RAPID ASSESSMENT OF REFRACTIVE ERROR (RARE)

RAPID ASSESSMENT OF

REFRACTIVE ERROR (RARE)

Professor Kovin NaidooGlobal Programs Director

IAPB AFRICA CHAIRPERSON

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• US $20-28 billion

Estimated loss in global GDP due to DVIUS $ 202 billion

Implications

Implications

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

RAREEvolved 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.

Globally285.389 mil VI

246.024 mil Blind

RARE STUDIES

LOCATE Blind

and VI

RegionalRAR

E

RARE STUDIES

EXPAND to the national or even global context

TOP-DOWN

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

DefinitionsCondition Definition

Visual ImpairmentBinocular Presenting VA<6/12 in the better eye

Uncorrected Refractive Error

(URE)

Presenting VA<6/12 but improving ≥6/12 with pinhole

PresbyopiaBinocular near vision < N8 at 33-35cms

Definition Description

URE(Unmet need)

Unaided VA <6/12 but improving to 6/12 or better with pinhole and no spectacles

Uncorrected Presbyopia

(Unmet need)

Binocular Unaided near vision <N8 in subjects aged >35 years with no distance VI and no spectacles

Corrected RE(Met need)

Unaided VA<6/18 but improved to 6/18 or better with spectacles

Corrected Presbyopia (Met

need)

Unaided near vision < N8, but improved to N8 or better with their spectacles

Definitions

Equipment PurposeSnellen 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 examinationReady made spectacles (+1.0 to +3.0 Ds)

Best corrected near vision assessment in individuals with presbyopia

RARE Toolkit

OUTPUTS OF RARE STUDIESMagnitude 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

Lack of awareness

Personal reasons

Lack of access

Lack of felt need

Economic reasons

0

5

10

15

20

25

30

35

12.916.5 16.5

23

30.9

Current and future RARE studies• Studies conducted

1. Eritrea2. Ghana3. Uganda4. South Africa5. Tanzania

• Studies in preparation 6. Mozambique7. Gambia8. Zambia9. Cameroon10. 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

Eritrea Ghana Uganda Tanzania (South Africa)

0

2

4

6

8

10

12

4.4

2.9

7

10.4

1

6.4 6.6

8.6

5.7

1.2

VIRE

References1. 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