Estimation of Visual Performance in Children with and without Binocular Anomalies by Means of a Computerised Coding Test

Coding tests are regularly used to estimate the capacity for mental work in children entering school and for younger schoolchildren. The task of the child is to fill a special form by putting conventional symbols (codes) under the rows of test objects in accordance with a sample. The results of such testing reflect both visuomotor and intellectual capabilities since, on one hand, a subject has to perform fast eye and hand movements comparing test objects with the sample and drawing codes but, on the other hand, it is not forbidden to memorise codes and to use an optimal strategy for filling the form. In order to make the coding test more suitable for estimating purely visual capabilities, we evolved a computerised version in which codes were changing at each step, thus making their memorisation useless. Such a coding test was used in an examination of 22 children (age 6 – 7 years) with binocular anomalies (strabismus, amblyopia) from special kindergartens and 190 normal children (aged 6 – 9 years) (63 from kindergartens and 127 from school forms 1 – 3).

The difference between children with binocular anomalies and normal children of the same age was statistically significant (p<0.005). The average indices for normal children of different ages differed significantly increasing from 11.8 (at 6 years) to 24.6 (at 9 years) symbols per minute. The effect of learning was also evident: the indexes of 7-year-old children from the first school form were better than in children of the same age from a kindergarten. The correlation between coding indexes and reading rate was positive but rather weak (0.28) in 52 first-form children tested.