Suppression on the Worth 4 dot test and its relationship to stereo acuity

Title Suppression on the Worth 4 dot test and its relationship to stereo acuity
Author, Co-Author Raiju Babu, Rajkumar Nallour Raveendran
Topic Binocular Vision/Pediatrics
Program Number
Ballroom A-B
Waterloo School of Optometry & Vision Science

Purpose: The Worth 4Dot test (W4DT) is routinely used to evaluate binocular sensory status. In this study we investigated whether two possible W4DT outcomes, suppression or fusion, relate to clinical measures of stereopsis in individuals with amblyopia.

Methods: 131 patients with amblyopia (69 adults [18-65yrs], 62 children [7-17 yrs]) completed the W4DT at distance (6 m) and near (33 cm) subtending visual angles of 1° and 6° respectively the Randot Preschool Stereoacuity test and the Titmus Stereo Fly test as part of a baseline assessment for a randomized clinical trial of amblyopia treatment (the BRAVO study). For each stereotest, normal stereoacuity was defined as ≤60 sec arc.

Results: For the Randot test, 128 (98%) patients had reduced stereopsis and 90 (69%) had nil stereopsis. For the Titimus test 109 (83%) had reduced stereopsis and 30 (23%) had nil stereopsis. Log stereoacuity thresholds were statistically significantly correlated between the two tests (rs = 0.65, P < .001). Only 21% of those with abnormal stereopsis on the Randot test exhibited suppression on the near W4DT. This increased to 52% for the distance W4DT. A similar trend was present when considering patients with nil stereopsis on the Randot test. 28% of these patients exhibited W4DT suppression at near and 57% exhibited suppression at distance.

Conclusions: The Worth 4 dot percept of suppression does not consistently predict reduced stereopsis in amblyopia. The relationship is improved when imagery does not exceed 1°. This is consistent with the gradient of strong central suppression to weaker peripheral suppression that we have previously observed in patients with amblyopia.

Affiliation of Co-Authors University of Waterloo