The optical industry is massively shifting towards digital surfacing technology.
But, are all digital lenses better than conventional lenses?
Only when they are designed properly.
Advanced technology only makes sense when patients can see a real benefit, so the first crucial step is to research how to improve the wearer's visual experience.
To begin, let’s understand the reasons that make conventional lenses less than optically perfect.
Lens performance becomes lower as we look away from the optical center.
This is a result of the oblique aberration that appears when light is refracted obliquely, which happens whenever we look in lateral gaze directions.
Those lateral rays do not focus on the retina.
Oblique aberration reduces the quality of vision outside the centre of the lens.
For high prescriptions and wrap frames the effect is even stronger.
Therefore, Franklin Free Form Lenses have integrated the Digital Ray Path Technology - a set of mathematical methods that calculates the optimal lens surface for everyone.
Digital Ray Path is based on a simulation of virtual rays or beams.
This beam comes from the outer environment and refracts on the front and back surface of the lens.
The back surface is then modified using this refraction so that the beam changes its focus to the center of the retina, the fovea.
In the Franklin Free Form Lenses this procedure is repeated for every direction of sight until the entire back surface of the lens is adjusted, and all simulated beams focus in the fovea.
The result is a fully optimized lens, improved not only in the center, but optimized all over the surface of the lens.
A lens with accurate power in all gaze directions, a high definition Single Vision lens providing clarity from centre to edge.
Resulting in the best possible Franklin Free Form Lens for the wearer.
For progressive Franklin Free Form Lenses, oblique aberration correction is even more important.
Stable usable areas for far and near vision are located away from the optical center, so lens optimization is more significant.
As with single vision lenses, the optimization is based on the Digital Ray Path method.
It is extended to simulate far vision, intermediate vision, and reading vision.
In the upper part of the lens, designed for far vision, the passage of rays coming from distant objects is simulated.
In addition, the calculation takes into account the vertical movement of the eye, and simulates the rays representing the intermediate vision.
Finally, there is a simulation of rays from objects closest to the eye – the reading zone.
The ray tracing method is extended to include the “space object”.
This mathematical model simulates thousands of rays coming from different zones through the front and back surface of the lens, which is optimized during the beam refraction.
It is essential to optimize the progressive design of modern rimless or sport frames with a large curvature.
Here, the lens is often skewed and turned towards the eye, which significantly changes the viewing angle of individual zones.
For this reason HB Optical has integrated the Digital Ray Path technology in all FRANKLIN FREE FORM lenses; making these zones maximized and optimized for both the biometrics of the wearer and the shape of the frame.
The result is comfortable near vision as well as distance vision.
Accuracy, comfort, and aesthetics all come together in Franklin Free Form Lenses.