Validity of simple measurement to diagnose pupillary dilation

Study Objective The aim of the study was to compare the validity of 3 methods of detecting pupillary dilation: bright-light measurement, room-light measurement, and gestalt judgment. Methods In reach volunteer, by random assignment, placebo was instilled in one eye and dilute phenylephrine in the other. Emergency care providers judged whether each pupil was dilated and measured it in bright light (>54 000 lux) and in room light (2700-5400 lux) while the other eye was covered. Test characteristics for measurement were determined according to published cut-points, and measurement methods were compared using receiver operating curve analysis. Results There were 136 pupillary assessments—68 in placebo and 68 in phenylephrine eyes. Compared with gestalt judgment, bright-light measurement had higher specificity (0.94 vs 0.68) but lower sensitivity (0.43 vs 0.79). Bright-light measurement was more discriminating than room-light measurement. Conclusion Bright-light measurement has higher specificity, but lower sensitivity, than gestalt judgement, and is superior to room-light measurement.