Equipment for the production of contact lenses for eyes. Manufacturing of hard contact lenses

Modern rigid contact lenses are made from gas-permeable materials containing silicone, which makes them more flexible than earlier gas-permeable PMMA lenses, as well as being permeable. large number oxygen through the lens to the cornea. This allows rigid gas permeable contact lenses to provide a significantly more comfortable and healthier wearing experience compared to their gas-permeable predecessors, which are no longer commonly prescribed.

Advantages hard contact lenses

Compared to soft contact lenses rigid gas-permeable contact lenses provide significant better vision, since due to their higher rigidity they retain their shape during blinking and therefore the image remains stable at all times. Soft contact lenses crumple slightly when closing the eyelids, which leads to the fact that the picture seems to “float”.

With proper care, hard gas permeable contact lenses can be worn for at least 1 year due to the fact that they are resistant to almost all types of deposits, since their surface is less porous and easier to clean than the surface of soft contact lenses. They are also more difficult to damage or tear than soft contact lenses.

Rigid contact lenses are made taking into account the individual parameters of the patient's cornea, so their shape is more congruent with the shape of the cornea, that is, it fits it perfectly. The mobility of a hard contact lens is 2-4 times greater than the mobility of a soft one. All this ensures a much better exchange of tear fluid in the sublens space and a much greater supply of oxygen to the cornea, and therefore a less frequent development of hypoxic (associated with a lack of oxygen) complications.

In addition, there are situations when soft contact lenses cannot be offered to the patient in principle and hard contact lenses are the only possible means of vision correction for such people.

Hard contact lenses for high degrees of myopia (nearsightedness) and hypermetropia (farsightedness)

The range of optical power (diopters) of most modern soft contact lenses does not exceed -12.00 D - +8.00 D. And the properties of the materials of those contact lenses that will provide high-quality vision at higher degrees of myopia and farsightedness ( up to 20.00 D), unfortunately, leave much to be desired, so wearing such soft contact lenses often leads to the development of complications. In addition, you need to understand that the higher the degree of myopia, the thicker the soft contact lens along the periphery, and the higher the degree of hyperopia, the thicker it is in the center, which, taking into account the tighter fit compared to hard contact lenses again leads to the development of hypoxic (associated with a lack of oxygen supply through a thick lens) complications when wearing soft contact lenses.
What can these unfortunate people do? Or be content with incomplete and insufficient correction, depriving yourself of the opportunity to see and enjoy well full life, or use soft contact lenses, wearing which will almost inevitably lead to the development of complications. They, of course, can be offered spectacle correction, but glasses with such diopters will have very pronounced peripheral aberrations (distortions), which will make their use very uncomfortable, and their aesthetic properties will be very questionable (spectacle lenses will be thick, and the eyes behind them will be will be either very large with high degrees of farsightedness, or very small with myopia).
But in reality there is a choice! Rigid contact lenses typically have more wide range refractions ( -25.00 D to +25.00 D), and due to the use of materials with high coefficient refractions remain quite thin even at large diopters. In addition, due to better exchange of tear fluid in the sublens space, they ensure adequate oxygen supply to the cornea.

Rigid contact lenses for high astigmatism

Optical power The cylinder of most toric soft contact lenses does not exceed 2.25 D, some of them have restrictions on the axes of the cylinder, which in some cases makes it impossible to provide quality vision to patients who need it.
Rigid contact lenses, due to a fundamentally different system for correcting astigmatism, make it possible to cope with this problem.

Hard contact lenses for presbyopia (age-related farsightedness)

To correct vision in patients over 40 years of age, in addition to glasses, special multifocal soft contact lenses can be used. But all multifocal soft lenses presented on the domestic market have limitations on optical power for distance ( -10.00 D to +6.00 D) and cannot be offered to patients with astigmatism, since toric multifocal soft contacts are not represented in our country in principle.
Hard contact lenses do not have such restrictions: they can be selected for patients over 40 years of age, both with high degrees of farsightedness and myopia, and for those who have astigmatism.

