Essilor Lenses: lenses for prescription glasses.
Essilor lenses with UV Protection · fog resistance · blue light protection · smudge resistance · scratch resistance · clear vision · close up vision · distance vision · Lenses for extreme conditions · Lenses for indoor and outdoor
The Varilux X lens resulted from continuous refinement since 1959 of the first version of the progressive lens (also called multifocal) to correct presbyopia now with more than 50 patents for cutting-edge progressive lens technology as a world leader. The Varilux X series was found to benefit arm’s length vision or intermediate vision. The volume of vision offers user-friendly optical ranges allowing not just reading but multiple tasks in a near-intermediate distance between 40 and 70 cm and clear vision beyond those regions. Nano-Optics, Synchron Eyes and Xtend Technology provide accurate 3-dimensional measurements such as Pupillary Distances (Mono/Total), Fitting Heights, Natural Head Position (Head Cape), Eye Rotation Center, frame width, height, Pantoscopic Tilt, Wrap Angle, Vertex Distance, Leading Dominant Eye, Head/Eye Movement Ratio, Stability Coefficient and Reading Distance.
Their Essilor Vision Institute has enabled multifocal lenses to be more readily adopted than bifocal lenses.
The Silmo d’Or ( Salon Mondial de l’Optique 2017 (SILMO) ) award-winning Varilux X series progressive lenses meet the visual needs of today’s highly connected generation X presbyopes.
Varilux range
The VisiOffice system precisely measures many aspects of your eyeglasses in an as worn position that can influence the success of your prescription. Visual performance can suffer greatly due to inaccurate centration. Wearer studies mean much Essilor can gather statistical information to refine and improve the lens designs. We can also help choose frames and the right lenses and learn all about lenses, your vision, and what activities need a special vision for the stages of your life.
Customisation levels :
Level 1 Tilt, wrap, BVD.
Level 2 adding dominant eye, optional progression length
Level 3 adding centre of rotation, reading distance
Level 4 adding near-vision behaviour
Inferior designs and poor centration are often at the root of poor optical performance. Frame size, depth and width and bridge design will all affect the positioning of the lens to the eye. All spectacle frames must be custom fitted to the wearer to accommodate their facial and head requirements. Most eyes should be situated in the top third of the frame for aesthetic balance and usability. This also allows the lens optical centre and the centre of rotation of the eyes to close.
- From the Front View Image, when the patient is instructed to gaze directly forward, the Visioffice System will be tracking three patient head position measurements:
Head Cape (Rotation), Head Inclination (Up or Down), and Head Tilt (Left or Right)
Using the Visioffice, we know the position of the COR and with the position of the corneal Purkinje images calculations such as the far point sphere (FPS) for the patient’s eyes so developed optical designs can then be recalculated according to the FPS of the patient’s eye and other wearer parameters, even for squint conditions.
This can manifest particularly with contrast sensitivity function for the wearer and larger clearer optical zones. For the customised lenses, all measurements for both eyes are required even if only one lens was to be replaced as the lenses take into account binocular vision to ensure the lenses are balanced correctly.
The spectacle frame has to be tailored to fit the individual.
All frames have their sides at a let-back angle of approx 95° with the frame front. Triangle of force or the Fitting triangle is where the frame only makes contact on the head/face at 3 points. It rests on the nose (not gripped or clamped by it) and rests against the side of the head just before each ear and against the side the of the head behind the ears (anatomical bend) causing friction (not pressure) that keeps the frame from sliding forward. All side bends need to be sharp and not curved or at right-angles behind the ears.
Very few people are perfectly symmetrical. The correctly adjusted fitted frame will sit comfortably and should never create pressure. It should only create friction which will stop it from slipping and sliding forward so fitting lens or frame measurements can be reliably taken.
The correct spectacle frame fit
- Correct Frame front alignment including:
- In horizontal alignment, the frame must sit level on the face
- Bridge fit needs to sit comfortably, sharing the weight evenly across the nose.
- Face form angle to ensure each rim is equidistant from the eyes.
- Correct Pantoscopic angle for the face
- Avoid the rims touching brows and cheeks
- Correct Side width
- Avoid touching the sides of your face/head until just in front of your ears. The frame sides should not touch or rest and never press against the side of the head.
- Correct Side bow
- Sides should have a slight bow near the ears following the contour of the head at this point.
- Correct Length to bend
- Side’s turn down (hockey bend) about 2 mm behind the root of the ear.
- Correct Anatomical bend
- This needs to have the appropriate turn into the side of the head behind the ears (to create friction, NOT pressure), and the temple end should follow the contour of the mastoid area to allow it to rest gently there, distributing the weight evenly over these undulations.
All frames, in standard alignment, should have their sides at a let-back angle of 95° with the frame front when looking down onto the frame
The side length should follow the ‘Goldilocks principle’ not too long or not too short but be just right for the length of the head. The 3 point touch I referred to relates to the Triangle of force or the Fitting triangle where the frame only makes contact on the head/face at 3 points. It rests on the nose (not gripped or clamped by it) and rests against the side of the head just before each ear and against the side the of the head behind the ears (anatomical bend) causing friction (not pressure) that keeps the frame from sliding forward. All side bends need to be sharp and not curved or at right-angles behind the ears. Some frames can be fitted without any side bend depending upon design.
The side length’s turn down commences 2 mm behind the top of the root of the ear. When the lenses are fitted to the frame, the spectacles will become heavier, and gravity will kick in and the extra weight of these together with facial flexing and movement (speaking, smiling etc.) will allow the frame to settle gently behind the ear without digging in, and causing welts.
Looking at the frame front, if we wish to lift the left-hand side of the frame up, we need to angle the left side downwards. This will push the left side of the frame front up on the left; we can also achieve this by angling the right side up, so the frame front on the right side sits down more, levelling the front of the frame. This allows the frame to sit level on uneven ear heights. If we want one side of the frame front to be raised, we angle that frame side downwards to push that up. Conversely we angle the opposite side upwards to allow the front to sit lower and create an even look. Frames quite often have to be taken out of standard alignment when they’re custom/tailored to fit the client’s head/facial requirements.
