An interventional study of Eyeglasses and Prescription slip in Refractive Errors, sponsored by University of Minnesota. Terminated at 1 site in Sierra Leone. Open to participants aged 9 Years to 20 Years. Per ClinicalTrials.gov, last updated 2026-01-20.
Sponsored by University of Minnesota · Not applicable, Interventional, and Treatment
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.
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.
420 studies on the registry are indexed under Refractive Errors; 59 are open to participants now.
This study's enrollment of 1,821 is above the median of 76 across 301 interventional studies indexed under Refractive Errors.
Browse Refractive Errors studies →University of Minnesota is the lead sponsor of 1,216 studies on the registry; 197 are open to participants now.
Of its 136 completed or terminated interventional studies of FDA-regulated products, 95 (70%) have results posted.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
1. Other ocular problems preventing visual acuity > 6/12 in both eyes.
An eyeglasses prescription and letter to parents, with free eyeglasses at endline.
Other: Prescription slip
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.
Also known as: Glasses, Spectacle
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
Foundational mathematic and literacy skills
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.
Time frame: Month 1 and 9 months after glasses are provided
Anxiety
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.
Time frame: Month 1 and 9 months after glasses are provided
Prosocial
Measured using Strengths \& Difficulties Questionnaire with the prosocial score ranges from 0 to 10 and higher scores indicate more prosocial behaviour.
Time frame: Month 1 and 9 months after glasses are provided
Social and emotional problems
Measured using Strengths \& Difficulties Questionnaire with the score ranges from 0 to 40. Higher scores indicate more social and emotional problems.
Time frame: Month 1 and 9 months after glasses are provided
Teacher-observed wearing of eyeglasses of children
Proportion of children observed wear across all children at daily assessments
Time frame: Month 1 to Month 9 after glasses are provided
Self-reported wearing of eyeglasses compliance
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
Time frame: Month 9 after glasses are provided
Enumerator-observed wearing of eyeglasses
Actual presence of spectacles on the child's face (rather than having glasses at school) at the time of an unannounced examination
Time frame: At Months 3, 6 and 9 after glasses are provided
Cost-effectiveness 1
Total eyeglasses distribution cost (excluding study cost) per child receiving, and wearing, eyeglasses at endline
Time frame: Through study completion, an average of 9 months
Cost-effectiveness 2
Total eyeglasses distribution cost (excluding study cost) per 0.1 standard deviation test score gain
Time frame: Through study completion, an average of 9 months
School attendance
Attendance data will be collected from attendance registry at school. This will be expressed in percentage. Lowest attendance being 0%, highest being 100%.
Time frame: Daily from Month 1 to Month 9
Plan to share: Yes — Only deidentified data will be shared, on request.
Supporting information: Statistical analysis plan
Time frame: Data will be available once they are cleaned and de-identified, kept for at least 10 years after study completion
Access criteria: Those who wish to access the de-identified data will need to request formally with the research team.
This study is terminated, as verified in Jan 2026. You cannot join it, but the record below documents what was studied.
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