Would you say your face is rather narrow, medium or wide? This question is the basis and the starting point for the next step, because it depends on the size of the glasses you choose. If you already have a pair of glasses, you can use the measurements from your old frame to determine the correct size and width. Simply measure the distance from one end to the other at the front to know its width.
A word of advice: we have developed a search option that will help you find other frames with the same width or similar to yours. You will find this search option directly under the “Face Type” filter on the home page of our sunglasses or prescription glasses. In addition, in our guide to the right size of glasses, we explain exactly how to do it.
Choose the right width
Below you will find more details and advice on the size of the glasses.
The size mainly refers to the width of the saddle. If it is too large or too narrow, the glasses can easily be dislodged or even bruised. To find a frame that fits you perfectly, orient yourself across the width of your face, obviously without your hair. For style reasons, there is no exception to this rule: the butterfly or Cat Eye glasses are always a little wider, while the metal frames must be a little narrower.
The width of the bridge is the shortest distance between the two panes under the support bridge and is measured from one of the interior edges of the crack to the other. You wonder why this little piece is so important. For the glasses to fit perfectly without moving, the ridge of the frame must be compatible with the width of your nose. If the frame is not resting correctly on the nose, it can not only cause discomfort or headaches, but also impair visual ability, since a poorly positioned frame can also distort the optical center of the lenses.
3. Width and height of windows
Let's talk about your visual field. With a glass that is too small, it will be limited, and with a glass of generous dimensions, the eyes will also capture what is happening in the lateral areas. However, the glasses should not be wider than the face itself and the eyebrows should be visible. Sunglasses can skip this rule, as they often also cover the eyebrows to provide optimal protection from the sun. The crystals are measured at the widest and highest points, the sharpest point being in the center of the crystals.
The length of the rods will determine the comfort of the glasses. The rods must be adjusted correctly: if they are too long, the glasses will be unstable, and if they are too short, the frame will be too rigid, causing bruises and annoying headaches. The rods can be adjusted optically.
A word of advice: you can order up to 4 frames to try them free at home without obligation for 10 days1. In this way, you can make sure that the model chosen meets your expectations, and all this comfortably from your home. More information: Free 10-day trial at home.
Advice according to the type of glasses and their use
Of course, the choice of frame will also depend on the use you want to make of your new glasses.
How many diopters do you have?
There is a basic rule for short-sighted and farsighted people: the more diopters you have, the thicker your graduated crystals will be. Therefore, if you have a very high graduation, it would be better to opt for a thick frame that hides the edges of the crystals. If you do not have many diopters, you can easily opt for fine supports.
Office, sports or progressive glasses…?
Despite an ergonomic workstation, you may have difficulty seeing the keyboard clearly, concentrating on your documents, or simply finding a comfortable position in front of your computer, for example. All of this could be an indication that you may need optimized office glasses, called professional glasses. Progressive lenses are certainly a great invention, but for working in front of a computer screen, there are better solutions.
In sports, it is essential that your glasses adapt perfectly to your face and do not move from side to side. Sports can also be a challenge for your glasses, so you should be able to feel comfortable and safe with them. A good prescription or even progressive sports glasses will help you give the best of yourself.
See sports glasses
Do you need progressive lenses in your daily life? If you need progressive glasses, opt for frames capable of accommodating glasses of a certain height.
If you have already found the perfect frame for you and know your prescription, you can order your new glasses. If you are not sure of your prescription or if the glasses do not fit your face perfectly, we advise you to consult an optician to have an eye exam and to focus and / or individually adjust the glasses. In the following article, we give you more information on vision tests and crystal centering.
Our visual ability almost always varies gradually and gradually, so it's hard to tell when it's getting worse. For this reason, it is advisable to have your eyes examined annually or every two years. In the case of children and the elderly, even more often. There is a lot of talk about an annual eye exam.
We have summarized below the most important points relating to this subject.
How often is it recommended to have an eye exam Why is a periodic exam so important to the ophthalmologist or optician?
At what intervals is it recommended to have an eye exam?
Sudden worsening of vision and any type of eye condition are causes of visit to the ophthalmologist or optician. Even if you don't have any of these symptoms, an annual or semi-annual eye exam is recommended. Since our visual ability usually deteriorates gradually without us being aware of it, symptoms like headaches, fatigue and irritated eyes may indicate that a change is taking place. Therefore, it is always best to make an appointment for an eye exam. In the case of children and the elderly, the following should be taken into account:
Vision screening in children
Do not hesitate to take your children to the ophthalmologist when they are very young. Children do not know the difference between correct vision and impaired vision and therefore have no reason to express to themselves that they are having difficulties. As a rule, it can be said that children should undergo an ophthalmological examination before the third year of life, in order to avoid visual impairment. With one exception: if there is a family history of serious vision problems, take your child to the ophthalmologist at the age of six to twelve months. In addition, you may want to have another eye exam before you start school.
A word of advice: be on the lookout for the first symptoms which may indicate visual problems. If your child frequently complains of headaches, has trouble writing correctly, has problems concentrating, or expresses a desire to always sit in front of everyone in the classroom, near the blackboard, this may indicate that he has a visual impairment.
Children who already wear glasses should be screened annually as their prescription can change quickly when they are growing.
Eye examination in adults
In the elderly, graduation can get worse quickly. An annual review is therefore recommended. In addition, at an advanced age, the probability of developing diseases such as cataracts or glaucoma increases.
