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

Dineen B, Gilbert CE, Rabiu M, Kyari F, Mahdi AM, Abubakar T, Ezelum CC, Gabriel E, Elhassan E, Abiose A, Faal H, Jiya JY, Ozemela CP, Lee PS, Gudlavalleti MV - BMC Ophthalmol (2008)

Bottom Line: All those who had undergone cataract surgery were refracted and best corrected vision recorded.The field work for the study was completed in 30 months over the period 2005-2007 and covered 305 clusters across the entire country.Analysis of the data is currently underway.

View Article: PubMed Central - HTML - PubMed

Affiliation: International Centre for Eye Health, London School for Hygiene and Tropical Medicine, UK. brendan.dineen@nuigalway.ie

ABSTRACT

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.

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Related in: MedlinePlus

Flow Chart of Examination Protocol.
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Figure 2: Flow Chart of Examination Protocol.

Mentions: Participants with LogMar score of ≤ 24 optotypes (i.e. < = 6/12) in one or both eyes were marked as "red cards" while those with a score of 25 or more were marked as "green cards". This division defined the subsequent sequence of examinations that each individual underwent. Participants with red cards had extensive examination including dilated funduscopy. A flow chart of the survey examination procedures is presented in Figure 2.


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

Dineen B, Gilbert CE, Rabiu M, Kyari F, Mahdi AM, Abubakar T, Ezelum CC, Gabriel E, Elhassan E, Abiose A, Faal H, Jiya JY, Ozemela CP, Lee PS, Gudlavalleti MV - BMC Ophthalmol (2008)

Flow Chart of Examination Protocol.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2572038&req=5

Figure 2: Flow Chart of Examination Protocol.
Mentions: Participants with LogMar score of ≤ 24 optotypes (i.e. < = 6/12) in one or both eyes were marked as "red cards" while those with a score of 25 or more were marked as "green cards". This division defined the subsequent sequence of examinations that each individual underwent. Participants with red cards had extensive examination including dilated funduscopy. A flow chart of the survey examination procedures is presented in Figure 2.

Bottom Line: All those who had undergone cataract surgery were refracted and best corrected vision recorded.The field work for the study was completed in 30 months over the period 2005-2007 and covered 305 clusters across the entire country.Analysis of the data is currently underway.

View Article: PubMed Central - HTML - PubMed

Affiliation: International Centre for Eye Health, London School for Hygiene and Tropical Medicine, UK. brendan.dineen@nuigalway.ie

ABSTRACT

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.

Show MeSH
Related in: MedlinePlus