Production of contact lenses. Manufacture of hard contact lenses

ZhGKL are made strictly according to custom order, taking into account all the parameters of the patient, since they require a more accurate match inner surface corneal surface lenses.

Wholesale price from 2500 rubles

ALWAYS MADE TO INDIVIDUAL ORDER

without prepayment - for regular customers

30% prepayment - for new clients (Moscow, Kaluga, Obninsk + all other regions of Russia)

full prepayment - for residents of other countries

CONVENTIONAL MANUFACTURING (GROUP): lenses are sent for manufacturing upon ordering (from 30 lenses), without additional margin.

Order formation is usually carried out from 3 weeks to 2 months (check the stage with the operator). Then the lenses are made within about 2-3 weeks + 3-10 days for delivery from the manufacturer. That is, the order comes approximately 1-3 months after registration.

URGENT PRODUCTION (CUSTOMIZED) : Your order is sent for production individually, right on the day of registration, without any expectations, and also arrives individually, without waiting for other orders. That is, the order comes approximately 2-4 weeks after registration.

When ordering by large wholesale is free

When ordering by average wholesale + 600 rubles

When ordering by small wholesale + 999 rubles

When ordering at retail + 1500 rubles

Material: F2 made by CONTAMAC

Manufacturing method: turning

Packing: vial with 1 pcs

Rigid lenses for astigmatism correction:

- inner radius from 7.9 to 9.0, step 0.05

-toricity T3-T12

- eccentricity from 0.2 to 1.2, step 0.1

Rigid lenses for the correction of keratoconus:

- inner radius from 4.8 to 7.2, step 0.05

- inner optical zone diameter from 5.5 to 6.5, step 0.1

- eccentricity from 1.0 to 2.8, step 0.2

To place an order for rigid gas permeable lenses You need to specify in " Additional Information"lens diameter (mm), optical zone inner diameter (mm), number of internal radii (chamfers), including optical zone, value of each radius (mm), width of each radius (mm), feed value for each radius (mm), refraction lenses (dptr).

For example, the lens diameter is 9.6 mm, the diameter of the optical zone is internal 7.3 mm, the number of internal radii is 4, the refraction is -6.5 diopters,

magnitude of each radius, width of each radius, feed
8,69 0,45 0,000
8,11 0,35 0,680
7,82 0,35 1,016
7,60 7,30 1,260

For keratoconus, you need to specify in the "Additional Information" the lens diameter (mm), the inner diameter of the optical zone (mm), the number of internal radii (bevels), including the optical zone, the value of each radius (mm), the width of each radius (mm), the value feed for each radius (mm), lens refraction (dptr).

For example, the lens diameter is 9.5mm, the inner diameter of the optical zone is 6.0mm, the number of inner radii is 8, the refraction is -10.5 diopters,

magnitude of each radius, width of each radius, feed

9,50 0,156 0,000

8,50 0,241 1,155

7,50 0,244 2,337

7,20 0,282 2,695

7,00 0,231 2,930

6,80 0,248 3,162

6,30 0,240 3,738

If necessary, a copy of the certificate is issued along with the order.

These lenses are available at wholesale prices!

3250 rub for 1 lens when ordering Concor products in excess of 5,000 rubles at small wholesale prices (small wholesale)

2900 rub for 1 lens when ordering Concor products in excess of 10,000 rubles at average wholesale prices (average wholesale)

30-11-2011, 12:33

Description

In specialized laboratories of the country for the manufacture contact lenses both domestic and imported equipment is used.

The set of technological equipment includes: precision lathes for preliminary processing (facing, preliminary rounding) of workpieces; spherical lathes for processing the inner and outer surfaces of lenses (Fig. 73, 74); polishing machines for removing roughness and improving the cleanliness of the spherical surfaces of lenses (Fig. 75); special machines for polishing the edge of the lens and manufacturing tooling.

The machines are equipped with special devices and fixtures, which include: a centering device, sets of mandrels and satellites to hold contact lens blanks during their processing, a set of parts for the manufacture of polishers.

As a cutting tool for processing the concave, convex and edge surfaces of the lenses, diamond cutters of a special profile are used.

The composition of the technological equipment of the laboratory should also include: a heating cabinet for annealing blanks, an electric stove with a thermostat for sticking and centering blanks on mandrels, an ultrasonic bath for washing lenses and a magnetic stirrer for carrying out the process of hydration of soft contact lenses.

When processing the surfaces of contact lenses, the following technological materials are used:

Compositions for the manufacture of mass polishing;

polishing suspensions;

Adhesive materials used to secure and center lens blanks during their turning;

Polishing cloth.

