Light exposure and near work are known risk factors for myopia. Current technology allows for objective measurements of light exposure; however, quantification of near work is typically assessed via questionnaires, which are subject to poor recall and biases. Additionally, it is not possible to evaluate viewing behavior from questionnaires. The RangeLife was developed for continuous, objective measurement of near work to quantify risk factors related to myopia, and to provide feedback to the wearer when the working distance is too close or a distance viewing break should be initiated. The RangeLife instrument was developed using an infrared time-of-flight (TOF) distance sensor and real-time clock (RTC) controlled by an Arduino microprocessor coupled to a micro secure digital card data logger. Open-source programming libraries for the TOF, RTC, and data logger components were used to write running code for the device. Power is supplied by a rechargeable lithium polymer battery to provide greater than 16 hours of continuous distance logging at 1 Hz. The sensor is 1 x 1 x 0.2 cm, with a 1 m wire leading to the microprocessor. Results show that the RangeLife is providing accurate, continuous and objective measurements of near working distances. The devices exhibit a linear calibration function, and increasing beam diameter with distance. Preliminary testing shows that near working distances can be binned in 10 cm intervals from 10 cm to 100 cm, with values < 100 cm being considered "distance viewing," and a corresponding near work classification system was developed. Ongoing studies are aimed at incorporating wireless technology into the device, and characterizing near work behaviors between emmetropic and myopic adults and children to understand potential influences of viewing behavior on refractive error development. The device can also be used to alert the wearer when the viewing distance is too close or a viewing break should be implemented.