Typical visual problems due to accommodative or binocular disorders are straining, tired eyes and headaches (increasing during the day). A medical history is therefore always an important part of a complete analysis.
The Binocular Test Sequence Olten (BTSO) is used for screening to quickly and easily assess the most important visual functions. Optometry, ophthalmic optics or strabology practitioners are instructed in how to perform the classification themselves.
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Subjective complaints can be recorded more or less well. But what about people who consider their visual problems to be normal? The minimal test battery makes it possible to detect these problems too.
If abnormalities are found, the next step should be to investigate the cause. For this purpose, the measurement results can be transferred into 10 classes in order to determine the best recommended intervention.
The underlying internationally established classification of non-strabismic binocular vision is based on A. Duane. A great deal of research has been carried out in this area, resulting in reliable findings.
Over time, these classes have largely been retained and only slightly expanded, for example by Scheiman and Wick with their “Integrative Analysis” (Scheiman & Wick, 2020).
The BTSO uses standard values from the literature that are applicable for Central Europe and for age groups from 6 to > 80 years. The basic idea of a minimal test sequence originates from the BAND study series: from the outset, the aim was to find a test sequence that was as simple and quick to perform as possible and based on representative data.
In the BAND 1 study, a total group of 3024 schoolchildren between the ages of 7 and 17 in urban and rural areas in southern India were examined (Hussaindeen et al. Binocular vision anomalies and normative data (BAND) https://doi.org/10.1111/cxo.12475). The examinations of the extensive test series take about 45 minutes per child and include the following parameters:
The measurement data were used to calculate normal values and standard deviations for the various age groups in this population.
In BAND 2, the frequency of non-strabismic anomalies was determined (https://doi:10.1111/cxo.12496). Approximately 30% of the children had abnormalities after the provision of current refractive corrections had already been ensured as a prerequisite for participation.
The most common disorders were found to be:
1.) Convergence insufficiency with 17% and
2) Accommodation infacility with 10%
Around 80% of children with anomalies were symptomatic. The BAND 3 study calculated the minimum necessary test battery from the available data (https://doi:10.1111/cxo.12628). For this purpose, the cut-off values and ROC curves (receiver operating characteristic curves) were calculated, always compared for detailed classification.
For example, the diagnosis of “convergence insufficiency” is possible with KNP > 10cm with penlight and red glass with 80% sensitivity and 73% specificity. Accommodative inflexibility is found with 92% sensitivity and 90% specificity due to an accommodative facility of < 7 cycles/minute.