PMC5141371  PMID: 27924740
glaucoma; blindness; vision loss; late diagnosis; early detection; care pathway; Nigeria
3.  A Population-based survey of the prevalence and types of glaucoma in Nigeria: results from the Nigeria National Blindness and Visual Impairment Survey 
BMC Ophthalmology  2015;15:176.
Background
Glaucoma is the leading cause of irreversible blindness worldwide. There tends to be a lower reporting of glaucoma in Africa compared to other blinding conditions in global burden data. Research findings of glaucoma in Nigeria will significantly increase our understanding of glaucoma in Nigeria, in people of the West African diaspora and similar population groups. We determined the prevalence and types of glaucoma in Nigeria from the Nigeria National Blindness and Visual Impairment cross-sectional Survey of adults aged ≥40 years.
Methods
Multistage stratified cluster random sampling with probability-proportional-to-size procedures were used to select a nationally representative sample of 15,027 persons aged ≥40 years. Participants had logMAR visual acuity measurement, FDT visual function testing, autorefraction, A-scan biometry and optic disc assessment. Participants with visual acuity of worse than 6/12 or suspicious optic discs had detailed examination including Goldmann applanation tonometry, gonioscopy and fundus photography. Disc images were graded by Moorfields Eye Hospital Reading Centre. Glaucoma was defined using International Society of Geographical and Epidemiological Ophthalmology criteria; and classified into primary open-angle or primary angle-closure or secondary glaucoma. Diagnosis of glaucoma was based on ISGEO classification. The type of glaucoma was determined by gonioscopy.
Results
A total of 13,591 participants in 305 clusters were examined (response rate 90.4 %). Optic disc grading was available for 25,289 (93 %) eyes of 13,081 (96 %) participants. There were 682 participants with glaucoma; a prevalence of 5.02 % (95 % CI 4.60–5.47). Among those with definite primary glaucoma that had gonioscopy (n = 243), open-angle glaucoma was more common (86 %) than angle-closure glaucoma (14 %). 8 % of glaucoma was secondary with the commonest causes being couching (38 %), trauma (21 %) and uveitis (19 %). Only 5.6 % (38/682) of participants with glaucoma knew they had the condition. One in every 5 persons with glaucoma (136;20 %) was blind i.e., visual acuity worse than 3/60.
Conclusion
Nigeria has a high prevalence of glaucoma which is largely open-angle glaucoma. A high proportion of those affected are blind. Secondary glaucoma was mostly as a consequence of procedures for cataract. Public health control strategies and high quality glaucoma care service will be required to reduce morbidity and blindness from glaucoma.
doi:10.1186/s12886-015-0160-6
PMCID: PMC4676891  PMID: 26653326
Prevalence; Glaucoma; Epidemiology; Nigeria; Open-angle glaucoma; Angle-closure glaucoma
4.  Genetic and Dietary Factors Influencing the Progression of Nuclear Cataract 
Ophthalmology  2016;123(6):1237-1244.
Purpose
To determine the heritability of nuclear cataract progression and to explore prospectively the effect of dietary micronutrients on the progression of nuclear cataract.
Design
Prospective cohort study.
Participants
Cross-sectional nuclear cataract and dietary measurements were available for 2054 white female twins from the TwinsUK cohort. Follow-up cataract measurements were available for 324 of the twins (151 monozygotic and 173 dizygotic twins).
Methods
Nuclear cataract was measured using a quantitative measure of nuclear density obtained from digital Scheimpflug images. Dietary data were available from EPIC food frequency questionnaires. Heritability was modeled using maximum likelihood structural equation twin modeling. Association between nuclear cataract change and micronutrients was investigated using linear and multinomial regression analysis. The mean interval between baseline and follow-up examination was 9.4 years.
Main Outcome Measures
Nuclear cataract progression.
Results
The best-fitting model estimated that the heritability of nuclear cataract progression was 35% (95% confidence interval [CI], 13–54), and individual environmental factors explained the remaining 65% (95% CI, 46–87) of variance. Dietary vitamin C was protective against both nuclear cataract at baseline and nuclear cataract progression (β = −0.0002, P = 0.01 and β = −0.001, P = 0.03, respectively), whereas manganese and intake of micronutrient supplements were protective against nuclear cataract at baseline only (β = −0.009, P = 0.03 and β = −0.03, P = 0.01, respectively).
Conclusions
Genetic factors explained 35% of the variation in progression of nuclear cataract over a 10-year period. Environmental factors accounted for the remaining variance, and in particular, dietary vitamin C protected against cataract progression assessed approximately 10 years after baseline.
doi:10.1016/j.ophtha.2016.01.036
PMCID: PMC4882156  PMID: 27016950
CI, confidence interval; DZ, dizygotic; FFQ, food frequency questionnaire; HATS, Healthy Ageing in Twins; LOCS, Lens Opacity Classification System; MZ, monozygotic; NDS, nuclear dip score; RRR, relative risk ratio; SD, standard deviation
5.  Human resources, patient load, and infrastructure at institutions providing diabetic care in India: The India 11-city 9-state study 
Background:
There is a lack of information on the practice patterns and available human resources and services for screening for eye complications among persons with diabetes in India.
Objectives:
The study was undertaken to document existing health care infrastructure and practice patterns for managing diabetes and screening for eye complications.
Methods:
This cross-sectional, hospital-based survey was conducted in 11 cities where public and private diabetic care providers were identified. Both multispecialty and standalone diabetic care facilities were included. A semi-structured questionnaire was administered to senior representative(s) of each institution to evaluate parameters using the World Health Organization health systems framework.
