Running an efficient school programme: refractive error component

Child Eye Health course: IAPB General Assembly

Clare Gilbert, ICEH, LSHTM

School eye health programmes:questions that need to be addressed

Is a school eye health programme indicated?• prevalence of uncorrected refractive errors• prevalence of endemic diseases e.g. VADD; trachoma• resources available

Age at which vision should be tested? Which schools should be included? How often should vision be tested? Who will measure the vision? What chart should be used? What should the cut-off visual acuity be? Should each eye be tested separately?

School eye health programmes – questions that need to be asked for uRE

Who should refract, where and how? Should prescribing guidelines be used? How will children needing glasses get them? What about children found with other eye conditions? What factors influence spectacle wearing rates and how can wearing

rates be improved? Are ready-made / self-adjusting spectacles suitable? How will it be monitored and evaluated? How can quality be assured? Will the programme be cost effective?

School eye health programmes – questions that need to be asked for uRE

Who should refract, where and how? Should prescribing guidelines be used? How will children needing glasses get them? What about children found with other eye conditions? What factors influence spectacle wearing rates and how can wearing rates

be improved? Are ready-made / self-adjusting spectacles suitable? How will it be monitored and evaluated? How can quality be assured? Will the programme be cost effective? Will it make any difference to childrens’ lives?

School eye health programmes:questions that need to be addressed

Is a school eye health programme indicated?• prevalence of uncorrected refractive errors• prevalence of endemic diseases e.g. VADD; trachoma• resources available

Age at which vision should be tested? Which schools should be included? How often should vision be tested? Who will measure the vision? What chart should be used? What should the cut-off visual acuity be? Should each eye be tested separately?

A neglected area until recently VISION 2020 Refractive Error Working Group

– recommended standardised surveys– results from 8 standard surveys now available

More data available other studies Still to be determined:

– Global importance of RE as a cause of blindness and visual impairment in children

Prevalence and types of uncorrected RE in children

Prevalence of visual impairment (acuity <6/12 in one or both eyes)(REWG)

0

5

10

15

20

25

Pre

vale

nce

(%

)

Uncorrected

Presenting

Best corrected

Prevalence of visual impairment (acuity <6/12 in one or both eyes)

0

5

10

15

20

25

Pre

vale

nce

(%

)

Uncorrected

Presenting

Best corrected

Met need

Unmet need

Refractive errors as a cause of visual impairment

0%

20%

40%

60%

80%

100%

Chinarural

Chinaurban

India rural Indiaurban

Nepal Malaysia Chile SouthAfrica

TanzaniaS

Refractive error Amblyopia Other

Data from other studies Asian school children 7-9 years [Saw]• Myopia ≥0.5D• Malays in Singapore 22%; in Malaysia 9%• Chinese Singapore 40%; in Malaysian 31%

Malaysian primary school children [Hashim]• Criteria <6/12 uncorrected• All children 8%

Chinese children in rural junior schools [He]• Criteria ≥6/12 uncorrected• All children 17%

Data from other studies Different ethnic groups in the UK aged 10-11 years [Rudnicke]• Myopia & VA ≤6/9• South Asian 25%• Black African Caribbean 10%• European 3%

Tanzania, rural primary school attendees aged 7-19 year [Wedner]

• <6/12 in both eyes 0.6%• <6/12 in one eye 0.4%

India: urban population(retinoscopy findings)

Myopia ≥ -0.5D

Age (yrs) Myopia (D) Hyperopia (D) % (95% CI) % (95% CI)

China: urban population(retinoscopy findings)

Age (yrs) Myopia (D) Hyperopia (D) % (95% CI) % (95% CI)

Myopia ≥ -0.5D

Age (yrs) Myopia (D) Hyperopia (D) % (95% CI) % (95% CI)

South Africa: semi-urban pop (retinoscopy findings)

1% had the potential to benefit from spectacles

Summary of evidence

Regional differences in prevalence: Asia > Europe/Latin America > Africa low prevalence in Africa may not justify the RE

component of school eye health programme

Type of refractive error and age: myopia increases with age hypermetropia decreases with age

Urban / rural differences: myopia more common in urban areas

Which schools and how often?

In Asia focus on: • middle/secondary schools• urban then rural schools (unmet need high even in urban areas) South Asia:• include primary school children Africa:• pilot studies and decide if a good use of resources Frequency of visits:• No evidence• ? every 2-3 years if prevalence <5% and but 1-2 years if

prevalence >5%

School eye health programmes:questions that need to be addressed

Is a school eye health programme indicated?• prevalence of uncorrected refractive errors• prevalence of endemic diseases e.g. VADD; trachoma• resources available

Age at which vision should be tested? Which schools should be included? How often should vision be tested? Who will measure the vision? What chart should be used? What should the cut-off visual acuity be? Should each eye be tested separately?