Selection of hard contact lenses

So what exactly is selection of hard contact lenses?
This procedure is carried out on the basis of examination data using an autorefractometer and visometry. After these studies are completed, lenses from a diagnostic kit are installed on the patient’s eyes, the “fit” of which is assessed after 20 minutes by a doctor during a slit-lamp examination and fluorescein staining. The visual acuity obtained with hard contact lenses is also checked. As a rule, in most cases, successful fitting requires trying on 1 to 3 diagnostic hard contact lenses in each eye. This is necessary in order to achieve complete perfect fit inner surface rigid contact lens surface of the cornea, and thereby ensure its correct centering, sufficient mobility and, as a result, ensure comfortable and healthy wearing.

After completing all the described procedures, having decided on the parameters of the hard contact lenses the patient needs, we can already send an order for their individual production.

Manufacturing of rigid contact lenses

Wanting to offer our patients the best, we collaborate with the German company Wöhlk, which has 60 years of experience in producing premium hard contact lenses. The level of this company is evidenced by the fact that such an optical giant with a worldwide reputation and excellent reputation as Carl Zeiss entrusted it with the production of its soft contact lenses. The Wöhlk plant is located in northern Germany in the town of Schenkirchen, and every product produced there is subject to the most stringent controls and has a guarantee of the highest quality. All orders for hard contact lenses are manufactured using high-precision equipment according to the individual parameters of each individual patient. The waiting time for such an order, including delivery from Germany, is usually 14 working days.

Training and dynamic observation

If you want to wear hard contact lenses, it is important to understand that they not only provide high quality vision, but also impose significant responsibility. Wearing such lenses requires more frequent visits to the ophthalmologist for a dynamic assessment of the condition of the eyes than when using glasses and soft contact lenses. Yes, and lenses require certain procedures when caring for them. An important factor in the safety of wearing them is compliance with hygiene rules, including when putting them on and taking them off.
That is why in our vision correction offices, at the final stage when issuing hard contact lenses, we inform our patients in detail about how to wear and care for them correctly.
An indispensable condition is to purchase a starter kit, which includes a set of all necessary funds and accessories for the first time.
When purchasing a starter kit patient education independent skills of putting on and removing hard contact lenses, if they are choosing lenses for the first time, as well as dynamic observation by an ophthalmologist during the entire period of wearing the lenses, for free.

Production and sale of contact lenses – profitable business. It is not surprising that competition in this market is very high, especially among Western companies. In other countries, as in Russia, the main positions in the contact correction market are occupied by four main companies.

Slightly less than half of the market belongs to Johnson & Johnson. The shares of CIBA Vision Cooper Vision products account for 18% of the total volume. Bausch&Lomb takes fourth place with 12%. All other companies, including domestic manufacturers, account for the remaining 4%. Among the most popular means Contact lens care experts call: Opti - Free RepleniSH (about 23%), Renu MultiPlus (22%) and Free Express (17%). The remaining 38% are products from other brands.

As a result of the study foreign markets contact vision correction products conducted by the independent research and consulting company Eurolens Research, the following portrait of the average lens user emerges. The average age of the consumer is 30 years. Moreover, in countries with a developed market for the consumption of contact correction products middle age turns out to be higher (in Australia – 34.7, in the UK – 35.1, in Canada – 32.4).

In countries where this market is in its infancy and development, this figure is somewhat lower. Thus, in Russia the average age of an active contact lens user is 26.4 years. This is explained by the fact that young people, as a rule, care more about convenience and their appearance, they tend to experiment and try everything new, unlike older people who are more conservative.

In addition, according to statistics, women are much more likely than men to wear contact lenses. Moreover, if in other countries the percentage is 67% and 37%, respectively, then in Russia more than 83% of the fair sex refuse glasses in favor of lenses. As a result, in our country the demand for colored contact lenses is especially high (about 14% of the total volume of soft contact lenses sold). Until recently, hydrogel contact lenses occupied the first place in sales. However, every year the popularity of daily contact lenses is increasing, which, however, still lags behind in sales volumes.

In developed countries, the situation is exactly the opposite: most Europeans prefer to use more harmless and comfortable contact lenses for daily wear, and lenses with a replacement period of 3-6 months have not been sold abroad for a long time. Unfortunately, Russian consumers prefer to save on their health by choosing lenses that can be changed less often.

