7 research outputs found
Sensitivity and specificity of a visual acuity screening protocol performed with the Lea Symbols 15-line folding distance chart in preschool children.
Purpose: The aim of this study was to assess the feasibility of a visual acuity
(VA) test using the Lea Symbols 15-line folding distance chart and its diagnostic
validity in detecting VA deficiency in preschool children.
Methods: A group of 149 children aged 38–54 months underwent VA examination
performed with the Lea 15-line folding optotype at a distance of 3 metres,
according to a test protocol described in the Methods section. After the VA test,
a complete ophthalmological examination, including cycloplegic retinoscopy,
a cover test and examination of the anterior and posterior segments, was performed
on each child in order to detect any VA-threatening ocular abnormality.
The Lea Symbols test’s sensitivity, specificity, positive and negative likelihood
ratios (LR +, LR )) and the receiver operating characteristic (ROC) curve
were calculated by means of standard procedures using each VA level of the
chart from 0.1 to 1 (1–0 logMAR) as a cut-off point.
Results: The Lea Symbols test could be successfully used in 95.9% of the population.
The most useful cut-off points for screening preschool children were
found to be 0.8 (LR +5.73, LR ) 0.05) or 0.63 (LR +11.7, LR ) 0.23).
Conclusion: The Lea Symbols test proved to be clinically useful in detecting
VA deficiency in preschool children. The choice between the two best performing
cut-off levels should be made according to the expected cost-effectiveness
of the screening programme