Vision Screening Online Training Program - Cross Cover

Vision Screening Online Training Program

Module 4 (continued): Unilateral Cover Tests at Near and Distance

The goal of the Unilateral Cover tests is to detect mild strabismus that is often not detected by observation alone. These tests replace the previously recommended cross cover test. Unlike the cross cover test any eye movement with the Unilateral Cover tests is considered abnormal.

If the stronger eye is covered during the Unilateral Cover tests, the weaker uncovered eye will move to maintain visual focus. Repeatable movement should always be referred for evaluation. Remember if a child resists having an eye covered, it is most often because the covered eye has clearer vision than the uncovered eye.

Perform the Unilateral Cover test only at near distances for children under three years of age. This is because many children under three years have mild myopia, or difficulty seeing at a distance. For children three years and over, the Unilateral cover test is performed both at near and at far distances. Performing both tests for children over 3 years of age can pick up mild strabismus when a child has myopia (near sightedness) or hyperopia (Far sightedness).

Unilateral Cover Test - At Near

Ages
Six months to 20 years of age.

Purpose
To assess ocular misalignment in primary gaze.

Description
Observing the uncovered eye for movement while child fixates on a target.

Equipment
Handheld occluder, small single hand held target (i.e. a sticker on a tongue depressor or Popsicle stick, not a pen light).

Screener qualifications
Can be performed by screeners with recommended training.

Facility
A well-lighted area, free of distractions.

Procedure

  1. Have the child seated in front of examiner, while the examiner holds a fixation target 15 inches in front of child; ensure the child acquires fixation.
  2. Cover the child's left eye with the occluder, watch the uncovered eye (right eye) for movement.
  3. Uncover both eyes and have child reacquire fixation.
  4. Cover the child's right eye with the occluder, watch the uncovered (left eye) for movement.
  5. This procedure should be repeated 2 or 3 times.

PASS
No detection of movement in the uncovered eye.

REFER
Repeatable movement of the uncovered eye or resistance to occlusion by child for one eye but not the other.

Unilateral Cover Test - At Distance

Ages
Three years to 20 years of age.

Purpose
To assess ocular misalignment in primary gaze.

Description
Observing the uncovered eye for movement while the child fixates on target.

Equipment
Handheld occluder, small single target at 10 feet (i.e. visual acuity chart).

Screener qualifications
Can be performed by screeners with recommended training.

Facility
A well-lighted area, free of distractions.

Procedure

  • Have child seated in front of examiner and fixate on the target 10 feet away.
  • Cover the child's left eye with the occluder, watch the eye not being covered (right eye) for any movement.
  • Uncover both eyes and have child reacquire fixation.
  • Cover the child's right eye with the occluder, watch the eye not being covered (left eye) for any movement.
  • This procedure should be repeated 2 or 3 times.

PASS
No detection of movement in the uncovered eye.

REFER
Repeatable movement of the uncovered eye or resistance to occlusion by the child for one eye but not the other.



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