Wrap and inclination angles also have an effect.
Essilor summary of Varilux digital designs - progressive lenses.
Higher-order aberrations (HOA) could account for 20% of the clarity of our vision – with 5% influence due to the tear film constantly shifting
Aberrometers have evolved and measure HOA’s in one direction of gaze, but the eye will rotate behind the lens surface, so the centre of rotation needs to be measured for the particular eye. The most advanced optical labs work with designs based on the wavefront exiting, e.g. on the back surface of a progressive lens (using adaptive optics calculations) involving a pupil map – measuring the size of the pupil according to Rx, age (add), near distance and light conditions with the pupil sizes being plotted across the lens surface. Peripheral vision is compromised with a variety of lens forms which is improved by better lenses. Optimised progressive lenses use default measurements that consider how the frame might sit on the patient’s face.
Personalised lenses incorporate specific measurements such as facial dimensions, back vertex distance, pantoscopic tilt and facial wrap of the frames. This changes the effect of the prescription by adapting the lens design and matching the prescription from its written form to the as-worn position on the face.
Computer Numerical Control (CNC) technology in the manufacturing process has been the key to producing highly accurate lens designs, known as digital or freeform surfaced progressive lenses.
Traditionally, lenses were designed with the power of progression on the front of the lens; however, the advent of digital and freeform surfacing has allowed this also to be done on the back. This has advantages of a wider field of view. Some lens companies have 1000 or more individual value points on a lens, essentially like 1000 individual tiny lenses in one lens.
Essilor’s Varilux range of lenses, spearheaded by the Varilux X Series, encompass more than 50 patents, with each lens incorporating up to 30 patents alone. In the traditional surfacing process, the back of the lens was cut using two curves to produce the sphere, cylinder and axis of the prescription. Once completed, the rough surface was “fined” and “polished” using a metal tool to match the two curves. Specific pads on the tools removed the roughness before making the lens transparent.
Today’s more advanced digital surfacing process allows the back of the lens to take any form, such as an aspheric design or progressive surface. Manufacturers can also use this complex surface to overcome the shortcomings of the base curve, regardless of whether it is a simple or more complex front surface. The surface is cut with a precision diamond tool. The design is a computer file and is generated for each lens via complex calculation software, which can take into account new parameters such as the frame tilt, wrap and back vertex distance and other information added into the calculations. The surface is cut so finely that the only additional process is called ‘soft polishing’ – a gentle polishing that removes just enough material to make the lens transparent without impacting the complex surface that has just been cut. There are many tiers of quality over a broad range of price points.
Quality depends on
• The machinery involved to manufacture highly accurate lens surfaces.
• The process, including the operating procedures, software system, calculation engine, consumables, experience and quality control.
• The design, capturing the latest innovation in the science of sight, the source of the optical benefits to the wearer.
Some Varilux products were worn by many thousands of people around the world in clinical trials before they went to market.
Reducing swim effects and broadening the field of vision are the most common issues optical engineers have been attempting to overcome
for decades. Essilor elevates its premium progressives, such as its top of the range Varilux Xclusiv, to the level of personalisation using an iPad app that simulates the way people read without using text. It involves the patient tracking a blue dot across the screen, while the iPad camera measures the downward gaze, offset from the centre and the reading distance. It also factors in the patient’s visual behaviour. At one extreme, keeping their eyes still and tracking with their head or, at the other, keeping their head still and tracking with their eyes – and all the combinations in between.
From this personal data, the design of the lens is modified to shift their volume of vision to exactly match their parameters.
All the below progressives are Digitally surfaced aspheric / atoric back surface and the moulds for any semi-finished; therefore, the front surface are digitally surfaced aspheric
• some out of range are done with conventional surfacing otherwise
• Back surface digital surfacing with both the Rx and the progressive surface on the back is done for Varilux Comfort
• Dual Surface – i.e. part of the progressive design is on the front and part is on the back – Vx Physio and Vx X series – a specific aspheric on the front and aspheric / atoric on the back.
Xclusive allows for a min fitting height of 14 mm and a max corridor length of 17mm in 0.1mm steps.
The heights and frame parameters are measured with natural posture adopted by the Visoffice2 technology. Then the length of progression and the inset are tailored in line with the prescription, the frame measurements and the fitting parameters.
The minimum progression length from Essilor and Nikon is 9mm and the max is 12mm – shorter than 9 creates issues with the intermediate, longer than 12 creates issues with finding the near.
Nikon defines their lengths in absolute terms i.e. the length to 100% of the add versus to 85% for Essilor lenses e.g. a Varilux X design short will be 9mm but an equivalent Nikon lens will be 12mm for the short version.
| Lens Design | Centration | Heights | Tilt and Wrap | Back Vertex distance | Head cape | Notes |
| XCLUSIVE | ERCD PD’s | ERCD Heights | √ | √ | √ | Custom PAL Length, Dominant Eye, Near Vision Behaviour Nano-Optics, Synchron Eyes and Xtend Technology |
| X FIT | ERCD PD’s | ERCD Heights | √ | √ | √ | Optional length Nano-Optics, Synchron Eyes and Xtend Technology |
| PHYSIO 3.0 FIT | ERCD PD’s | ERCD Heights | √ | √ | Binocular Booster Technology to prevent Image Jump and minimize Visual Distortion | |
| PHYSIO 3.0 | Monocular | Monocular | ||||
| PHYSIO F 360 NE | √ | √ | Allows for More Customization – Wrap, Tilt and BVD of the pioneering technology | |||
| PHYSIO NE | Improved Vision in Low Light design | |||||
| COMFORT 3.0 | W.A.V.E front Aberration Control | |||||
| STYLISTIC | Monocular | Monocular | √ | √ with frame base curve | W.A.V.E front Aberration Control | |
| COMFORT NE | Monocular | Monocular |
The Varilux Xclusive uses the Near Vision Behaviour (NVB) App + Visioffice ERCD (eyecode) to personalise the lenses for the patient.