Results:
We interviewed physicians in 73 hospitals (61.6% multispecialty hospitals; 38.4% standalone clinics). Less than a third reported having skilled personnel for direct ophthalmoscopy. About 74% had provision for glycated hemoglobin testing. Only a third had adequate vision charts. Printed protocols on management of diabetes were available only in 31.5% of the facilities. Only one in four facilities had a system for tracking diabetics. Half the facilities reported having access to records from the treating ophthalmologists. Direct observation of the services provided showed that reported figures in relation to availability of patient support services were overestimated by around 10%. Three fourths of the information sheets and half the glycemia monitoring cards contained information on the eye complications and the need for a regular eye examination.
Conclusions:
The study highlighted existing gaps in service provision at diabetic care centers in India.
doi:10.4103/2230-8210.179769
PMCID: PMC4847444  PMID: 27144131
Diabetes; health care facilities; human resources; India; referrals
6.  Situational analysis of services for diabetes and diabetic retinopathy and evaluation of programs for the detection and treatment of diabetic retinopathy in India: Methods for the India 11-city 9-state study 
Background:
Diabetic retinopathy (DR) is a leading cause of visual impairment in India. Available evidence shows that there are more than 60 million persons with diabetes in India and that the number will increase to more than a 100 million by 2030. There is a paucity of data on the perceptions and practices of persons with diabetes and the available infrastructure and uptake of services for DR in India.
Objectives:
Assess perception of care and challenges faced in availing eye care services among persons with diabetics and generate evidence on available human resources, infrastructure, and service utilization for DR in India.
Methods:
The cross-sectional, hospital-based survey was conducted in eleven cities across 9 States in India. In each city, public and private providers of eye-care were identified. Both multispecialty and standalone facilities were included. Specially designed semi-open ended questionnaires were administered to the clients. Semi-structured interviews were administered to the service providers (both diabetic care physicians and eye care teams) and observational checklists were used to record findings of the assessment of facilities conducted by a dedicated team of research staff.
Results:
A total of 859 units were included in this study. This included 86 eye care and 73 diabetic care facilities, 376 persons with diabetes interviewed in the eye clinics and 288 persons with diabetes interviewed in the diabetic care facilities.
Conclusions:
The findings will have significant implications for the organization of services for persons with diabetes in India.
doi:10.4103/2230-8210.179770
PMCID: PMC4847445  PMID: 27144132
Access to health care; diabetes; diabetic retinopathy; India; patient care
7.  Perceptions and practices related to diabetes reported by persons with diabetes attending diabetic care clinics: The India 11-city 9-state study 
Background:
India has the second largest population of persons with diabetes and a significant proportion has poor glycemic control and inadequate awareness of management of diabetes.
Objectives:
Determine the level of awareness regarding management of diabetes and its complications and diabetic care practices in India.
Methods:
The cross-sectional, hospital-based survey was conducted in 11 cities where public and private providers of diabetic care were identified. At each diabetic care facility, 4–6 persons with diabetes were administered a structured questionnaire in the local language.
Results:
Two hundred and eighty-five persons with diabetes were interviewed. The mean duration since diagnosis of diabetes was 8.1 years (standard deviation ± 7.3). Half of the participants reported a family history of diabetes and 41.7% were hypertensive. Almost 62.1% stated that they received information on diabetes and its management through interpersonal channels. Family history (36.1%), increasing age (25.3%), and stress (22.8%) were the commonest causes of diabetes reported. Only 29.1% stated that they monitored their blood sugar levels at home using a glucometer. The commonest challenges reported in managing diabetes were dietary modifications (67.4%), compliance with medicines (20.5%), and cost of medicines (17.9%). Around 76.5% were aware of complications of diabetes. Kidney failure (79.8%), blindness/vision loss (79.3%), and heart attack (56.4%) were the commonest complications mentioned. Almost 67.7% of the respondents stated that they had had an eye examination earlier.
Conclusions:
The findings have significant implications for the organization of diabetes services in India for early detection and management of complications, including eye complications.
doi:10.4103/2230-8210.179771
PMCID: PMC4847446  PMID: 27144133
Awareness; diabetes; healthcare utilization; India; perceptions
8.  Eye care infrastructure and human resources for managing diabetic retinopathy in India: The India 11-city 9-state study 
Background:
There is a paucity of information on the availability of services for diagnosis and management of diabetic retinopathy (DR) in India.
Objectives:
The study was undertaken to document existing healthcare infrastructure and practice patterns for managing DR.
Methods:
This cross-sectional study was conducted in 11 cities and included public and private eye care providers. Both multispecialty and stand-alone eye care facilities were included. Information was collected on the processes used in all steps of the program, from how diabetics were identified for screening through to policies about follow-up after treatment by administering a semistructured questionnaire and by using observational checklists.
Results:
A total of 86 eye units were included (31.4% multispecialty hospitals; 68.6% stand-alone clinics). The availability of a dedicated retina unit was reported by 68.6% (59) facilities. The mean number of outpatient consultations per year was 45,909 per responding facility, with nearly half being new registrations. A mean of 631 persons with sight-threatening-DR (ST-DR) were registered per year per facility. The commonest treatment for ST-DR was laser photocoagulation. Only 58% of the facilities reported having a full-time retina specialist on their rolls. More than half the eye care facilities (47; 54.6%) reported that their ophthalmologists would like further training in retina. Half (51.6%) of the facilities stated that they needed laser or surgical equipment. About 46.5% of the hospitals had a system to track patients needing treatment or for follow-up.
