Instinctive® and Instinctive Short: Proven Optical Performance Now with More Frame Choices

Progressive Lenses by Carl Zeiss Vision

By Darryl Meister, ABOM

Instinctive progressive lenses represented an achievement in elegant lens design that both eyecare professionals and eyeglass wearers continue to appreciate. The Instinctive lens design relies upon the use of superposition optics with algorithmic smoothing, combined with a variety of the kind of design features that you would expect in a high-performance progressive lens. Now, Instinctive has been matched with Instinctive Short, a short-corridor version that provides this proven performance in broader range of frame choices, down to a minimum fitting height of only 14 mm.

Proven Performance Through Elegant Design

The continued success of Instinctive progressive lenses among 18 MM MINIMUM ULTRA-SOFT wearers reflects the proven quality of the lens design, which balances FITTING HEIGHT PERIPHERY performance with simplicity. A great general-purpose progressive lens must offer performance that wearers can rely on, regardless WIDE DISTANCE 1.0 BALANCED

& INTERMEDIATE 1. BINOCULARITY of where they look through the lens. The viewing zones must be 1.0 5 2.0 properly allocated over the lens, providing excellent visual utility in GENEROUS MULTI-DESIGN the distance, near, and intermediate zones without compromising NEAR ZONE 1.1.5 CONSISTENCY image integrity in the periphery. The lens must also be easy to dispense, minimizing sensitivity to potential fitting and fabrication INSTINCTIVE errors with gentle power transitions. Finally, the lens must be equally Figure 1. Instinctive relies on superposition optics with algorithmic smoothing comfortable to wear, resulting in fast adaptation for the wearer. combined with a variety of lens design features to deliver excellent utility.

Rather than relying on extensive engineering manipulation, the Because of these patented technologies, Instinctive boasts a number Instinctive lens design delivers the smoothest progressive optics of lens design features that wearers appreciate immediately. An possible by utilizing an elegant mathematical solution inspired by exceptionally large distance zone combined with a soft periphery the harmony of nature, Dirichlet’s principle, after the renowned delivers a single-vision-like viewing experience that wearers will German mathematician Johann Peter Lejeune Dirichlet. Also known adapt to effortlessly. Smooth progressive optics ensure effortless as the principle of minimum potential energy, Dirichlet’s principle focusing and transition from one zone to another. A wide progressive accounts for the distribution of energy associated with many natural corridor and generous near zone provide excellent mid-range and phenomena, such as the distribution of electrical potential around a reading vision utility. Instinctive progressive lenses also offer the kind charged conductor and the distribution of temperature in a material of lens design features that you have come to expect from high- body. This mathematical technique spreads the intermediate curves performance progressive lenses (Figure 1): of the progressive surface in a manner the mimics natural physical • A superposition lens design with algorithmic smoothing produces phenomena, resulting in the smoothest surface possible. an ultra-soft periphery and generous viewing zones. The reliance on a smoothing algorithm that reflects the behavior • An expansive distance zone combined with a generous near zone of changing quantities in nature provides a very natural viewing ensure great overall visual utility. experience for the wearer, with markedly lower levels of unwanted • The use of multi-design technology provides consistent near vision astigmatism, skew distortion, and image swim. But this is not the utility, regardless of addition power. only innovation that makes Instinctive progressive lenses work so • A variable near zone inset and balanced peripheral optics provide well. Many progressive lenses are often characterized as either hard, excellent binocularity and comfort. with wide viewing zones, or soft, with a gentle periphery. However, Instinctive relies on a unique superposition design technique that combines the best features of both types of lens designs, resulting in generous central viewing zones along with a soft, usable periphery. Progressive Lenses by Carl Zeiss Vision

Algorithmically Smooth, Superposition Optics

Early progressive lens designs relied upon fairly simple surface SIMPLE PROGRESSIVE WITH BIPOLAR DESIGN WITH geometries with circular horizontal cross-sections to provide the HORIZONTAL CURVES DIRICHLET SMOOTHING progressive increase in addition power. The simplest way to visualize these early lens designs is to imagine inserting intermediate segments INTERMEDIATE D into an Executive-style (i.e., lined, full-width) multifocal lens. With CURVES the insertion of each new intermediate segment, the difference in addition power between each segment becomes smaller while +0.50 +0.50 +1.00 +1.00 the ledge between adjoining segments becomes narrower. As the +1.50 +1.50 +2.00 +2.00 number of segments approaches infinity, the changes in addition N power become continuous while the ledges vanish entirely. The result is a progressive surface that is simple to design and manufacture.

