5
ENGLISH
This test is designed to rapidly test for amblyopia, strabismus and other binocular acuity problems using
stereopsis (depth perception) for subjects ages preschool thru adult.
Depth Perception: (n) The ability to perceive spatial relationships, especially distances between objects,
and three dimensions.
Lea Symbols®: (n) 4 symbols, House, Circle, Square & Apple, developed by Lea Hyvärinen, MD, for
screening children of all developmental abilities and languages designed to blur equally at threshold –
children only see one shape when the symbol size becomes too small to see clearly.
House
Circle
Square
Apple
FAMILIARIZE YOURSELF WITH THE TEST
Test consists of:
• 1 booklet – 2 vectographic pages (3 Sections)
Page 1 (Section A – Parts A, B, C & D)
4 levels of gross disparity
Page 2 (Section B)
12 levels of disparity for critical testing
Page 2 (Section C)
3 gross levels of disparity
• 1 pair adult polarized viewers
(NOT TO BE USED AS SUNGLASSES)
• 1 pair pediatric polarized viewers
(NOT TO BE USED AS SUNGLASSES)
• Answer Key on back cover
TESTING CONDITIONS
• Well-lit, glare-free area
• If reflections or glare on the vectographic pages can be seen, try tilting the booklet or choose another
testing location