What solutions are there for correcting visual conditions?

Glasses: their history

A pair of glasses is a complete unit: a frame supporting two lenses. In other words, an association between aesthetics influenced by fashion and very high technology. To arrive at this formula, which appears so simple, it took seven centuries! 

The correction — undoubtedly still approximate — of hyperopia and presbyopia dates from the late 13th century. The specialists of the time cut lenses from beryl: a precious stone made of aluminium silicate and beryllium. Later, this material would give rise to the word "bernicles" (an early term for spectacles). These beryl lenses were shaped like two small moons (lunettes) connected by frames made of horn held together by a pin, between the eyebrows. 

Originally from Venice, this invention evolved very slowly up to the present day. Three centuries were needed to learn how to correct myopia; five centuries to conceive the principle of spectacle arms, and six to develop bifocal lenses.

In the 17th century, glasses were a mark of a certain intellectualism or a sign of belonging to the nobility! Nowadays, practically 30 million glasses-wearing French people — 58% women and 42% men — live with this accessory in a far more relaxed and less elitist way! Glasses have become an everyday accessory, accessible to all.

Spectacle frames: look and comfort

For pleasure, they are chosen first. Most people walk into an optician's with an idea of shape, colour, model and brand in mind: sportswear, fashion designer, perfumer or jeweller. 

Needing to take into account our visual defect or our activity, the optician is there to help us reconcile everything. Consciously or not, three concerns inspire our choices: 

• the desire to match our frames to our style;
• making them "fit" our activity;
• and to our budget.

Metal-rimmed frames evoking seriousness, butterfly-shaped frames set with rhinestones favoured by eccentric American women… These accessories truly give a face its character and personality. Like clothing, spectacle frames can define an era. 

For several years now, glasses have been all the rage. A phenomenon that would have been unthinkable in the past: the editors of women's magazines put them on the noses of models, children and adults alike, for the duration of a photo shoot! One would love to own as many pairs as outfits and change them like lipstick or a tie… Unfortunately, our finances do not always allow for it. 

Sports glasses or glasses for everyday use — our requirements vary. In the first case, one chooses flexible temples that wrap around the ears, absorb and protect against impact; frames that float if lost in the water while windsurfing… And if one drives a great deal, wider, wraparound frames providing a broad panoramic view are preferable. 

Whatever our aspirations, there is something for every taste, every age, and every budget.

Clean glasses

Looking after your glasses is very important. Indeed, this optical device is a precious object that requires a minimum of care. When glasses are not worn permanently, it is necessary to store them in a rigid case to prevent the frame from becoming misshapen. Similarly, it is best not to place them lens-side down if you want to keep them intact for a long time.

It is also ideal to wash them occasionally with warm water and soap, drying them with a lint-free cotton cloth. A quiet little revolution has transformed the lives of wearers of anti-reflective lenses, which used to attract more dirt. This is the anti-smudge, anti-stain, anti-mark, oleophobic, hydrophobic treatment… It makes it easy to wipe away fingerprints on the lenses, or dust — all those flaws that impair vision through anti-reflective lenses, which are perfectly transparent. 

If, finally, your glasses are truly "grimy", particularly between the frame and the lenses, entrust them to us for a thorough cleaning in an ultrasonic bath. 

Contact lenses: the discreet charm

Many famous names, and some lesser-known ones, punctuate the history of contact lenses. Leonardo da Vinci was the first, in 1508, to describe the principle.

The French philosopher and mathematician René Descartes (1596–1650) devised the calculations, but the very first experiments date from the late 19th century. At the time, the forerunner of the lens was a glass cup which, by retaining tears on the eye, corrected visual defects. The idea was sound, but the object was unbearable.

One must wait until 1948 to see the first rigid plexiglass lenses appear, covering only the iris. This is a first revolution. The second comes in 1965, when Otto Wichterlé, a chemist from Prague, invents soft lenses.

Since then, there have been no major upheavals, yet significant advances have continued to follow one another for these little-known centenarians, whether rigid or soft. 

Over the years, contact optics specialists have become increasingly adept at meeting the demands of the cornea.

They therefore design increasingly biocompatible lenses — lenses capable of letting the cornea breathe, allowing its cells to renew themselves and maintaining the integrity of the tear film.

Thanks to these continually improving advances, contact lenses today satisfy not only aesthetic concerns but also visual quality, regardless of the defect — since even those with presbyopia can, at last, be corrected by wearing lenses!