Why is it important to do a periodic review?
Nowadays, the probability of suffering from a visual defect is very high, because we offer little rest to our eyes: television, video games, mobile phones, work in front of the computer, school or university studies…. All this represents a considerable effort for our eyes. Stress, lack of sleep and various environmental agents can also negatively affect them, causing itching and temporarily impairing our visual ability.
Deterioration of visual ability does not usually appear overnight. Particularly in the case of myopia and when there is a considerable difference in the graduation of the two eyes, it is possible that the “good” eye compensates to a certain extent for the defect of the other eye for a certain time. But that does not mean that there is no longer any default as such. The only way to know if we have a visual impairment or not is to have a visual acuity test.
Go to the ophthalmologist or optician?
An ophthalmologist and an optician / optometrist can have an eye exam. It is up to you to decide who to contact to measure your visual abilities. Yet everyone has their strengths. Here are some recommendations to help you make the best decision based on your needs.
Eye ophthalmologist / ophthalmologist
If you experience acute discomfort or any other special discomfort, such as pain, feeling of a foreign body in the eye, itching, itching or redness, you should always consult an ophthalmologist or ophthalmologist. It is also possible that your eyes may be irritated or sick without you noticing any symptoms. If you want to not only measure your visual ability, but also want to make sure your eye health is intact, it's best to see your eye doctor. Normally, a visual acuity test carried out by an ophthalmologist or an oculist is a service covered by social security, because they are doctors specialized in ophthalmology. The relatively long waiting times for an appointment can be a disadvantage.
Optician / optometrist
If you suspect that your prescription has changed, but are not experiencing any symptoms or eye discomfort, you can consult an optician. Generally, in an optician's office, you will be immediately taken care of without having to make an appointment too far in advance. In addition, depending on the results of the visual acuity test, you do not need to go to another store to choose new glasses. Eye exams in an optician's store are not covered by social security and are not always free, although the price is usually discounted on the final amount of the glasses if purchases are made in the same establishment.
Caution In both cases, be sure to tell your eye care professional if you have a chronic condition or are taking medication regularly, as this could affect your visual ability and, therefore, the result from your eye exam. Also, it makes no sense to take the visual acuity test after using drugs or alcohol.
An eye exam is an essential prerequisite for purchasing new glasses that will correct your vision perfectly. Once you have taken all the necessary steps, you will know what graduation you need to be able to see clearly. But even if you're not wearing glasses yet, it might be a good idea to have an eye exam. Headaches, irritated eyes, or tiredness are just a few of the signs that may prompt you to wear glasses or contact lenses.
An eye exam is worth it, whether you've been wearing glasses for some time or have never had a vision problem. As the visual capacity changes little by little, several times without realizing it, it is recommended that all wearers of glasses carry out a routine check every year or every two years.
But people who don't wear glasses, but who often suffer from headaches, eye irritation or fatigue, can also benefit from a visit to an ophthalmologist for an eye exam. Undetected poor vision can be the cause of these symptoms. The need to force your eyes to see clearly, the difficulty in recognizing objects, people and especially reading problems are more than obvious signs that it is time to consult an ophthalmologist or an optometrist.
Eye examination, explained step by step Centering the lenses and adjusting the frame In the ophthalmologist's or optician's office, how often should the eye be checked?
Eye exam explained step by step
The first step in determining your diploma will take you to the so-called refraction room. Here, a qualified optician-optometrist will examine your eyes using various advanced devices and technologies. This way you will know if it is a good idea to start wearing glasses or to change your existing glasses. Your graduation will be measured step by step.
If you do not have the values of your old glasses or the latest prescription, the optician or optician will perform a preliminary measurement with an autorefractometer, a device capable of measuring the optical power of your eyes by infrared. You will first need to look through the device with one eye, then with the other. The result gives you an estimate of your visual abilities. We can also make a pre-measurement to have a first clue about a possible change in your graduation.
Visual acuity measurement
The actual measurement of visual acuity is made with a phoropter or conventional test glasses. The optician can thus determine your visual acuity. You will discover to what extent your eyes are able to perceive the contrasts and contours of your environment. Visual acuity varies with age, optical resolution of the eyes, and retinal integrity, among other factors.
To check the visual acuity of your eyes, the optician will place different lenses in the test glasses or in the phoropter. With these, you should focus the familiar tables with letters or numbers of different sizes, while answering the professional if you see them more or less clearly and answering different questions (for example, if you recognize all the numbers in the last row), which will determine your visual acuity. This is why we often talk about a subjective refraction test.
Optical note: In young people, visual acuity is simply measured from a distance. However, due to presbyopia or eyestrain, from the age of 40, the near value should also be taken into account. To do this, you need to put on a pair of test glasses and hold a text in your hands to read it aloud.
Prepare for your eye exam
- Come check your eyes when you are rested and relaxed.
- You should have eaten and drunk enough.
- Take some time for testing, don't do it too quickly.
- If you wear contact lenses:
- You should not wear contact lenses for 24 hours before your eye exam.
- If you wear contact lenses all the time: have your eyes examined immediately after removing them.
- It is advisable to make an appointment for an eye exam.