The Varilux Xtrack Fit uses the Eyeruler 2 to take Fit measurements and the Near Vision Behaviour (NVB) App to personalise the lenses for the patient.
The Varilux X4D uses the Visioffice to take the ERCD (centre of rotation of the eye) + dominant eye.
The X 3D is Fit measurements + dominant eye
The X Fit is fit measurements.
There are regular and short options of the Varilux X design, Varilux Physio 3.0 or Varilux Comfort
Varilux Xclusive 4D 17mm Personalised / Visioffice only: NVB (App Only), Eyecode data (Monocular Pupillary Distances, Fitting Heights & Eye rotation centre
distance), Frame wrap, Pantoscopic tilt, Back Vertex Distance, Dominant Eye, Head cape & Head / Eye coefficient
Varilux Xtrack Fit 17mm Personalised: NVB (App Only), Monocular Pupillary Distances, Fitting Heights, Frame wrap,
Pantoscopic tilt & Back Vertex Distance
Varilux X 4D 17mm Personalised / Visioffice only: Eyecode data (Monocular Pupillary Distances, Fitting Heights & Eye rotation centre distance),
Frame wrap, Pantoscopic tilt, Back Vertex Distance, Dominant Eye, Head cape & Head / Eye coefficient
Varilux X 3D 17mm Personalised: Monocular Pupillary Distances, Fitting Heights, Frame wrap, Pantoscopic tilt, Back Vertex Distance & Dominant Eye
Varilux X Fit 17mm Personalised: Monocular Pupillary Distances, Fitting Heights, Frame wrap, Pantoscopic tilt & Back Vertex Distance
Varilux X Design Short 14mm Short corridor: Monocular Pupillary Distances and Fitting Heights
Varilux X Design 17mm Monocular Pupillary Distances and Fitting Height
Varilux Physio 3.0 17mm Monocular Pupillary Distances and Fitting Heights
Varilux Physio 3.0 Short 14mm Short corridor: Monocular Pupillary Distances and Fitting Heights
Varilux Physio 3.0 Fit 17mm Personalised: Monocular Pupillary Distances, Fitting Heights, Frame wrap, Pantoscopic tilt & Back Vertex Distance
Varilux Comfort 3.0 Standard 17mm corridor : Monocular Pupillary Distances and Fitting Heights
Varilux Comfort 3.0 Short 14mm Short corridor: Monocular Pupillary Distances and Fitting Height
Essilor Essentials Assent Standard 17mm Monocular Pupillary Distances and Fitting Heights
Essilor Essentials Assent Short 14mm Short corridor: Monocular Pupillary Distances and Fitting Height
VARILUX X SERIES
The Varilux X series was found to benefit arm’s length vision or intermediate vision. The volume of vision offers user-friendly optical ranges allowing not just reading but multiple tasks in a near-intermediate distance between 40 and 70 cm and clear vision beyond those regions. Nano-Optics, Synchron Eyes and Xtend Technology provide accurate 3-dimensional measurements such as Pupillary Distances (Mono/Total), Fitting Heights, Natural Head Position (Head Cape), Eye Rotation Center, frame width, height, Pantoscopic Tilt, Wrap Angle, Vertex Distance, Leading Dominant Eye, Head/Eye Movement Ratio, Stability Coefficient and Reading Distance.
Prescription lenses can be more advanced and personalised than ever with an adequately adjusted frame. In this as-worn position, the fitting parameters are linked so the optimised lens design can minimise some lens aberrations that may impact the wearer.
Whilst the average distance to the computer is 63 cm, 95% of people use it between 38 and 88 cm, so there is a 50 cm variation depending on the user.
Ultra near vision & screen distance personalisation enables more comfortable digital screen use.
• People whose head/body posture is causing them discomfort while using computers and digital devices.
• People whose hobbies and leisure activities require specific correction.
Do you experience back or neck discomfort when spending prolonged time on your digital devices?
How often do you have to lift your chin and down to make things clear when using your computer or digital device?
Varilux Digitime is personalised to ensure your head and neck are comfortable throughout the day.
Minimum fitting height: 18 mm to ensure extra power but 24 mm is needed to get the full benefit.
Varilux Digitime, recommended with Crizal prevencia, enables clear and comfortable visual posture for digital activities by catering for specific gaze directions used in viewing screens compared to paper.
The average distance to a smartphone is 33 cm but can vary compared to the standard reading distance of 40 cm, whereas the average distance to the computer is 63 cm.
Of the Varilux Digitime the Mid design is the most commonly prescribed. However the specific design chosen will be determined on the individuals needs.
Screen distance personalisation has an impact on the minimum depths of field. If the parameter is not measured, the average value (63cm) will be used to calculate the design.
The effective power changes take place over:
Nikon Soltes 19mm Nikon Home & Office 22mm
- Varilux Digitime is more compressed by comaprison over 12mm from near to intermediate / working distance power (for direct comparison with Soltes and Home and Office) and 24 mm including the Ultra near power (+0.50D for the Near and +0.25D for the Mid version +0.12D for the Room version)
Personalisation options Screen distance
- Mono distance PDs, Mono height
- Wrap angle, Pantoscopic angle
- Vertex distance, Eye rotation centre distance
- The Head cape is the measured angle of the patient’s Natural Head Posture (NHP). When asked to look straight ahead, if the patient slightly rotates their head to the left or right while focusing forward, this is their Head Cape.
The newer ‘as worn’ lens designs can be optimised for the position of wear and have newer surfacing techniques including atoric designs.Older PPL designs are still available and can be provided as a budget alternative.
• Varilux Comfort – released 1992; Varilux Comfort NE released 2011; Varilux 3.0 released 2018
• Varilux Physio – released 2006; Physio NE – released 2015; Physio 3.0 released 2018
Recent low cost non varilux lenses include Quadro,Assent and Accord (though there a myriad of digitised and non digitised options) as examples of simple back surface designs and don’t offer customisation.
