Detecting Visuoperceptive Defects in Adult Disabled Readers with the TETRA Analyzer™. Normative Data and Test-retest Reliability

Aims: To collect normative data in adult readers with the TETRA Analyzer™, a tool developed to detect the visuoperceptive alterations supposedly involved in dyslexia.

Study Design: Epidemiological study.

Place and Duration of Study: Service of Neuro-Ophthalmology, University of Turin, Italy, between June 2015 and March 2016.

Methodology: We enrolled 95 normal adolescent and adult readers (34 males, 61 females; age 12-26 years), with BCVA 60/60 and satisfying academic achievement. In the recruited subjects three visuoperceptive functions believed to play a major role in reading have been examined with the TETRA Analyzer™. The instrument is made up of three exams suitable to evaluate ocular dominance (Domitest-M), spatial relationship perception (Eidomorphometry), and interocular sensory pattern (Domitest-S). In case one or more of these functions were found abnormal, a fourth exam (REPORT) checks their effective involvement in the reading disability. In addition, retest reliability has been estimated.

Results: The prevalence of strong, stable dominance in the sample was 86.3%; the remaining 13.7% showed dominance instability to a variable degree. Mean spatial relationship anisotropy was 1.32% (±2.5%). The binocular sensory pattern was overall balanced: in fact, almost one third (30.8%) of the sample did not show asymmetry of the visual input. The distribution of the interocular inhibition was weak, with median interocular inhibition index (an index of interocular suppression ranging from 0 to 2) = 0.10 (IQR: 0.3). Reading rate was insensitive to interletter spacing (words: R2=0.12, p=.29; non words: R2=0.01, P=.72). Reliability was overall satisfying in all the exams.

Conclusion: Considering the role impaired visuoperceptive functions can have not only in children but even in adult dyslexics, the collection of normative data, so far only available for school age pupils, has been extended to adolescents and adults, with the aim to allow future investigations in this type of patients.