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The most common eye care questions answered

Just put on some glasses and you’ll be able to see well - this is how it works in the best case scenario. It all sounds simple enough, yet there’s a lot of science that goes into producing a pair of glasses. There are so many questions about visual health: Can sunlight damage my eyes? How do self-tinting lenses work? Can I buy glasses online from home? Is blue light from smartphones harmful to my eyes?

Four ZEISS experts answer the most frequently asked questions. If you are a journalist we will provide you with the videos (also as raw material) for editorial purposes on request. You have specific questions, you want to have answered for your magazin? Please find our contact below. Likewise, if you want to conduct an interview with one of our experts.

Inkeri Klomsdorf, Digitization Expert and Head of Remote Platforms Vision Technology Solutions

Désirée Niendorf, Optician and Head of Product Management Vision Technology Solutions

Dr. Philipp Jester, Mathematician and Head of Lens Design Solutions

Dr. Christian Lappe, Physicist and Director Scientific Affairs & Technical Communication

Inkeri Klomsdorf

Inkeri Klomsdorf works at ZEISS Vision Technology Solutions as Head of Remote Platforms and in this role drives the topic of telemedicine. She also knows exactly what digitalization has in store for eye health and can explain what ZEISS has to do with it. Logically, she can also provide insights into the subject of data protection.

Can I take an eye test online or do I still have to visit an optician?

You can take an eye test online but still need to see an optician

Video transcript

There are already good opportunities for taking an eye test online. But in reality, this isn’t a suitable alternative for visiting an optician, an optometrist, or an eye specialist at present. You can find great tests online or in apps to give you an initial indication if you notice that your vision is getting poorer or if you simply want to check your eyes now and then. And these tests are great because they are easy to access and ready to use anytime, which is fantastic, and they also make people more aware that they need to be taking care of their eyes, of course. But as things currently stand, they are not a replacement for the technology a specialist has at their disposal.

Has telemedicine in optometry already advanced to the point that eye tests can be carried out by operating devices remotely?

Yes, thanks to telemedicine in optometry you can carry out eye tests by operating devices remotely

Video transcript

Definitely, yes; many of our high-precision measuring instruments, devices, and technology that we use as opticians or optometrists can be remotely controlled very effectively. And this is a perfect fit for telemedicine because the specialist operating the equipment and then evaluating the resulting measured values and data can do this just as well from a different location. So in this sense, it’s very suitable for telemedicine.

Isn’t telemedicine just basically a video consultation?

Why telemedicine is more than a video consultation

Video transcript

Telemedicine isn’t just a video consultation. That’s part of it, but we can do so much more with telemedicine now than just setting up a video meeting with the doctor or specialist. For example, a specialist can already control a wide range of devices remotely these days. They don’t have to be there in person. And even if they don’t control the equipment remotely, they can still evaluate the data and measurement results from elsewhere, of course, and therefore provide feedback and make a diagnosis based on these results.

Will telemedicine still be relevant after the COVID-19 pandemic?

Telemedicine will be relevant in the future

Video transcript

Yes, definitely, in my opinion. We were already using telemedicine in optometry before the pandemic. And while the pandemic did give it a big boost, it wasn’t the starting point. I think telemedicine will continue to be used, and the reason I think this is because of the different drivers behind it, such as digitalization across the entire healthcare sector. But many people are having to visit their doctor or a specialist in particular for their eyes just because of demographic changes. And on the other hand, there are fewer specialists available, and they aren’t distributed at all evenly across the map, so to speak. And telemedicine is a perfect fit in this situation because you can connect the specialists and the people who need them much more effectively.

Why do eye care specialists offer telemedicine?

There are many reasons to offer telemedicine in eye care

Video transcript

There can be many reasons for this. I’d like to pick two examples to talk about. For instance, telemedicine can allow a specialist to expand his or her reach significantly if the specialist wants to assist more people. Because it lets them use their time more efficiently and effectively. And because they don’t have to travel to a different location, for example, or they can offer opening hours that might be outside their normal opening hours.