Digital devices, e.g. smartphones, are changing our visual needs and ranges. The growing use of digital devices is modifying the typical working distances. Today more and more time is spent on digital devices hence the evolution of specific lens designs.
90% of 45-65-year-olds use one digital device daily and accordingly changed their visual/ postural behaviour, creating discomfort,
tired eyes and often associated neck and shoulder pain.
Near vision tasks, especially reading, are becoming even more challenging as characters become smaller and digital devices are being held closer.
Digital technology usage means newer optical standards such as reading distances and eye declination have evolved.
While almost all wearers increasingly use their screens at close distance, conventional single-vision lenses are optimized for far vision only. This means when wearers look at close-distance objects through the bottom of their lenses, they experience some optical aberrations.
Essilor summary of designs - Extended Near and optimised Single Vision
Our standard Rx will give us about 75% of the clarity we should have from our vision.
The challenge for optical designers is correcting for higher-order aberrations (including Coma, Spherical aberration and trefoil)
Spherical aberration is increased after myopic LASIK surface ablation and the bigger pupil of night vision. It results in halos around point images.
Pupil size can vary, e.g. between day and night.
Most progressive powered lenses (PPL) have aspheric front curves, sometimes spherical. Basic and older PPL designs have conventional back curves (spherical or toric curves) with aspheric FC. Some older designs have been rejuvenated by having the back surface digitally surfaced.
The most advanced optical labs work with designs based on the wavefront exiting eg on the back surface of a progressive lens (using adaptive optics calculations) involving a pupil map – measuring the size of the pupil according to Rx, age (add), near distance and light conditions with the pupil sizes being plotted across the lens surface.
Spectacle designs can be
1. Back surface spherical (and/or toric).
2. Front Surface Aspheric Standard fare (flatter FC for plus lenses).
3. Back Surface Aspheric Benefits atoric designs where the cylinder is on the back
4. Dual Surface Freeform High-end designs where the additional power can be shared between both surfaces allowing them to create wider channels and reading areas
In the Eyezen Start lens, the mean power and astigmatism at this close vision point will be the same as the mean power and astigmatism at the far vision point, ensuring maximum acuity in far and near vision zones. The Eyezen Start lens is locally modified to provide the right prescription to the wearer according to an object’s location, no matter which part of the lens is accessed.
Eyezen DualOptim technology considers the gaze direction and objects distance at each lens point to ensure the purest wearer’s prescription throughout the whole lens. Subjects with optical markers on their helmets and their torsos to record movements. Data is recorded in three different postures: standing, sitting on a couch, lying on a bed, using a smartphone, tablet, and eBook reader. The eye declination with electronic devices (as they are closer) is higher than when interacting with paper.
Varilux digitime near is similar to Type 1 Nikon soltes
Varilux digitime mid is similar to Type 2 Nikon soltes
Varilux Digitime Can be substituted for Soltes but not Nikon H&O. Has other benefits that Nikon do not such as power booster for smartphones.
| Lens Name | Lens Type | Fit Parameters | Height Measurements | Shifts Available | Power At Pupil | Notes |
| EyeZen | Modified Single Vision | Monocular PD’s heights, Distance Rx | Pupil heights, Min ht 15mm | 0.40,0.60 or 0.85D over 15mm | Distance Rx | For the relief of symptoms of visual fatigue brought on by long periods of close work specifically on hand-held or portable digital devices. Suitable for all people with accommodation / binocular vision issues |
| Varilux Digitime | Extended Focus | Monocular PD’s height, Full Rx | Pupil height as per Progressive lens. Min ht 18mm with some boost,24mm for entire boost | Three styles: Near = e.g. computer + mobile phone; Mid = computer + desk; Room = computer + around the office. | Customised to the wearers screen/working distance.EG for Add+2.00,screen distance 50cm.Power will be set for 50+15cm=65cm Power =2.00-0.46=1.54D at pupil | Ideal for variety of occupational needs from computers to mechanics etc. |
| Essilor Interview | Extended Focus | Monocular PD’s height, Near Rx | Top of lower lid approx 6mm below pupil centre) | 0.80D (Interview Low) 1.30D (Interview High) | Reading Add-shift E.g Add +2.00 with low shift. 2.00-0.80=1.20D at pupil | Full add 10mm below pupil.Suitable for near to intermediate screen distances. Ideal replacement for SV near. |
Read more on optimised Single Vision
EYEZEN Start
Introducing two reference points in far and near vision for the lens calculation means the whole lens surface is optimised for both far and near vision to improve acuity and reduce deviation from the prescription according to object location.
Power error corresponds to a deviation from the prescribed mean sphere value. Power error either generates blur (for a positive power error) or induces accommodation effort (for a negative power error). For example, a level of power error of 0.18 D causes an acuity loss of approximately 0.05 logMAR, which corresponds to a half-line on a logMAR acuity chart (Fauquier et al., 1995).
Unwanted astigmatism corresponds to a deviation from the prescribed cylinder value and/or axis, reducing the sharpness of vision. Fauquier showed a level of unwanted astigmatism of 0.25 D causes an acuity loss of approximately 0.05 logMAR, which again corresponds to a half-line on a logMAR acuity chart.
Maintaining power error under 0.18 D and unwanted astigmatism under 0.25 D guarantees maximum visual acuity.
Effects of astigmatism and high-order aberrations of progressive-power lenses on visual acuity are always the subject of research and development.
The actual power and astigmatism of a lens depend on the gaze direction but also the object distance. Usually, when a lens is designed, it is assumed that all objects are located at infinite. In reality, they are not. That’s why the lens power and astigmatism are incorrect.
Cones of gaze directions are calculated, where power deviation is lower than 0.18 D, and astigmatism deviation is lower than 0.25 D. These threshold values are chosen because beyond them, wearers will suffer an acuity loss equal or greater to one half-line on a logMAR acuity chart.
In comparison, the performance factor of Eyezen Start lenses to standard single vision lenses is 49% larger than standard lenses.