Measuring visual acuity

Teachers measuring visual acuity in school children in Brazil

Measuring visual acuity

Teachers are used in many programmes Can reliably test in the short term

• in China: 85% sensitivity and specificity [Sharma] How do they perform long term? What criteria make good VA testers? How can their motivation be maintained? Also trainee optometrists and nurses; army cadets

Sharma A. Strategies to improve the accuracy of vision measurement by teachers in rural Chinese secondary school children. Arch Oph 2008 1434-40

School eye health programmes:questions that need to be addressed

Is a school eye health programme indicated?• prevalence of uncorrected refractive errors• prevalence of endemic diseases e.g. VADD; trachoma• resources available

Age at which vision should be tested? Which schools should be included? How often should vision be tested? Who will measure the vision? What chart should be used? What should the cut-off visual acuity be? Should each eye be tested separately?

Vision testing

Cut off options: 6/9 or 6/12 Chart options: Full chart vs relevant row Eyes: Separately vs together

Cut off options:

• 6/9: many false positives which can overload the system

• 6/12: more likely to find significant myopia/astigmatism

• Both can miss hypermetropia Chart options:

• one row is quicker.

• more care with quality control

Uniocular vs binocular VA screening in Tanzania

Methods: Secondary school pupils (n=2,379; 12-23 yrs) tested with full

Snellen: each eye separately and both eyes together Refracted if <6/9 in one eye or <6/9 testing binocularly RE needing correction (in better seeing eye) defined as:– myopia -1.0D or more– hypermetropia +3.0D or more– Astigmatism cyl 1.5D or more

Results: <6/12 both eyes had highest PVP (71.4%) & PNV (99.7%)

Shilio B. MSc dissertation, ICEH. 2000

Prescribed glasses

Country VA tested R and/or L

N tested

Age group

Refracted Of thoserefracted

Overall

India 1993-7[Limburg]

<6/9 5.39m 6-15 205,000 (4%) 24% 0.8%

S Africa[Congdon]

≤6/12 8,500 6-19 2,120 (25%) 38% 9.5%

Mexico[Holgiun]

≤6/12 10,096 6-18 5,772 (57%) ND ND

China[Li]

≤6/12 1,892 11-15 960 (50%) 70% 28%

Mozambique[Roba]

<6/9 10,320 5-15 3% 67% 1%

Tanzania[Wedner]

<6/12 6,900 11+ ND ND 1.8%

VA tested, age and rates of refraction and prescribing

Influence of age at VA testing in India (<6/9)

Only 1 in 200 primary school children tested at <6/9 were prescribed glasses compared with 1 in 83 middle school children

Prescribed glassesSchools Age group N tested Refracted Of

refractedOverall

All 6-15 5.39m 205,000 (3.8%) 24.4% 0.8%

Middle 11-15 3.23m 148,200 (4.6%) 26.5% 1.2%

Primary 6-10 2.16m 56,900 (2.6%) 19.0% 0.5%

School eye health programmes – questions that need to be asked for uRE

Who should refract, where and how? Should prescribing guidelines be used? How will children needing glasses get them? What about children found with other eye conditions? What factors influence spectacle wearing rates and how can wearing rates

be improved? Are ready-made / self-adjusting spectacles suitable? How will it be monitored and evaluated? How can quality be assured? Will the programme be cost effective? Will it make any difference to childrens’ lives?

Refraction, prescribing and dispensing

Refraction: Lots of options: ideal = high quality refraction done at the same

time as VA testing, preferably at the school, to improve uptake

Prescribing and dispensing: Lots of options: ideal = only children who will really benefit are

dispensed high quality spectacles, using prescribing guidelines to prevent over prescribing

Should not treat the myopia, but functional impairment arising from it.

Type of RE and protocols for prescribing

Country Type of prescription (RE) Protocols for prescribing

India No data ? Up to local optom

S Africa 60% none (<+/-0.5D); 35% myopia; 5% hyperopia Yes ? Followed

Mexico 85% myopia; 10% no RE; 5% hyperopia No data

China No data Yes

Tanzania 86% myopia No data

School eye health programmes – questions that need to be asked for uRE

Who should refract, where and how? Should prescribing guidelines be used? How will children needing glasses get them? What about children found with other eye conditions? What factors influence spectacle wearing rates and how can wearing rates

be improved? Are ready-made / self-adjusting spectacles suitable? How will it be monitored and evaluated? How can quality be assured? Will the programme be cost effective? Will it make any difference to childrens’ lives?