Conclusions:
The study highlighted existing gaps in service provision at eye care facilities in India.
doi:10.4103/2230-8210.179768
PMCID: PMC4847447  PMID: 27144134
Diabetes complications; diagnostic equipment; diabetic retinopathy; health facilities; human resources; India
9.  Perception of care and barriers to treatment in individuals with diabetic retinopathy in India: 11-city 9-state study 
Background:
Diabetic retinopathy is a leading cause of visual impairment. Low awareness about the disease and inequitable distribution of care are major challenges in India.
Objectives:
Assess perception of care and challenges faced in availing care among diabetics.
Materials and Methods:
The cross-sectional, hospital based survey was conducted in eleven cities. In each city, public and private providers of eye-care were identified. Both multispecialty and standalone facilities were included. Specially designed semi-open ended questionnaires were administered to the clients.
Results:
376 diabetics were interviewed in the eye clinics, of whom 62.8% (236) were selected from facilities in cities with a population of 7 million or more. The mean duration of known diabetes was 11.1 (±7.7) years. Half the respondents understood the meaning of adequate glycemic control and 45% reported that they had visual loss when they first presented to an eye facility. Facilities in smaller cities and those with higher educational status were found to be statistically significant predictors of self-reported good/adequate control of diabetes. The correct awareness of glycemic control was significantly high among attending privately-funded facilities and higher educational status. Self-monitoring of glycemic status at home was significantly associated with respondents from larger cities, privately-funded facilities, those who were better educated and reported longer duration of diabetes. Duration of diabetes (41%), poor glycemic control (39.4%) and age (20.7%) were identified as the leading causes of DR. The commonest challenges faced were lifestyle/behavior related.
Conclusions:
The findings have significant implications for the organization of diabetes services in India.
doi:10.4103/2230-8210.179772
PMCID: PMC4847448  PMID: 27144135
Clients; diabetic retinopathy; health care utilization; India; perceptions; risk factors
10.  Is India's policy framework geared for effective action on avoidable blindness from diabetes? 
Background:
The growing burden of avoidable blindness caused by diabetic retinopathy (DR) needs an effective and holistic policy that reflects mechanisms for early detection and treatment of DR to reduce the risk of blindness.
Materials and Methods:
We performed a comprehensive health policy review to highlight the existing systemic issues that enable policy translation and to assess whether India's policy architecture is geared to address the mounting challenge of DR. We used a keyword-based Internet search for documents available in the last 15 years. Two reviewers independently assessed retrieved policies and extracted contextual and program-oriented information and components delineated in national policy documents. Using a “descriptive analytical” method, the results were collated and summarized as per themes to present status quo, gaps, and recommendations for the future.
Results:
Lack of focus on building sustainable synergies that require well laid out mechanisms for collaboration within and outside the health sector and poor convergence between national health programs appears to be the weakest links across policy documents.
Conclusions:
To reasonably address the issues of consistency, comprehensiveness, clarity, context, connectedness, and sustainability, policies will have to rely more strongly on evidence from operational research to support decisions. There is a need to involve multiple stakeholders from multiple sectors, recognize contributions from not-for-profit sector and private health service providers, and finally bring about a nuanced holistic perspective that has a voice with implementable multiple sector actions.
doi:10.4103/2230-8210.179773
PMCID: PMC4847449  PMID: 27144136
Chronic disease; diabetes; diabetic retinopathy; health policy; India
11.  Estimating the proportion of persons with diabetes developing diabetic retinopathy in India: A systematic review and meta-analysis 
Background:
Available evidence from India shows that the control of diabetes is poor in majority of the population. This escalates the risk of complications. There is no systematic review to estimate the magnitude of diabetic retinopathy (DR) in India.
Materials and Methods:
A systematic literature search was carried out in Ovid Medline and EMBASE databases using Mesh and key search terms. Studies which reported the proportion of people with diabetes with DR in a representative community population were included. Two independent reviewers reviewed all the retrieved publications. Data were extracted using a predefined form. Review Manager software was used to perform meta-analysis to provide a pooled estimate. Studies included were assessed for methodological quality using selected items from the STROBE checklist.
Results:
Seven studies (1999–2014; n = 8315 persons with diabetes) were included in the review. In the meta-analysis, 14.9% (95% confidence interval [CI] 10.7–19.0%) of known diabetics aged ≥30 years and 18.1% (95% CI 14.8–21.4) among those aged ≥50 years had DR. Heterogeneity around this estimate ranged from I2= 79–87%. No linear trend was observed between age and the proportion with DR. The overall methodological quality of included studies was moderate.
Conclusions:
Early detection of DR is currently not prioritized in public health policies for noncommunicable diseases and blindness programs. Methodological issues in studies suggest that the proportion of diabetics with DR is underestimated in the Indian population. Future research should emphasize more robust methodology for assessing diabetes and DR status.
doi:10.4103/2230-8210.179774
PMCID: PMC4847450  PMID: 27144137
Diabetes; diabetic retinopathy; India; meta-analysis; screening
12.  Strengthening diabetes retinopathy services in India: Qualitative insights into providers' perspectives: The India 11-city 9-state study 
Context:
There is a lack of evidence on the subjective aspects of the provider perspective regarding diabetes and its complications in India.