The prescription is considered maintained when the following is true:
• Unwanted astigmatism < 0.25 D or
• Power errors < 0.18 D
A factor of 100% means the prescription is maintained for all gaze directions in the usage zone. Eyezen Start lenses are also the only single vision lenses that consider convergence, which happens when the wearer looks at objects at close distances. Indeed, the vergence angle increases. This is why Eyezen Start lenses are asymmetrical lenses by design.
Lens calculation now considers the gaze direction and the object distance at each point of the lens. This calculation ensures the optical power for the wearer remains unchanged from the prescription values. The wearer benefits from the same wearer power and low unwanted astigmatism in the whole lens.
| Product Features | Standard Single Vision Distance Lens | Eyezen Start Optimised Single Vision Lens (Ordered with distance vision prescription checked at the distance checking circle, monocular PDs and fitting heights. |
| Far Vision | √ | √ |
| Near Vision | — | Prescription maintained (no boost), Enhances acuity |
| Lens Type | Spherical/Aspherical | Digitally Optimised |
| Blue Light Protection | Optional | Standard |
| Blue Light Protection Options | Smart Blue Filter and/or Crizal Prevencia | Blue UV Capture or Smart Blue Filter |
| Reducing Visual Fatigue | — | √√ |
| Better Comfort and Clarity | — | √√ |
| Better Contrast | — | √√√ |
| Age Guide | 8-40 years | 8-40 years |
• Eye-Device distance• Head declination• Eye declination• Head Roll (rotation of the head around an anteroposterior axis were recorded as are important in Computer Vision Syndrome (CVS). CVS has been defined by the American Optometric Association (AOA) as a combination of eye and vision-related problems due to prolonged use of computers. Combining too much screen time and vision issues such as myopia, hyperopia, and astigmatism can strain the eye. Fatigue can set in as the eyes strain to correct for vision issues while focusing on complex digital content
E-SPF: Eye-SUN PROTECTION FACTOR
Surveys have shown more than two-thirds of consumers were unaware that clear lenses offered any protection against UV.
The E-SPF protocol has been developed and endorsed by independent third parties. It provides an objective laboratory index for eyewear, certifying the lens from UV light’s invisible and often irreversible dangers.
UV light has accelerated eye ageing, skin cancer, and cataracts. Children are particularly vulnerable to UV rays, and their annual exposure is three times higher than that of adults as they spend more time outdoors.
UV rays pose a threat 365 days a year, even in cloudy weather, as 40% of UV exposure occurs when people are not in full sunlight.
Essilor/Nikon suntinted,mirror,Stylistic wrap lenses
E-SPF is an index rating the overall UV protection of a lens. E-SPF was developed by Essilor International and endorsed by third party experts.
The E-SPF index relates to lens performance only and excludes direct eye exposure that depends on external factors (wearer’s morphology, frame shape, position of wear).
They offer the essential level of protection when conditions demand the wearing of tinted sun lenses (strong sunlight, altitude, beach, etc) lenses or Xperio polarizing lenses.
In today’s optical market, 56% of Australian’s require visual correction solutions. Out of those, only 5% use a prescription sun lens.
Regardless of the tint or polarised colour protection of Crizal Sun UV (up to E-SPF 50) is available and the option of a fashionable mirror coating.
“SolarFlair Sun UV” lens treatment, if being used with a tinted or polarised lens (this treatment is not able to be applied to mirror coated lenses – as the lens will come with a generic multi-coat).
Crizal SapphireHR (high resistance), with its transparency (360° Multi-angular Technology) and durability, has the best anti-reflection coating overall.
High Resistance Technology means Crizal SapphireHR has 70% more scratch resistance and 20% more thermal resistance than previous generations.
Abrasion resistance is a combination of different factors—adhesion, hardness, flexibility and impact resistance.
Bayer Abrasion: The Bayer test is one of the most often cited test methods for resistance involving abrasion from oscillating alumina-zirconia sand. The Bayer ratio is the ratio of haze gain of the uncoated lens to the coated lens.
Crizal RockTM(thermal resistance) is the best combination of scratch and smudge resistance. It features High-Resistance Technology with a High Surface Density top coat, making cleaning easy. Crizal Sapphire and Prevencia have Bayer grades of 10, and Crizal EasyPro ( an easy-to-clean and maintain anti-reflection coating to resist smudges and repel oil and water for ease of cleaning. Poorer coatings may have a rating of 1 or 2.
Processing variables such as temperature and humidity also impact these features. It is essential to have a clean and controlled process to achieve a coating with optimized optical properties and mechanical performance. There is no such thing as a scratch-proof coating. Instead scratch resistance is achieved by hard coating in the mould or by spin or dip methods. TD2 is a two-layer dip coating on both sides as opposed to a front side hard coat only.
Spin and dip are methods of applying hard coat varnish – spin being that the lenses are spun, and the varnish is dripped onto them.
Dip coating is a much more intensive and consistent process using two different layers and different curing processes – it gives a much more even hard coat.
TD2 provides the scratch resistance almost that of glass in the airwar material as the flexibility of polycarbonate (Airwear) is very similar to the material used in the construction of the TD2 coating, hence the lens substrate and the coating flex together as the lens heats or cools, or is knocked or bumped.
Any material >1.5 index blocks UV 100% up to 380nm from being transmitted through the lens;
any index >1.6 will block a bit of blue light which is why they are a little yellow compared to 1.5 or polycarbonate
The Crizal UV coating on the back surface of the lens blocks 96% of UV that can reflect from the back surface of a spectacle lens
Prevencia coating blocks 20% of the visible blue-violet light by reflecting it away from the front surface.
Any material >1.5 index blocks UV 100% up to 380nm transmitted through the lens.
The Crizal Prevencia has the same UV properties on the back surface as Crizal UV
On any index, material Transitions blocks 100% of UV even when clear
To block reflected UV from the back surface requires a Crizal UV coating, so the back surface will block 96% of UV that can reflect from the back surface of the lens
The Transitions dyes, when clear, block 20% of the visible blue-violet light by absorption in the lens material, which is why they are a little yellow compared to 1.5 or polycarbonate
In the darkened state, Transitions blocks at least 85% of blue light by absorption in the material
On a 1.5 index lens, the transmission of UV is not blocked by the SBF material.
