ROAD 2 Driving safety

Are you seeing everything out there on the road?

Did you know 73% of motorists say they experience visual discomfort from the glare of oncoming headlights? 60% of motorists feel affected by poor vision when driving. 50% of motorists struggle with night driving. 1/6 of road collisions are a direct result of a driver with substandard eyesight on the road.*

Common vision causes of car accidents include:

– visual fatigue

– failing to look

– looking but failing to see

– distractions from instruments

– dazzle or glare

– misjudging road conditions

Seeing the road ahead

While not all of these factors may be completely eliminated it is easy to see how good vision and lenses designed for driving may be of great benefit in reducing these numbers. The Rodenstock Road 2 lens is now available at Hannaford Eyewear, bringing with it some of the most advanced designs and technology to ensure the safety of you and your loved ones on the road.

Glare – and advanced filter system blocks specific wavelengths of light identified to be the causes of glare and discomfort

Fatigue – cutting edge lens designs and the same filters have been demonstrated to reduce driver fatigue

Clarity – multifocal wearers will now be able to enjoy the absolute widest fields of vision available in a lens

Road 2 lenses are specifically designed to allow drivers to view their wing mirrors with minimal or no head turn, mimicking natural vision as closely as possible. This wider field of vision is key to the importance of the Road 2 lenses as a valuable safety tool.

Enhance your driving experience and look forward to a safer, more comfortable journey with the Road 2 lens, available at Hannaford Eyewear Bowral.  Click on the image below to view the Rodenstock Road 2 lens video.

*http://www.rodenstock.com/uk/en/news.html

5 reasons progressive lenses fail

5 Reasons Progressive Lenses Fail1523023

Progressive, or multifocal, lenses have developed an undeserved reputation for being difficult to use. People have reported that they feel unstable, can’t read or even can’t see out of them at all.

The vast majority of adaptation issues with progressives lenses aren’t from the lenses at all, rather they are caused by the fitting of the lenses to the patient. Here are five of the most common errors that cause non adaptation to progressive lenses.

1. PD (Pupillary Distance)

There may have been a time when using a ruler for inter pupillary measurements sufficed, those days are long gone. Modern lens designs require the most accurate measurements available, this means monocular PD’s measured with sub millimetre accuracy.

Using binocular measurements fails to account for the fact that our eyes are rarely symmetrical and any uncompensated asymmetry will narrow the field of vision. In extreme cases this can result in complete failure of the patient to fuse their image at near or have their field of vision offset to the point where clear vision is only achievable by significantly turning the head to the side.

2. Heights

I have worked with practitioners who claimed that taking the correct fitting heights for their progressive lens patients was unnecessary. Their argument was that the patient should be able to move their head to find the correct zone in the lens. What was the result? The wearer had to either drop their chin to drive or raise their chin up high to read. The instances where the fitting just so happened to match what the patient needed were so rare as to be c12bd2bab97b3c76d81393f13796f7f9remarkable and the failure rate was so high that the lens companies would send out their representatives to figure out what was going wrong. Of course they didn’t admit to the ‘no heights’ policy to the rep which was proof enough
that they were not doing the right thing.

Progressive lenses are designed to be fit at a specific point relative to the eye, this is considered carefully by the lens designers and changing any parameters can have quite significant effects.

3. Frame

Progressive lenses are made to several standards which tend to be based around the level of customisation. Basic lens designs make a set of assumptions about how the frame fits the face and these are not always correct. For example, if the lens design assumes a vertex distance of 14mm but the frame is worn at 10mm then there will be a fundamental power difference between the prescribed lenses and the final result. In short, the resultant prescription may not be correct!

Another common source of problems are the tilt and wrap of the frame. Unless the design specifically calls for these parameters it is unlikely that they will be compensated in the final lens. As we all remember from our basic optics, tilting or wrapping a frame can lead to changes in the amount and orientation of cylinder, rendering once good lenses completely unwearable.

4. Design

On the subject of parameters, how many different measurements are taken for progressive lenses? Is it just heights and PD?

What about the ‘top of the line’ or ‘premium’ lens?

RodenstockMetropolitan300What extra measurements are being taken to allow the premium lens designs to perform at their best? Yes, basic progressive lenses necessarily make assumptions on the designs for tilt, vertex, wrap etc, that is how the cost is kept down.

However, the whole point of the premium lenses is that they are more customised for the patient. Unless the extra measurements are being taken then assumptions are being made at the lab and this erodes the benefit to the patient. On that note, the range of tools available for taking a full suite of measurements is larger than ever before. It ranges from simple kits to full video centration systems so that practitioners can ensure they are taking the most accurate measurements possible.