The mystery of lenses

How do contact lenses manage to compensate for visual defects, and by what mystery do they not fall off under the action of the eyelids or when one tilts one's head?

Whatever the visual defect, the principle of correction remains the same. A lens calculated to correct that defect is placed on the cornea. The contact between the lens and the eye is not direct, as a film of tears intervenes.

It serves a dual function: ensuring the cornea's metabolic needs are met and keeping the lenses on the eyes despite movement. Specialists call this phenomenon "capillary force".

30 million contact lens wearers

Why choose contact lenses when glasses can correct all visual defects? 

The primary motivation is, most often, aesthetic. Many women — though men are increasingly joining them — prefer their "natural" face. Having chosen this option, everyone then discovers and appreciates the other advantages of lenses: a quality of vision superior to that achieved with glasses, and an unlimited field of vision.

Worldwide, 30 million people wear contact lenses, of whom 18 million are in the United States and 1.2 million in France. The latter figure is currently rising, thanks to technical advances made to these products and the arrival of men in this market — some of them taking their first steps into the world of lenses in order to practise a sport without worrying about misting, rain or sunlight… The trend for "gliding sports" — skiing, windsurfing, surfing… — Has greatly contributed to the phenomenon, as glasses are hardly compatible with waves and wind combined with intense sunshine. 

According to a SOFRES survey, 96% of contact lens wearers say they are very satisfied. So there is every reason to take the plunge! There are two main families of contact lenses: rigid (chosen by 20% of wearers) and soft (chosen by 80%). Today, they correct all visual defects, including astigmatism and presbyopia. 

Contact lenses can be worn at almost any age. In infants, once the mother has learned how to handle them, they can be a better means than glasses for preventing amblyopia or strabismus.

For children, it is best to wait until they are old enough to manage their lenses on their own: around 13–15 years old for boys and 10–12 years old for girls, provided they are careful and motivated by an aesthetic concern. When accepted and ideally requested, lenses are a good method for pre-adolescents with significant visual defects and keen young athletes. 

Contact lens correction must meet three requirements:

• respect for the metabolism of the eyes: their need to breathe;
• effective optical correction;
• a comfort so great that you forget they are there.

Eye oxygenation

Like the skin, the cornea needs to breathe. Air contains 20% oxygen. The presence of a contact lens slightly deprives the eye of a portion of this element.

Studies have shown that, to remain healthy, the cornea must receive at least the equivalent of 12% oxygen when the eyes are open and 18% when they are closed during sleep.

The amount of oxygen reaching the cornea depends on the thickness of the lenses, the type of material from which they are made, and their diameter. Some lenses are so thin that they measure less than a tenth of a millimetre in thickness. And depending on whether they are rigid or soft, they use different means to breathe.

Rigid lenses, sometimes called flexible lenses, are manufactured from a polymer material — a plastic containing silicone and fluorine: two substances that, by virtue of their permeability, contribute to transporting oxygen, thus making the lenses very comfortable. 

Soft lenses are made from a material called hydrogel, which has the particular property of absorbing a large quantity of water. The higher their water content, the more oxygen-permeable they are. This is why specialists frequently speak of lenses with greater or lesser high water content. Today, some lenses contain around 80% water.

As for the diameter of the lenses, it should be as small as possible. Rigid lenses are smaller than the iris: they measure between 8 and 10 mm in diameter. Soft lenses are slightly larger: between 12 and 16 mm.

Rigid or soft contact lenses: making the right choice

Let us be clear: the comfort of rigid lenses is never as good as that of soft ones. Several weeks are needed to completely forget their presence, and they cannot be kept in when swimming.

They also demand a high level of technical expertise from fitting specialists, who must measure the curvature radii of your cornea before trying different types of lenses to find the right "fit". 

Rigid lenses are, however, easier to handle than one might think, and very simple to maintain. Other advantages: they deliver an incomparable quality of vision and alert the wearer to the slightest ophthalmic problem by becoming uncomfortable. Finally, they correct astigmatism very effectively and have a lifespan of over two years. 

Soft lenses are very comfortable from the very first fitting: adaptation is immediate. This quality means that, if desired, they can be worn alternately with glasses. They can also be kept in when swimming, or even for sleeping.

Their handling and maintenance require, on the other hand, greater care, and they must be replaced after no more than 18 months. Beyond that, they lose their optical quality. Soft lenses also require that one pay close attention to eye health.

Lenses for every eye

Lenses allow all visual defects to be corrected, including presbyopia. 

