Purchase this article with an account.
J.S. Brown, M. Figueroa, E.L. Francis, G.E. Quinn, G.–S. Ying, R.A. Stone, D.I. Flitcroft; An Approach to Temporal Patterns of Nearwork . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2738.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: This study assessed the feasibility of using a head–mounted, computerized ultrasonic ranging device to better characterize the temporal patterns of nearwork. Methods: We developed a nearwork monitor that measures the time that a subject’s head, and presumably eyes, are directed toward a near object. We attached an ultrasonic range finder (Devantech SRF04 UltraSonic Ranger) to an adjustable hat. An OOPic–based microprocessor and data storage device controlled the ultrasonic transducer and logged the data to non–volatile storage devices (EEProm’s). The directionality of the transducer was determined by taking a grid of measurements of a 10cm x 10cm object in a large, indoor open space at 25cm, 50cm, 75cm, 100cm, 200cm, and 300cm from the transducer. In addition, a pilot study was conducted with the subjects wearing the near–monitor while completing 2 predefined nearwork tasks: reading and computer game playing. Results: At 25 cm, the nearwork monitor detected the object within a 50° cone. With increasing distance the cone narrows (less than 30° at 1 m, approximately 10° at 3m). In a pilot study with 5 adult subjects and with 4 participating a second time, working distance was farther and less varied with computer use compared to a reading assignment. For the initial study the mean reading distance was 30.8cm (SE 0.43cm) (range 26.4–34cm) compared to a mean computer use distance of 48.3cm (SE 0.12cm) (range 35.9–60cm). For the repeat study the mean reading distance was 33.8cm (SE 0.30cm) (range 22.7–41.6cm) compared to a mean computer use distance of 49.3cm (SE 0.07cm) (range 36.3–58cm). Conclusions: We have developed a protocol nearwork monitor that detects reliably and quantitatively working distances for common near–tasks. We conducted a pilot study and found that different tasks appear to have different routine working distances and temporal characteristics. This study demonstrates the feasibility of quantifying nearwork and its temporal characteristics at high frequency in real time. Whether this approach for measuring nearwork and its temporal characteristics is clinically relevant will require further investigation.
This PDF is available to Subscribers Only