Seeing to Learn in Sierra Leone (SLII)

January 16, 2026 updated by: University of Minnesota

Seeing to Learn in Sierra Leone: Impact of Spectacle Correction on Children's Academic Performance and Mental Health Wellbeing

The main objective of the Sierra Leone Sees to Learn (SL2) trial is to assess the educational impact of providing free eyeglasses to students aged 9-20 years with uncorrected refractive error in Sierra Leone. The procedures include baseline questionnaires and educational assessments to collect data on students and schools, and then the provision of free eyeglasses to students who have uncorrected (or undercorrected) refractive error (URE). The questionnaires and student assessments will take 1-2 hours. The duration of the study timeframe is one school year. The end-line questionnaires and student assessments will be administered at the end of the school year.

Study Overview

Status

Terminated

Conditions

Intervention / Treatment

Detailed Description

Objective: The main objective of the Sierra Leone Sees to Learn (SL2) trial is to assess the educational impact of providing free eyeglasses to students aged 9-20 years with uncorrected refractive error in Sierra Leone.

Sample frame: Approximately 2400 children with uncorrected (or undercorrected) refractive error (URE) at 300 randomly-selected schools in Freetown and Bo City. A similar number of children from the same schools but without vision problems will also be included, at baseline only, to compare their basic demographic characteristics and daily activities to those of the children with URE. The sample size may vary depending on the percentage of children with URE obtained from screening a total of 40,000 children. All children with URE as specified in the enrolment criteria below will be part of the study.

Design: Cluster-randomized control trial (cluster RCT), with schools as clusters.

Randomization, interventions and balancing: All eligible children will be randomized by school to receive at the start of the school year either: free ready-made or custom eyeglasses (Intervention), or an eyeglasses prescription and letter to parents, with free eyeglasses at end-line (Control). The clusters (schools) will be stratified into groups based on the prevalence of refractive error and on the score on the baseline mathematics and reading exams. The division of the sample into schools in the two cities (Bo and Freetown) will be in the same proportion as the proportion of the number of public schools in those two cities.

Power calculations (reading and math exams): Setting power = 0.8, statistical precision = 0.05, intracluster correlation = 0.2 (from 2019 Sierra Leone grade 8 learning assessment), 80 treated schools, 80 control schools, 15 students/school with uncorrected error, yields the following minimal detectable effect (MDE) sizes as a function of correlation between baseline and end-line tests:

MDE Correlation of baseline and end-line tests 0.101 0.7 0.127 0.6 0.148 0.5

A nested focus-group study will explore children's, parents' and teachers' attitudes towards vision, student learning, and wearing of eyeglasses, in order to design a locally-tailored intervention to promote wearing of eyeglasses.

Regression Framework:

The investigators will estimate the effect of the program using a single difference cross-sectional ordinary least squares regression (OLS), and a difference-in-difference (DID) OLS regression that includes observations at both end-line and baseline. The investigators will report two types of effects: the intent-to-treat (ITT) effects and local average treatment effects (LATE), using treatment assignment as an instrumental variable for participation. Analysis will use the observed baseline characteristics as control variables and account for school-level variation through a fixed effect.

Study Type

Interventional

Enrollment (Actual)

1821

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Sierra Leone
      • Freetown, Sierra Leone
        • Innovations for Poverty Action (IPA)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Presenting (with or without glasses) distance visual acuity of 6/12 or worse in the better-seeing eye;
  2. Refractive error of at least 0.75 diopters (D) of myopia, 2.00 D of hyperopia or 1.00 D of astigmatism;
  3. Visual acuity is correctable to 6/7.5 or better with eyeglasses.

