Correlations between clinical measures and symptoms: Report 1: Stereoacuity with accommodative, vergence measures, and symptoms.

AIM: The aim of this study was to explore associations between reduced stereoacuity and clinical measures of accommodation, vergences, and symptoms which could facilitate the development of quick and reliable screening tools. METHODS: Using a multi-stage random cluster sampling, 1211 high school students (481 males and 730 females) between 13 and 18 years of age, were selected and examined. Visual acuity, stereoacuity and suppression, refractive errors, near point of convergence, heterophoria and fusional vergences, as well as, amplitude of accommodation, accommodative response, facility and relative accommodation were evaluated. Correlations among variables and the validity of Randot stereoacuity to distinguish between children with and without defective clinical measures as well as symptomatic versus asymptomatic children were characterized by the sensitivity and specificity of the tests. RESULTS: The overall mean stereoacuity was 43.9 ±â€¯25.23 s arc, and 18.9% [95% Confidence Interval, 16.6-21.4%)] of the participants had reduced stereoacuity (defined as ≥60). Stereoacuity values and symptoms scores were worse in children with defective clinical measures. The Receiver Operation Curve showed that maximum sensitivity and specificity was obtained with near point of convergence break (≥10 cm) of (0.70 95% confidence interval: 0.63-0.77) with Randot stereoacuity test (defined as ≥60 s arc). The correlations between reduced stereoacuity and symptoms scores was moderately strong and statistically significant (Pearson's, r = 0.507, p = 0.01). The Receiver Operation Curve showed that maximum sensitivity and specificity obtained with the Convergence Insufficiency Symptoms Survey was 0.57 (95% Confidence interval = 0.53-0.62, p = 0.001), sensitivity of 90.26%, and specificity 15.26% with the Randot stereoacuity test. CONCLUSION: Reduced stereoacuity, defective clinical measures and symptoms of asthenopia were prevalent among sample of school children studied. Randot stereoacuity test could fairly distinguish between defective and normal clinical measures; though the accuracy to differentiate between symptomatic and asymptomatic school children is poor. These findings highlight the need for validation of a simple and fast screening tool in school settings. Further studies to confirm above findings will be needed.

Rendimiento de la prueba estereoscópica Random Dot con símbolos de Lea / Performance of Random Dot stereoscopic test with Lea Symbols

El examen de estereopsis informa sobre la calidad de la visión binocular del paciente y orienta sobre la existencia y severidad de supresiones binoculares. Objetivo: determinar la sensibilidad y especificidad de la prueba Random Dot con símbolos de Lea en niños de edad preescolar de la ciudad de Bucaramanga, entre agosto del 2009 y abril del 2010. Metodología: se aplicaron las pruebas a 349 niños. Se usó como referencia la prueba estereoscópica Randot® Preschool, confrontada con la nueva prueba Random Dot con símbolos de Lea. Dos observadores clínicos se encargaron de realizar cada uno una prueba diferente. Resultados: se observó una sensibilidad del 79,31 % y una especificidad del 80 % para la prueba Random Dot con símbolos de Lea. Valor Predictivo Positivo (VPP): 26,44 %; Valor Predictivo Negativo (VPN): 97,7 %. Conclusiones: la prueba Random Dot con símbolos de Lea no representa un valor confiable para usarla como única prueba de tamizaje visual en la detección de alteraciones de la visión binocular. La baja prevalencia (8,3 %) de la condición dentro de este estudio aumenta su VPN. Esto unido a su alta especificidad hace que la prueba sea muy eficiente cuando se trata de confirmar la probabilidad de no tener la alteración cuando otra prueba, previamente, la ha clasificado con resultados normales.

The stereopsis test reports on the quality of the patient’s binocular vision and provides guidance on the existence and severity of binocular suppressions. Objective: To determine the sensitivity and specificity of the Random Dot test with Lea symbols in preschool children from the city of Bucaramanga, between August 2009 and April 2010. Methodology: The tests were applied to 349 children. The Randot® Preschool stereoscopic test was used as reference, confronted with the new Random Dot test with Lea symbols. Two clinical observers were responsible for performing a different test each. Results: A sensitivity of 79.31 % and a specificity of 80 % were observed for the Random Dot Test with Lea Symbols. Positive Predictive Value (PPV): 26.44 %; Negative Predictive Value (NPV): 97.7 %. Conclusions: The Random Dot test with Lea symbols does not represent a reliable value to use as single visual screening test for the detection of binocular vision disturbances. The low prevalence (8.31 %) of the condition in this study increases its NPV. This, together with its high specificity, makes the test very efficient when it comes to confirming the likelihood of not having the disorder when a different test has already classified it with normal results.