Characterizing the Randot Preschool stereotest: Testability, norms, reliability, specificity and sensitivity in children aged 2-11 years

Abstract

PurposeTo comprehensively assess the Randot Preschool stereo test in young children, including testability, normative values, test/retest reliability and sensitivity and specificity for detecting binocular vision disorders.MethodsWe tested 1005 children aged 2–11 years with the Randot Preschool stereo test, plus a cover/uncover test to detect heterotropia. Monocular visual acuity was assessed in both eyes using Keeler Crowded LogMAR visual acuity test for children aged 4 and over.ResultsTestability was very high: 65% in two-year-olds, 92% in three-year-olds and ~100% in older children. Normative values: In 389 children aged 2–5 with apparently normal vision, 6% of children scored nil (stereoblind). In those who obtained a threshold, the mean log threshold was 2.06 log10 arcsec, corresponding to 114 arcsec, and the median threshold was 100 arcsec. Most older children score 40 arcsec, the best available score. We found a small sex difference, with girls scoring slightly but significantly better. Test/retest reliability: ~99% for obtaining any score vs nil. Agreement between stereo thresholds is poor in children aged 2–5; 95% limit of agreement = 0.7 log10 arcsec: five-fold change in stereo threshold may occur without any change in vision. In children over 5, the test essentially acts only as a binary classifier since almost all non-stereoblind children score 40 arcsec. Specificity (true negative rate): >95%. Sensitivity (true positive rate): poor, <50%, i.e. around half of children with a demonstrable binocular vision abnormality score well on the Randot Preschool.ConclusionsThe Randot Preschool is extremely accessible for even very young children, and is very reliable at classifying children into those who have any stereo vision vs those who are stereoblind. However, its ability to quantify stereo vision is limited by poor repeatability in children aged 5 and under, and a very limited range of scores relevant to children aged over 5.

Stereotest Comparison: Efficacy, Reliability, and Variability of a New Glasses-Free Stereotest

“…This is because most subjects with a normal stereo threshold are able to achieve the best threshold value of 20 arcsec on Randot Circles; therefore, there is little discrimination among individuals with different stereo performance. Thresholds on ASTEROID are distributed roughly log normally, in agreement with lab studies of stereoacuity 20 , 26 ; consistent with this, the interquartile range was approximately 1.35× the standard deviation ( Table ), as expected for a normal distribution. In contrast, the interquartile range for the Randot tests is less than their standard deviation, reflecting the highly non-normal distribution of results.…”

“…We performed statistics on log thresholds, rather than threshold values, as log thresholds are closer to normally distributed (see Ref. 26 for further details). Similarly when combining different thresholds obtained for the same subject, we took the mean of log thresholds (equivalent to the geometric mean of the thresholds).…”

Percentile curves of stereacuity in a Spanish paediatric population

“…Nonetheless, they also concluded that the ability of this test to quantify such values in children aged under five years of age is relatively poor. 3 The Randot test is based on discriminating patterns in random dots, and it is one of the most widely used tests in clinical practice. However, Afsari et al reported that the Randot Preschool stereoacuity test was the most reliable and replicable of all of the tests that were compared in their study.…”

“…However, several studies have shown that it is possible for stereoacuity exploration tests such as the Randot test to be used to determine the stereoscopic vision values, observing that subjects aged between three and five years of age attained similar values to those recorded in the adult population. 3 , 4 , 5…”

ASTEROID stereotest v1.0: lower stereo thresholds using smaller, denser and faster dots

“…b: Bland‐Altman plots showing difference in log arcsec (log 10 θ 2 − log 10 θ 1 ) plotted against the mean (log 10 θ 2 + log 10 θ 1 )/2. A log transform is used since log thresholds are closer to normally distributed than the original log thresholds 44 . Horizontal black line shows 0 difference; solid purple line shows mean of observed differences, or bias; dashed purple lines show the limits of agreement, ±1.96 standard deviations of the observed differences, or 95% coefficient of repeatability; both are given in the text box.…”