Objectives:
The study was undertaken to understand the providers' perspective on the delivery of health services for diabetes and its complications, specifically the eye complications in India.
Settings and Design:
Hospitals providing diabetic services in government and private sectors were selected in 11 of the largest cities in India, based on geographical distribution and size.
Methods:
Fifty-nine semi-structured interviews conducted with physicians providing diabetes care were analyzed all interviews were recorded, transcribed, and translated. Nvivo 10 software was used to code the transcripts. Thematic analysis was conducted to analyze the data.
Results:
The results are presented as key themes: “Challenges in managing diabetes patients,” “Current patient management practices,” and “Strengthening diabetic retinopathy (DR) services at the health systems level.” Diabetes affects people early across the social classes. Self-management was identified as an important prerequisite in controlling diabetes and its complications. Awareness level of hospital staff on DR was low. Advances in medical technology have an important role in effective management of DR. A team approach is required to provide comprehensive diabetic care.
Conclusions:
Sight-threatening DR is an impending public health challenge that needs a concerted effort to tackle it. A streamlined, multi-dimensional approach where all the stakeholders cooperate is important to strengthening services dealing with DR in the existing health care setup.
doi:10.4103/2230-8210.179775
PMCID: PMC4847451  PMID: 27144138
Diabetes; diabetes retinopathy; health system response; India; providers perspective
13.  The Arclight Ophthalmoscope: A Reliable Low-Cost Alternative to the Standard Direct Ophthalmoscope 
Journal of Ophthalmology  2015;2015:743263.
Background. The Arclight ophthalmoscope is a low-cost alternative to standard direct ophthalmoscopes. This study compared the Arclight ophthalmoscope with the Heine K180 direct ophthalmoscope to evaluate its reliability in assessing the vertical cup disc ratio (VCDR) and its ease of use (EOU). Methods. Eight medical students used both the Arclight and the Heine ophthalmoscopes to examine the optic disc in 9 subjects. An EOU score was provided after every examination (a higher score indicating that the ophthalmoscope is easier to use). A consultant ophthalmologist provided the reference standard VCDR. Results. 288 examinations were performed. The number of examinations that yielded an estimation of the VCDR was significantly higher for the Arclight ophthalmoscope (125/144, 85%) compared to the Heine ophthalmoscope (88/144, 61%) (p < 0.001). The mean difference from the reference standard VCDR was similar for both instruments, with a mean of −0.078 (95% CI: −0.10 to −0.056) for the Arclight and −0.072 (95% CI: −0.097 to −0.046) for Heine (p = 0.69). The overall EOU score was significantly higher for the Arclight ophthalmoscope (p < 0.001). Conclusion. The Arclight ophthalmoscope performs as well as, and is easier to use than, a standard direct ophthalmoscope, suggesting it is a reliable, low-cost alternative.
doi:10.1155/2015/743263
PMCID: PMC4589625  PMID: 26457197
14.  The role of heredity in determining central retinal thickness 
The British Journal of Ophthalmology  2007;91(9):1143-1147.
Aims
To examine the relative roles of genetic and environmental factors in central retinal thickness, by performing a classical twin study.
Methods
310 subjects were recruited from the TwinsUK adult registry at St Thomas' Hospital. Optical coherence tomography (Zeiss, stratus OCT3) was used to measure the average retinal thickness in the central 1 mm diameter area. The covariance of central retinal thickness (CRT), within MZ and DZ twin pairs, was compared and genetic modelling techniques were used to determine the relative contributions of genes and environment to the variation in CRT observed in this population.
Main outcome measure
CRT (average retinal thickness in the central 1 mm diameter area, centred on the fovea).
Results
The mean CRT of all subjects was 212.1 μm (range 165–277). CRT was statistically related to refractive error, with increasing myopia associated with a thinner CRT. CRT was more highly correlated within MZ twin pairs (r = 0.88) than with DZ twin pairs (r = 0.58), suggesting a genetic role. A model combining additive genetic and unique environmental factors provided the best fitting model and gave a heritability estimate of 0.90.
Conclusion
Genetic factors appear to play an important role in CRT, with a heritability estimate of 0.90.
doi:10.1136/bjo.2007.114215
PMCID: PMC1954930  PMID: 17360735
15.  The key informant method: a novel means of ascertaining blind children in Bangladesh 
Background
Most information on the causes of blindness has come from examining children in special education. To obtain a more representative population‐based sample of children, a novel method was developed for ascertaining severe visually impaired (SVI) or blind (BL) children by training local volunteers to act as key informants (KIs).
Objective
To compare the demography and cause of blindness in children recruited by KIs with other ascertainment methods.
Method
Children with SVI/BL were recruited in all 64 districts of Bangladesh. Three sources for case ascertainment were utilised: schools for the blind (SpEdu), community‐based rehabilitation (CBR) programmes and KIs. All data were recorded using the standard WHO/PBL Eye Examination Record.
Results
1935 children were recruited. Approximately 800 KIs were trained. The majority of the children were recruited by the KIs (64.3%). Children recruited by KIs were more likely to be female (odds ratio (OR) 1.6, p<0.001), of pre‐school age (OR 14.1, p<0.001), from rural areas (OR 5.9, p<0.001), be multiply impaired (OR 3.1, p = 0.005) and be suffering from treatable eye diseases (OR 1.3, p = 0.005) when compared with those in SpEdu. Overall a child with an avoidable causes of SVI/BL had 40% (adjusted CI 1.1 to 1.7, p = 0.015) and 30% (CI 1.0 to 1.7, p = 0.033) higher odds of being ascertained using the KIs compared with SpEdu and CBR methods, respectively.