In the late seventies and eighties, our country developed and then put into practice in the laboratories of contact vision correction the following materials:

1. Compounds for casting polishing pads, consisting of fine abrasive powder, paraffin and polyethylene or polypropylene wax.

2. Polishing slurry for polishing hard lenses when using polishing pads, consisting of specially prepared barium carbonate, glycerin and water.

3. Polishing suspension for processing soft lenses, consisting of finely dispersed magnesium oxide and kerosene.

4. Glued material (adhesive composition) for fixing and centering blanks of hard and soft lenses on a flat metal mandrel during lens turning, consisting of modified pine rosin and paraffin.

Manufacturing LCL by turning

Harvesting operations

For the manufacture of rigid corneal contact lenses from PMMA, cylindrical blanks with a diameter of 12.0 to 12.5 mm and a thickness of 4.0 to 5.0 mm are used.

Workpieces of the specified dimensions can be obtained from sheet material using a hollow tool (tubular drills or cutters).

Preparatory work

Before fabrication of LCL from PMMA blanks are annealed in order to relieve internal stresses in the material, leading to a change in the dimensions of the finished lens. To do this, the blanks are placed in a laboratory oven, in which the temperature is set to +130-135°C, where they are kept for at least 8 hours. Temperature fluctuations in the heating cabinet should not exceed ± 5°C. Then, over the next 8-10 hours, the temperature in the cabinet is gradually reduced to room temperature (temperature control is carried out using a thermometer). After cooling, the workpieces are removed from the heating cabinet and the residual stresses in them are checked on a polariscope for the presence of color patterns. Their observation is carried out from the side of the cylindrical generatrix, i.e., perpendicular to the axis of symmetry of the workpiece. In the presence of residual stresses, the annealing process is repeated. After annealing, the blanks go into production.

For polishing lens surfaces prepare lapping polishes. For their manufacture, a special, developed by the domestic industry, polishing material PMP-3 or PMP-1 is used. Polishing material PMP-3 is used for polishing concave surfaces, and PMP-1 - for polishing convex surfaces. The softening temperature of the polishing material is 100-120°C. It is possible to use imported materials.

To make a polishing pad, the material is melted in a porcelain cup to a creamy state. A brass shaping cylinder, put on a special substrate, is placed on a hot electric stove. Before casting, the inner walls of the cylinder are lubricated vaseline oil. The mold is then filled with molten polishing material. After the mold has cooled, the polishing pad is removed from the cylinder. As a rule, several polishers are made at the same time.

The technological process of manufacturing rigid corneal lenses by turning includes the following steps:

Calculation of technological parameters of processing (radii, thicknesses, diameters of the corresponding surfaces, spindle feed of a spherical lathe), based on the standard size of the manufactured lens;

Processing of the overall diameter and edge zone of the lens;

Turning and polishing the concave surface of the lens, its control;

Convex surface turning and polishing, its control;

Polishing of the edge zone of the lens;

Control of the geometric and optical characteristics of the lens.

Turning and polishing a concave surface

With the help of a special glued wax material HB-N, the blank from which the lens will be made is glued and centered on a steel substrate preheated on the tile. After cooling to room temperature, the substrate with the glued workpiece is fixed in the collet of the machine for turning the concave surface of the lens. In some machines, the substrate is not used, and the workpiece itself is fixed in the collet.

Processing begins with turning the workpiece to a given overall diameter of the lens. The diameter value is set using an appropriate dial indicator. Then the turning of the edge zone is performed, and then the concave surface of the lens is machined according to the specified parameters.

Formation of a multi-radius surface carried out in accordance with the calculated parameters specified in the "Tables of technological and control parameters of rigid corneal contact lenses" (1981), or according to photokeratometry. These parameters contain values ​​of zone curvature radii, spindle feed rate, total lens diameter and optical zone diameter. Spindle feed refers to the amount of displacement of the workpiece along its axis in the direction of the axis of the rotary support.

The radius value is set by a dial indicator mounted on the machine's rotary support, and the feed rate is controlled by the spindle feed indicator. Turning starts from a surface with a larger radius. Its processing is carried out in several successive passes with a depth of cut of 0.2 mm for roughing and 0.05 mm for finishing. After that, the spindle feed indicator is set to zero. Then, according to the indicator of the rotary support, the next (smaller) turning radius is set in the table, the cutter is removed from the cutting zone, and the spindle moves to set value filing. Turning of the remaining surfaces is carried out sequentially. Then polishing is done.

