Prototype Device for Driving Suitability Tests in Sunglasses

Wearing inadequate sunglasses while driving may lead to dangerous misunderstandings in objects and traffic lights recognition. Sunglasses standards propose transmittance requirements that sunglasses should fit to be classified as suitable for driving. Transmittance tests are time-consuming and laborious. Also, it requires a spectrophotometer and a skilled technician to be performed. The aim of this study was to develop and to build an easy-to-use, quick and accurate device for luminous and traffic lights transmittance tests which runs the tests by itself in a way anyone can operate it without any training. A microcontrolled prototype was developed and built using a white LED and a four-channel sensor combination. This combination generated luminous and traffic lights weighting functions similar to standard ones. Using our prototype and a gold standard (VARIAN Cary 5000 spectrophotometer), luminous transmittance and relative attenuation quotients for traffic lights were measured in 128 sunglasses lenses. Bland-Altman method was used to assess concordance between both measurement methods. The bias was insignificant for all measurement and the limits of agreement were broad for luminous transmittance and for relative attenuation quotient for blue light detection, and narrow for the others. Thus, within the predefined tolerance, prototype measurements are equivalent to gold standard ones for relative attenuation quotients for red, yellow and green light detection. Despite not all prototype measurements being equivalent to gold standard ones, results were accurate; only 5 from 128 lenses were defectively classified as to suitability for driving (2 for luminous transmittance, 1 for red light quotient and 2 for blue light quotient). Our prototype creates means to general public to assess characteristics of their own sunglasses including whether they are suitable for driving according brazilian and ISO standards.