Conclusion
Using this innovative approach has resulted in one of the largest studies of SVI/BL children to date. The findings indicate that KIs can recruit large numbers of children quickly, and that the children they recruit are more likely to be representative of all blind children in the community.
doi:10.1136/bjo.2006.108027
PMCID: PMC1954788  PMID: 17431019
16.  Epilation for Minor Trachomatous Trichiasis: Four-Year Results of a Randomised Controlled Trial 
PLoS Neglected Tropical Diseases  2015;9(3):e0003558.
Background
Trachomatous trichiasis (TT) needs to be managed to reduce the risk of vision loss. The long-term impact of epilation (a common traditional practice of repeated plucking of lashes touching the eye) in preventing visual impairment and corneal opacity from TT is unknown. We conducted a randomized controlled trial of epilation versus surgery for the management of minor TT (fewer than six lashes touching the eye) in Ethiopia. Here we report the four-year outcome and the effect on vision and corneal opacity.
Methodology/ Principal Findings
1300 individuals with minor TT were recruited and randomly assigned to quality trichiasis surgery or repeated epilation using high quality epilation forceps by a trained person with good near vision. Participants were examined six-monthly for two-years, and then at four-years after randomisation. At two-years all epilation arm participants were offered free surgery. At four-years 1151 (88.5%) were re-examined: 572 (88%) and 579 (89%) from epilation and surgery arms, respectively. At that time, 21.1% of the surgery arm participants had recurrent TT; 189/572 (33%) of the epilation arm had received surgery, while 383 (67%) declined surgery and had continued epilating (“epilation-only”). Among the epilation-only group, 207 (54.1%) fully controlled their TT, 166 (43.3%) had minor TT and 10 (2.6%) had major TT (>5 lashes). There were no differences between participants in the epilation-only, epilation-to-surgery and surgery arm participants in changes in visual acuity and corneal opacity between baseline and four-years.
Conclusions/ Significance
Most minor TT participants randomised to the epilation arm continued epilating and controlled their TT. Change in vision and corneal opacity was comparable between surgery and epilation-only participants. This suggests that good quality epilation with regular follow-up is a reasonable second-line alternative to surgery for minor TT for individuals who either decline surgery or do not have immediate access to surgical treatment.
Author Summary
Trachoma causes visual impairment through the effect of in-turned eyelashes (trichiasis) on the surface of the eye. Epilation is a common traditional practice of intermittent plucking of lashes touching the eye, however, its long-term effectiveness in preventing visual impairment is unknown. We conducted a randomized controlled trial of epilation versus eyelid surgery (the main treatment option) in 1300 people with mild trichiasis in Ethiopia. We defined mild trichiasis as fewer than six lashes touching the eye. We have previously reported results to two years and have now re-assessed these individuals at four years. Overall, we found no difference between the epilation and surgery groups in terms of change in vision and corneal opacity between baseline and four years. Most mild trichiasis participants randomised to the epilation arm continued epilating and controlled their trichiasis. This suggests that good quality epilation is a reasonable second-line alternative to surgery for mild trichiasis for individuals who either decline surgery or do not have immediate access to surgical treatment.
doi:10.1371/journal.pntd.0003558
PMCID: PMC4358978  PMID: 25768796
17.  Prevalence and risk factors for diabetes and diabetic retinopathy: results from the Nigeria national blindness and visual impairment survey 
BMC Public Health  2014;14:1299.
Background
In Nigeria, urbanisation and increasing life expectancy are likely to increase the incidence of non-communicable diseases. As the epidemic of diabetes matures, visual loss from diabetic retinopathy (DR) will increase unless mechanisms for early detection and treatment improve, and health systems respond to the growing burden of non-communicable diseases.
Methods
A nationally-representative population-based sample of 13,591 participants aged ≥40 years selected by multistage-stratified-cluster-random-sampling with probability-proportional-to-size procedures were examined in 305 clusters in Nigeria between January 2005 to June 2007. All were asked about history of diabetes and underwent basic eye examination. Visual acuity (VA) was measured using logMAR E-chart. Participants with VA<6/12 and/or DR detected underwent detailed eye examination including dilated retinal examination and retinal photography. Systematic sampling of 1-in-7 gave a subsample (n=1759) examined in detail regardless of VA; and had random blood glucose (RBG) testing. Images were graded by Moorfields Eye Hospital Reading Centre. Participants were defined as having diabetes if they were previously diagnosed or RBG>11.1mmol/l or had DR. Data in the subsample were used to estimate the prevalence and to analyse risk factors for diabetes and DR using multivariable logistic regression. Additional information on the types of DR was obtained from participants not in the subsample.
Results
In the subsample, 164 participants were excluded due to missing data; and 1,595 analysed. 52/1,595 had diabetes, a prevalence of 3.3% (95%CI 2.5-4.3%); and 25/52(48%) did not know. Media opacity in 8/52 precluded retinal examination. 9/44(20.5%) had DR. Higher prevalence of diabetes was associated with urban residence (Odds ratio [OR]1.87) and overweight/obesity (OR3.02/4.43 respectively). Although not statistically significant, DR was associated with hypertension (OR3.49) and RBG>15.0mmol/L (OR8.10). Persons with diabetes had 3 times greater odds of blindness. Of 11,832 other participants in the study sample, 175(1.5%) had history of diabetes; 28 had DR. Types of DR (total=37) included 10.8% proliferative, 51.4% macular oedema.
