[Sources of error in the performance of the R5 test]

A prospective study examining 48 children (age 3.5-7 years) without any ophthalmological symptoms was comparatively performed using the Rodenstock R5 screening test and free examination of visual acuity, phoria and stereopsis. Besides this retinoscopy, interpupillary distance and inclination to instrument accommodation were determined. Using stereopsis targets 121 and 122, the findings of Marquardt (3- to 4-year-old children incline to prefer certain figures, leading to wrong results) can be confirmed. If the actual interpupillary distance is apart from the instrument eyepiece distance, especially if the child's distance is smaller, esophoria can be simulated. Instrument myopia on the one hand may appear as decrease of visual acuity, on the other hand it can be misinterpreted as esophoria. Being aware of these possible errors, the rate of wrong results (mean 22%) can be reduced, leading to better agreement between both methods.