Also, soft toric lenses are not in great demand in the domestic market. Experts are confident that the future belongs to silicone hydrogel contact lenses, which have a high moisture content and allow more oxygen to pass through to the cornea than common hydrogel lenses.

The production of contact lenses is a high-tech process that requires special equipment, qualified workers, and strict quality control. But there is no need for large areas: the production itself and the warehouse finished products can be located in the same room. There are several ways to make the most common soft contact lenses: centrifugal forming, turning, casting and a combined method.

When producing contact lenses using the centrifugal molding method, special molds are used in which the starting material, a liquid polymer, is placed. Under the influence of ultraviolet radiation and high temperature, the polymer hardens. During this process, the mold is constantly rotating: its speed of movement, ambient temperature, and the amount of polymer directly affect the final product. After the polymer has hardened, the lens is removed from the mold and undergoes a hydration process.

This type of production is less expensive compared to others, and at the same time allows you to produce quality lenses with good stability and reproducibility of specified parameters. However, this method is not suitable for the production of lenses with a toric surface.

The production of contact lenses using the turning method is more complex and labor-intensive, therefore the cost of a product produced in this way will be higher. As a rule, lenses are produced by turning by individual orders or in small batches. The lens is literally machined from dense blanks of polymerized material.

Production consists of several stages. First, the workpiece is processed on a lathe, during which a lens with a thickness of 0.1 mm is obtained. Then it is polished, hydrated (placed in a special solution, after removal from which it becomes soft), chemical disinfection and tinted. Once the lens passes quality control, it is sterilized, packaged and labeled. Because each lens is turned almost by hand (albeit under computer control), it is thicker than lenses made by other methods and, as a result, has less oxygen permeability. Most Russian companies produce traditional lenses this way.

Large Western companies that produce lenses for routine replacement and daily wear in large volumes use a casting method that can significantly reduce costs during large-scale production. In this case, a base is first created in the form of a metal matrix with predetermined parameters. It is needed for making plastic replica molds.

The liquid polymer is then poured into bottom part form and is closed by its upper component. The mold is irradiated with ultraviolet light, under the influence of which the polymer hardens. After which the used form is deleted. The remaining steps are similar to those used in other production methods: hydration, chemical disinfection, toning, quality control, sterilization, packaging and labeling. The resulting lenses are very thin - their thickness is about 0.03 - 0.05 mm.

The last, combined method, as the name implies, includes all methods of making lenses: first, using centrifugal formation, a lens with a smooth surface is produced, which then undergoes additional processing by turning.

The main domestic manufacturers of contact vision correction products are Optikon (Moscow), Optimedservice (Ufa), Concor (Vologda), Octopus (Samara). They work on modern computerized production lines and use imported material, produce lenses and produce lens care products (although more often solutions for lens care are made to order abroad under their own brand).

Their main advantages: low cost products, strict quality control, wide choice large diopter lenses (from -26 to +26). Lenses of such refractions are not available in the range of Western companies. However, domestic products cannot yet withstand competition with foreign brands. Most of it consists regular lenses, while all over the world they have long been supplanted daily lenses and scheduled replacement lenses.

The profitability of enterprises that produce lenses using the turning method is 10-12%. The profitability of production using injection molding technology reaches 100%. However, the costs of equipment in the latter case are many times higher, and they can only be recouped through large sales volumes. Meanwhile, sales volumes of the largest Russian manufacturers, which have their own representative offices in various Russian regions, amount to no more than 300 thousand lenses per year. To promote sales, lens manufacturers actively cooperate with specialists in contact vision correction, offering them training, bonus programs, preferential conditions, etc.

Experts recommend Russian companies who are running a business producing contact lenses, pay attention to the niche special lenses– toric and bifocal, which are more expensive than usual. The demand for them, although not high, is still there, but there are practically no offers.

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We work with various types hard contact lenses (Wohlk, Boston, Rose-K, SoClear, etc.).

Our specialists can select exactly those contact lenses that will provide the highest quality of vision in your case.

What are rigid gas permeable contact lenses?

It sounds kind of scary.