A second application that’s ideal for telemedicine is the situation we have in some countries where people who need new glasses have to visit two different specialists – one who checks their vision for them and does the eye test, and then they have to take the result to a different one to select frames and lenses. And of course, it’s a big deal for them to visit two specialists and have two appointments and so on when they need new glasses. And in this case, the perfect solution is simply setting up our measuring instruments that we would have at the optometrist at the retailer instead who also sells the glasses. In Germany, this would be the optician, and then the doctor would come online and do all the relevant eye checks and vision tests and could also add their digital signature to the exam online. This way, the person has new glasses with just one appointment at just one location.

How does ZEISS make sure that my health data is secure in apps and telemedicine applications?

Data protection is important to ZEISS

Video transcript

That’s a very important question, and it’s important for ZEISS as well. Because we are a global company, we are subject to all the data regulations that exist around the world, and we also comply with them. The same is true of all the security requirements.
There’s also the Medical Device Regulations and so on. And we of course have dedicated departments and employees who take care of this, and who also take care of it in every country because every country has different specifics of its own.

Désirée Niendorf

Désirée Niendorf is a qualified optician and Head of Product Management for Vision Technology Solutions at ZEISS – where it is all about devices, platforms and systems. Désirée answers all questions about buying glasses, measuring eyes and how modern devices can support work in ophthalmic optics.

Why does the optician draw crosses on my new eyeglass lenses?

This is why opticians draw crosses on your lenses

Video transcript

The optician does this to mark the optical center of the lenses. In other words, the optical center always has to be precisely in front of the eye because this the point where our vision is optimal. The process itself is called centration. Making a mark with a pen is a very traditional approach that can be used also for follow-up checks to see whether the optical center is really in front of the eye. And opticians today often like to complement this with modern measuring technology.

I have a new pair of glasses that match my prescription, but I still can’t see really well. What could be the problem?

This is why you might not see very well although your new pair of glasses match your prescription

Video transcript

Generally speaking, there might be a number of reasons for this. The most important thing, of course, is to always check whether the prescription is correct. Do I really have the right lens power to correct the optical error? If you do have the right prescription, it might be that the lenses aren’t positioned correctly in the frame. In this case, the optical center won't be directly in front of your eye. This is always extremely important because this is the point where our vision is optimal. And this factor is particularly crucial if you have high diopters or if you have complex eyeglass lenses such as progressive lenses that integrate multiple lens power for different distances in the lenses. And this can actually lead to significant problems if the position isn’t correct. If this has happened, the only option is to remake the lens.

How can modern devices help eye care professionals with the centration process?

How modern devices help eye care professionals with the centration process

Video transcript

Thanks to modern measuring technology, centration is a very fast and comfortable process for consumers today. This involves taking one or a number of images of the person wearing the glasses. These are then evaluated using software. The centration parameters can then be generated automatically from this data. Another advantage of this is that the head and body posture can be evaluated at the same time to ensure they are exactly the same as in the wearer’s day-to-day life. The software can then be used to compensate for errors caused by incorrect head posture or turning the head when the measurement was taken. In this way, modern devices support opticians in their work.

Can you really try on glasses from your home?

You can try on glasses from the home

Video transcript

In principle, yes; but it goes without saying that it’s especially important to pay close attention to the size of the frames in this case to make sure they are really a good fit for the wearer afterwards. ZEISS offers a solution for this that involves having a so-called avatar of yourself created at the optician’s store. The avatar is a 3D image of your face that is created to scale. Using this avatar, it’s then completely flexible and convenient to try on eyeglass frames at home. A high-precision 3D scan is also created of the frames themselves. And this makes it possible to really ensure that the process is highly realistic and, above all, is scaled correctly in relation to your face. Plus, you can even project tints and anti-reflection coatings into the frames so you can see the combination as a whole. If you’ve selected your frames online you can order them directly from the optician where you previously had your avatar created. The optician usually already has the correct prescription, and you don’t even have to go through the centration measurement again because it can be taken directly from the avatar image which is true to scale. In other words, I can then pick up my glasses from the optician directly after ordering them. And I can have them adjusted to make sure they fit my face. And it goes without saying that it’s still important to visit an optician regularly to have the prescription checked and to have the glasses realigned or get further advice.