Conclusion
The age-adjusted prevalence of diabetes in Nigeria was 3.25% (95%CI 2.50-4.30) and over 10% of people with diabetes aged ≥40 years had sight-threatening-DR. These data will enable the development of better public health strategies for the control of diabetes and planning services for DR to prevent vision loss.
doi:10.1186/1471-2458-14-1299
PMCID: PMC4301086  PMID: 25523434
18.  The Heritability of the Ring-Like Distribution of Macular Pigment Assessed in a Twin Study 
Purpose.
It has been suggested that ring-like patterns of macular pigment, as measured with dual wavelength autofluorescence, are observed less frequently in subjects with age-related maculopathy. We explored relative contributions of genetic and environmental factors in macular pigment optical density (MPOD) distributions using a classic twin study.
Methods.
As part of a previous nutritional study, 322 healthy Caucasian female twins, aged 16 to 50 (mean 40) years, underwent measurement of MPOD optical density by two-wavelength fundus autofluorescence. In the present study, the right eye MPOD profile was assessed for the presence of a ring-like pattern by two graders independently, using common criteria, with a third grader arbitrating in cases of disagreement. Concordance was calculated as 2C/(2C + D), where C is the number of twin pairs concordant, and D the number discordant, for the ring-like pattern. Also, heritability was calculated using maximum-likelihood structural equation modeling.
Results.
Images and zygosity data were available for 314 twins (88 monozygotic [MZ] and 69 dizygotic [DZ] pairs). The overall prevalence of the ring pattern was 25.8%. Respective concordances for MZ and DZ twins were 0.75 and 0.22. Additive genetic factors were estimated to contribute to 84.0% of the total variance (95% confidence intervals, 63.7%–94.6%).
Conclusions.
Concordance for MZ twins was over three times that for DZ twins, with heritability estimated at 84%, indicating that genetic factors contribute to the development of the ring structure. Studies have suggested that ring-like patterns of macular pigment can affect risk for age-related maculopathy. In a classic twin study, we found that the presence of such a pattern was highly heritable.
doi:10.1167/iovs.13-13829
PMCID: PMC3979519  PMID: 24609627
macular pigment; heritability; lutein
19.  The Impact of Climatic Risk Factors on the Prevalence, Distribution, and Severity of Acute and Chronic Trachoma 
Background and Objectives
Trachoma is the most common cause of infectious blindness. Hot, dry climates, dust and water scarcity are thought to be associated with the distribution of trachoma but the evidence is unclear. The aim of this study was to evaluate the epidemiological evidence regarding the extent to which climatic factors explain the current prevalence, distribution, and severity of acute and chronic trachoma. Understanding the present relationship between climate and trachoma could help inform current and future disease elimination.
Methods
A systematic review of peer-reviewed literature was conducted to identify observational studies which quantified an association between climate factors and acute or chronic trachoma and which met the inclusion and exclusion criteria. Studies that assessed the association between climate types and trachoma prevalence were also reviewed.
Results
Only eight of the 1751 papers retrieved met the inclusion criteria, all undertaken in Africa. Several papers reported an association between trachoma prevalence and altitude in highly endemic areas, providing some evidence of a role for temperature in the transmission of acute disease. A robust mapping study found strong evidence of an association between low rainfall and active trachoma. There is also consistent but weak evidence that the prevalence of trachoma is higher in savannah-type ecological zones. There were no studies on the effect of climate in low endemic areas, nor on the effect of dust on trachoma.
Conclusion
Current evidence on the potential role of climate on trachoma distribution is limited, despite a wealth of anecdotal evidence. Temperature and rainfall appear to play a role in the transmission of acute trachoma, possibly mediated through reduced activity of flies at lower temperatures. Further research is needed on climate and other environmental and behavioural factors, particularly in arid and savannah areas. Many studies did not adequately control for socioeconomic or environmental confounders.
Author Summary
Trachoma – the leading cause of infectious blindness – is spread through contact with infected persons by hands and towels, and by ‘eye-seeking flies.’ Trachoma prevalence is high in areas characterised by poverty, inadequate water supply, and poor sanitation. Trachoma is controlled by the SAFE strategy: S = surgery to the upper eyelids; A = antibiotics for active infection; F = facial cleanliness; and E = environmental improvement. In this study we reviewed the scientific literature to assess the extent to which climatic factors (e.g., rainfall, heat, dust, altitude) influence trachoma distribution. A systematic review of the literature found eight papers that measured an association between a climatic factor and trachoma in children or adults. Several studies reported that trachoma is less common at higher altitudes, indicating that temperature may play a role in trachoma transmission. Some studies also reported that trachoma is higher in areas with low rainfall, which is consistent with anecdotal evidence that trachoma is associated with dry environments.
doi:10.1371/journal.pntd.0002513
PMCID: PMC3820701  PMID: 24244768
20.  Ocular parameters of biological ageing in HIV-infected individuals in South Africa: relationship with chronological age and systemic biomarkers of ageing 
Mechanisms of ageing and development  2013;134(9):10.1016/j.mad.2013.08.002.