While the best lens designs have many excellent features, their excellence is predicated on a foundation of accurate, detailed data.

 What design did your patient wear before?

Considering the previous wear patterns has a large impact on the success of a lens, if a specific design has been worn in the past we need to know how to consider the way the style and feel of the lens will relate to the new design, prescription and fitting.

Patients will occasionally elect to get the ‘best lens available’ only to have it fail, two of the big causes of this are failure to take adequate measurements and failure to relate the new design to previous wear. Talking to the lens companies directly will help a practitioner get a feel for how a given lens performs and relates to it’s predecessors.

 

5. Corridor

I know that some people will say ‘but that is a design consideration’. Yes, it is, but it is so often overlooked that it deserves it’s own point.images

The Minkwitz condition dictates the relationship between the add power and the corridor length. It is possible to completely change the way a patient views the world by simply changing the corridor length. Similarly, when we consider the previous wear patterns we can carefully manipulate the corridor length to manipulate the design of the new lens, effectively making the change to a new progressive lens more comfortable.

What can we do for you?

Grant Hannaford and the team at Hannaford Eyewear are dedicated to providing the best in optical education for their patients and the ophthalmic industry as a whole. Why not get in touch with them today to see if they can help you, or if you’re in the industry we can help your practitioners grow their knowledge of optics and dispensing beyond the graduate level.

Making your spectacles

Why is it so?

A clear lens casts a black shadow. How?

DSC_0316

 

We thought we’d post this picture we took during concept development of our upcoming blue light window display. So why is it that the spectacles and the large lens leaning at top left cast a black shadow but the two lenses at the bottom do not?

The savvy readers will already have figured out that it is due to the wavelength of the light from the globe, what the picture shows is some of our lenses as compared to a more basic offering on the market.

What does this tell us? Well, we used a UV lamp to illuminate the scene and our lenses are the ones that are casting the black shadow. This is because all of our lenses contain UV inhibitors, unlike the ones at the bottom left of the picture. So you can be sure that you are getting all the protection you need, every time.

How much extra does this cost? From us it doesn’t cost one cent more. We put top quality hard coated, UV blocking lenses in every pair of spectacles we make, so you can be assured you are getting the best quality, performance and protection.

At Hannaford Eyewear we know optics. Contact us to discuss your needs today.

Individual Fit, Premium Care, Hannaford Eyewear.

Anti Glare Coats?

Anti Reflection lenses or Anti Glare?

This is a remarkably big topic but we do get asked this a lot so we shall try our best to explain without descending into anything too horrendously complex!

Is there any such thing as an anti glare coat? Not in the sense that some advertising campaigns might have you believe. In fact, many of the coatings that are touted as being anti glare are actually anti reflection (AR) coatings, something quite different indeed!

Reflections and Coatings

corning-gorilla-glass-1

The centre of this sheet has had a circle of anti reflection coating applied.

The surface of every lens reflects some light, with this amount varying according to several factors such as materials and even pre existing coatings like hard coats. Typically uncoated or hard coated lens surfaces reflect around 7% of light, which of course means that only 93% of the available light is making it to your eye. For thinner, higher index lenses this number drops to as low as 85%. The result of this is that we now have lenses that not only show reflections, but they are also not allowing all of the light through, impeding better vision.

What can we do about this? The solution to reducing reflections and increasing light transmission is rather ingenious and makes use of  destructive interference. By placing a coating on the surface that makes the reflected light out of phase with the incident light we can get the ‘peaks’ of the incident waves to interact with the troughs of the reflected waves and vice versa causing the reflection to be cancelled. To do this the coat needs to be 1/4 of the wavelength thick, or odd multiples of this number to maintain the out of phase relationship.  Because visible light has a range of wavelengths an average value roughly around yellow is often used, which while not perfect, does allow for optimal results. Modern AR coats will also have multiple layers to reduce the issues caused by the averaging even more, plus there are extra coatings that are added for resilience, hence another name for AR coats is ‘multi-coats’.

constructive-destructive-wave1

Click image for link to original at www.tutorcircle.com

If that sounds excessively complex then think of waves at the beach, sometimes two waves can arrive at the same time, resulting in a bigger wave as their energy combines. Other times a wave will arrive at the same time as a gap in the swell so it is fallen into the ‘gap’ and is cancelled out, it’s this cancelling out effect that we want to achieve.

