Efficacy of Visual Screening in Ontario

Amblyopia Clinical Trial

Official title:

The Efficacy of a Visual Screening Program to Reduce Later Amblyopia and Untreated Refractive Errors

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02458846
• Other study ID #: 1000045972
• Status: Completed
• Phase: N/A
• Start date: September 2014
• Est. completion date: December 15, 2019

Study information

• Verified date: March 2020
• Source: The Hospital for Sick Children
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

Amblyopia (lazy eye), is the leading treatable cause of vision loss in childhood. Uncorrected refractive errors (ie farsightedness) can lead to difficulties in school. Unfortunately, many children do not receive vision screening until they have already developed irreversible vision problems. We will conduct a cluster randomized clinical trial in which schools, not individual children, are randomly allocated to receive a kindergarten visual screening program or to receive no intervention by the research team (i.e., "care as usual"). We will compare the prevalence of visual problems (and proportion of children with reading problems) when the children are in Grade 2, after allowing for at least one year of treatment.

Description:

The proposed study is a single-masked cluster randomized clinical trial, with randomization and analyses occurring at the level of "schools" (i.e., we are not randomly assigning individuals to groups). To assess the efficacy of a visual screening program, we will compare visual outcomes in 25 schools randomly chosen to receive the program and 25 schools allocated to "care as usual" one year after screening. The screening tools are HOTV crowded acuity, Preschool Randot Stereoacuity Test, and Plusoptix Autorefractor. The outcome measures will assess later differences between schools receiving the visual screening program and control schools for prevalence of (1) visual and (2) reading problems. A lower prevalence of either or both problems in schools where the visual screening program was offered would provide evidence for the efficacy of vision screening. Primary outcome measure is the prevalence of amblyopia, reduced stereo vision, and untreated clinically significant refractive errors in "screened" versus "care as usual" schools. Secondary outcome measure is the proportion of children performing 1 standard deviation below average on reading scores in "screened" versus "care as usual" schools.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 2597
• Est. completion date: December 15, 2019
• Est. primary completion date: December 15, 2019
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 3 Years to 8 Years

Eligibility

Inclusion Criteria:

• Screening: children enrolled in senior kindergarten (age 5-6 years)

• Follow-up: children enrolled in Grade 2 (age 7-8 years)

Exclusion Criteria:

• None

Related Conditions & MeSH terms

• Amblyopia

Intervention

Other:
• Crowded HOTV Acuity Test
This is one of the most sensitive tests of acuity for vision screening of young children. The child is asked to recognize a letter (H,O,T,V) that is surrounded by bars to induce the crowding effects typical of amblyopia. Children were tested monocularly and was required to achieve at least 20/32 in each eye to pass. Children already wearing glasses were tested with their glasses on.
• Preschool Randot Stereoacuity Test
This is a reliable screening test for stereo depth perception for young children. Children wear polarized stereoglasses and are asked to identify or match shapes that are "hiding in the snow", which cannot be perceived if the child has abnormal binocular vision. Children were required to achieve at least 60 arcseconds of disparity to pass. Children already wearing glasses were tested with their glasses worn under the stereo glasses.

Device:
• Plusoptix Autorefractor
Autorefractors are electronic devices that measure refractive errors by focusing a light onto the child's eyes and recording how their reflections from the retina return to the camera. The Plusoptix has been shown to have high sensitivity and specificity in previous research. AAPOS (2013) guidelines were used to determine the referral criteria.

Other:
• Comprehensive Eye Exam
Children who did not pass all three screening tests were referred for full cycloplegic optometry exams, with a parent/guardian present. Optometrists assessed visual history, monocular visual acuity (near & far), strabismus, binocular function, abnormalities of the anterior segment, and cycloplegic refraction. If the optometrist prescribed glasses, frames were chosen at the time of the exam and the glasses were dispensed either at school (with an optician) or at the optometrist's office.

Locations

Country	Name	City	State
Canada	The Hospital for Sick Children	Toronto	Ontario

Sponsors (1)

Lead Sponsor	Collaborator
The Hospital for Sick Children

Country where clinical trial is conducted

Canada, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Prevalence of amblyopia	Prevalence of suspected amblyopia, defined as 2-or-greater line difference in acuity between eyes	16 months
Primary	Prevalence of refractive errors	Untreated clinically significant refractive errors defined by AAPOS (2013) guidelines	16 months
Primary	Prevalence of reduced stereo vision	Stereoacuity is often reduced in patients with some types of amblyopia, and will defined as worse than 30 arcsec	16 months
Secondary	Proportion of below-average readers Year 1	Proportion of Grade 1 children reading 1 SD below average	10 months
Secondary	Proportion of below-average readers Year 2	Proportion of Grade 2 children reading 1 SD below average	22 months