Exclusion Criteria:

1. Other ocular problems preventing visual acuity > 6/12 in both eyes.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: Control
An eyeglasses prescription and letter to parents, with free eyeglasses at endline.
Other: Prescription slip
Children with uncorrected/under-corrected refractive error will be provided with an eyeglasses prescription and letter to parents, but all of them will get eyeglasses at the end of the trial
Experimental: Intervention
free ready-made or custom eyeglasses
Device: Eyeglasses
Children with uncorrected/under-corrected refractive error will be provided with either ready made or custom eyeglasses based on their magnitude and types of refractive errors.
Other Names:
  • Glasses
  • Spectacle

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Foundational mathematic and literacy skills
Time Frame: Month 1 and 9 months after glasses are provided
Item Response Theory to estimate a student's ability on a continuous scale and subsequently standardize students' scores on a continuous scale with respect to the control-group distribution at baseline (mean zero, standard deviation of one). Lower scores will indicate lower performance, and higher scores will indicate higher performance. A -1 would indicate a student's performance is 1 standard deviation below the mean of the control-group performance distribution at baseline. A zero would mean the student performed like the mean student in the control group at baseline.
Month 1 and 9 months after glasses are provided
Anxiety
Time Frame: Month 1 and 9 months after glasses are provided
Measured using Generalized Anxiety Disorder 2-item (GAD-2) questionnaire, the highest score is 8 and the lowest score is 2. Higher scores indicated more severe anxiety disorders.
Month 1 and 9 months after glasses are provided
Prosocial
Time Frame: Month 1 and 9 months after glasses are provided
Measured using Strengths & Difficulties Questionnaire with the prosocial score ranges from 0 to 10 and higher scores indicate more prosocial behaviour.
Month 1 and 9 months after glasses are provided
Social and emotional problems
Time Frame: Month 1 and 9 months after glasses are provided
Measured using Strengths & Difficulties Questionnaire with the score ranges from 0 to 40. Higher scores indicate more social and emotional problems.
Month 1 and 9 months after glasses are provided

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Teacher-observed wearing of eyeglasses of children
Time Frame: Month 1 to Month 9 after glasses are provided
Proportion of children observed wear across all children at daily assessments
Month 1 to Month 9 after glasses are provided
Self-reported wearing of eyeglasses compliance
Time Frame: Month 9 after glasses are provided
Proportion of children who reported to be wearing their eyeglasses 1. Not at all 2. Sometimes 3. Most of the time 4. All the time
Month 9 after glasses are provided
Enumerator-observed wearing of eyeglasses
Time Frame: At Months 3, 6 and 9 after glasses are provided
Actual presence of spectacles on the child's face (rather than having glasses at school) at the time of an unannounced examination
At Months 3, 6 and 9 after glasses are provided
Cost-effectiveness 1
Time Frame: Through study completion, an average of 9 months
Total eyeglasses distribution cost (excluding study cost) per child receiving, and wearing, eyeglasses at endline
Through study completion, an average of 9 months
Cost-effectiveness 2
Time Frame: Through study completion, an average of 9 months
Total eyeglasses distribution cost (excluding study cost) per 0.1 standard deviation test score gain
Through study completion, an average of 9 months
School attendance
Time Frame: Daily from Month 1 to Month 9
Attendance data will be collected from attendance registry at school. This will be expressed in percentage. Lowest attendance being 0%, highest being 100%.
Daily from Month 1 to Month 9

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Minnesota

Collaborators

Innovations for Poverty Action
Peek Vision
Vision Action

Investigators

  • Principal Investigator: Nathan Congdon, MD, Queen's University, Belfast

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 25, 2023

Primary Completion (Actual)

January 31, 2025

Study Completion (Actual)

January 31, 2025

Study Registration Dates

First Submitted

September 21, 2023

First Submitted That Met QC Criteria

September 29, 2023

First Posted (Actual)

October 4, 2023

Study Record Updates

Last Update Posted (Actual)

January 20, 2026

Last Update Submitted That Met QC Criteria

January 16, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Glewwe Transfer

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Only deidentified data will be shared, on request.

IPD Sharing Time Frame

Data will be available once they are cleaned and de-identified, kept for at least 10 years after study completion

IPD Sharing Access Criteria

Those who wish to access the de-identified data will need to request formally with the research team.

IPD Sharing Supporting Information Type

  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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