First, prepare the polisher for work. To do this, the cast blank of the wax polishing pad is installed on a spherical lathe (for convex surfaces), where the working surface of the polishing pad of the required radius is machined.

Polishing is carried out on a special polishing machine (single or multi-spindle). The surface of the polishing pad is wetted with a polishing slurry. Polishing of the concave surface of the lens begins with the optical zone. The peripheral zone of the lens is polished on special polishing pads moistened with a suspension. Polishing time - from 0.5 to 1 min.

After polishing, the cleanliness of the lens surface is checked using a binocular microscope or magnifying glass with a magnification of 5-10x. The radius of curvature of the optical zone is measured on a radius meter. There should be no scratches, bubbles, gouges on the polished surface; the surface should be smooth, shiny, without rough areas. The radius of the optical zone must correspond to the specified one, within the established tolerance. If after the control it turns out that these requirements are not met, then the processing process is adjusted.

The controlled workpiece is removed from the steel substrate by heating on a tile until the sticker wax softens. After that, it is thoroughly cleaned of wax. Then the thickness gauge (indicator) measures its central thickness. The measured thickness value is taken into account when processing the outer (convex) surface of the lens.

Convex surface turning and polishing

The radius of curvature of a convex surface can be calculated using the following formula:

where: r1 - radius of curvature of the convex surface, mm;
r2 - radius of curvature of the optical zone of the concave surface, mm;
D - vertex refraction of the lens, in diopters; n is the refractive index of the lens material;
t is the thickness in the center of the lens along its axis, mm.
Depending on the given refraction, values ​​of the central thickness from 0.1 to 0.5 mm are recommended.

On a preheated spherical mandrel with a radius corresponding to the radius of the optical zone of the semi-finished product, sticker wax is applied and the semi-finished product is glued from the side of the treated concave surface. Centering is carried out on a special centering device with an accuracy of 0.02-0.04 mm.

After cooling, the mandrel, together with the semi-finished product centered on it, is installed on the landing cone of a spherical lathe for processing a convex surface.

The calculated radius is set by the indicator located on the rotary support. With the help of another indicator mounted on the machine spindle, the thickness of the layer of material removed during processing is determined. The turning of a convex surface is carried out in several passes (similar to the processing of a concave surface) until the specified thickness is reached in the center of the lens.

Polishing of the convex surface is carried out with a special polishing pad moistened with a polishing suspension on a polishing machine (single or multi-spindle). Polishing time - from 2 to 5 minutes (depending on the material).

Cleanliness of the optical surface of the lens controlled with a binocular microscope or magnifying glass immediately after the manufacture of the lens before removing it from the mandrel with a central hole. Optical power is measured on a dioptrimeter. If during the control process it turns out that the processing results are not satisfactory, then the process is adjusted.

After finishing the polishing and checking the optics, the lens is removed from the mandrel and cleaned of adhesive wax.

In the manufacture of the outer surface of the lenses of negative refraction first, a spherical surface is machined with a calculated radius of curvature of the optical zone to a predetermined thickness in the center, and then a lenticular zone is machined with a predetermined edge thickness until mating with the optical zone. The radius of curvature of the lenticular zone is calculated and depends on design features lenses. When calculating, it should be borne in mind that the thickness of the lens along the edge should not exceed 0.2 mm, and the diameter of the optical zone of the outer surface should be at least 7.5 mm.

In the manufacture of the outer surface of lenses of positive refraction, first a spherical surface is machined with a calculated radius to a thickness in the center that exceeds the required one by 0.03 mm. The value of the radius depends on the thickness of the lens in the center and along the edge. Then the lenticular zone is machined, starting from the edge of the workpiece to the calculated diameter of the optical zone outer surface, which is selected 0.4-0.5 mm larger than the diameter of the inner surface. The indicator sets the calculated radius of the optical zone. By turning the cutter mounting support and correspondingly feeding the workpiece, the cutter tip is aligned with the peripheral portion of the optical zone, and the optical zone of the convex surface is processed. Polishing is carried out on a polishing machine using a special polishing pad moistened with a suspension.

The production of FPJCL is carried out according to the same scheme, but less intensive processing modes are used and special formulations for cleaning and polishing these materials.

Fabrication of spherotoric rigid corneal contact lenses

When processing spherotic lenses, the concave spherical surface of the lens is first machined according to the method discussed above, and then, to obtain a toric surface on the periphery, it is processed with a toric tool (usually a grinder and polisher) with specified radii of curvature of the surfaces in two mutually perpendicular planes (Fig. 76) . The number of prepared toric tools depends on the required number of toric surfaces in the flattening (sliding) zone.

