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Tuesday / August 9.
HomemilensesSOLA Elan HDV: An Evolution in Versatile Progressive Lenses

SOLA Elan HDV: An Evolution in Versatile Progressive Lenses

SOLA Elan HDV is the latest generation progressive lens from SOLA. Based on a unique lens design platform, SOLA Elan HDV delivers a lifestyle-based lens design incorporating Physiologically Mapped Optics, which delivers excellent optical performance, regardless of the wearer’s type of refractive error or stage of presbyopia.

SOLA guided a new era of progressive lens performance with the launch of SOLAOne, an award-winning*
progressive lens design that achieved versatile performance by offering a patented balance of visual utility across the most common viewing tasks.1 The performance and wearer satisfaction of SOLAOne set a new standard for general-purpose progressive lenses. The newest progressive lens by SOLA promises to
deliver greater versatility and performance for even more progressive lens wearers.

SOLA Elan HDV represents the latest-generation progressive lens design by SOLA and is the result of years of ongoing research into presbyopic visual lifestyle demands. SOLA Elan HDV combines proven features
with wider viewing zones and a more advanced prescription design strategy called Physiologically Mapped Optics.

Customised Progressive Lenses

With conventional, factory-molded front surface progressive lenses, the through power optical performance is compromised in most prescriptions and no consideration is given to the position of wear of the final product.

“The back-surface progressive lens design has been fully customised to the exact prescription and fitting requirements of each wearer.”

This is mainly because the interaction between the front and back surface, which can cause ‘oblique astigmatism’ that interact with the unwanted astigmatism across the progressive lens surface. These optical interactions can also degrade the clarity of the central viewing zones of the lens and cause the viewing zones to shrink or even become distorted in shape (Figure 1).

With traditional, semi-finished progressive lenses, the design is only optimised for a single prescription and a single set of fitting parameters, referred to as the ‘position of wear’. Typically, this ideal lens design is calculated for a specific sphere power located near the centre of the prescription range associated with each base curve using a set of average values for vertex distance, pantoscopic tilt, and frame wrap angle. Prescription combinations or ‘positions of wear’ that deviate from these specific parameters cause deterioration in optical performance and lens design. Traditional progressive lenses may therefore deliver poorer vision quality and reduced visual utility (Figure 2).

Unlike traditional progressive lenses, SOLA Elan HDV is fully customised in ‘real time’ for the wearer’s exact
prescription requirements using SOLA’s exclusive optical design software engine and patented2 free-form technology. This proprietary design engine utilises sophisticated computer ray tracing and complex optimisation algorithms to calculate and to refine the optics of the lens design as perceived by the actual wearer.

The back-surface progressive lens design has been fully customised to the exact prescription and fitting requirements of each wearer. The lens design is then accurately replicated onto a lens blank using precise free-form surfacing technology. This state-of-the-art optical optimisation and lens production process custom-tailors the optics of each lens to ensure that the intended optical performance of the SOLA Elan
HDV lens design is preserved for every wearer, regardless of his or her unique prescription or fitting requirements. As a result, SOLA Elan HDV progressive lenses will offer up to 50 per cent larger fields of clear vision compared to traditional progressive lenses (Figure 3).

Figure 1.

Figure 2.





Figure3.

Figure 1. As these ray-traced contour plots of the optical astigmatism experienced by the actual wearer indicate, the specific prescription requirements and fitting geometry of a given progressive lens can significantly impact the optical performance of the lens design.

Figure 2. Traditional progressive lenses are designed for a handful of “average” prescription sphere powers in an “average” position of wear, which can result in compromised optical performance and reduced utility for many wearers.

Figure 3. Unlike traditional progressive lenses, SOLA Elan HDv is customised for the wearer’s exact prescription requirements and position of wear, which ensures the widest, clearest fields of vision possible

Morphing Generation Technology

Mass produced semi-finished progressive lenses are mostly made available in one or two corridor lengths. Although ‘standard’ progressive lenses with longer corridor lengths and ‘short-corridor’ progressive lenses offer sufficient visual utility broad range of frame sizes, the majority of frames fall somewhere between these two extremes. (Figure 4).

SOLA Elan HDV employs SOLA’s patented3 Morphing Generation technology, which manipulates the size
and shape of the distance, intermediate, near, and peripheral zones of the lens design in ‘real time.’

By combining sophisticated computer interpolation with curvature vector mapping algorithms that can literally
expand or contract the various zones of the lens as needed, the overall geometry of the progressive lens design can be modified on the fly to maximise the performance of the lens for each wearer. This technology
is similar to the software used to create the computer-generated special effects often seen in films and television.

Morphing Generation technology allows SOLA’s free-form optical design engine to match the ideal corridor length and viewing zone sizes of the lens design to the fitting height and frame size selected by each wearer (Figure 5). The ideal balance between reading utility and the size of the remaining zones of the lens design is thof only 14mm. Each SOLA Elan HDV lens is engraved with a code to identify the unique lens design associated with the specified fitting height.

Each SOLA Elan HDV lens design is directly surfaced onto the lens blank using precision free-form manufacturing ensuring accurate replication of the progressive lens design. Placing the progressive optics on a single surface also eliminates the possibility of misalignment between the optics of the front and back
surfaces. Moreover, the use of backsurface progressive optics maximises the fields of clear vision by placing the viewing zones closer to the eyes, while minimising unwanted magnification effects, such as skew distortion and image swim.

Figure 4.



Figure 5.


Figure 4. As these contour plots of unwanted surface astigmatism within a frame of moderate size indicate, many wearers must tolerate either insufficient reading utility or unnecessarily small viewing zones with greater peripheral astigmatism.

Figure 5. SOLA’s patented Morphing Generation technology expands or contracts the corridor length and viewing zones of the lens design to the wearer’s selected frame style and fitting height in order to maximise optical performance and reading utility, regardless of frame size.

Next-Gen Optical Performance

SOLA Elan HDV has been engineered to deliver superior performance across the full range of daily visual tasks faced by today’s demanding presbyopes. Further, using Physiologically Mapped Optics, this performance has been fine-tuned for the visual lifestyle habits and physiological characteristics of all presbyopes, regardless of their type of ametropia or state of presbyopia. Newly developed optical design tools and a variety of unique design features have resulted in a progressive lens that delivers perfectly balanced visual utility.

Mark Thyssen is a trained Optician (Optical Dispenser) and Director of Product Management Asia Pacific at Carl Zeiss Vision.
References:
1. Miller A. and Varnas S. “Balanced progressive lens.” US Patent 7 066 597; 2005.
2. Hof A. and Hanssen A. “Spectacle Lens with Spherical Front Side and Multifocal Back Side and Process for Its Production.” US Patent 6 089 713; 2000.
3. Fisher S. and Varnas S. “Method of designing progressive lenses.” US Patent 7 344 245; 2005.
* Winner of the 2004 Optical Laboratory Association’s Award of Excellence in Lens Design.