RAPID ASSESSMENT
OF
REFRACTIVE ERROR (RARE)
Uncorrected Refractive Error (URE)
“The Crisis”
• URE is most common cause of Visual impairment (VI)
worldwide and 2nd most common cause of blindness1,2
• URE drives children and adults further into poverty:3
− Limits opportunities to education
− Employment
− Seriously impacts quality of life and productivity
• Link between poverty and VI due to URE places heavy
economic burden on individuals  families  affected
nations
What is the status of URE?4
Prevalence of Visual Impairment
• 158 million cases of Distance VI
• 544 million cases of Near VI
Human Resources Required
• 47000 full-time refractionists
• 18000 ophthalmic dispensers
Cost of Human Resource Development
Implications
• US $20-28 billion
Implications
Estimated loss in global GDP due to DVI
US $ 202 billion
Historical Situation
• Paucity of Data
• Refractive data elicited through:
− RESC studies
• From community to school
• Children only
− Conventional Population based studies
•
•
•
•
Prohibitively expensive
High level of expertise
Few and far between
Lag between completion and Program implementation
timelines
CONTEXT SETTING
• Why and where do we need data
− National level
•
•
•
•
Planning
Evaluation
Awareness
Advocacy
− Regional level
• Advocacy
• Establish priorities for investment in regions
RARE
Evolved out of RACSS and RAABS
Rapid
Quick
Cost
effective
Assessment
Simple
Results
Refractive
Error
Prevalence
Barriers
How does RARE data help?
• RARE data can be used in a top-down or bottom-up approach.
TOP-DOWN
Globally
285.389 mil VI
246.024 mil Blind
Regional
RARE
RARE
STUDIES
RARE
STUDIES
LOCATE
Blind
and
VI
EXPAND to the national
or even global context
BOTTOM-UP
METHODOLOGY
Target Group
• RARE studies used to assess prevalence of
URE, presbyopia, spectacle coverage, and
barriers to uptake of services for refractive errors
and presbyopia5
Studies are focused on:
• Younger age groups more affected by RE
• Presbyopia
• 15-49 years
Definitions
Condition
Visual Impairment
Definition
Binocular Presenting VA<6/12 in the
better eye
Uncorrected Refractive Presenting VA<6/12 but improving
Error (URE)
Presbyopia
≥6/12 with pinhole
Binocular near vision < N8 at
33-35cms
Definitions
Definition
URE
Description
Unaided VA <6/12 but improving to 6/12 or
(Unmet need)
better with pinhole and no spectacles
Uncorrected
Binocular Unaided near vision <N8 in
Presbyopia
subjects aged >35 years with no distance VI
(Unmet need)
and no spectacles
Corrected RE
Unaided VA<6/18 but improved to 6/18 or
(Met need)
Corrected Presbyopia
(Met need)
better with spectacles
Unaided near vision < N8, but improved to
N8 or better with their spectacles
RARE Toolkit
Equipment
Purpose
Snellen chart (E,
Alphabet optotypes)
Distance Visual Acuity
Measuring tape or
String
Measure testing distance: subject
and chart
Multiple pinhole
occluder
Presenting VA, if VA<6/12
N notation chart
Near vision
Torch light
External examination
Ready made spectacles
(+1.0 to +3.0 Ds)
Best corrected near vision
assessment in individuals with
presbyopia
OUTPUTS OF RARE STUDIES
Magnitude of RE (uncorrected)
Prevalence of presbyopia
Spectacle coverage and utilisation patterns
Understanding barriers to access of services
Provide baseline information
Trends in prevalence determined on follow up studies
What is the impact of gathering this information? ....
Spectacle Coverage
[met need’ ]
.
[(‘met need’ + ‘unmet need’) X 100]
Barriers – URE6
35
30.9
30
25
23
20
15
16.5
16.5
Personal
reasons
Lack of
access
12.9
10
5
0
Lack of
awareness
Lack of felt Economic
need
reasons
Current and future RARE studies
•
Studies conducted
1. Eritrea
2. Ghana
3. Uganda
4. South Africa
5. Tanzania
•
Studies in preparation
6. Mozambique
7. Gambia
8. Zambia
9. Cameroon
10. Ethiopia
11. Malawi
MAJOR BARRIERS IDENTIFIED IN RARE
STUDIES CONDUCTED
Affordability of the spectacle exam
Aware of problem but felt no need for consultation
Unaware of problem
Cannot afford the cost of glasses
Comparison of visual impairment and refractive
error prevalence across various RARE studies
12
10.4
10
8.6
8
6.6
6.4
7
5.7
6
VI
RE
4.4
2.9
4
1 1.2
2
0
Eritrea
Ghana
Uganda
Tanzania
(South
Africa)
References
1. Resnikoff S, Pascolini D, Mariotti S, Pokharel P. Global magnitude of visual impairment caused by uncorrected
refractive errors in 2004. Bull World Health Organ 2008;86:63-70.
2. Holden BA, Fricke T, Ho S, Wong R, Schlenther G, Cronje S, et al. Global vision impairment due to uncorrected
presbyopia. Arch Ophthalmol 2008;126:1731-9.
3. Fricke TR, Holden BA, Wilson DA, Schlenther G, Naidoo KS, Resnikoff S and Frick KD. Global cost of correcting
vision impairment from uncorrected refractive error.
4. Naidoo KS, Wallace DB, Holden, BA, Minto H, Faal HB, Dube P. The challenge of uncorrected refractive error:
driving the agenda of the Durban Declaration on refractive error and service development. Clin Exp Opt 2010:
93(3): 131-136.
5. Marmamula S, Keeffe JE, Rao GN. Uncorrected refractive errors, presbyopia and spectacle coverage: Results from
a Rapid Assessment of Refractive Error survey. Ophthalmic Epidemiology 2009;16:269-74.
6. Marmamula et al. Population-based cross-sectional study of barriers to utilisation of refraction services in South
India: Rapid Assessment of Refractive Errors (RARE) Study. British Medical Journal.
Acknowledgements
• Pirindha Govender
• Brien Holden Vision Institute (Public Health
Division) – Research Department