Window centering and frame adjustment
Once you've chosen a frame, it's important to center the lenses for the best result. In order to incorporate the crystals with millimeter precision, two points must be found: the pupillary distance and the pupil height. Centering the crystals is necessary to prevent discomfort such as headache, visual fatigue and discomfort. In addition, this method also makes it possible to obtain the best possible correction of the glasses.
First of all, the glasses are individually adjusted, i.e. the frame adapts to the shape of your face and the anatomy of your head, so that the glasses are correctly placed in front of your eyes . The rods and possibly also the nose pads will be tailored specifically for you. In addition, the height of the pupil will be measured: the vertical distance between the center of each pupil and the lower edge of the glass.
In order to obtain precise centering of the lenses, the optician will carry out a series of additional measurements. It will be a question of finding the happy medium: an important aspect also when it comes to buying new glasses. In order to ensure optimal light refraction and therefore the best possible correction, the optical center of the crystals must be determined. It is the exact point on the crystal where the rays of light pass through its front face without undergoing any deviation. In concave lenses, it coincides with the thinnest point of the crystal, and in convex lenses, with the thickest.
The optician will then find the distance between the center of each pupil and the nasal bridge, also called pupillary distance (PD).
You will use a special ruler, a pupilometer or a video centering system to find the distance between the center of each pupil and the middle of the nasal bridge for each eye separately, since few faces are perfectly symmetrical. Finally, all the parameters found will be noted in your card or recipe.
Advice from our opticians: If your prescription glasses still do not fit you correctly when you receive them, you can return to the optician to have them adjusted to your frame.
You now have all the necessary parameters. In the next step, you will need to choose your graduated crystals. Read on to find out what options are available to you.
At the ophthalmologist or at the optician?
Many will wonder if it is better for an ophthalmologist or optician-optometrist to perform the eye exam. First, you can go to an ophthalmologist or optician for an eye exam. However, each option has different advantages.
Advantage for the ophthalmologist or the oculist: this eye health professional will also examine your eyes in order to detect possible diseases and, if necessary, to establish the corresponding diagnosis. If necessary, it can intervene directly.
The advantage of the optician or optometrist: you only have to make one trip, because you can normally pass a spontaneous eye exam without prior appointment and then buy your new glasses in the same establishment. Therefore, choosing this option can save you time and effort.
Caution: Do not come to have your eyes examined unless you are in good health, that is to say if you do not suffer from an acute illness, and if you do not take medication, as this could modify the results. .
If it is not possible for you to stop taking your medication because you have a chronic illness, tell your optician or your eye doctor so that he can assess the possible differences in the results. The visual capacity can also undergo changes during pregnancy, so it is advisable to make an appointment for a visual examination after the pregnancy and the weaning of the baby.
First of all, we would like to emphasize that today, only 10% of the graduated crystals used in optics are made up of glass itself, that is to say of mineral (silicate). 90 % graduated glasses are made of plastic (usually CR 39 or polycarbonate). These so-called organic crystals have the advantage of being lighter, but also more durable and more resistant to impact and sunlight.
To make your choice easier, we tell you what the main types of crystals are, what thicknesses exist and what different treatments can be applied to them.
Which crystals are best for me? which reduction index is suitable for my prescription? what are the most suitable treatments for my crystals? Organic crystals vs mineral crystals
Which crystals are best for me?
Basically, we make the difference between monofocal and multifocal crystals:
As the name suggests, monofocal lenses correct only one type of visual defect: myopia, hyperopia or, in some cases, presbyopia. These lenses are used in monofocal glasses.
Today, among multifocal lenses, progressive and professional lenses stand out above all else. Bifocal or trifocal crystals are no longer commonly used, so we will not describe them in detail.
- Progressive crystals: Progressive lenses are generally used by people over 40 years of age. Opticians recommend them when the need arises to alternate several different glasses in order to see clearly at different distances (from near and far), or to constantly put on and take off glasses. Progressive crystals, in addition to correcting myopia or presbyopia, also compensate for presbyopia, while allowing clear vision in the far, medium and near planes, with a smooth transition (without breaks or "jumps") between the upper visual field, intended for distant distances, passing through the center for intermediate distances, and down for near objects. Modern progressive lenses are very discreet, relegating the use of bifocal and trifocal lenses to the past: Professional glasses are mainly incorporated in glasses intended for workplaces that require prolonged use of the computer. Like progressive crystals, professional crystals also have different fields of vision with a smooth transition between them. The difference consists in the absence of the field intended for the distant plan, giving more space to the intermediary and the near. These glasses are perfect for working at the office or at the computer, and even for DIY, because they optimize the remote vision of interior spaces.
Caution: Due to the limitation of these glasses to close distances, they should never be used for driving.
What is the appropriate reduction rate for my graduation?
The more diopters, the thicker the corrective lenses of your glasses. Therefore, if you have a high prescription, the glasses in your glasses can reach considerable weight, which in the long run could cause some discomfort or discomfort.
This is where the reduction index comes in, which makes it possible to reduce the thickness of the crystals: crystals with a high reduction index will be thinner than standard crystals with a reduction index of 1.5 with an identical graduation.
The reduction index
The reduction index refers to the refractive power of the light of the crystal, hence its name "refractive index". A higher index means greater refraction of light, so a crystal with a high reduction index requires a smaller thickness to obtain the same result as a crystal with a lower index.
The refractive power of the crystal also varies depending on the material: it can be between 1.5 and 1.74 in organic crystals and between 1.5 and 1.9 in mineral crystals. Due to the higher density of mineral crystals, they will in principle be finer than organic crystals. However, they are also heavier and more fragile.
