Efficacy of Visual Screening in Ontario

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.

Conditions

• Amblyopia

Interventions

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.

OTHER

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.

Sponsors & Collaborators

• The Hospital for Sick Children

  lead OTHER

Principal Investigators

• Agnes Wong · The Hospital for Sick Children

Study Design

Allocation

NON_RANDOMIZED

Purpose

DIAGNOSTIC

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

3 Years

Max Age

8 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2014-09-30

Primary Completion

2019-12-15

Completion

2019-12-15

Countries

• Canada

Study Locations