While these early progressive lenses often provided wide distance and near zones, the use of circular horizontal cross-sections for the MAXIMUM MAXIMUM ASTIGMATISM > 9 D ASTIGMATISM = 2 D intermediate zone produced extremely high levels of unwanted

1.0 1.0

surface astigmatism (cylinder error) in the lateral blending regions of 1. 1.0 5

5 5

5 5 .

9.0 8.0 5 1. .5 0 6.

2.0 2.0

8. 5 5 5 5

5 5.

0 3. 3. 0 7. 4.

5 5.0

0 3.

4. 4.0 3. the lens surface. This unwanted astigmatism results in blurred vision 2. 7.0 5. 6. 6.0 2.0 5 1.

for the wearer as well as unwanted magnification effects, such as 1.0 1.5 skew distortion (the apparent shearing of objects) and image swim (the apparent undulation of objects). Over the years, progressive lens designers have developed various methods to better manage Figure 2. Using Dirichlet’s principle, the intermediate zone curves of Instinctive (shown in 0.25 D steps) are spread smoothly between the distance (D) and unwanted astigmatism in progressive lenses, including the use of near (N) zone poles of the lens, resulting in dramatically less astigmatism aspheric cross-sections or numerical optimization techniques. compared to a simple progressive lens with circular horizontal cross-sections.

Eventually, it was discovered that progressive lenses could be made Instinctive also utilizes a patented† superposition progressive lens “alogrithmically smooth” by minimizing mathematical functions design technique. The total progressive surface geometry of a based on Dirichlet’s principle. This patented* technique spreads superposition lens design consists of the weighted mathematical the intermediate curves of the lens surface in a manner that mimics average of a hard-type progressive design and a soft-type design, natural physical phenomena. For the Instinctive lens design, Dirichlet’s allowing the lens designer to combine the best features of both. principle is used to distribute the power and astigmatism smoothly Consequently, Instinctive combines the excellent central viewing between the centers of the distance and near zone boundaries of the zone utility of a hard-type design with the visually gentle periphery of surface, which serve as the two poles of a bipolar lens coordinate a soft-type design (Figure 3). These patented technologies from Carl system (Figure 2). In fact, the use of Dirichlet’s principle assures the Zeiss Vision continue to deliver proven performance. For the wearer, smoothest possible progressive lens optics for a given distance and generous viewing zones and a usable periphery ensure that the lens near zone size, creating a more natural viewing experience for the is easy to wear. For the dispenser, more forgiving progressive optics wearer. and fast adaptation ensure that the lens is equally easy to dispense.

SOFT DESIGN HARD DESIGN SUPERPOSITION Figure 3. Using superposition lens design, +25 a soft-type progressive lens design that +20 provides a gentle, usable periphery is GENTLE WIDE BENEFITS combined mathematically with a hard- +15 PERIPHERY VIEWING ZONES OF BOTH DESIGNS +10 type lens design that provides wide, clear viewing zones, resulting in Instinctive, a +5 1.0 1.5 1.5 1.0 1.0 2.0 superposition progressive lens that offers 0 1. 1.0 5 2. the best features of both lens types (as 5 –5 2.0 2.0 shown by these contour plots of ray- –10 5 1. traced unwanted astigmatism). –15 1.5 1.0

–20 1.0 –25 50% OF FINAL LENS DESIGN 50% OF FINAL LENS DESIGN FINAL SUPERPOSITION DESIGN

* US Patent 4 861 153 2 † US Patent 5 726 734 Progressive Lenses by Carl Zeiss Vision Progressive Lenses by Carl Zeiss Vision