For turning a grinder use a special lathe designed for the manufacture of toric tools. In this case, the following rules should be followed:

1. Based on the difference between the radii in the main meridians, the transverse displacement of the spindle relative to the rotary caliper is set. The movement is controlled by a dial indicator. For example, for a toric tool with radii of 8.0/8.5 mm, this value, called the toric difference, will be 0.5 mm.

2. By rotating the rotary support, the tool blank is machined to a depth of not more than 0.05 mm for each pass, until a given radius is obtained, counted from the indicator of the rotary support.

Then the manufactured tool is installed in special device("toric fork") polishing machine.

The substrate with the machined workpiece is rigidly fixed to the leash of the toric fork. Then the leash is installed in the grooves of the fork so that the concave surface of the workpiece rests on the working surface of the toric tool. The pin of the upper spindle of the polishing machine fixes the leash of the toric fork. By vertical movement of the rocking head of the finishing machine, it is necessary to achieve such a position of the workpiece that it moves only in the central part of the toric tool. Grinding is carried out with grinding powder M7 and M3 until a given size of the optical zone is obtained. The grinding time depends on the ratio of the lens radii and the toric difference of the tool. The control of the resulting size of the optical zone is carried out using a measuring magnifier with a magnification of 10x.

Polishing of the toric peripheral zone is carried out on a soft polishing pad with a special polishing paste. The polishing of the optical zone is carried out in the same way as for axisymmetric lenses.

AT recent times Contact lenses are becoming the main means of vision correction.

It is understandable, it is convenient, it provides a full view (and not cut off at the periphery like glasses), they do not need to be corrected (at least not as often as glasses), and generally lead active image life.

Every year lenses become more comfortable and safer, and lenses made only 10 years ago are no match for what is being produced now. But, as with any product of progress, we often do not know how they are made. Let's briefly look at the production methods, but for a better understanding of the technical process, consider the types of existing contact lenses.

Types of contact lenses

In general, contact lenses are divided into two groups (according to the degree of rigidity):

— Soft;
- Rigid.

Rigid contact lenses

Rigid lenses were invented back in 1888 (by the Swiss ophthalmologist Adolf Fick, although the drawings of nothing like this were found by Leonardo da Vinci, but the first “working” prototypes were created by Fick). They are used to correct vision in severe cases (such as astigmatism), as well as orthokeratology (changing the shape of the cornea using a special lens).

Due to the rigidity of its rigidity and shape, the use of these lenses can maximize visual acuity. The main disadvantage is that hard lenses are much more likely than soft lenses to cause eye irritation.

Soft contact lenses

Soft lenses were invented in 1960 by Otto Wichterl and Dragoslav Lim, from Czechoslovakia, and have since been adopted by 90% of contact lens wearers on the planet. They were called "soft" because of the main polymer in their composition. It has an unusual ability to absorb water (up to 38% of its mass) and becomes very soft and elastic when saturated. Further improvement of this polymer took place.

And now soft lenses, subdivided into 3 classes (according to the name of the polymer included in their composition):

- Hydrogel (invented in the 1970s);
- Silicone hydrogel (invented in 1999);
— Water gradient (presented in 2016);

Silicone hydrogel lenses, in addition to their high elasticity, became permeable to oxygen (although it would be more correct to say that the cornea receives the necessary oxygen through the lens fluid, in any case, for soft lenses it was a “breakthrough”).

It does not have its own blood vessels, and the supply of oxygen and nutrients comes from the marginal vasculature(in the case of oxygen, also partly from the environment), which is located along the periphery of the cornea (in the so-called limbus region). And the main problem of lenses is the creation oxygen starvation cornea (scientifically - hypoxia), because the lens just closes the cornea, which does not receive the oxygen it needs in the right way. Hypoxia, on the other hand, stimulates the production of special substances, which, in turn, cause the growth of old and the appearance of new vessels, which will have to compensate for the lack of oxygen (neovascularization).

However, along with new vessels, a dense layer will grow on the cornea. fibrous tissue. It allows the body to heal damage faster. But this fibrous tissue is not transparent. And this can subsequently be manifested by visual interference (an incomprehensible veil before the eyes), deterioration of vision (up to its complete loss). Therefore, doctors recommend that you carefully consider the choice of lenses, and even more so, they advise you not to leave them overnight (this was one of the reasons that spurred the creation of one-day lenses).

In other matters, silicone hydrogel lenses were the first lenses suitable for continuous use for a sufficiently long time (from 7 days to 30 days), due to the slower evaporation of water from the lens surface, and the cornea remains moist longer.

