Quantitative determination of pupil by dynamic pupillometry using infrared videography – Role in evaluation of autonomic activity

Abstract

IntroductionPupillometry is a simple, non-invasive method capable of measuring static and dynamic pupil response in several physiological and clinical conditions. The latest digital camera can be slightly modified to obtain real time pupil response under infrared videography and analyzed by image analysis. So the current study has undertaken to confirm characterization of the system by comparing with manual measurements in healthy volunteers. MethodsThis study was conducted in 40 healthy volunteers aged between 18 and 25 years. The system was calibrated by measuring the known length of 3 different lines for reliability. Later real time static pupil pictures were measured and compared with the manual examination of pupil determined by a ruled scale with 0.5 mm accuracy. ResultsThe Image J software was precalibrated with known length and estimated 5 mm, 10 mm and 15 mm lines respectively. The results are 5.01 ± 0.14 mm, 10.01 ± 0.36 mm and 15.02 ± 0.23 mm. There were no significant differences observed between the values analyzed by two examiners. Later the results were compared between manual examination and real time image analysis. ConclusionThe present study suggested that the static and dynamic pupil measurements with real time pupillometer are accurate and probably as reliable as those obtained by manual examination of the pupil using the flashlight test. This system is cost-effective, portable in nature which can produce authentic results of the pupil.