Unsurpassed Utility in More Frame Choices

Small, fashionable frames that require short fitting heights remain 14 MM MINIMUM ULTRA-SOFT popular among eyeglass wearers. Traditional progressive lenses, FITTING HEIGHT PERIPHERY however, frequently cannot satisfy the fitting height requirements

of these modern frame styles. Standard progressive lenses typically SUPER-SHORT 1.0 BALANCED 9 MM CORRIDOR BINOCULARITY have a minimum fitting height of 18 mm, although nearly 30% of

2.0

1. eyeglass orders require a fitting height below 18 mm (Figure 4). 5 LARGE FULL ADD 1.5 MULTI-DESIGN Because of this, the proven optical performance of Instinctive has POWER AREA CONSISTENCY now been paired with a short-corridor version. With Instinctive Short, 1.0 wearers can finally enjoy the exceptional optics of Instinctive lenses in INSTINCTIVE SHORT a broader range of frame choices, down to a minimum fitting height Figure 5. Instinctive Short relies on the same features that made Instinctive of only 14 mm. successful along with a 9-mm corridor to deliver more utility in small frames.

The optical performance of a progressive lens design is closely linked This impressive optical performance was achieved through the to the length of the progressive corridor: Short corridors necessitate application of the same patented technologies and lens design more rapidly increasing levels of unwanted astigmatism. Since short- features that made Instinctive progressive lenses so successful (Figure corridor progressive lenses were first invented for small frames in 5). Like Instinctive, Instinctive Short is also a superposition lens design 1998 by a division of Carl Zeiss Vision, the company has continued to that relies on algorithmic smoothing between the distance and make great strides in improving upon these lenses. Instinctive Short near poles using Dirichlet’s principle. By combining the near zone is the result of an award-winning lens design platform that achieves functionality of a hard-type design with the usable periphery of a unsurpassed reading utility in small frames while maintaining a soft, soft-type design, Instinctive Short can provide unsurpassed reading usable periphery. Instinctive Short has a corridor length of only 9 mm utility in small frames without introducing intolerable levels of from the fitting cross to 85% of the specified addition, resulting in unwanted peripheral astigmatism, skew distortion, and image swim considerably more add power area inside small frames. in the periphery of the lens, which would normally occur in short- corridor progressive lens designs. DISTRIBUTION OF PROGRESSIVE FITTING HEIGHTS Because of this unique design strategy, Instinctive Short delivers 20% STANDARD PROGRESSIVES significantly more reading utility in small frames than many short- corridor progressive lenses from competitors, without unnecessary 15% compromises in visual performance (Figure 6). In fact, Instinctive Short

10% will provide wearers with sufficient reading utility in even the smallest fashion frames, with B dimensions as shallow as 21 mm. Further, 5% the use of multi-design optics that vary the size of the near zone as a function of add power ensures that wearers will enjoy sufficient

SHARE OF EYEG LA SS ORDERS 0% reading utility in small frames even in higher additions. Between 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 FITTING HEIGHT (MM) Instinctive, with a minimum fitting height of 18 mm, and Instinctive Short, with a minimum fitting height of 14 mm, progressive lens Figure 4. Standard progressive lenses with a minimum fitting height of 18 wearers now have a virtually unlimited range of frame choices. mm fail to satisfy nearly 30% of eyeglass orders with shorter fitting heights.

INSTINCTIVE SHORT COMPETITOR A COMPETITOR B Figure 6. As these plots of ray-traced add power demonstrate, Instinctive Short provides a shorter progressive corridor with a much larger area of add

1 1 power (within ±0.25 D of the specified addition) inside small frame styles at short fitting heights 5 1.0 11. 1.0 1.0 than many short-corridor progressive lenses from 0 2 2.0 1.1 5 11..5 competitors.* 02.2 0 11. 1.75 . ++1.7 5 .5