Now that all of that is out of the way we can think about what it means. When we apply an AR coat to a lens it is actually increasing the transmission of light to effectively reduce the effect of the lens on light transmission. What we want to achieve is a situation where the prescription can do it’s work with as little awareness of a lens being there as possible for the wearer. That’s pretty much the opposite of anti glare!

content_tratam_solcrystal_trafic

The glare from these headlights is caused in part by the lens, which is why AR coats can be beneficial for night driving by actually increasing light transmission.

What do you see on an AR coated lens? As a wearer you will get more comfortable vision as the lens will let through as much light as possible. For situations where you need to concentrate for extended periods this is a tremendous advantage. A similar effect is observed driving at night and particularly in the rain, halos from streetlights are reduced and general comfort is increased. For people looking at you there will always be some slight reflection as we cannot cancel every wavelength simultaneously, because of this AR coated lenses will tend to have a slight green or blue reflection which we refer to as the bloom.

A downside to the extra clarity is the fact that AR coated lenses may show dirt and marks more easily. They don’t necessarily get any dirtier or scratch easier than other lenses, in fact they are designed to be tougher than ever, but they do show marks simply as a result of the more refined surface. The good news is that modern coatings are constantly improving and are now easier to clean than uncoated lenses so you can have the best of both worlds.

There are some circumstances in which a lens itself will create reflections but it is important to realise that this is not ‘glare’. These can be troublesome reflections, ghost images or even halos around lights that are a result of light interactions inside the lens. Night driving and driving in the rain is a perfect environment for these kinds of halos (see the image above), thankfully AR coats are very useful in reducing these effects to.

One cosmetic benefit of AR coats is the decreased awareness of the lens when looking at the wearer, meaning that we all get to see your eyes. This is especially useful for film and television where coatings have long been used to eliminate reflections, I often look for the AR coats on actors spectacles in films and try to identify the company that made them. And yes, I realise how nerdy that sounds.

Reducing Glare

If we consider glare as originating from a light source or surfaces like sand or water then we can begin to understand the techniques needed to reduce its impact. Glare by definition is a strong or dazzling light source so when we consider this in the context of AR coats we should readily see that increasing light transmission will do very little to reduce discomfort caused by glare or bright light, if it is performing as intended then it will have no effect on the glare at all.

To reduce glare we need to reduce the amount of light reaching the eye. This can be in the form of a tint, polarisation or very specific lenses like the new blue control types of lens. In any event what we see for glare reduction is an attenuation or blocking effect. Lenses with this in place will not look as clear as an AR coated lens, (obviously in the case of sunglasses!) but even the new generation of blue control lenses will have a light tint to them.

Screen Shot 2016-12-19 at 12.10.11 pmYellow tints have been cited anecdotally as reducing glare at night but their actual effect is somewhat more complex that this. By design yellow filters will reduce some effects of glare by blocking a percentage of the blue light from headlights for example. However, the trade off is that a percentage of the overall light level has been blocked in the process, so we have a reduction in glare but also a reduction in transmitted light. Consider the effect of that at night when driving where it is generally desirable that we get more rather than less light to the eye, if only for the sake of safety. Because of this tints for night time driving are rarely recommended.

What should I use?

So know you know the difference between reducing reflections and reducing glare the big question is ‘what do I want to actually achieve?’. Consider your symptoms and what may be causing them. Is it fatigue or glare? Do you want to increase or decrease the amount of light coming through the lens?

The easiest way to work out your requirements is to talk to a qualified professional like those at Hannaford Eyewear. Why not contact us today?

High powered spectacles

How high is a high prescription?

How long is a piece of string? The highest powered spectacles that we have ever made at our practice were a set of -35.00 diopter lenses for a worker at a Mongolian orphanage. This is certainly well above the normal power range 0f around 0.00 to 4.00 diopters but shows that limits are made to be pushed! How did they look? They were very thick indeed but the patient was happy to report that the trees outside their window now had leaves and they could function in their role at the orphanage, so they got the job done.

One of our more recent efforts was a -22.00D lens that we made for a patient. Again our patient was happy with the resultant vision and this time we managed to get some photos of the finished job too.

What did we do?

DSC_0536

Power compensation

First and foremost the power of the prescription as written is examined. In this case we were able to determine that the test was performed with the frame at one distance from the eye but the new spectacle frame was sitting much closer. This results in a need for compensated powers to ensure that the prescription in the new spectacles is the same as that experienced in the eye test. By doing this we can ensure that the patient is getting exactly what the doctor ordered.

In some cases this can result in a remarkable change in powers so it is vital that these things are considered, not just for extremely high powers but even for prescriptions that may not seem overly strong at first glance.

