Smartphone-based pupillary light reflex test system

The pupillary light reflex (PLR) test is the method of examining the immediate reaction of the pupil by light stimuli, and dysfunctions in autonomic nervous system can be evaluated quickly and easily through this method. Existing pupillary light reflex examinations utilize medical penlights to provide light stimuli at the pupil of the examined person, directly observe and assess the changes in the pupil based on the stimuli, and record them. Therefore, they have weaknesses in that the recorded results can vary depending on the examiner, and as the changes of the pupil are not measured quantitatively, such methods do not allow objective assessments. The proposed system in this study utilizes the flash LED of the smartphone to provide light stimuli to the patient's pupil, and the resulting reactions are recorded as images and videos to be analyzed. In case of video recording, the user can turn the flash on or off at the desired moment and data acquisition time was set to be 6 seconds. For the image mode, the system was designed to acquire one image prior to light stimulation and 4 images after light simulation, so that temporal changes in pupil sizes with passing of time can be compared. The system developed in this study utilizes smartphones so that anyone can easily utilize the tool conveniently without restrictions of time and location. Further, other strengths include the fact that light stimulation can be provided using the flash function built within the smartphones, as well as the fact that patient data could be saved and managed easily, and shared using the email transmission function.