Dr. Christian Lappe

Dr. Christian Lappe is Director Scientific Affairs & Technical Communication. He knows how to package science in an understandable way and does not leave out any important detail. He explains what UV radiation or blue light does to our eyes, whether smartphones make us sleep worse or why gamers wear orange glasses.

What is blue light?

This is blue light

Video transcript

Blue light is a much-discussed topic. We are surrounded by radiation of different wavelengths – the so-called electromagnetic spectrum. Only a very small part of this spectrum is perceptible to humans as visible light. This ranges from short-wave blue light to longer-wave red light. Blue light represents the part of the visible spectrum with the shortest wavelengths between 380 and 500 nanometers.

  • Blue light is a major component of our daylight.
  • The natural source of blue light is the sun.
  • We are increasingly exposed to artificial light sources such as LED technology or all the displays and screens.
  • All these digital devices emit a lot of blue light.

In short, blue light is part of the visible spectrum and is present in artificial and natural light sources. Read more frequently asked questions and answers about blue light and good, healthy vision in the digital world here:

Is blue light harmful to my eyes?

Here is the answer to whether blue light is harmful to my eyes

Video transcript

Blue and especially blue-violet light has very high energy due to the short wavelengths and thus the potential to cause eye-damage. This is especially true for the retina, where the light is bundled and interacts. But we must differentiate between:

  1. long-term damage
  2. acute short-term damage

Short-term effects:

A typical example of short-term effects occurs when looking into a glaring, very bright light source. In this case, the wavelength is almost irrelevant. We should not do that anyway because it is definitely hazardous for the eye.

Long-term effects:

That is the continuous exposure of the retina to a specific lighting source, which can lead to metabolic processes and changes in the retina. One example related to blue light is the so-called photooxidative stress. This could lead to metabolic changes or deposits associated with AMD, the age-related macular degeneration. This long-term effect needs to be addressed. But the intensities of artificial blue light from LEDs and screens are far below any currently defined thresholds related to blue light hazards.

The photobiological risk assessment specifies certain thresholds at which we must classify sources of light. Standard electronic lighting falls below these thresholds by a factor of 40 to 200.

This doesn’t apply to outdoor activities. When we spend time in daylight and are exposed to the sun outside, protection from UV radiation and intense blue light is definitely a good idea.

Does blue light have an influence on our well-being?

Blue light and the influence on our well-being

Video transcript

Blue light has a significant impact on our well-being. In addition to blue light, which our eyes perceive as blue color, it’s interesting to know that there are also photoreceptors that aren’t responsible for vision – these pick up light intensities instead. Such photoreceptors are very sensitive to the intensity and presence of blue light. And it’s for a very different process that’s important for humans.

They control our circadian rhythm – the regulation of our “internal clock”, which creates the rhythm that wakes us up when it’s daytime. It’s a very complex process but works quite simply:

When blue light reaches the retina in our eyes, a stimulus is transmitted to suppress the release of the so-called sleep hormone melatonin. This means we’re awake, stay awake, and are alert.

This is the case during the day when the sun is shining – so humans are conditioned to the circadian rhythm. When the blue light decreases or disappears, this blockage of secretion is stopped, the sleep hormone melatonin can flow through our body and we become tired and sleepy as a result. Besides this very positive effect that blue light has during the day, there’s also a certain danger associated with interrupting this rhythm. This can happen if we let a lot of blue light into our eyes outside this normal daily rhythm at night and in the evening – typically due to artificial lighting. This affects the day-night rhythm and the sleep-wake rhythm.  

Does blue light reduce visual comfort?

Here is the answer to whether blue light reduces visual comfort

Video transcript

Blue light has an influence on human vision. Two examples to illustrate it:

1. Example “why is the sky blue rather than a different color?”

The first effect which is also responsible for the sky being blue involves scattering. The scattering depends on the wavelength and blue light is scattered more intensely. The eye produces a certain amount of scattered light, especially at the ocular media through which light passes, called visual noise. You could also describe this as an image in the eye that isn’t seen sharply but instead produces noise. In extreme cases, this can cause a perception of glare or reduced contrast. This is one of the effects where blue light plays a role.