You will find below the properties of the different refractive indices:
- Thickness in negative crystals
- Thickness of positive crystals
Reduction index 1.5
Our standard crystals are used to correct slight visual defects up to ± 2.00 diopters. They are not suitable for major graduations.
Reduction index 1.6
For graduations between ± 2 and ± 4 diopters, crystals with a reduction index of 1.6 are used. These crystals are significantly finer and their weight is about 20 % lighter than standard crystals.
Reduction index 1.67
Very fine crystals with a reduction index of 1.67. So fine that even high graduations of ± 4 to ± 6 diopters will go unnoticed, while the weight of the crystals will be reduced, since they are about 40 % lighter than standard crystals.
Reduction index 1.74
NEW - Super fine crystals with a reduction rate of 1.74, up to 60% thinner and lighter than standard crystals. They can be used to correct high graduations of ± 6 diopters.
Aspherical crystals help improve image quality and reduce optical aberrations at the edges. In addition, the aspherical surface makes the eyes more natural, since they do not deform their size, which in the case of conventional positive lenses would be increased and in the case of conventional negative lenses, reduced. All our crystals with a reduction index of 1.67 are aspherical by default.
Early detection of a visual abnormality in children can prevent, or at least alleviate, a more serious problem in adulthood. The challenge is to detect a possible visual defect in children, because young children cannot inform their parents of the problem themselves, because they have never had a different vision. In this article you will find more information about this. We provide advice and recommendations to detect visual problems in children and when to buy a pair of children's glasses.
When is it necessary for my child to wear glasses, how can I detect a vision defect in children? Preventive visit to the ophthalmologist Buying glasses for children: points to consider Periodic checks
When should my child wear glasses?
Seeing is like walking: all children get there, but it is an ability that must develop over time. Between two and four months, babies can already recognize facial structures such as the mouth and eyes.
Curiosities: It is completely normal that the young children are farsighted. This is not a problem, because the elasticity of the eye can compensate for this. Normally, as the eye matures, farsightedness disappears.
A child will need prescription glasses in the following cases:
- Hyperopia / considerable difference between the graduation of the two eyes
- myopia, which is often not detected before the child enters school
- Astigmatism, which prevents the child from having a clear vision.
- Strabismus, deviation from the alignment of one eye (strabismus)
One or other of these visual defects must be corrected with yes or no in order to avoid the appearance of a possible amblyopia, which can cause visual problems for life due to a lack of adequate visual stimulation. .
How to detect visual defects in children?
Several indicators can alert us to the existence of visual defects in children:
Babies and young childrenChildren in kindergarten and schoolChildren in kindergarten and schoolCloud cloudConstant eye rubbing Eyes, inflammation, tears or yellowing of the eyes Eyes Very short distance between eyes and books or screens Strabismus Defects at sunset or weak light Eyelid diseases Eye dysfunctions Balance defects Baby does not have eye contact
In older children, there are indicators such as headache, fatigue, insecurity in taking objects, reading and writing difficulties or attention difficulties.
Prevention is better than cure, so if you are suspicious, it is advisable to take the child to the ophthalmologist for a preventive examination.
Preventive visit to the ophthalmologist
It is advisable to go to all the preventive pediatric examinations envisaged by the health system.
Tip 1: The schedule of pediatric examinations of the public health system provides for a series of preventive inspections, covered by social security, which also include the examination of the child's visual capacity.
Since these examinations do not make it possible to detect all possible visual defects, it is advisable to consult an ophthalmologist specialized in childhood ophthalmology, at the latest when the child is between two and four years old, or even during his first year life if their parents or siblings suffer from an eye disease, including severe visual defects or strabismus.
Tip 2: Many eye diseases are inherited and can be corrected if detected early.
Recommendation for all parents: Before school, have your children's visual acuity tested. In this way, you can make sure that they have no visual defects that prevent them from paying attention in class or that their graduation has not worsened.
Buying children's glasses: things to remember
When purchasing baby glasses, there are a number of special requirements that should be taken into account. Ask an expert for advice to help you find the material and type of frame that is right for you, as custom designs are often used for this purpose.
For children's or adolescents' glasses, the requirements do not differ significantly from those that apply to adult glasses. The glasses should be adjusted to the size and shape of the head, providing firm support and precise centering of the glasses, being robust and as light as possible. Of course, the design of the glasses is also an important point, because we want children to feel comfortable wearing them.
Tip 3: Some autonomous communities offer help with the purchase of prescription glasses for children.
The psychological aspect plays an important role, because starting to use glasses implies a huge change for the little ones and sometimes it requires a period of adaptation, among other things by reducing their visual field. That’s why it helps if your kids like their glasses. Let them choose their preferred model and reinforce them with a positive attitude towards their use. Because what is clear is that the more your child likes his glasses, the more he will be motivated to wear them.
Here are some recommendations to facilitate the purchase of children's glasses.
The most important criterion at this stage is the strength of the material, both in the frame and in the panes. Children do not stop to think about the possible fragility of their glasses. As far as glasses are concerned, organic glasses are preferable because they are shock resistant and do not break when the glasses fall. It is advisable to use flexible supports made of paste or titanium.