Any material >1.5 index blocks UV 100% up to 380nm from being transmitted through the lens.
The SBF material blocks 20% of the visible blue-violet light by absorption in the lens material.
It may appear a little grey compared to 1.5 or polycarbonate as it contains a colour corrector.
To block reflected UV from the back surface requires a Crizal UV coating, so the back surface will block 96% of UV that can reflect from the rear surface of the lens.
Crizal coatings ^ best in class
Blue light protection ( harmful blue versus beneficial blue)
Beware of excessive heat eg the summer heat on a car dashboard, as the issue is simply down to expansion and contraction of materials. It depends on several factors such as the thickness of lenses, tension, and flexibility of the frame. Bead or air blowers can even quickly destroy a lens coating. Each pair of spectacles will be susceptible to heat, just varying consequences depending on Rx, frame, temperature ranges and speed of temp change, as well as repetitions of high heat change. However, the rule of thumb >55 degrees coatings reform after cooling >70 the coating will likely be genuinely damaged.
Computer eyestrain is the main office health-related complaint -computer vision syndrome or digital eye strain, dry eyes, eye irritation, blurred vision, and double vision. The short wavelengths of blue light scatter quickly to produce discomforting glare and reduce contrast. This has significance when using digital devices and also driving in low light conditions and at night. Blue Light, unlike candlelight of yesteryear, stimulates the pituitary and pineal glands which suppresses melatonin production, which is required to fall asleep. Anti-Reflection Coatings tints to reduce blue light, and the lens material itself can influence the amount of blue light transmitted.
^Transmission of light to the aging human retina: possible implications for age-related macular degeneration Experimental Eye Research, 79(6), 753-759, 2004
So, clear lenses can also protect your vision by protecting your eyes and the coating, particularly in these cases, to constitute medical benefits. Essilor has developed technologies to protect the eyes against the potential dangers of blue-violet Light by at least 20% of harmful blue-violet light up to 455 nm.
Furthermore, some of these technologies can be combined to further reinforce the protection against potentially harmful blue-violet light up to 35%
The essential light (blue turquoise wavelength between 465 and 495 nanometres on the Light spectrum ) contributes to well-being. Research shows that exposure to this light plays an essential role in the regulation of the circadian rhythm (sleep-wake cycle ) by stimulating melanopsin-containing retinal ganglion cells. The blue-violet light between 415 to 455 nanometres on the light spectrum is believed most toxic to retinal cells and for long-term vision issues such as age-related macular degeneration^
There are two ways to cut blue-violet light: via the substrate or via a Smart Blue filter coating. Crizal Sapphire UV is not a blue cut coating, but it can be combined with an embedded blue cut filter or Transitions lens technology.
The blue hazard is from 400 – 455nm; it is virtually all from sunlight, there is some question over high output industrial LED lighting, but it is still very small compared to sunlight; and is specific for the at-risk group of patients – those with a direct family history of AMD, smokers; those who are obese or have poor nutrition; people taking photosensitising medications and those who spend their working life outdoors. These people are at risk from the oxidation processes in the outer retina that many researchers have well documented. Crizal Prevencia and SBF both block 20% of the light from 400 – 455nm, which in the lab reduces RPE death by 25%—combining the two increases filtering to 35%, corresponding to cell death in lab experiments.
The sleep/wake cycle – melanopsin is active from 465 – 495nm; blue filters can’t increase the number of these wavelengths arriving at the retina but shouldn’t block them as Gunnar blue-blocking lenses do.
The optometrist vision tests you can expect for complicated or common eye conditions, eye diseases and vision symptoms that occur at different stages of life will serve to reduce your problems that can occur.Glasses or contact lenses may offer special vision protection
Essilor launched in 2013 Crizal Prevencia, in 2016 the smart blue filter and in 2018 widened harmful blue light protection as a specific category in its portfolio of lenses following on from other major cagegory breakthroughs.
Essilor invented the progressive lens category in the 1950’s to correct vision across a visual zone from near to far,beyond the restrictive arm length.
As a world leader in prescription lenses continuous refinements followed.
In 1993 the anti-reflective category of clear and more scratch resistant lenses were developed and all continously improved through R+D.
Percentage of harmful blue violet protection
| Value | |
| Standard lens | 5% |
| Essential Blue Series SBF | 20% |
| Essential Blue Series SBF with Crizal Prevencia | 30% |
| Transitions 7 unactivated | 20% |
| Transitions 7 activated | 85% |
| Transitions Xactive unactivated | 35% |
| Transitions X active activated | 88% |
UV transmission via the lens front surface is cut purely by the nature of the material
UV Cut: Front surface with or without Crizal UV or Crizal Sapphire UV or Crizal Prevencia
all indices > 1.50 = 100% UV cut at 400nm
Transitions all indices = 100% UV cut at 400nm
1.50 = 96% cut at 400nm
Reflected UV via the lens back surface is cut purely by anti reflection coatings
UV Cut: back surface reflected UV without Crizal UV or Crizal Sapphire UV or Crizal Prevencia
all indices / all materials = 0% UV cut at 400nm
UV Cut: back surface reflected UV with Crizal UV or Crizal Prevencia
all indices / all materials = 96% UV cut at 400nm
with Crizal Sapphire UV = 98% UV cut at 400nm
Crizal UV (also known as Crizal Forte UV) – has no blue blocking effect
The front surface – transmits 99.2% of light with a residual bloom in the yellow green range.
Any UV filtering via the front surface of the lens is solely dependent on the monomer of the base lens e.g. CR 39 only takes out 94% of UV while all of the indices above that take out 100% of the UV.
The back surface – blocks 96% of the UV reflected by the back surface of the lens with an incident angle of 135 degrees.
Crizal Sun UV (applied to the back surface of sunlenses ) in this case no multicoat layers on the front.