2. Example “effect of light splitting in a prism”

When directing white light into a prism, the spectral colors appear at the back. Similar to that, the second effect is the refraction of light, which depends on wavelength. One keyword that describes this is “dispersion”. Dispersion causes the different wavelengths in the eye to have other focal points. And light with a shorter wavelength – such as blue light – is refracted more intensely. The focal point is slightly in front of the retina; in other words, in front of the point of sharpest vision – while the focal points of green or red light are further back. This effect also leads to limitations, for example, in terms of focus and visual contrast. Some people have also experienced this at night when colors shift and you suddenly can’t see so sharply.

Dispersion and scattering are thus two effects that depend on the wavelength and can affect visual comfort and quality of vision.

Many of us are using digital devices more when working from home – how can this damage our eyes?

The consequences of the increased use of digital devices in the home office

Video transcript

The good news is that there aren’t any studies showing that the shift in the workplace toward working from home and mobile work would cause harm to our eyesight. This is true as long as we follow a few simple and sensible rules that affect our vision. There are two findings that are important – and have also been addressed in science and research:

One is children’s eye development – referred to as emmetropization, in other words the development of a child’s ability to see – which can be negatively influenced. Many studies from Asia have demonstrated that this occurs due to extremely near work. So, if we work very near to an object for an extended period – which happens very frequently due to electronic devices – this can negatively impact eye development. This is a fundamental issue to be aware of in the case of children, and a similar effect happens in adults. This involves temporary myopia that can occur after working and focusing on the close range for a long time. After this, you may become nearsighted for a short period because your eye has become accustomed to continuously focusing on close range.

So, there are a few rules to follow:

  • Provide sufficiently well-lit conditions and room lighting. Because the eye needs certain contrasts to work well.
  • Fresh air and blinking are essential too.
  • 20-20-20 rule, which states that, if possible, you should direct your eyes from near work (which is one meter) to a distance of at least 6 meters, or 20 feet, for 20 seconds every 20 minutes. This relaxes the eyes muscular.

To sum up, working from home isn't known to cause any damage to the eyes, but following these rules can support good and healthy vision.

Do I need blue light filter glasses if I’m a gamer?

Here is the answer to whether gamer need blue light filter glasses

Video transcript

We can’t answer this question with a conclusive yes or no. Studies and reports – including many subjective reports – are now available, indicating that gamers who sit in front of monitors for a long time experience lenses with an integrated blue filter more comfortable. This is not easy to prove scientifically – as it tends to be a subjective feeling. But we know that certain effects related to blue light can impact visual comfort and perceived visual stress. So, in this respect, the subjective perception makes complete sense.

Do gamers have to have blue filter glasses?

No. But they can wear them. It's an option – and if it's comfortable for them, then that's important.

We should mention that such lenses that reduce blue light have different filter strengths, and what is suitable and comfortable for a person in front of a computer screen may have its limits in everyday life. So, in this context, be sure to check that these lenses have a solid level of blue filtering. However, in traffic or other everyday situations – including when viewing colors – they may not be the optimal choice. That's why there are different filter strengths to deal with when considering such a solution.

As a gamer, what can I look for when buying glasses?

Things I should keep in mind as a gamer when buying glasses

Video transcript

There are different options and things to keep in mind when buying glasses as a gamer. Because when you sit in front of these monitors for a long time, it’s essential to understand how visual gaze behavior works:

You probably sit relatively rigidly, let your eyes do a lot of the work, and don’t move your head very much because that takes time.

This means the gamer community has very special requirements. And we assume that the visual needs in this gaming environment may benefit from specific eyeglass lens designs that can accommodate such deflections of the eye and oblique views through the lens. So, what’s important then?

  1. Blue light filters are an option that should be considered.
  2. The second option is to look at the lens itself: what correction it provides and how the design supports those slanted views through the lens to ultimately get a fast, sharp image.

Why are the lenses of gaming glasses often yellow or orange?

The reason why gaming glasses are often yellow, or orange tinted

Video transcript

This is due to their nature. They filter out a part of the blue light spectrum – this changes the rest of the spectrum and, of course, the person’s actual visual perception. If these lenses have powerful filters, then a huge part of the spectrum is missing, and thus the color perceived through the lens itself shifts to this amber, orange, yellow. So, it’s a simple physical problem.