We also made sure that the lenses made use of an appropriate material and lens design that balanced thickness reduction with the visual requirements of the patient. By making use of our in house design facilities it was possible to gain visual acuities and visual fields that enabled this patient to retain their drivers license, something they had previously been told was impossible.

 

DSC_0535

Asymmetric prescriptions

Various eye conditions can result in a patient having asymmetric powers (i.e. one eye needing a much stronger prescription that the other). Lenses made for these patients will give different image sizes and rates of image movement, the effects for the patient can range from mild discomfort to extreme visual distress and nausea. Patients who have had one cataract removed and are waiting on the other to be operated on will often experience this condition known as anisometropia (unequal refractive power).

In many cases it is possible to overcome the difference in powers by manipulating the relative curvatures of the lens surfaces as well as several other factors. Lenses made to correct this condition are known as iseikonic lenses and can look a little interesting with various curves and thicknesses, but if the end result is clear, comfortable vision these are small considerations.

Prism

Many people are unaware of what prism actually is, but those who do need it are very aware as it enables them to get one clear image of the world rather than double vision. The causes of prismatic prescriptions are varied but can include issues with the muscles of the eye or even traumatic injuries to facial bones.

We use prism to help a patient ‘fuse’ the two images received by the eyes and the amounts required to do this will vary according to each case. Most patients who need it will have somewhere between 0.50D and 2.00D, the highest we have seen was 26.00D which was one of the most challenging cases we have experienced.

In some cases the amount of prism required will vary between distance and near vision. These require special solutions as we need to bring many disparate elements together in one pair of spectacles. One of the best solutions for these is actually one of the oldest lens designs, the ‘Franklin Split Bifocal’. At Hannaford Eyewear we are proud to manufacture our own Franklin Split Bifocals on site which means that you can be sure that we are working with you to reach your optimal vision.

So even if you have been told that your prescription is too high or too hard to make up, contact us or come and see our team, you might be surprised at what we can achieve for you.

Can I reuse my old frame?

Why should I get a new frame? My old one is just fine!

We get asked this regularly in our practice and the answer is not straightforward, although we do endeavour to make it as simple as possible for our patients.

There are many factors that influence the suitability of a frame for taking another set of lenses, almost all of them directly relate to how long we expect the frame to last. While it is certainly possible for us to put new lenses in almost any frame that is brought to us there must be a reasonable lifespan expectation. That being said, there is always the possibility of false economy when reusing a frame as they may require replacement in the near future due to unforeseen failure or breakage.

One important thing to consider when looking at re-using an old frame is ongoing repairs and warranty. Of course an old frame has no warranty available and will often also prove difficult to find parts to fit. While we have the capability for fabrication of custom parts for some cases, this process is often expensive and outweighs the benefits of keeping the old frame. The safest way to assess these points is to bring them in to us and we will be more than happy to see if they can be reused.

What do we look for?

When assessing a frame we look first at the material and determine the build quality. For example, cheap injection moulded plastics will generally prove unsuitable for having new lenses inserted as their lifespan is very short. Conversely, top of the line hand made acetates will often see several successful lens insertions before we start to see the telltale wear and tear that render a frame beyond reasonable use.

Metal frames will often last well through several usage cycles and depending on the material may have repairs effected to extend their life considerably.

We will look at a frame under very high power magnification and search for cracks or any other indicators that the frame may fail in the near future. While we can’t predict the lifespan of a frame we have found that careful examination will give us a very good idea of whether a frame will survive the fitting process and have a reasonable lifespan.

More than just glasses.

There are exceptions though, sometimes spectacles carry so much of the personality and history of a person that they are worth almost any amount of effort to keep going.

One notable instance for us was the case of the gentleman who bought two pairs of spectacles in Paris after VE day in WWII, one to wear home and one to wear on his wedding day. After years of good wear he began to be told that they were no longer serviceable and so they were treasured but never again used. When this gentleman spoke to us about these glasses at his first eye test with us we asked him to bring them in, partly out of curiosity but also because we have had some experience in rebuilding frames. Happily we were able to rebuild both pairs with some custom parts and fit lenses to them, it was a memorable moment for us when he brought his wife in to collect them. He sat with us and told us stories from both during and after the war and became a weekly visitor to the practice for years, where he would pop in to chat on a Thursday morning. After he passed away his wife came to the practice with a small box containing one of the pairs of glasses, he wanted us to have a pair because we had given him a chance to wear them again just as he had when he got home from the war. That pair of spectacles sits above Grant’s desk where we get a regular reminder that the value of our work goes well beyond vision itself.