Soft contact lenses – the name is much more pleasant. However, you will be surprised that hard contact lenses allow oxygen to reach the cornea at a much faster rate. more than regular soft contact lenses and even the newest silicone hydrogel lenses, which are now the safest and most advanced soft contact lenses. And this indicator is almost the most important for those who constantly wear contact lenses.

Besides this hard contact lenses provide higher clarity of vision, are more resistant to deposits, and are much cheaper than soft contact lenses, since one pair of lenses is designed to be worn for up to 1-2 years.

Why then doesn't everyone wear hard contact lenses?

First - You will need adaptation, i.e. necessary certain time to get used to wearing hard contact lenses. This time is very individual from 3-4 days to 2-3 weeks. And it doesn't hurt.

Secondly, to successfully wear hard lenses you need to wear them every day(with a few exceptions), because if you don't wear them for a while, then you will need some time to adapt again

Hard contact lenses - an excellent option for those people who cannot achieve ideal vision with soft contact lenses. This is possible in several cases:

those people who have higher demands on the quality of vision, for example shooters, operating surgeons, pilots, jewelers, etc.;
those. who has astigmatism, especially of a high degree, and due to this, 100% vision is not achieved in soft contact lenses;
patients with keratoconus (irregular cornea shape);
patients who need correction after previously performed surgical operations on the cornea ( laser operations to eliminate myopia, corneal transplantation, lens removal).
patients who have problems wearing soft contact lenses (corneal vascularization, recurrent eye inflammation, excessive accumulation of deposits)

If you already use hard contact lenses and would like to purchase a new set, please note:

You can order or purchase hard lenses from us if the lenses were selected in our office. Hard lenses cannot be ordered in absentia, using a prescription for glasses/soft lenses or the parameters of old ones hard lenses. To purchase lenses in our office, you need to make an appointment, take a break from wearing your lenses for several days, and bring with you all the data that you have (from examination data to old glasses and contact lenses).

You can sign up for a consultation and selection of hard contact lenses...
Ask your doctor a question about hard lenses online right now... or by phone. 730-52-60, 730-53-35.

Contact lenses are small clear lenses that are placed directly on the iris of the eye. The main purpose of such lenses is to correct refractive errors (increase visual acuity). The exception is decorative and cosmetic contact lenses, which are mainly used as decoration, although they often perform a double function - vision correction and eye decoration.

According to statistics, at least 125 million people use contact lenses, which is approximately 2% of the entire population. More than 40% of contact lens users are young people aged 12-25 years.

People use contact lenses for optical or functional reasons. Lenses, compared to glasses, generally provide better peripheral vision and do not fog up in extreme weather (rain, snow, humidity). This makes them more suitable for outdoor use, especially when active activities sports. There are also a number ophthalmological diseases(for example, aniseikoria, etc.) the correction of which is more effective when wearing contact lenses rather than glasses.

The main optical difference between contact lenses and glasses is the absence of distance between the eye and the optical glass, which ensures distortion - the visibility of objects without distortion.

A little history

Incredibly, this is the first time the idea has been used contact correction Leonardo da Vinci came back in 1508. While sorting through the archive of his works, scientists came across drawings of a ball filled with water, through which a person with poor vision could look at surrounding objects. In addition, his notes contain diagrams of lenses that can easily be called a prototype of modern ones.

In 1637, the work of Rene Descartes was published, with drawings of an optical device. The device was a glass tube filled with water, to the end of which a magnifying glass was attached, and the other end was placed against the eye. This device was subsequently modified by the English physicist Thomas Young, who used a shorter tube, thereby compensating for the shortcomings of refraction.

The German physiologist Adolf Fick described a glass lens in 1888, with optical power. A made an optical lens and introduced its use in medical practice ophthalmologist August Müller in 1889. His lens became a new correction method and the topic of his doctoral dissertation.

