Evaluation of stereo tests for screening of amblyopia

One of the most dramatic sensory ocular anomalies is the low visual acuityof one eye known as amblyopia. The goal of preschool vision screening is to detect childrenwith amblyopia. Stereopsis is an important indicator of the state of binocularity. Previousstudies showed a disagreement on the reliability of stereo tests as screening tools foramblyopia. This study was performed to compare visual acuity testing with the ability ofTNO, Titmus and Randot stereo tests for detection of amblyopia. A total of 1000 pupils, aged 6-12 years were examined in a field study in Shiraz.In addition to the 3 stereo tests of TNO, Titmus and Randot, the examination included visualacuity, cover testing and inspection of red reflex. According to definite fail pass criteria,abnormal cases were referred to pediatric eye clinic for complete eye physical examination.Similar to the first part, in the second part of the study, 100 amblyopic students aged 6-12years, were referred to pediatric eye clinic for complete physical examination. Sensitivityand specificity of each stereo test for detection of amblyopia was calculated. In screening situation, the sensitivity of stereo tests was 55.5% for TNO with acutoff point of 240", 48.8% for Titmus with a cutoff point of 70" and 44.4% for Randot stereotest with cutoff point of 100". Specificity of these tests in screening situation was86.9%, 94.4%, and 98.4% respectively. The respective sensitivity of these stereo tests inclinical situation was 74%, 68%, and 62%. Considering these fail-pass criteria, none of the TNO, Titmus, and Randot stereotests can be recommended as a screening method for detection of amblyopia in children.