In fact, Lang-Stereotests I and II, and even more so the Lang-Stereopad, are able to provide reliable results even in children younger than 2 years. The Lang-Stereotest is one of the stereotests that has been shown in larger studies to be the easiest and most reliable stereo vision test to perform compared to other tests. In an Australian study of 2189 children aged 6 to 72 months, the Lang-Stereotest II could be used in children as young as 6 months of age and was found to be feasible in 94.4% of the whole collective, overall more frequently than any other test compared. https://pubmed.ncbi.nlm.nih. gov/22525178/
Although not provided for in the guidelines of the Joint Federal Committee on the Early Diagnosis of Diseases in Children (Children's Guideline), given the fact that amblyopia can develop in children as early as the first and second year of life, and the availability of suitable test procedures, in particular the Lang-Stereopad with the Preferential Looking Method, routine stereoscopic screening could be justified before U7a, ideally from the beginning of the second year of life, and in children with a family history of strabismus even from the 6th month of life. This is all the more true This is all the more so as in recent years the examination of infants and toddlers with photo scanners has become established in many places. Although these give good results on refractive anomalies and other disorders, they do not provide reliable information on stereopsis and fail in the case of small-angle strabismus (microstrabismus).
In Germany, there are no prevalence data on amblyopia up to the age of 7. However, according to a study by Elblein (2015), it was 5.6 % in adults between 34 and 44 years of age. According to a parent survey, 2.6% of children had strabismus in the first year of life, 2.2% in the second, 3.3% in the third and 4.1% in the fourth. These figures suggest that despite stereoscopy at the U7a screening, there are still too many cases of amblyopia which could have been diagnosed and treated earlier.
The reasons for abandoning stereoscreening would therefore have to be found in the decision-makers and the availability of the corresponding tests, especially as long as outdated convictions persist, such as this one that early detection is only worthwhile for children from the time they start school because it cannot be reliably carried out before that...
In other countries, too, stereoscreenings are often scheduled too late, due to lack of resources, but also when paediatricians or family doctors are absent or not involved in the screening, or when even ophthalmologists stick to the conventional tests that require glasses due to lack of knowledge of the Lang-Stereotests (e. g. e.g. Titmus fly or TNO) and therefore completely refrain from early testing.