Until the second half of the last century, the material used for making contact lenses was organic glass (PMMA). These lenses were hard and uncomfortable to wear, causing the sensation of a foreign body in the eye. In addition, they absolutely did not allow oxygen to reach the cornea, which is necessary for its normal functioning. In 1960, the Czech scientist Otto Wichterle synthesized new look polymer (HEMA) from which soft contact lenses were first made. HEMA polymer had the ability to absorb water (up to 38%), after which it became elastic and soft. Not more than 10 years ago, a new generation of contact lenses was created - silicone hydrogel. These soft lenses provide even greater comfort and absolute safety when worn.

Today, I use a lot of classifications for contact lenses: according to the material of manufacture, according to the frequency of replacement (the period after which the lenses are replaced with new ones), according to the mode of wearing them (daytime, extended, continuous, etc.), according to design (spherical, toric, multifocal ), according to the degree of transparency/color (transparent, colored, decorative). But they are all divided into two main groups: soft lenses and hard ones.

Soft contact lenses are preferred by up to 90% of all contact lens users. In turn, such contact lenses are divided into hydrogel and silicone hydrogel.

Hard contact lenses are usually used for correction complex cases vision pathologies (for example, with high degrees of astigmatism and keratoconus), in addition, only they are used in orthokeratology - a relatively new direction of ophthalmology. The new generation of hard lenses not only perfectly holds their shape, which makes them more convenient to use, but also provide a high degree of oxygen transmission to the cornea. These lenses are called rigid gas permeable contact lenses.

Colored contact lenses are designed to radically change the color of the iris, while tinted contact lenses are designed to enhance or change the shade of the existing color. Such lenses can be made with diopters, in which case, in addition to changing eye color, they will improve vision. But in most cases, such lenses are produced “zero” - without diopters and are necessary only for a cosmetic effect.

On the color perception of visible objects, colored and tint lenses do not affect, since they are transparent in the center. True, such lenses are not recommended for use in low light conditions (in twilight and darkness), because the human pupil dilates when there is insufficient lighting and then the colored part of the lens will fall into the visibility zone, which will cause vision difficulties. Such lenses should not be worn while driving or engaging in activities requiring high attention.

Designation of contact lens parameters

All contact lenses have the following characteristics (parameters), which must be indicated on the sales packaging:

Material of manufacture.
Lens diameter (D, BCR).
Radius of curvature (ВС, ВСR).
Optical power of the lens.
Thickness of the center of the lens.
Cylinder axes.
Construction (design).
Optimal mode wearing.
Replacement frequency.

Long-term wear lenses (6-12 months) are usually packaged in special bottles. For lenses that need to be replaced more frequently, blisters are used as packaging.

Wearing mode - the period of time that lenses can safely remain on the eyes:

Daytime (put on in the morning, remove before going to bed at night).
Long-lasting (worn for 7 days, not removed at night).
Flexible (worn for 1-2 days, not removed at night).
Continuous (worn continuously for up to 30 days, do not remove at night). A similar regime is possible for some types of silicone hydrogel lenses and requires consultation with an ophthalmologist.

Nightwear (should be put on before bed and taken off in the morning). Orthokeratological lenses after which the patient sees perfectly all day without additional funds corrections.

Design (construction) of contact lenses

Spherical. Their purpose is to correct myopia and hypermetropia.
Toric - for the correction of myopia and hypermetropia with accompanying astigmatism.
Multifocal - for the correction of presbyopia.

Improving the quality of vision in any type of lens is achieved by their aspherical design. Various polymers are used in the manufacture of contact lenses. The main part consists of hydrogel and silicone hydrogel materials, of which there are about 10 types.

The properties of a contact lens are mainly determined by the material it is made of. The main characteristics of contact lens material are considered to be: its water content and oxygen permeability.

Low water content (<50%).
Average water content (50%).
High water content (>50%).

The more water a hydrogel lens contains, the more oxygen the cornea will receive, which has a positive effect on eye health. But the increase percentage water in the lens makes it softer, making it more difficult to handle. Therefore, the water content in hydrogel lenses usually does not exceed 70%.

The main indicator for silicone hydrogel lenses is the oxygen transmission coefficient (Dk/t), which is in no way related to the water content. In this case:

Dk is the oxygen permeability for the lens material.
t is the thickness at the center of the lens.

