Development of a compact pupillometer for emergency vehicles

We summarize herein the results of research and development concerning a compact light-reflex pupillometer designed for use in emergency vehicles. Conventional methods of analog pupillary light reflex examinations performed in emergency vehicles are associated with errors that result in inaccurate measurements of changes in pupil size. To establish a simple method for quantifying nervous function in prehospital care, we applied an image processing technique based on the Laplace transform for video images captured by a CCD camera. This method produces more accurate measurements of rates of change in pupil size. While this method can be used to assess both direct and consensual light reflexes, we focused in our study on developing a direct light reflex measuring instrument because this choice presents greater technical challenges and offers the potential for a device of significantly smaller dimensions. The performance of the prototype was determined to be satisfactory. Personnel in emergency vehicles equipped with this pupillometer should be able to form objective assessments of pupil contraction rates before arrival at the hospital. We believe this pupillometer will prove useful in primary care and in selecting appropriate destination hospitals by facilitating patient assessments performed during transport, including neurological evaluations, assessments of consciousness, and confirmation of medical history items such as dementia or diabetes.