Are sunglasses appropriate for driving? Investigation and prototype for public testing

BACKGROUND: Good vision through sunglasses is important to safety when driving and ISO 12312-1:2013 sets requirements for luminous transmittance and the transmittance of traffic signals. METHODS: We measured the spectral transmittances, 380–780 nm in 5-nm steps, of 232 sunglasses lenses and calculated the luminous transmittance, category (1–4) and transmittance of red, yellow, green and blue traffic signals (Q values). Furthermore, we developed a prototype for the general public to self-check sunglasses regarding safety for driving. We combined a white LED, a photodetector, and calculations to measure luminous transmittance, traffic signal transmittance, category, and Q-factors in sunglasses. RESULTS: Spectroscopy shows that 75% of sunglasses on the Brazilian market comply with ISO 12312-1:2013 requirements to be suitable for driving. The prototype was validated by testing 232 samples by trained users. Additionally, 60 other samples were tested by untrained users and results were compared to spectrophotometric measurements. Bland–Altman analyses showed no significant biases and 95% agreement of limits within the pre-defined tolerances for all measurements. CONCLUSIONS: Our prototype offers the general public a way to check whether their sunglasses are suitable for driving. As tested, 24.6% of sunglasses are not appropriate for driving and consumer must be more attentive to this information. SIGNIFICANCE: Immediate attention regarding checking sunglasses for driving conditions is needed for non-certified sunglasses.