Zimbabwe Eyecare And Learning(ZEAL):Formative Research on Hyperopia and Educational Outcomes in Primary School Children

Trials in Asia have shown that correction of myopia (close-sightedness) in children has improved educational performance with an effect size larger than for any other school-based health intervention. Myopia prevalence which is, generally inversely associated with the prevalence of hyperopia, appears low in African children. Globally, uncorrected hyperopia (long-sightedness) has a higher prevalence and is present in 12-26% of children, depending on location and age, but the impact of its correction on educational outcomes is not well understood. All-age prevalence of hyperopia is higher in Africa than in any other global region. Despite the traditional view that moderate hyperopia is generally benign, emerging evidence suggests that even moderate uncorrected hyperopia is associated with reduced near function, poorer educational outcomes and lower reading scores. A recent trial in the USA showed that providing refractive correction improved reading scores but did not distinguish between myopia and hyperopia. Another trial in the USA found only small benefits from refractive correction in 1- to 2-year-olds. However, no trial to date has studied the educational impact of hyperopic correction in school-aged children with +2.00 Dioptres (D) or more of hyperopia.

While the gold standard for detecting hyperopia in children during vision examinations requires cycloplegic eye drops to temporarily inhibit accommodation (focusing effort to see near objects), using these eye drops requires trained providers and clinical supervision. It is not typically feasible in vision screening settings. The Vision in Preschoolers study showed that two autorefractors (Retinomax, SureSight) and non-cycloplegic retinoscopy had high discriminatory power to detect young children with hyperopia. However, non-cycloplegic retinoscopy requires trained providers, SureSight is no longer commercially available, and the Retinomax is cost-prohibitive for many screening programs. This limits the availability of hyperopia prevalence data in African children, though, as noted above, available evidence suggests high rates. Most screening programmes use 6/12 as an optimal cut-off value for distance vision. However, studies have reported that measuring distance vision alone is ineffective in detecting hyperopia. Literacy rates remain particularly low among primary school children in sub-Saharan Africa compared to other regions. The challenges and importance of maximising children's early learning, and the potentially important role of vision correction, are not well-understood in this setting. However, these initiatives have focused on myopia, not hyperopia.

Study plan: 2000 study participants (1000: Grade 2, 1000: Grade 4) will be recruited from primary schools selected by the Ministry of Primary and Secondary Education (MoPSE) in Mashonaland Central province in Zimbabwe.

Study design:

Objectives 1, 2 and 3 use a cross-sectional study design to assess the following:

• To assess the prevalence of moderate to high hyperopia (≥ +2.00D) among primary school children in Grades 2 and 4 from Mashonaland Central province in Zimbabwe.
• To accurately detect moderate to high hyperopia (≥ +2.00D) using four screening tests compared to the gold-standard cycloplegic refraction.
• To study the association between uncorrected and corrected moderate to high hyperopia (≥ +2.00D) and baseline reading levels.

Objectives 4 and 5 use a longitudinal intervention design to assess the following:

• To compare near visual acuity and reading levels at baseline and at six months between moderate to high hyperopic (≥ +2.00D) children compared to age-, gender-, and school-matched controls with no vision problems.
• To compare spectacle compliance among newly diagnosed hyperopic and newly diagnosed myopic (short-sighted) school children at six weeks and 14 weeks.

Inclusion criteria

for the cross-sectional assessment of hyperopia prevalence and diagnostic tool development evaluation:

• Grades 2 or 4 from the list of selected primary schools by the Ministry of Primary and Secondary Education (MoPSE)

Inclusion criteria

for the baseline and longitudinal assessment of reading performance

Primary school children will be eligible to participate in the 'reading assessment' if they fulfil the following criteria:

Hyperopic cohort:

• In Grade 2 or 4 from the list of selected schools by the MoPSE.
• Presence of moderate to high hyperopia, defined as ≥ +2.00D in the more hyperopic meridian, in the more hyperopic eye, using cycloplegic autorefraction with an average of three consecutive readings taken.

Emmetropic cohort:

• In Grade 2 or 4 from the list of selected schools by the MoPSE.
• Meets criteria for visually normal (unaided distance visual acuity 6/6 monocular and near visual acuity N5), based on an absence of significant refractive error.
• Presence of emmetropia, defined as < +1.00D to >-0.50 Dioptre in the more hyperopic meridian, in both eyes using cycloplegic autorefraction with an average of three consecutive readings taken to record the refractive status.

Newly diagnosed hyperopic and newly diagnosed myopic children will be eligible to participate in the 'spectacle compliance' assessment if they fulfil the following criteria:

Hyperopic cohort:

• Presence of hyperopia, defined as ≥ +2.00D in the more hyperopic meridian, in the more hyperopic eye by cycloplegic autorefraction.

Myopic cohort:

• Presence of myopia, defined as <-0.50D in the more hyperopic meridian, in either eye by cycloplegic autorefraction.

Exclusion criteria

for the baseline and longitudinal assessment of reading performance and spectacle compliance.

Children in either cohort will be ineligible if they have:

• History of systemic disease or ocular disease and/or medications known to have an impact on accommodation.
• History of previous spectacle wear

Children in the hyperopic cohort will be ineligible if they have:

• Vision limitation in either eye for reasons other than hyperopia (including amblyopia defined as <6/12 in the better eye).