The frame should not be too small or too large, as this is the only way to achieve precise centering of the lenses. The size of the window frame should match that of the eye sockets and the frame should not be wider than the child's face. In addition, it should not cause pressure on the cheekbones or behind the ears. A small frame causes less discomfort than a very large one. However, the crystals must always be large enough to allow the child to have an adequate field of vision.
The centering of the glasses is an aspect directly linked to the frame, because only a correct adjustment of the frame can guarantee precise centering, especially when the child is moving and running. Poorly centered glasses can cause double vision, headaches, or adverse reactions like narrowing of the eyes.
Rods and pads
The ears and the bridge of the nose are the points where the pressure points often seem annoying when wearing glasses. It is therefore advisable to ensure that the nose has a large bearing surface so that the weight of the glasses is uniformly distributed, as is the case with an anatomical paste nose which adapts to the shape of the nose and can be shaped individually. It is advisable to bet on long and flexible rods which can be folded behind the ears so that the glasses do not fall when the child is moving. In addition, it is recommended to invest in sturdy hinges, preferably spring-loaded, as they are stronger and more durable.
The choice of crystals
Organic crystals are stronger and lighter than glass minerals. In order not to scratch easily, it is essential that they have a hardening treatment. If the child needs glasses with a very high prescription, it is advisable to choose high quality glasses that reduce the effect of the enlargement or optical reduction of the eyes, so that they have a more natural appearance. . By choosing small, high-quality glasses, you also reduce the weight of your glasses. The crystals must be anti-reflective, to avoid reflections of light which could disturb the child.
Tip: Consult your optician to choose the model of glasses that is right for your child. This advice is absolutely essential for finding the right model.
Which crystals are suitable for driving?
Make sure that the lenses of your glasses meet your needs as a driver perfectly. First of all, it is worth mentioning a good super anti-reflection treatment, which reduces the sensation of dazzling caused by irritating reflexes and improves visibility even in low light conditions. In addition, we recommend that you invest in a hardening layer and an anti-fouling treatment so that your glasses do not get dirty and scratch the lenses.
The essential anti-reflection treatment
The headlights of other vehicles can really make driving difficult, especially at night, at sunset or in diffuse lighting conditions. Crystals without anti-reflective treatment would further aggravate the situation, since acting as a mirror would enhance the reflections. The anti-reflective treatment reduces these reflections, prevents glare and offers us a clean and transparent vision. The more effective the anti-reflective treatment on your glasses, the better your visibility behind the wheel.
Polarized glass for added protection
Polarized lenses provide good protection against horizontal light reflections. These crystals filter the light that can be reflected on a wet road or other water surfaces, eliminating much of the reflections that can be found behind the wheel. The result is clear visibility with a high degree of contrast, which helps us to detect oncoming vehicles at all times.
A dose of additional comfort: tinted glass
Certain tinted lenses can facilitate and improve vision while driving. For example, the brown or gray tint improves the visibility of traffic lights, brake lights and other light signals, thereby increasing our reaction speed. The gradient glass is ideal for keeping an eye on the dashboard of the car while driving.
More intense contrast with the blue light filter
A blue light filter not only protects your eyes from the high energy blue light of the visible spectrum, emitted mainly by mobile phones and computer screens, but also increases the perception of contrasts and minimizes glare, for example by driving in the evening or at night, and protects your eyes every day so that they always give the best results. This has a positive effect when driving a vehicle, as driving requires a high level of concentration, which can sometimes cause too much eye strain.
Important: The shades of red and blue are not suitable because they reduce the perception of contrast. In total, the crystals should not have a hue greater than 25%, as we will also want to use them for driving at night. To lead to daylight, they must not exceed 85% in shade.
Driving with progressive lenses: points to consider
In principle, it can be said that there is no difference between driving with monofocal glasses and driving with progressive lenses. However, progressive lenses are generally not prescribed before a certain age. This is why, after several years of wearing monofocal glasses, the eyes need a period of adaptation to get used to the new progressive lenses. Of course, even when it comes to driving.
Tip: Take the time to get used to wearing your new progressive glasses. However, if your vision does not improve after a few weeks, you should return to the optician, as the frame may not be perfectly adjusted in this case.
At the wheel, it is mainly the mirrors that can cause some difficulties. The exterior mirror is located in the lower part of the windows, and therefore in the area dedicated to close-up. This is why, to see the exterior mirrors, you must always tilt your head a little forward. In addition, you will have to turn your head in the direction of the mirror in question in order to see it clearly, since the refractive power of the progressive crystals is weaker at the edges.
For the interior mirror, you will probably have to find the sharpest point for a while until you can clearly focus on it. Even if you only take a second, it will be strange at first and can therefore be a little difficult until you get used to it.
Driving glasses: other important issues
In principle, glasses perfect for driving consist of a frame with special lenses, optimized specifically for circulation. The main requirements are as follows: facilitate night vision, in the rain and on wet roads, minimize light reflections, compensate for sudden changes in lighting conditions (for example at the entrance or exit of tunnel) and ensure perfectly clear vision when a quick glance is taken at the mirrors or the dashboard before cropping on the road.
This is also the reason why the field of vision of glasses optimized for driving is a little wider than that of conventional glasses: to give us a clear and uniform vision, so that we do not miss a single detail, even if we briefly look at the mirror. They also improve contrast and perception of distance.