HIV-infected individuals have an increased risk of age-related morbidity despite antiretroviral treatment (ART). Several anatomic and functional ophthalmological parameters are associated with increasing chronological age. These may, therefore, potentially serve as biomarkers of ageing. We investigated associations between ocular parameters (lens density, retinal vessel calibre, corneal endothelium and retinal nerve fibre layer thickness) and two ‘cellular’ biomarkers of ageing (leukocyte telomere length and CDKN2A expression) and with frailty in a cross-sectional study of 216 HIV-infected individuals. All ocular parameters, telomere length and frailty were associated with chronological age, whereas CDKN2A expression was not. Retinal venular calibre and lens density were associated with shorter telomere length (p-trend=0.04, and 0.08, respectively), whereas CDKN2A expression and frailty status were not associated with ocular parameters. Longitudinal studies are warranted to assess the integration of retinal vascular calibre and lens density with systemic markers to develop an overall index of biological ageing in HIV infection.
doi:10.1016/j.mad.2013.08.002
PMCID: PMC3818088  PMID: 23994067
Telomeres; CDKN2A; lens density; retinal vessel calibre; HIV
21.  Prevalence and risk factors for hypertension and association with ethnicity in Nigeria: results from a national survey 
Cardiovascular Journal of Africa  2013;24(9):344-350.
Summary
Background
Non-communicable diseases are now a global priority. We report on the prevalence of hypertension and its risk factors, including ethnicity, in a nationally representative sample of Nigerian adults recruited to a survey of visual impairment.
Methods
A multi-stage, stratified, cluster random sample with probability proportional to size procedures was used to obtain a nationally representative sample of 13 591 subjects aged ≥ 40 years. Of these, 13 504 (99.4%) had a blood pressure measurement.
Results
The prevalence of hypertension was 44.9% [95% confidence interval (CI): 43.5–46.3%]. Increasing age, gender, urban residence and body mass index were independent risk factors (p < 0.001). The Kanuri ethnic group had the highest prevalence of hypertension (77.5%, 95% CI: 71.0–84.0%).
Conclusions
The high prevalence of hypertension in Nigeria is a cause for concern and suggests that it is inevitable that the impact of hypertension-related ill health is imminent, with the accompanying financial and societal costs to families and the state of Nigeria.
doi:10.5830/CVJA-2013-058
PMCID: PMC3896106  PMID: 24042732
hypertension; ethnicity; Nigeria; survey
22.  Candidate gene study of macular response to supplemental lutein and zeaxanthin☆ 
Experimental Eye Research  2013;115:172-177.
Supplementation with carotenoids is proposed to protect against age-related macular degeneration. There is, however, considerable variability in retinal macular pigment response, which may be due to underlying genetic variation. The purpose of this study was to determine whether genetic factors, which have been previously associated with cross-sectional macular pigment levels in the retina or serum lutein, also influence response to supplementation.
To this end we conducted an association study in 310 subjects from the TwinsUK cohort between variants in 8 candidate genes and serum lutein and retinal macular pigment optical density (MPOD) levels before and after supplementation. Four variants were associated with MPOD response to supplementation (p < 0.05): rs11057841 (SCARB1), rs4926339 (RPE65), rs1929841 (ABCA1) and rs174534 (FADS1). We also confirmed previous associations between rs6564851 near BMCO1 (p < 0.001) and rs11057841 within SCARB1 (p = 0.01) and baseline measures of serum lutein; while the latter was also associated with MPOD response, none of the BMCO1 variants were. Finally, there was evidence for association between variants near RPE65 and ELOVL2 and changes in lutein concentration after supplementation.
This study is the first to show association between genetic variants and response to carotenoids supplementation. Our findings suggest an important link between MP response and the biological processes of carotenoids transport and fatty acid metabolism.
Highlights
•Four variants were associated with macular pigment response to supplementation.•We replicated associations between BMCO1 variants and lutein at baseline.•Carotenoids transport may affect macular response to supplementation.•Lipid metabolism may affect macular response to supplementation.
doi:10.1016/j.exer.2013.07.020
PMCID: PMC3819993  PMID: 23891863
macular pigment; lutein; genetics; supplementation; macular degeneration; CAREDS, Carotenoids in Age Related Eye Disease Study; MP, macular pigment; L, lutein; MPOD, macular pigment optical density; LZ, lutein and zeaxanthin; Z, zeaxanthin
23.  Retinal Nerve Fibre Layer Thickness and Contrast Sensitivity in HIV-Infected Individuals in South Africa: A Case-Control Study 
PLoS ONE  2013;8(9):e73694.
Background
Antiretroviral treatment (ART) has altered the spectrum of HIV-related eye disease, resulting in a lower prevalence of retinal opportunistic infections (OIs). However, abnormalities in visual function have been reported in HIV-infected individuals despite effective viral suppression and the absence of retinal OIs. These changes may be mediated by an HIV-associated ‘neuroretinal disorder’, characterized by changes in the retinal nerve fibre layer (RNFL). HIV infection may also be associated with accelerated biological aging. The aim of this study was to investigate the relationships between contrast sensitivity, RNFL thickness, HIV infection and frailty in South African adults.
Methods
Case-control study of 225 HIV-infected individuals without retinal OIs and 203 gender/age-matched HIV-seronegative individuals. Peri-papillary RNFL thickness was determined with spectral domain optical coherence tomography in four quadrants. CS was measured using a Pelli-Robson chart. Frailty was assessed using standard criteria. Multivariable linear and logistic regression were used to assess associations between HIV status and RNFL/CS and frailty.