Blue light filtering can be achieved by:

  • either adding absorbers to the material of the lens
  • or by adding a coating to the lens that filters out parts of the spectrum.

Both leads to the same effect of less blue light getting through which can cause this color shift. You can compensate this tint with other additives in the material, as is sometimes done in the industry. This takes away the yellow tinge. But this type of lens then looks somewhat grayish. And another consequence that occurs is, that the overall transmission – in other words the clarity of the lens – is negatively impacted. So, the more I want to filter a blue light component, the more I have to accept either perceiving colors slightly differently or a grayish, less clear lens.

Does sunlight harm my eyes?

The damaging effects of sunlight on eyes

Video transcript

Sunlight can be pretty dangerous. Many people talk about the dangers of UV radiation when they are in the sun, and this also applies to the eyes. UV rays are everywhere when the sun is out. This is even true in the shade due to the refraction of UV rays.

So, you can’t really protect yourself. For the skin, you can use sunscreen and clothing to cover the different areas. It’s much more difficult with the eyes – and just a few people will apply sunscreen to the eyelid and still not have adequate protection for the eyes themselves. In other words, you need suitable sunglasses. There are various quality standards for UV protection these days. The limit is 400 nanometers – this represents an overlapping range that includes parts of blue and blue-violet light. Good sunglasses usually have this as a standard. In 2018, ZEISS took the step of incorporating this UV protection up to 400 nanometers into transparent, normal eyeglass lenses as a standard because not everyone wears sunglasses outside consistently. So, full UV protection up to 400 nanometers is the best way to protect the eyes and surrounding skin from intense daylight and UV radiation – even with clear lenses.

What can I do about presbyopia or age-related vision impairment?

Ways to address presbyopia, i.e., age-related farsightedness

Video transcript

The simple answer is: There’s nothing we can do about it. This change affects all of us because it’s an age-related change in the eye. Presbyopia is not an age-related farsightedness but the declining ability of our visual system to focus on objects at close distances.

To describe it briefly:

The eye contains our eye lens, a very flexible element that we can contract to vary degrees when we look at short distances.

  • The eye lens loses this flexibility as we age.
  • When we don’t have this flexibility anymore, we no longer have the capacity for near accommodation – or focusing on short distances.
  • This process affects us all.

Unfortunately, there’s no known way of stopping this process as of now. So, we have to live with it. It starts at some point in our thirties and then extends into their forties for many. This is when people often notice that their reading distance or the distance, they need to see sharply becomes larger. Since we can’t stop this process – because it’s simply an aging process – the question is: what tools do we have to help us live well with it?

  • The simplest solution of the eyeglass lens industry are reading glasses. In other words, a pair of glasses that makes the near range near again.
  • A smarter solution involves progressive lenses – where different optical effects are built into the lens, allowing for sharp vision at a distance and sharp near vision at the same time.

If I’m nearsighted, is it possible that this will compensate for often so-called age-related “farsightedness”?

Nearsightedness and the chance to compensate for it with age-related farsightedness

Video transcript

In optometry, it is not possible that two refractive errors such as nearsightedness and farsightedness compensate each other.

However, we often observe an effect or behavior in older people with a high degree of nearsightedness who take off their glasses, which generally have a corrective effect, and hold an object relatively close to their eyes to look at it up close or to read something. Due to presbyopia, this isn’t possible anymore – because the lens of the eye is no longer elastic and can no longer accommodate. The example just given is a spatial constellation in which the two refractive errors have precisely one common point at which sharp vision is possible. An older person who is farsighted or has a normal vision cannot experience this - because it only works in the described exact combination.

Dr. Philipp Jester

Dr. Philipp Jester is Head of Lens Design Solutions and understands the science behind a good lens design. He knows everything about how glasses work and the latest technological innovations. He can answer questions such as: where innovations are to be expected, how does a lens work and why do self-tinting lenses turn dark outside.

Have eyeglass lenses reached a point of no further development, or is there still room for genuine innovations?