By the way, this type of glasses you can also wear perfectly in your day to day, so you do not need to buy several different. When you select the lenses with which the glasses will be graduated, simply indicate that you want to use them also for driving, so that your optician can recommend the optimal glasses and treatments. There are different types of lenses and treatments, both for monofocal lenses and for progressive lenses.
Many people know more or less what we are talking about when we tell them that we are myopic or farsighted. Not if we're talking about astigmatism. Behind this term hides a fairly common visual defect that affects a large part of the population. If you want to know how this ametropia appears and how it can be corrected, you have come to the right place.
What is astigmatism?
So that we can see clearly, the cornea and the crystalline lens of a healthy eye "gather" the rays of light, directing them towards the interior of the eye so that they converge exactly towards the retina. Most people know this effect because a magnifying glass works the same way. However, this is only true if the surface of the cornea is symmetrical, like that of a perfect sphere. On the other hand, if the cornea had, for example, a different radius on the X axis than on the Y axis, that is to say an oval shape, then we speak of astigmatism. In this case, the light rays passing through the lens no longer converge at the same point on the retina, forming so-called focal lines instead of a single focal point. Therefore, a round point will be perceived as distorted and elongated. Unlike myopia and hyperopia, astigmatism not only affects near and far vision, but also causes distortion of vision at any distance.
Besides: in reality, the cornea is not always guilty of astigmatism, although this defect is generally directly associated with a deformation of the cornea. An asymmetry in the curvature of the lens has the same effect. In this case, we would speak of lenticular astigmatism, a much less common phenomenon.
What causes astigmatism?
In general, astigmatism has genetic causes. As with nearsightedness or farsightedness, people with mild astigmatism will hardly notice it, because the brain can compensate for the problem, to some extent, automatically. Consequently, estimates of the prevalence of this visual anomaly vary between 20 and 40 % of the population. Other factors that can cause marked asymmetry of the cornea include eye disease as well as surgery.
How to deal with this refractive error?
Fortunately, correcting astigmatism is not a problem. In addition, it is possible to correct astigmatism alone or with other ametropia, which is generally the most common case. To compensate for the irregular shape of the cornea, prescription glasses or contact lenses are used, the surface of which is asymmetrically curved (so-called toric lenses). Graduated crystals for astigmatic people are called cylindrical and are recognized by the abbreviation "CYL" or "CIL" in the ophthalmological prescription. This name is due to the fact that, if you look closely, its surface looks curved around a cylinder. The values necessary for the graduation of cylindrical crystals include the diopters of astigmatism, as well as the position of its axis in degrees, which refers to the position of the cylindrical axis in the crystals.
The simultaneous correction of several visual problems, such as the combination of myopia, presbyopia and astigmatism, is not difficult today either. Modern progressive lenses can be graduated using a cylinder and can therefore also compensate for astigmatism. At the same time, they offer the comfort of traditional progressive lenses and allow clear vision at any distance.
Farsightedness, like myopia, is a very common visual problem. It is estimated that around 20 % of the Spanish population is farsighted. Many do not even know it because, unlike other visual problems, early presbyopia does not always show obvious typical symptoms.
What are the right lenses for people with farsightedness?
Hyperopia can be corrected with so-called positive crystals, because their power is measured in positive diopters. These are converging and convex lenses, thicker in the center than at the edges, which concentrate the light to compensate for the insufficient refractive power of the lens of the eye. Like all graduated crystals, they can be composed of organic or mineral materials. For people with high graduations, there are glasses with higher refractive indices, which do not become so thick and can be installed even in thin and light frames without the lenses having a coarse appearance.
It is also possible to use contact lenses with the appropriate prescription. Both options offer specific advantages. A pair of glasses is distinguished above all by its ease of use. In addition, today prescription glasses have become a fashion accessory and are perfect for emphasizing our individual style. The advantages of contact lenses become obvious during sports: unlike glasses, they are not likely to be damaged by sudden movements, for example. Many athletes also appreciate the wider field of vision they offer, as well as the ability to combine contact lenses with non-prescription sports glasses.
Note: In our guide you will find more information on choosing the right glass.
What is hypermetropia ?
Hyperopia is a visual defect characterized by an insufficient refractive power of the lens or cornea of the eye, or by a too short eyeball. Therefore, when the eye muscles are relaxed, the focal point in which light, even that reflected by distant objects, converges, is located behind the retina of the eye. In close objects, this effect is even more pronounced. The lens is relatively flexible thanks to the ciliary muscles, the eyes can compensate to a certain extent for this defect, so that many affected people are hardly aware of it. The problem usually becomes evident between the ages of 30 and 40 as the ability of the eye to adapt decreases. Result: at the beginning, it is the close objects which lose their sharpness, while the most distant continue to be perceived normally, that is to say that it is more difficult for us to see close up. Over time, we will also become increasingly difficult to see clearly from a distance. This hyperopia is called hyperopia or hyperopia. Not to be confused with tired eyesight, also known as presbyopia.
How does hyperopia arise and when should it be corrected?
Farsightedness is generally hereditary and congenital. In principle, it is not considered a disease. It often needs to be corrected when the first discomfort comes from concentrating on nearby objects, such as headaches or eye pain, as well as constant blinking while reading or working at the computer.
An important exception concerns children with very marked hyperopia or whose prescription varies considerably from one eye to another. In this case, a correction is absolutely necessary, otherwise secondary problems, such as strabismus, can arise. For this reason, if you have suspicions, it is always advisable to consult an ophthalmologist.
