Do automotive window films affect drivers’ safety by decreasing vision sensitivity? A Cross-sectional study

Abstract

Objective: To measure visual acuity in high contrast and low contrast sensitivities in different grades of visible light transmission films in three different positions (front, lateral and rear windows). Methods: Forty-four healthy volunteers between 30-75 y-o, with BCVA better than 0,5, were tested in the 5 following vehicles with different grades of visible light transmission films. Vehicle 1: 75% in the front and 70% in the lateral and rear windows; Vehicle 2: 70% in the front and lateral windows and 28% in the rear; Vehicle 3: 70% in the front, 28% in the lateral and 15% rear; Vehicle 4: 35% in all 3 windows; Vehicle 5: 50% in the front, 20% in the lateral and 15% in the rear. Descriptive statistics were used and the average of the 3 measurements of VA was considered. Wilcoxon Test was applied to compare the average visual acuity in each vehicle and position. P value<0.05 was considered statistically significant. Results: According to the Brazilian Traffic Regulations for driving in categories C/D/E, when low contrast was tested in the front window, all visible light transmissions were borderline, in the lateral window they were all outside the limit, while in the rear window for both low and high contrast, all visible light transmissions tested were outside the limit and also borderline for driving in categories A/B, with the exception of the vehicle with visible light transmission of 35%. Conclusion: Visual acuity is affected, especially in the rear window, by the use of automotive films. The study is an alert that window films is a possible cause of accidents and may contribute to the revision of traffic regulations worldwide.