The Dk/t indicator for hydrogel lenses is usually in the range of 20-30 units. For daytime wear, this is enough, but to keep the lenses on your eyes at night, much higher values are needed. Silicone hydrogel lenses have a Dk/t value of approximately 70-170 units.

The diameter of the contact lens and its radius of curvature affect how the lens “sits” in the eye. As a rule, lenses are produced with one or two radii of curvature. If a contact lens does not fit well due to a discrepancy between the radius of its curvature and the shape of the cornea, serious discomfort occurs, which can lead to refusal to wear lenses.

The main optical indicators of a contact lens are: sphere power (with a plus or minus sign, in diopters), cylinder power (indicated in diopters), localization of the cylinder axis (indicated in degrees). The last two parameters are necessary only for toric lenses that correct astigmatism.

The parameters of contact lens indicators for one and the other eye of a patient may be different.

Terms of use

If you select incorrect contact lenses and their improper landing, interference and discomfort are inevitable. To eliminate it, you should contact an ophthalmologist. If the radius of curvature of the lens is larger than necessary, they seem to “float” in the eye, and if it is smaller, on the contrary, they “get stuck” and this part of the cornea is no longer supplied with oxygen. In both cases, such lenses should be replaced with lenses with the desired radius of curvature. Properly selected lenses are characterized by slight movement when blinking (fitting without rigid fixation), but most of the time they are in a central place. At long-term wearing lenses with a smaller radius of curvature often cause corneal hypoxia without oxygen, which increases the risk of infectious processes, since when sufficient quantity Infectious agents cannot survive in oxygen.

You can swim in lenses only if you use special sealed goggles or a swimming mask. You cannot wear lenses to the sauna or bathhouse. If unboiled water gets on them (shower, swimming pool), they need to be replaced with fresh pair. Contact lenses are designed to be worn at any ambient temperature, including extreme heat and frost.

Contact lens wearers are required to undergo annual eye examinations with an ophthalmologist.

Possible complications

There are some complications associated with contact lens use, including:

Infectious diseases (keratoconjunctivitis sicca, etc.).
Allergic reactions.
Hypoxia reactions with oxygen deficiency for the cornea.
Mechanical damage cornea.

Neglecting the rules of hygiene or care of lenses (it is necessary to treat them with a special cleaning solution) can lead to infection of the mucous membrane. Violation of the terms of wearing lenses for planned replacement or wearing lenses with low rate oxygen permeability, possible growth of blood vessels into the cornea of the eye (neovascularization) and other complications, often irreversible. They become a contraindication to further use of contact lenses.

Manufacturing of contact lenses

The production of contact lenses is carried out in several ways: centrifugal molding, casting, turning. There are also methods that combine all of the above techniques.

Turning. With it, “dry” polymerized workpieces are processed on a lathe. Lenses with complex geometries are produced through the use of computer control programs. After grinding, the lenses are polished and saturated with water (hydrated) to the required parameters, then they undergo chemical cleaning. The final stage production includes lens tinting, sterilization, inspection, packaging and labeling.
Casting. This is a less labor-intensive method than turning. First, a special metal matrix mold is made for the lens. Then plastic copy molds are cast using a matrix and liquid polymer is poured into them, which hardens under the influence of ultraviolet light. The finished lenses are polished, hydrated, tinted, sterilized and packaged.
Centrifugal molding is the oldest method of producing contact lenses. In this process, a liquid polymer is injected into a mold rotating at a certain speed and exposed to high temperature and/or UV radiation, which is necessary for its hardening. Then the workpiece is removed from the mold, saturated with water and subjected to processing identical to the turning method.

One example of a combined method for producing contact lenses is the reverse process. With it, the centrifugal molding method is used to obtain the front surface of the lens, and turning is carried out to obtain the rear surface.

The world's largest manufacturers of contact lenses are recognized as: Johnson & Johnson (product "Acuvue"), Neo Vision, Bausch & Lomb, etc.

You can find out more about individual types of contact lenses in the relevant sections:

For the manufacture of contact lenses latest generation Highly sensitive soft materials that are particularly smooth are used. In order to facilitate manipulations with such lenses, maintaining the integrity and sterility of the contact surface, special tweezers are produced. They are used to remove lenses from the container; tweezers help when removing contact lenses and immersing them in a solution poured into the container’s tray, as well as during the process of rinsing them with special disinfectants.