Visual problems are very common and the most common is myopia, which often appears from childhood. Fortunately, this refractive error can be easily corrected. So far so good…. But what happens to us if we are shortsighted? Here you will find the answer to this interesting ametropia, as well as lots of information on its correction.
What is myopia ?
To see clearly, the focal point of the lens of the eye, that is to say the point of convergence of light rays, must be exactly on the retina, at the back of the eye. In order for this to work when looking at objects at varying distances, the lens (the lens of the eye) can be accommodated to some extent, thereby changing its refractive power. When the lens has excessive refractive power or when the eyeball is too long, the light rays reflected by distant objects converge before reaching the retina, so that they will be blurred, no matter how hard we see. However, myopia still works perfectly, which means that myopic people have trouble seeing well from far away.
The maximum distance at which objects can still be focused correctly depends on the degree of myopia of each person. Mild myopia can even go unnoticed on a daily basis. Even so, it can be problematic at school or driving, so it makes sense that children take a visual acuity test before school. To obtain a driving license, it is compulsory to do so anyway.
What are the causes of myopia?
There are two different types of myopia. Simple myopia affects about a quarter of the population of industrialized countries. The exact causes are not entirely clear. It is suspected that genetic factors and modern lifestyles may play an important role. These include, for example, intensive reading and the use of computers and mobile phones. Simple myopia is not considered a disease and is generally not very serious. This is not the case with its less common variant, so-called pathological myopia, which is typically hereditary. It causes more serious visual problems, which also tend to worsen with age.
How can you correct myopia?
Some prescription glasses for short-sighted people have so-called negative lenses, because their power in diopters is represented by the negative sign (for example, “- 4 diopters”). They are divergent lenses because they separate the light rays passing through them, thus compensating for the excessive refractive index of the lens of the eye. There are organic (plastic) and mineral (glass) crystals. Whatever their material, negative crystals are easily recognizable thanks to their concave shape: they are thicker on the edges than in the center. The thicker the myopia, the greater the difference in thickness. In order to be able to incorporate high quality negative crystals in an elegant setting, there are mineral and organic materials with high refractive indices. These allow the crystals to be thinner and achieve the same effect.
Alternatively, or in addition, contact lenses with negative diopters can also be used. Today, eyewear is considered a very elegant fashion accessory, so the decision will depend less on a question of personal image, but rather on functional aspects, for example, the advantages offered by contact lenses. in sports practice. Unlike glasses, they cannot slide out of the nose, no matter how difficult the exercise. In addition, they can also be worn under any type of sports glasses.
Glass cleaning guide
A word of advice: Do not use tissues to clean your glasses, because they retain the particles of dirt which can cause microscopic scratches when they are rubbed against the glass, which wears it over time and makes it lose its brightness and its refractive power.
Even small scratches, invisible to the naked eye, can irritate the eyes.
Glass cleaners, concentrated detergents and similar products damage the glass coating and the surface of the frame.
Do not use detergents or nourishing soaps which, while taking care of your skin, contain oily balms which leave residual marks on the crystals.
Wet wipes and dirty chamois
Most wipes contain alcohol, which can damage the organic lenses of your glasses, so you shouldn't use them.
Do not put too much pressure on the glasses when cleaning them to avoid deforming the frame and damaging the surface of the glasses.
Washing machine and dishwasher
Never use it! Detergents and salts from these machines can scratch your crystals. In addition, the frame can deform under the effect of excessive heat.
Always keep your glasses in their case. It is best to wrap the glasses in their microfiber cloth before putting them away. Of course, the chamois must be clean to prevent the glasses from coming into contact with sand or dirt particles.
The case itself is the best place to store chamois, as this prevents the accumulation of dust in the case. In case of dirt, you can wash the microfiber cloth with a detergent for delicate clothes, without using fabric softener and at a maximum temperature of 40 degrees.
When you cannot store your glasses in their case, always place them on the rods so that the glasses do not come into contact with a hard surface which could damage them. Of course, you should avoid storing your glasses directly in the pocket of pants or a jacket, for example.
You now have the most important elements for your new glasses: you have obtained your prescription, chosen your frame and the corresponding lenses. Only the last step is missing: the manufacture or assembly of the glasses by a qualified optician. It is a process that requires a lot of skill, because each mask must adapt to the needs of its new owner.
Production takes place step by step:
First of all, quality control is carried out to determine the condition of the graduated glasses: are they damaged, do they have scratches, bubbles or impurities? For added security, the correct crystal graduation is checked again. In general, graduated glasses are produced individually in a standard basic unpolished format.
For this reason, it is necessary to cut the glasses: during chamfering, their edges are polished until they have the shape that corresponds to the data obtained during centering of the frame, so that they fit perfectly . In this process, opticians work as precisely as possible because every millimeter counts. For this, advanced technologies are used.
The incorporation of the lenses depends on the material of the frame and is always done by hand. In the case of metal frames, the lenses are usually fixed with a screw, while the paste frames are heated to be flexible so that the lenses can be installed.
That's it: your glasses are ready to be sent directly to you or to the optician where you ordered them.
A word of advice: If when you receive our glasses, the frame does not perfectly fit your face, any optician can adjust the pads and the rods so that you can wear it comfortably.
It may take a few days for your eyes to get used to the new glasses, especially if this is your first time wearing progressive glasses.
