BETTER VISION: How do you test those kinds of lenses?
Frank Mielich: We put DriveSafe through a whole series of scientific analyses to give us the best possible insights into the three key issues we've been talking about. Test wearers tried out and verified each new design characteristic to see how it affected their vision when driving and whether each new DriveSafe prototype significantly improved their vision. That's how we got to the final version of the DriveSafe product.
We also carried out studies to find out when people feel dazzled. What are people's 'pain thresholds' when it comes to discomfort glare? How strong does glare have to be before you are unable to do something such as read letters? And how is that affected by different products, glare intensities and coatings/filters? We tested the lens prototypes exhaustively to discover how they affected people's vision. And we had multiple test subjects trying out our prototypes and giving us their subjective feedback based on a very extensive questionnaire. One of the most important things within the study, was how people felt wearing the new lenses, both when driving and in everyday use. This kind of real-life testing is crucial, so we made sure that extensive internal and external wearer trials were an integral part of this project.
We worked with the FKFS Research Institute of Automotive Engineering and Vehicle Engines Stuttgart to analyse how people move their eyes and head when driving. We wanted to know how they refocus their gaze, where exactly they look, and how long they maintain that focus, as well as how they move their eyes and head. We answered those questions by putting test subjects in a special test vehicle equipped with cameras and watching their head and eye movements while they drove. That gave us important insights into how we could optimise progressive lenses for driving.
BETTER VISION: What do people focus on when they drive? And how do they shift their focus? How is it different from other everyday activities?
Christian Lappe: The modern world demands more and more of our eyes. In many cases we are not even aware of this, but the way we live nowadays is forcing our eyes to work in new ways. The development of Digital Lenses is one example of how we have responded to these changes. We spend far more time using our close-up vision now that smartphones, tablets and similar devices have become so popular. As a result, we're constantly and rapidly shifting our attention and gaze from near to far objects. That gets tiring for our eyes in the long run, and it can eventually lead to symptoms of eye strain.
Driving involves a different kind of vision behaviour altogether, and it exerts a different kind of strain on our eyes. It requires a dynamic form of vision which involves constant head and eye movements. As well as keeping our eyes on the road, we have to monitor our surroundings – both directly and through our mirrors – and constantly glance at and operate dashboard instruments. The studies we carried out with FKFS showed that we look at the road 96% of the time. That surprised us because we thought the percentage would be lower, perhaps 80% of the time looking at the road and 20% at the instruments and mirrors. But we also found it reassuring, because keeping an eye on the traffic is, after all, the most important aspect of driving! Nevertheless it also means that we obviously squeeze all our glances at the wing mirrors, rear-view mirror, and dashboard into a very small period of time. That's certainly not 'normal' visual behaviour, and it’s extremely tiring for our eyes, and the visual system overall. Probably the only other situations where you would glance around so quickly would be when you are doing things such as crossing a major road in Paris or hunting for the best bargains in the sales! And when we're driving our eyes are having to do this for long periods, and sometimes in difficult conditions.
So I guess it's not so surprising that lenses specifically designed for this purpose can provide better and more relaxed vision.
Frank Mielich: And that's what our test wearers and the first DriveSafe lens wearers have told us, too. We were absolutely delighted with the tremendously positive feedback we got on the final product from both single vision and progressive lens wearers. And of course the DriveSafe range also includes a specific lens for wrapped spectacles.
BETTER VISION: What was the most exciting moment for you personally during the development of DriveSafe?
Frank Mielich: We started off by testing a few prototype versions with different combinations of lens designs and coatings (2x2 combinations) in a small group of experts. Testing a new product yourself is always an exciting moment in a project, perhaps the most exciting of all. That transition from theory to practice is full of unknowns, but it's exciting.
I took those lenses with me when I finished work that day and tried them out on the drive home. I wasn't impressed with the first version, so I switched to the next product combination and tried it out in front of my car's xenon headlights. It was an amazing feeling! I thought to myself: we could really be onto something here...