Myopia

88% of contact lens wearers are myopic. Myopia is indeed the ideal indication. All the more so if the myopia is between -1 and -5 dioptres. In that case, everything is possible: both rigid lenses and soft lenses with greater or lesser water content. In both cases, the result will be better than with glasses. Beyond -5 dioptres, it is better to opt for high water content soft lenses. 

Hyperopia

More and more people with hyperopia are wearing contact lenses. This condition is the opposite of myopia. Like myopia, it can be corrected with both rigid and soft lenses. However, due to their optical power, these lenses are thicker. For good tolerance by the eye, they require highly oxygen-permeable materials, particularly soft lenses with high water content. 

Astigmatism

Rigid lenses are the best solution for correcting astigmatism, especially when it is caused by the shape of the cornea — which accounts for the majority of cases. The tears contained in the space between the irregularly shaped cornea and the lens automatically compensate for the astigmatism. One may also choose specific soft lenses, known as toric lenses. 

Presbyopia

A new solution has recently emerged with progressive lenses. They allow clear images to be perceived at all distances. What is more, the adaptation period is very short, and they can be worn alternately with glasses without any discomfort. This immediate comfort represents something of a dream for those in the early stages of presbyopia: making presbyopia discreet. 

This innovation is the result of a great deal of work:

mastery of highly complex optical calculations;

the ability to manufacture lenses corresponding to these calculations;

the means to verify the impeccable quality of the optical corrections achieved.

There are also other "lens solutions" for correcting presbyopia, but they do not allow vision at all distances. It is therefore worth trying the different options to find the most satisfactory one:

the so-called "monovision" technique: one lens for distance vision on the dominant eye and, on the other, a lens for near vision. Disadvantage: binocular vision is imperfect. This was, however, until recently, the most widespread solution. It is said that all US presidents since Kennedy have dealt with this natural ageing of the eye in this way, with complete discretion;

bifocal lenses. There are two types. The more recent ones are called diffractive: they superimpose two images on the retina — one for distance, one for near — and the brain selects the one it needs. The others, which are older, are known as "alternating vision" lenses. They require meticulous fitting by a specialist, with no guarantee of success.

Solar lenses

Contact lens wearers are no longer simply vain individuals — women, mainly — who refuse to wear glasses.

An increasing number of sports enthusiasts are joining this ever-more-accessible club. Lenses are now worn, among other activities, for playing tennis but also for skiing, windsurfing and sailing. And since these are outdoor sports, some lenses today incorporate sun protection.

Direct sun glare and reflected light, salt water spray, wind exposure… Nothing is spared. Result: satisfaction among all users — both those with one or more associated visual defects and those who require no correction at all. 

Some solar lenses incorporate both a filter that protects against ultraviolet rays and a tinted anti-glare filter. So exercise caution with others, because — it has been proven — prolonged exposure to excessively strong sunlight can cause retinal damage. Not to mention the accelerated ageing of the lens, which can lead to premature cataracts.

Comfort: lenses that are gentle on the eye

Comfort in contact lenses is linked to several elements: the material, the manufacture of the lenses, and that "three-way partnership" formed by tears, lenses and their care. Lens manufacturing uses precision optics technology. There are three ways to produce lenses: by machining and polishing materials, by centrifugation, or by casting in a closed mould. Whatever the technology, the goal is to achieve, on the one hand, the exact shape required by the cornea and the type of correction desired, and on the other, a comfortable edge. 

One must also have "good tears" to wear lenses, since they "float" on the tear film. However, the quality and quantity of tears vary from one individual to another. In some people, they are too sparse and insufficient to lubricate the lenses, resulting in discomfort linked to dry eyes.

This can also result from a temporary disorder: illness, medication, cosmetic eyelid surgery… Everything will return to normal once the cause has disappeared. Even a simple flight can affect lens wear, as the cabin air is dry. It is better to remove lenses for a long flight, especially if you plan to sleep. In other cases, be aware that "artificial tears" exist — eye drops based on saline solution.

Rigorous hygiene

The quality of your vision, the lifespan of your contact lenses and their comfort all depend on how well they are maintained. Rest assured: it is becoming less and less demanding. Why maintain your lenses? First, to remove the components of tears that may have deposited on them: salt, proteins, fats, pollution from our environment… If these deposits are not removed, they eventually form a film or indelible stains on the lenses and risk making them unusable. Secondly, to prepare them for the following day's wear.