Everyone who uses contact lenses knows about the need to keep them perfectly clean, because the health of their own eyes and the quality of vision depend on this. In this regard, to avoid infection eye infections, at the same time as purchasing a new pair of lenses, it is worth buying a container for storing them, as well as a special solution that in the best possible way Suitable for both the eyes themselves and the optics.

New contact lenses from Baush + Lomb, called SofLens Daily Disposable, are affordable option daily lenses. They do not require daily maintenance and provide clear vision at any time and in any lighting thanks to improved optics.

Adria Color colored contact lenses from the Korean company Interojo are in great demand and are extremely popular. These are lenses that allow you to correct various degrees myopia and, as well as change tone, color and even appearance the eye completely. Used in the production of colored lenses innovative technology coloring. Thanks to it, the dye is, as it were, locked inside the lens material, which increases resistance to fading and makes wearing products of this brand absolutely safe.

Daily contact lenses are shining example convenience, comfort and safety. Another name for them is “daily replacement lenses”, because they are designed to make your eyes rested and bright every new day. What distinguishes them from the already familiar scheduled replacement lenses is that they must be opened every morning. new packaging, and every evening - dispose of lenses that have become unusable throughout the day. Actually, this is what makes silicone hydrogel daily lenses so reliable and comfortable.

Contact lenses were invented over a hundred years ago. For a long time, only hard lenses were produced, but in 1960 soft contact lenses were invented and received widespread. Unlike hard lenses, they are comfortable to wear and do not take a long time to get used to. Today, about 90% of users prefer soft lenses made from elastic, gas-permeable materials. When properly selected, they provide the owner with comfort, safety and ideal vision correction. Modern hard lenses are also gas-permeable, but due to difficulties in getting used to them, they are usually used only in isolated, particularly difficult cases.

Lens making methods

The production of modern contact lenses is based on several technologies:
- turning (turning);
- casting;
- centrifugal molding;
- combined methods that combine elements of the above methods, for example, the reverse reverse process.

Turning

The turning method is used for the manufacture of both soft and hard ones. Their production is carried out on the same equipment, but has some differences. Disc-shaped blanks are processed on special lathes; this process is almost completely automated. A computer program monitors compliance with all parameters.

At the first stage, a diamond-tipped cutter forms the inner curve of the lens, then polishes the surface to make it absolutely smooth. Next, the outer surface that will be in contact with the eyelid is processed, and the workpiece is given the required diameter. The outer surface and edges of the lens are also carefully polished. At the end of this stage, its thickness and other parameters are measured using a very precise instrument.

The difference between the production of soft lenses is that after the turning stage they are subjected to hydration - immersed in saline solution with optimal pH factor. Hydrogel and silicone hydrogel, from which soft lenses are made, absorb moisture well and swell, increasing to the right size. During hydration, the hard workpiece acquires the missing softness and elasticity. At the end, the finished product is tested for compliance with optical and geometric parameters. Before sale, lenses are cleaned, packaged and labeled.

Casting

Casting begins with the manufacture of a matrix with specified parameters that correspond to the characteristics of the future lens. Form copies are made from the matrix from plastic, which can be either disposable or reusable. The lower half is filled with liquid polymer and covered top part, forming an internal space shaped like a lens. The workpiece is irradiated with ultraviolet light, under the influence of which the polymer hardens. The lens is then hydrated, measured, cleaned and packaged.

Centrifugal molding

Centrifugal molding technology was developed by the Czech inventor of soft lenses, Otto Wichterle. A special mold with a concave bottom and cylindrical walls is filled required quantity monomer. During its rotation on special equipment, the composition spreads over the inner surface and hardens. The shape and thickness of the resulting lens depend on the amount of polymerization mixture and the speed of rotation of the mold.

Reverse reverse process

The reverse reverse process successfully combines the two technologies described above. First, the convex side of the lens is obtained by centrifugal molding, then processed by turning inner part. The resulting lens acquires the advantages of each method - smoothness outer surface and edges are combined with excellent functional qualities obtained by turning.