Here's the answer to whether there's still room for real innovation in the field of eyeglass lenses

Video transcript

Visual aids have been around for a long time. About 100 years ago, it was postulated that lenses have been fully optimized and there would be no more innovations possible. At least with the introduction of progressive lenses in freeform technology nearly 20 years ago, it was possible to offer lenses that are easy to adapt to.

Nevertheless, there is still plenty of room for innovation today:

  • new materials
  • new coating methods
  • new processes
  • more precise measuring technology at the eye care professional
  • changing fashion: larger frames, smaller frames
  • differently habits: different reading distances

All of this is considered in the development of a new generation of eyeglass lenses, so there is still much room for innovation.

Nevertheless, clear vision is the core intention for an ophthalmic lens. But today's lenses can do much more than that. For example, they offer protection against UV radiation or are suitable for special situations such as driving.

How is the price of eyeglass lenses set?

This is how the price for eyeglass lenses is set

Video transcript

First of all, there is a difference between a stock lens and individual prescription lenses.

  • Stock lenses are finished lenses that can be taken off the shelf for an order, prescription lenses are individually manufactured to the specific needs of the eyeglass wearer. The lenses are then custom-made for a particular order.
  • In addition, it also makes a difference whether you order cheap glasses on the Internet or go to the eye care professional around the corner.
  • For premium eyeglasses you pay not only the frame and the lenses, but also the eye care professional, the measurement with precise equipment, the material, the manufacturing of the lens, and research and development. All in all, you pay for years of good and healthy vision.

How do self-tinting lenses work?

How photochromic lenses work

Video transcript

In nature, some minerals change color – in particular become darker – when exposed to light. We apply the same principle to self-tinting lenses. These have been around since the 1960s and react to UV radiation. When exposed to sunlight, the eyeglass lenses turn dark. Molecules in the material change under UV radiation and then absorb visible light. This process is reversible. This means that the lenses become clear again as soon as the UV radiation is no longer present. When I walk out of a building into the sunlight, the eyeglass lenses become dark. As soon as I return to the building, the lenses must become clear again to see well indoors. Due to intensive research, it is now possible that photochromic eyeglass lenses not only darken fast, but also fade back to the clear state again more quickly.

Can I use photochromic lenses as a substitute for sunglasses?

The answer whether I can use photochromic lenses as a substitute for sunglasses

Video transcript

For general use, yes.

If I wear my eyeglasses a lot indoors and outdoors - both during the day and in the evening or at night - then self-tinting lenses provide good visual comfort with adequate glare protection.

Do photochromic lenses work in the car?

The answer whether I can use photochromic lenses in the car when driving

Video transcript

Self-tinting lenses react to UV radiation. But behind a windshield or even window glass, the amount of UV radiation is often no longer sufficient to darken the lens. For this reason, it’s recommended to have a suitable pair of sunglasses to make driving safe and relaxed, especially on longer trips.

What are manufacturing methods for making a single vision lens?

These are the manufacturing methods for single vision lenses

Video transcript

Basically, there are two methods:

  1. The first one involves casted lenses: Two molds are used for this purpose. A plastic monomer is filled between them and then polymerized. After that, the molds are opened, and you have the finished lens.
  2. Secondly, there is the so-called free-form technology, where we apply the optical surface to the back of a lens blank by diamond turning.

Are there still innovations in the field of single vision lenses?

Here is the answer whether there are still innovations in the field of single vision lenses

Video transcript

Absolutely! The next generation of ZEISS single vision lenses will offer even more visual comfort. We’re currently working to transfer the process for manufacturing progressive lenses to single vision lenses. This will let us offer eyeglass wearers even greater visual comfort in the future.

Get in Touch with Us

Joachim Kuss
Head of Communications: General topics and Sustainability
Mail: joachim .kuss @zeiss .com

Phone: +49 (0) 151 42112288

Julia Baier
International PR: Instruments, Tools and Digitalization
Mail: julia .baier @zeiss .com

Phone: +49 (0) 7361 591 400

Maria Conrad
International PR: Eyeglass Lenses, Coatings and Materials
Mail: maria .conrad @zeiss .com

Phone: +49 (0) 7361 591 1378