Re front surface – any UV filtering via the front surface of the lens is solely dependent on the monomer of the base lens e.g. CR 39 only takes out 94% of UV while all of the indices above that take out 100% of the uV
The back surface – blocks 98% of the UV reflected by the back surface of the lens with an incident angle of 135 degrees
Crizal Prevencia: front surface selectively reflects away 20% of the wavelengths between 400 and 455nm with a peak at 435nm, it allows through at least 98% of the wavelengths around 470 – 490nm in the range of the melanopsin receptors
The back surface – as for Crizal UV – the back surface blocks 96% of the UV reflected by the back surface of the lens with an incident angle of 135 degrees
Nikon Seecoat Blue UV The front surface reflects away 5% of the wavelengths between 400 and 500nm with a peak of 10% at 455nm .
Back surface -as for Crizal UV – blocks 96% of the UV reflected by the back surface of the lens with an incident angle of 135 degrees.
Blue Cut: Materials
Smart Blue Filter all indices = 20% between 400 & 500nm
Transitions Grey, Brown and Graphite Green – clear state indoors = 20% between 400 & 500nm
Transitions Grey, Brown and Graphite Green – dark state outdoors = min 85% between 400 & 500nm
All other materials regardless of index = minimum blue cut so technically = 0% between 400 & 500nm
Blue Cut Coating:
Crizal Prevencia = 20% between 400 & 500nm
No other Essilor coating cuts blue
Blue cut combining blue cut material and coating:
Smart Blue Filter all indices + Crizal Prevencia = 30% between 400 & 500nm
Transitions Grey, Brown and Graphite Green – clear state indoors = 30% between 400 & 500nm
Transitions Grey, Brown and Graphite Green – dark state outdoors = unchanged at min 85% between 400 & 500nm
As liquid coatings age, the viscosity and other features may change. This will result in changes to adhesion, abrasion resistance, tintability and coating thickness
Steel Wool Abrasion: Uses steel wool of known fibre size and quality under a specified weight for a specified number of cycles.
Adhesion: Poor adhesion results in delamination or peeling of the coating. A Cross Hatch test measures adhesion. A crosshatch pattern is cut into the surface of the lens. A piece of tape of a specific grade is then pressed against these lines. The tape is quickly lifted off and repeated three times. The crosshatch is then examined for delamination.
Coating Thickness: Coating thickness is typically measured by a UV/VIS spectrophotometer to reduce the risk of abrasion and delamination.
Printability is measured by subjecting the coated lens to a tinting bath and its effect.
Essilor and Nikon HMC (hard-multicoat) processes don’t use a spin coating. The testing regimes for establishing scratch resistance include.
– Tumble test – the lens is physically rolled around in a barrel with stones and abrasive materials of particular sizes.
– Bayer test is for abrasion and is done with sandy grit again of a particular size and the lens is shaken backward and forwards in a tray of this grit.
– 100 Blows test – an erasure, on the end of a 1kg weight, is wrapped in cotton fabric and moistened with alcohol, it is then rubbed backward and forwards 100 times across the surface of the lens.
– Crosshatch test – for adhesion – five razor blades mounted side by side – is used to make a cross-hatch pattern of 1mm squares on the surface of the lens and then powerful gaffer tape is applied and then ripped off in an attempt to take with it chunks of the coating.
Most manufacturers use a few of these tests or variations of them to verify their hard & HMC coatings – tintable coatings are less resistant. When coated most materials end up with similar scratch resistance.
Returns on HC and HMC lenses low if properly maintained but quality can vary markedly. The vacuum process applies the following layers:
Front surface: bonding layer,anti-reflection layers,topcoat – easy clean layer,the non-slip layer for edging (removable)
Back surface: bonding layer,UV cut layer anti-static,anti-reflection layers,topcoat,easy clean layer,the non-slip layer for edging (removable)
Transmission of UV is blocked by the material and reflection from the back is blocked by Crizal UV or Prevencia
Blue light can be blocked by reflection at the front surface or in the material by absorption for Transitions and SBF.
Physical vapor deposition (PVD) describes a variety of vacuum deposition methods which can be used to produce thin films and coatings often in multicoats of compounds such as silicon dioxide,zirconium dioxide,aluminium oxide in a number of layers where the refractive index and the thickness of each layer can be carefully controlled.
Scratch resistant coatings are thicker than the multicoats and can be a dip or spun process.In a normal lens, about 4 per cent of the light is reflected as it passes through each side of the lens. This means that approximately only 92 per cent of the light reaches the eye. Both ghosting from the front and flare from the back affect the quality of the image that you see.
Anti-reflective coating improves the light transmission through the lens to nearly 99 per cent and therefore can reduce the effects of ghost and flare substantially.
A blue light filter needs to allow through the wavelengths 465 – 495nm to allow the blue light that works on circadian rhythms to get to the eye. It can’t increase the amount of that blue light; that is up to the person as they need to go outdoors more often to get their circadian rhythms under control. Dim light (about as bright as a table lamp) can interfere with a person’s circadian rhythm and melatonin secretion.
Short sleep is linked to an increased risk of depression, diabetes and cardiovascular problems. Any light can suppress melatonin, but blue light is more powerful.
Harvard research compared the effects of 6.5 hours of exposure to blue light vs. the same exposure to green light. The blue light suppressed melatonin twice as long as the green; Shifted circadian rhythms 3 hours vs. 1.5 hours.
Source: http://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side
E-SPF 35 UV protection is standard across Crizal SapphireHR, Crizal Rock and Crizal EasyPro. When combined with all lens materials (except clear 1.5 index), 100% of transmitted UV is blocked and the coating’s special UV layer cuts UV rays reflected from the lens back surface.
Most eyeglass lenses prevent the transmission of UV rays hitting the front side of the lens.
Blocking UVR Transmission is not enough, though.
The typical claims of quantitative measures of UVR protection of lenses have been based solely on UVR transmission, a measurement of the fraction of radiation that is blocked from travelling through the lens.