Spectacle wearing/carrying rates

Country Wearing/carrying rates Independent variables associated with wearing spectacles

India 93% (? >100% some areas) No data

S Africa 31% Females

Mexico 47% (13% wearing) Higher myopic; rural; younger children

China 35% purchased specs24% wearing specs

Higher myopia; worse presenting VA; willingness to pay

Tanzania

47% if given free specs Higher myopia; worse presenting VA

(trial) 26% if given prescription

China(trial)

Intervention group of students: lower wearing rates

Types of spectacles prescribed/given

Mexico: very low spectacle wearing rates when children all given the same round framed spectacles.

Increased when more variety provided

Role of self- adjusting spectacles or ready-made spectacles

Self correction: Accuracy of refraction using “Adspecs” in China: VA corrected

with Adspecs lower than with standard methods, but were within 1 line in 98% of students [Zhang and Congdon]

Ready made spectacles: Up to 70% of adults have potential to benefit (pop based

surveys); in a clinical trial of adults ready made spectacles compared favourably with custom made. O studies in children [Keay and Friedman]

Other types of spectacles

Barriers to spectacle wearingMexico (1 reason given) Tanzania (FGDs) China (q’aire)

Forgot them Appearance /teasing No felt need

Appearance /teasing Parents fear VA will decline Make eyes “weak”

Broken / lost Mistrust of opticians Parents not involved

Use occasionally Prefer diet and traditional remedies

Cost

No improvement in VA Not a health priority

Conspiracy theories

Cost

School eye health programmes – questions that need to be asked for uRE

Who should refract, where and how? Should prescribing guidelines be used? How will children needing glasses get them? What about children found with other eye conditions? What factors influence spectacle wearing rates and how

can wearing rates be improved? Are ready-made / self-adjusting spectacles suitable? How will it be monitored and evaluated? How can quality be assured? Will the programme be cost effective? Will it make any difference to childrens’ lives?

Monitoring and evaluation

Some real M&E data.....

Are programmes cost effective?Methods: Mathematical simulation of annual screening for 10 years using

six different screening strategies Outcome: international $ / DALY averted Results: Most cost effective strategy: screening 11–15 year

olds Cost per DALY averted: $ 67 in Asia to $ 458 in Europe Incremental cost for 5–15 yr olds: $ 111 in Asia to

$ 672 in EuropeConclusions: Screening of school children for refractive error is economically

attractive in all regions in the world.Baltussen et al. Cost-effectiveness of screening and correcting refractive errors in school children in Africa, Asia, America and Europe. Health Policy 2008

Suggestions for RE based on available evidence 1

Is a programme indicated?1. Yes: urban schools in all areas but Africa, where pilot studies needed

2. Possibly: rural schools in Asia and Latin America - need pilot studies

3. Probably not: rural schools in Africa unless there is a high prevalence of trachoma etc

 

Prevalence criteria for uncorrected RE: ? ≥2%. Depends on available resources; competing demands; prevalence of other eye conditions

 

Age group: children aged 10/11 years to 15 years. Not younger

VA testing: teachers OK in short term <6/12 with available correction with both eyes open, but

needs more evidence that important pathology is not missed in worse eye

Prescribing: clear protocols need to be used and enforced to increase

compliance and reduce over prescribing:

Suggestions for RE based on available evidence 2

Prescribing: According to guidelines to prevent over prescribing of children

with minimal REDispensing: fashionable, acceptable frames at the school, if possibleCharging: depends on local situation must be affordableHealth education: essential: to dispel myths and increase compliance parents must be included

Suggestions for RE based on available evidence 3

What I would not advocate for RE Including children 6-10 years, except in China:

- prevalence is low- measuring vision is difficult <6 years- prescribing my interfere with emmetropization in

young children- too late to treat/prevent amblyopia

Using trained eyecare staff to measure visionUsing better level of vision as the cutoff, or

unilateral testing - many false positives- over prescribing of spectacles- increases cost

More evidence is badly neededImpact of programmes• do spectacles for low myopia improve function and quality of life? • does spectacle wearing improve school attendance/performance?• is there any harm from bullying/teasing for wearing glasses?Optimal screening VA Increasing compliance• what are optimal protocols for prescribing spectacles?• what is the most effective health education strategy? Factors which promote sustainability:• % of need that could be met by ready-made spectacles• willingness to pay

School health initiatives

UNICEF’s Child Friendly School Initiative WHO Global School Health Initiative : Health

Promoting Schools United Nations Girls Education Initiative (UNGEI) UNESCO Partnership for Child Development World Bank Millennium Development Goals

Integration

Work with Ministries of health / education so that• eye health is part of broader school and child health• schools are safe and healthy places• children learn about eye health

Should not be a stand alone, vertical program that only deals with refractive error