The accuracy of the plusoptix for measuring pupillary distance

Introduction: The plusoptiX photoscreener provides a number of measurements, including an estimate of inter-pupillary distance. We compare the plusoptiX photoscreening measurements of pupillary distance to that of an experienced optician in order to measure the accuracy of this reading. Methods: A retrospective chart review was done on 731 patients ranging in age from 1 to 16 years. Of these, 256 patients had both a plusoptiX photoscreening and a pupillary distance measurement by one of our office opticians. Results: Of the 236 patients evaluated, 142 were orthophoric, 97 were esotropic, and 17 were exotropic. The mean absolute difference for the entire group between the two measurements was 0.3mm. For the orthophoric patients, this metric was 0.3mm, while for the esotropic patients it was 0.8mm. There were too few exotropic patients to obtain reliable statistics. Conclusions: Although the average difference between the optician's measurements and those provided by the plusoptiX was within 0.5mm for orthophoric patients, the variability of the measurements provided by the plusoptiX was too great to permit us to recommend the device as an alternative to the optician for routinely dispensing spectacles.