In the background, each of the layers that make up the lenses of your glasses can be thought of as a basic lens treatment. The number of treatments applied depends on each person's needs and preferences, although there are treatments recommended for any user, regardless of the type of glasses you wear. Let yourself be convinced.
1. The basic crystal
It is sort of the raw material of the lens. The basic crystal can be:
- Concave: with the center thinner than the edges, to correct myopia.
- Convex: With the center thicker than the edges, to correct hyperopia.
It forms the base of the graduated glass, on which different treatments will be applied later.
The positive effects of the sun are indisputable, but so are the negative effects of ultraviolet (UV) rays. As for the eyes, they can damage the iris and darken the lens. Avoid UV rays especially in summer. It is therefore particularly important that the tinted lenses of sunglasses have a good UV filter. We can tell the difference between different UV protection categories:
- Category 0 = transmission factor of 88 %, insufficient UV protection
- Category 1 = transmission factor of 20 %, UV protection suitable for central Europe
- Category 2 = transmission factor of 6.5 %, good UV protection
- Category 3 = transmission factor 0 %, UV protection 100 % maximum (for high mountains and at sea)
Due to the harmful effects of UV radiation, transparent lenses with UV protection for prescription glasses are now also available on the market. These glasses do not need to be tinted, as UV rays are invisible, but they can of course be tinted if the user wishes.
Polarizing lenses absorb almost all reflections and offer optimal protection against glare, whatever the level of light. In this case, the treatment consists in applying a special polarizing layer on the lens of the glasses.
These lenses automatically darken, adapt to sunlight and brighten under more unfavorable lighting conditions. In addition to the comfort of this effect, photochromic lenses also offer protection against UV rays. You will find more information about these crystals in a specific article in this guide.
2. Extra hardened treatment
Our glasses and glasses must be extremely robust to meet the challenges we face every day. For example, when we play sports or when we treat them without the care they deserve in the hustle and bustle of everyday life, not to mention children's glasses. For this reason, organic crystals, which are relatively soft, are generally treated with a hardening layer. Besides, the thinner the glass, the greater the hardening layer. Thanks to it, organic crystals become more resistant and durable.
3. Super anti-reflection treatment
It is another treatment that has become a fundamental part of any graduated crystal. There are different degrees of anti-reflection treatments, from basic to super anti-reflection. Today, however, only the super anti-glare is used, which reduces glare by 98 %. Its purpose is precisely to avoid irritation of the eyes caused by light reflexes.
This processing works on the principle of optical interference. To do this, different layers are sprayed on the glass, one on top of the other, so that certain light waves cannot pass through the glass, thus preventing reflections. The more layers sprayed on the glass, the more effective the anti-reflective treatment.
Advantages: Anti-reflective lenses provide clear vision without unpleasant reflections. In addition, from the outside, your eyes will look more natural and the people in front of you will not be reflected in your crystals. While driving and in front of your computer screen, the anti-reflective coating allows for more relaxed vision and greater concentration.
4. Anti-fouling treatment
The anti-fouling layer is an extremely practical treatment, sometimes also called a “clean layer”. It is a coating made possible thanks to the latest advances in nanotechnology, which completely smoothes the glass surface, preventing dirt and dust from adhering to it. The Lotus effect also has similar properties. Thanks to its antistatic effect, the crystals repel water and grease.
What are the advantages of photochromic crystals?
Even if we don't realize it, the frequent changes in light strain our eyes, which adapt to a wide variety of light conditions every day. One of the most important advantages of photochromic lenses is that they automatically protect the eyes from glare when they darken.
In addition, they offer optimal protection against UVA and UVB rays from the sun, but also against blue-violet light emitted by many screens and electronic devices. These characteristics allow a better perception of contrasts and help us not to tire our eyes too much, so that at the end of the day our eyes will be much less tired.
Note: When driving, you should always wear conventional sunglasses. Since the car windshield absorbs much of the ultraviolet radiation, the photochromic glasses will not receive enough natural light to darken.
How do photochromic crystals work?
Photochromic crystals are covered with a layer of molecules that react to natural light, activating a chemical reaction on their surface. For this, in organic crystals, indolino spironaftoxacins are generally used, which darken the crystal when it grows in size when receiving sunlight, unfolding like the petals of a flower. This process is activated by the energy of UV rays. When UV exposure decreases, the crystals rinse again. Thus, these lenses combine the advantages of conventional glasses with those of sunglasses.
Photochromic lenses filter up to 85 % of light and may take 60 to 90 seconds to darken. The reverse process is a little longer: it can take between a minute and a half and two minutes before the glass has reached a partial transparency. Depending on the type of glass and the glass manufacturer, it can take up to ten minutes to become completely transparent.
In addition, temperature also plays a key role in this process: the lower the temperature, the faster the glass darkens and the longer it takes to rinse again.
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- Why is it important to do a periodic review?
- Go to the ophthalmologist or optician?
- Eye exam explained step by step
- Window centering and frame adjustment
- At the ophthalmologist or at the optician?
- Which crystals are best for me?
- What is the appropriate reduction rate for my graduation?
- The reduction index
- When should my child wear glasses?
- How to detect visual defects in children?
- Preventive visit to the ophthalmologist
- Buying children's glasses: things to remember
- Which crystals are suitable for driving?
- Driving with progressive lenses: points to consider
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