14 MM 11. 5 +1+1.7575 +1+1 775

1.0 1 .5 1 2 ADD IN FRAME = 32 MM2 ADD IN FRAME = 8 MM2 ADD IN FRAME = 8 MM2 * Plano Rx, +2.00 D Add

3 Progressive Lenses by Carl Zeiss Vision

Comfortable Vision with Easy Adaptation

Surface astigmatism is used to blend the flatter distance zone The binocular function of progressive lenses is another factor crucial curvature into the steeper near zone curvature of a progressive lens. to visual performance and wearer satisfaction. The intermediate and This surface astigmatism produces unwanted cylinder power, typically near zones of the lenses must be properly aligned when the eyes oriented at an oblique cylinder axis, which blurs objects seen through converge to read in order to provide the maximum binocular field of the periphery of the lens. The oblique magnification produced by this view. With Instinctive and Instinctive Short, the inset of the near zone cylinder power also distorts the shape of objects in the periphery, has been precisely computed for each base curve and add power causing things to appeared skewed or bowed. Further, variations combination in order to compensate for the effect of prism induced in magnification over the lens produce an apparent undulation or by the distance correction and for the effect of the reading distance “rocking” of objects that can elicit a visual “swimming” sensation or on ocular convergence. This ensures that the centers of the viewing a feeling of vertigo in the wearer, especially during dynamic vision. zones remain properly aligned with the lines of sight.

This skew distortion and image swim can disrupt comfortable vision Further, differences in unwanted prism and image quality between and increase adaptation time. However, the algorithmically smooth the two lenses must be minimized in order to preserve binocular surface designs of Instinctive and Instinctive Short assure that each fusion and stereopsis with accurate depth perception. The smooth lens produces the lowest rate of change in power and astigmatism transitions of power and astigmatism across the Instinctive and possible for a given set of viewing zone boundary conditions. These Instinctive Short lens designs result in inherently stable powers at smooth transitions of power and astigmatism reduce the intensity corresponding points over the right and left lenses. These low power of peripheral blur and minimize visually disturbing image swim for gradients produce only negligible differences in prism, power, and the wearer (Figure 7). Moreover, skew distortion is also minimized, magnification between the right and left lenses as the eyes track resulting in improved orthoscopy—or the quality of maintaining objects across the field of view. These lens design features ensure straightness in the image—for the wearer (Figure 8). comfortable vision with effortless adaptation for the wearer.

+25 +25 +20 +20 +15 HIGH SWIM +15 LENS X,Y +10(MM) LENS X,Y +1(MM)0 +5 +5 +0 +0

1.00 1. −5 −5 00 0.75 0.75 10 0.50 10 0.50 − 0.25 − 0. 0. 0.00 25 −15 00 −15 SWIM SWIM −20 −20 −25 −25 CONVENTIONAL LENS INSTINCTIVE CONVENTIONAL LENS INSTINCTIVE IMAGE SWIM = 3.30 IMAGE SWIM = 2.75 HIGH SKEW DISTORTION LOW SKEW DISTORTION Figure 7. Instinctive utilizes exceptionally smooth transitions of power and Figure 8. Instinctive’s smooth transitions of power and astigmatism also result astigmatism that result in less intense peripheral blur and less image swim in less skew distortion of images over the lens compared with conventional over the lens compared with conventional progressive lenses. progressive lenses, as shown by these ray-traced grid objects.

Availability

Product Color Instinctive Dia. Instinctive Short Prescription Range Addition Range 1.50 Hard Resin 75/80 mm* 72 mm +5.00 to −9.00 D, 4.00 D Cyl. +0.75 to +3.50 D 1.59 Hard Resin Transitions® Gray 73/78 mm* 72 mm +5.00 to −9.00 D, 4.00 D Cyl. +0.75 to +3.50 D 1.59 Polycarbonate 75 mm 72 mm +5.00 to −9.00 D, 4.00 D Cyl. +1.00 to +3.00 D 1.59 Polycarbonate Transitions® Gray 72 mm 72 mm +5.00 to −9.00 D, 4.00 D Cyl. +1.00 to +3.00 D * Physical blank size / effective blank size with 2.5 mm of blank decentration

Carl Zeiss Vision USA 866.289.7652, option 3 www.experiencevelocity.com