But transmission into the eye from the sides and reflections from the back surface can represent up to 50% of damaging UV light.
READ MORE ON THE BLUE LIGHT HAZARAD
Harmful blue light from the sun is more than 100 times more intense than the harmful blue light indoors from electronic devices and modern lighting. Exposure indoors is likely to increase as people convert from incandescent to modern LED lighting, including digital devices such as tablets, mobile phones, and personal computers emitting high energy visible (HEV) Light. HEV blue light, particularly at the 450nm level that digital devices produce, penetrates the retina. Blue Light between 380 and 470nm can cause cumulative damage to the retina, cataracts, and sleep disorders. The hormone melatonin is involved in regulating a wide range of circadian functions, including sleep. The synthesis and release of melatonin from the pineal gland are heavily influenced by light stimulation of the retina.
Blue wavelengths—which are beneficial during daylight hours because they boost attention, reaction times, and mood —can be most disruptive at night, which can upset your internal clock that aligns with the environment. Crizal Prevencia is the recommended coating as protection as it filters out harmful Blue-Violet light.
If there is a family history of medical conditions or advanced eye diseases such as AMD or other risk factors where transitions lenses are declined, combining SBF (smart blue filter), and Prevencia allows a maximum blue cut in a clear lens that would be worn outdoors by 30%.
The blue light hazard is also relevant to the sleep/wake cycle.
The most popular transparent spectacle lens materials do not entirely block the most plentiful source of UVR – the solar spectrum between 350 and 400nm.
Blue light filters benefit users of screens due to the improvement in contrast. Anti-reflection coatings and targeted blue light filtering will ensure visual comfort for screen users. It will cut down on the spectacle lenses internal and back surface reflections and reduce distracting and discomforting glare. The quality of coatings can vary markedly. Blue wavelengths are the shortest in the visible light spectrum and are most likely to scatter. Blue light may interfere with the body’s circadian rhythm, so blue light exposure in the evening may impede the ability to sleep.
E-SPF is a global index developed by Essilor, endorsed by independent third parties, measuring the lens’ UV protection, excluding direct eye exposure from around the lens. For example, an E-SPF of 25 means the wearer is 25 times more protected than without any lens.
Crizal Sun XProtect is exclusively for the Essilor Xperio tinted and polarised sun lens range. (Ionic Shield formulation, deposited in a vacuum, reinforces the front surface of the lens for best-in-class scratch resistance and superior smudge protection and a back-surface AR with higher UV protection allowing Sun XProtect to offer E-SPF 50 UV protection.
UV Protection indicates E-SPF 50 does not apply for Orma (1.5 indexes) without UVX.
Experiments splitting the visible light spectrum into 10nm bands and focusing the energy on swine retinal cells ( matches the human eye) that took four years of research identified that peak cell death occurs at 435nm, with a danger zone of +/- 20 nm.
Visible light (blue-Violet) from 415nm-455nm blue-violet light caused the most retinal cell death and oxidative stress.
Not all blue light damages the retina. For example, Blue-turquoise light from 465nm-495nm is beneficial to our sleep/wake cycles and hormone balance.
Blue-violet light can contribute to age-related macular degeneration and other factors determining a patient’s risk, such as age, race, genetics, diet, and smoking status.
Blue light protection glasses mirror developments such as GE Align, Apple Nightshift, Phillips Hue, Microsoft Night light, Samsung Galaxy Blue light filter and software such as F-lux, which reduce the artificial blue light from the screen.
The Essilor essential blue series lenses combine blue light protection and clarity. They provide up to 3 times more protection from harmful blue light than standard clear lenses while allowing beneficial blue light. Specific colour neutralizing molecules ensure transparency without any visible residual colour from the absorption of blue Violet light
Not all lens materials have the same UV cut-off point, the wavelength at which the material ceases to transmit ultraviolet radiation. However, all lenses should provide 100 per cent protection against UVA and UVB radiation, with a target UV cut-off of at least 380nm.
Like all visible light, blue-turquoise light helps you perceive colours and shapes. In addition, blue-turquoise light helps regulate your regular sleep cycle.
We still need to avoid reflections, so Crizal Sapphire UV ESPF 35 is best-in-class UV protection, approved by Cancer Council and is recommended.
The latest Sapphire optical lens coating comes with an E-SPF rating of 35 and a 25% reduction of those troublesome off centre reflections.
The ‘sapphire colour’ minimal bloom reflects away wavelengths that are the least sensitive for good vision, unlike, e.g. a commonly found green residual colour bloom on some lens coatings. However, excessive light leads to a world full of reflections for spectacles wearers – Back and front surface reflections, optical diffusion and ghost images.
A study conducted in 2014 by the Ipsos institute on four thousand people in France, the United States, Brazil, and China revealed over one out of two people are bothered by the intense brightness of their screens. Health agencies are now interested in risks related to new artificial light sources. Cool white LEDs, in particular, present an emission peak in the harmful blue-violet band and have a more elevated luminance/brightness than traditional sources. Even though these LEDs are now present in most modern lighting systems and on many screens, especially in computers, tablets, and smartphones.
We are more connected digitally than ever before and more dependent on digital screens. As a result, more people are presenting with digital eye strain symptoms. The blurring of vision can also be due to eye defects, natural deficiencies, illnesses, and pre-existing medical conditions.
Also, poor quality lenses and coatings can sometimes be a cause.
Optometrical and medical peak bodies recommend comprehensive eye care throughout life.
No matter the type of vision problem or medical problem, or medical condition, please consult a qualified professional even if you suspect it’s due to natural deficiencies.
Despite poor medicare rebates and some poor rebates from some private health insurers, and the plethora of advertising (lower-cost products claiming to be the complete solution for all) that concentrate on price, many patients find investing more complex and quality eyewear is worthwhile.
The in-store experience in the low-cost advertising store that attracts some people is one where alternative premium offerings are generally recommended way beyond the advertised claims and are generally in line with independents as far as price is concerned. The adage compares apples with apples applies as not all lenses and frames are the same.