Results
The median age of both groups was similar (41.2 vs. 41.9 years, p = 0.37). 88% of HIV-infected individuals were receiving ART and their median CD4 count was 468 cells/μl. Adjusted CS score was lower in HIV-infected participants compared to HIV-seronegative individuals (1.76 vs. 1.82, p = 0.002). Independent predictors of poor CS in the HIV-infected group were positive frailty status and current HIV viral load >2 log copies/ml. Lower CS score was also associated with thin temporal RNFL in HIV-infected individuals (p = 0.04). Superior quadrant RNFL thickness was greatest in ART-naïve participants relative to the HIV-uninfected group (p-trend = 0.04). Longer ART duration was associated with thinning of inferior and nasal RNFL quadrants (p-trend = 0.03 and 0.04, respectively).
Conclusions
Contrast sensitivity is reduced in HIV-infected individuals and functionally associated with frailty and unsuppressed viraemia. This may reflect structural changes in the RNFL that are evident despite the absence of OIs.
doi:10.1371/journal.pone.0073694
PMCID: PMC3777952  PMID: 24069225
24.  Ocular parameters of biological ageing in HIV-infected individuals in South Africa: Relationship with chronological age and systemic biomarkers of ageing☆ 
Highlights
•HIV is associated with age-related morbidity despite antiretroviral treatment.•Ocular age-related parameters may serve as biomarkers of ageing.•Lens density may have a role in the determination of biological age in HIV infection.
HIV-infected individuals have an increased risk of age-related morbidity despite antiretroviral treatment (ART). Several anatomic and functional ophthalmological parameters are associated with increasing chronological age. These may, therefore, potentially serve as biomarkers of ageing. We investigated associations between ocular parameters (lens density, retinal vessel calibre, corneal endothelium and retinal nerve fibre layer thickness) and two ‘cellular’ biomarkers of ageing (leukocyte telomere length and CDKN2A expression) and with frailty in a cross-sectional study of 216 HIV-infected individuals. All ocular parameters, telomere length and frailty were associated with chronological age, whereas CDKN2A expression was not. Retinal venular calibre and lens density were associated with shorter telomere length (p-trend = 0.04, and 0.08, respectively), whereas CDKN2A expression and frailty status were not associated with ocular parameters. Longitudinal studies are warranted to assess the integration of retinal vascular calibre and lens density with systemic markers to develop an overall index of biological ageing in HIV infection.
doi:10.1016/j.mad.2013.08.002
PMCID: PMC3818088  PMID: 23994067
Telomeres; CDKN2A; Lens density; Retinal vessel calibre; HIV
25.  The Outcome of Trachomatous Trichiasis Surgery in Ethiopia: Risk Factors for Recurrence 
Background
Over 1.2 million people are blind from trachomatous trichiasis (TT). Lid rotation surgery is the mainstay of treatment, but recurrence rates can be high. We investigated the outcomes (recurrence rates and other complications) of posterior lamellar tarsal rotation (PLTR) surgery, one of the two most widely practised TT procedures in endemic settings.
Methodology/Principal Findings
We conducted a two-year follow-up study of 1300 participants who had PLTR surgery, conducted by one of five TT nurse surgeons. None had previously undergone TT surgery. All participants received a detailed trachoma eye examination at baseline and 6, 12, 18 and 24 months post-operatively. The study investigated the recurrence rates, other complications and factors associated with recurrence. Recurrence occurred in 207/635 (32.6%) and 108/641 (16.9%) of participants with pre-operative major (>5 trichiatic lashes) and minor (<5 lashes) TT respectively. Of the 315 recurrences, 42/315 (3.3% overall) had >5 lashes (major recurrence). Recurrence was greatest in the first six months after surgery: 172 cases (55%) occurring in this period. Recurrence was associated with major TT pre-operatively (OR 2.39, 95% CI 1.83–3.11), pre-operative entropic lashes compared to misdirected/metaplastic lashes (OR 1.99, 95% CI 1.23–3.20), age over 40 years (OR 1.59, 95% CI 1.14–2.20) and specific surgeons (surgeon recurrence risk range: 18%–53%). Granuloma occurred in 69 (5.7%) and notching in 156 (13.0%).
Conclusions/Significance
Risk of recurrence is high despite high volume, highly trained surgeons. However, the vast majority are minor recurrences, which may not have significant corneal or visual consequences. Inter-surgeon variation in recurrence is concerning; surgical technique, training and immediate post-operative lid position require further investigation.
Author Summary
Trachoma is the most common infectious cause of blindness worldwide. It causes trichiasis (inturning of the eyelashes to touch the eye), which can cause visual loss. Trachomatous trichiasis (TT) affects over eight million people, 1.2 of whom live in Ethiopia – the most affected country worldwide. Surgery is the mainstay of treatment for TT. However, results of surgery in the field are often very mixed. We investigated the surgical outcomes of one of the two most widely used surgical techniques (posterior lamellar rotation), in 1300 individuals in the Amhara Region of Ethiopia. We found that recurrence occurred frequently: 315/1276 (24.7%) participants. However, recurrence was rarely severe (greater than 5 lashes): 42 participants (3.3%). Recurrence occurred much more frequently in participants who had severe pre-operative disease and with specific surgeons. The high recurrence rates and inter-surgeon variation is concerning. Further research will be required to investigate factors such as surgical technique, surgeon training and immediate post-operative lid position, in order to improve surgical outcomes.
doi:10.1371/journal.pntd.0002392
PMCID: PMC3749971  PMID: 23991241

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