Case of extremely high refractive error misdiagnosed as normal by PlusoptiX S09 photoscreener

Abstract

Amblyopia is the most common cause of monocular decreased vision in children, with a prevalence of three to five per cent.1 Studies have demonstrated that refractive errors are the most common cause of amblyopia.2,3 Because amblyopia can be treated most effectively when treated early, screening for amblyopia is recommended by the American Academy of Pediatrics and the American Optometric Association.4 Refractive measurement of children is challenging but new technologies are helping to improve screening. Photoscreeners are gaining importance because of their portability and ease of use in examining young and disabled children (for example, those with autism).5,6 PlusoptiX S09 (Plusoptix®GmbH, Nuremberg, Germany) is a binocular, portable infrared video refractor which uses the dynamic photosciascopy method. As a digital photoscreener, it records digital video using infrared beams and analyses data in seconds using software installed on the minicomputer of the handpiece. At the beginning of a measurement, the PlusoptiX camera takes a few pictures to determine whether the refractive error is outside measurement range. If it is, a ‘measurement out of range’ error message is shown on screen. In addition, the operator will find the words ‘myopia’ or ‘hyperopia’ instead of refractive readings in the output to indicate which limitation was exceeded. The measurement is aborted in this case and the screening result is ‘refer’. The method used to detect whether the refractive error is outside the measurement range is proprietary (RJ Jacobs, personal communication). Studies suggest that non-cycloplegic photorefraction has reasonable sensitivity and specificity compared with cycloplegic retinoscopy.5,7 We present this case to show how a photoscreener can misdiagnose a patient with very high refractive error as emmetropia.