The next step in the development of soft lenses was water-gradient lenses. The researchers set out to combine the high oxygen permeability of the lens with its high moisture content. And they did it. The moisture content of such lenses is 2-3 times higher than the best silicone hydrogel counterparts, and the thickness approached a record 80 micrometers (people who previously wore lenses of other types described that water-gradient lenses were almost not felt).

Methods for making contact lenses

The medical industry is currently using following methods production:

— Centrifugal molding;
— Turning;
— Casting;
— Pressing;

In addition to the above, production techniques that combine some of the above methods are used.

Centrifugal molding

The very first method of manufacturing soft lenses, invented by employees of the Institute of Macromolecular Chemistry in Prague in 1960 (actually, like soft lenses themselves). The method, in other matters, is used in our time. Its essence is simple, it lies in the fact that the required portion of the liquid rotating at a certain speed gradually solidifies.

At the first stage, the liquid monomer is placed in a special mold (which is a cylinder with a concave bottom) which then starts to rotate. Under the influence of centrifugal forces, the liquid monomer spreads inside the mold. Due to the fact that a certain amount of monomer is in the form, it rotates at a certain speed and all this happens at a certain temperature, the monomer solidifies into desired form(polymerizes, or simply turns into a solid polymer). Often faster hardening is achieved by using ultraviolet rays.

The hardened polymer preform is removed from the mold and hydrated. In short, this is the process of saturation with water (absorption) to the desired concentration. The main difficulty of hydration is that after hydration the dimensions of the lenses will be different than initially, therefore, a preliminary calculation of the change in the geometric dimensions of the contact lens is carried out.

This is followed by computer photocontrol (size, shape, polishing quality, etc.), after which the sterilization stage begins. In the process of sterilization, the surface of the lenses is cleaned of all microorganisms that "settled" on the lens during the processing of the original polymer blank. Usually they use all the same ultraviolet radiation (occasionally microwave), but they can also use chemical substances(something based on hydrogen peroxide), well, or the old proven method is to heat the lens to 120 degrees, and wait a bit.

After sterilization, contact lenses will only need to be tinted in the desired color (if necessary), packed and labeled. Ready-made packages with contact lenses are stored in sealed containers at a constant temperature. But this is not all, a certain part of the percentage of all finished lenses is sent to the laboratory for more detailed quality control, and if everything is fine, then the entire batch goes on sale.

Contact lenses obtained by rotation molding have an aspherical back surface (not spherical, but its shape depends mainly on the centrifugal force acting on it during solidification in the mold). Centrifugal molding is the cheapest production method. You can get soft contact lenses with a thin outer edge and not bad performance.

Turning

The method is suitable for the production of both soft and hard lenses (for example, with high optical characteristics).

The solidification of the monomer occurs in forms that are not subject to rotation. After hardening, the blanks are fed to a computer-controlled lathe, where, using specially developed software, it is possible to obtain lenses with a complex geometric shape (for example, with several radii of curvature). This requires maintaining constant environmental conditions (temperature +22 degrees, relative humidity 45%).

After turning, to give the surfaces the necessary smoothness, the lenses are sent for polishing. The lenses are then hydrated, chemically cleaned, quality controlled if tinted is required, and sterilized.

But this method is about 4-5 times more expensive than rotational molding.

Casting

Casting (also called "polymerization in the form") is a less expensive method than turning. At the beginning, a metal mold-matrix is ​​cast (unique for each set of lenses), polymer molds-copies are cast on it, into which the monomer is later poured. It hardens with ultraviolet rays. The resulting solid polymer is sent for polishing, and depending on the required hardness, it is hydrated. And then, similarly to other production methods - tinting, quality control, sterilization, packaging and labeling.

With the invention of silicone hydrogel contact lenses, after molding, plasma polishing began to be used (the lens is placed in a special liquid through which a certain type of electric current is passed) polishing. This allows you to increase the future wettability of the lens.

Currently, molding is used to produce soft contact lenses for scheduled replacement, and about half of disposable (one-day) lenses.

Pressing

Occasionally, a not very popular production method, such as pressing, is used. This method resembles casting, but not a liquid monomer is poured into a mold, but an already hardened polymer “blank” is pressed by specially prepared molds (dry pressing), or a “blank” that has undergone hydration is immediately pressed

mixed methods

The most common of the mixed methods is the so-called. Reverse process III. In it, the front surface of the lens is made by centrifugal molding, and the back - by turning.

All this contributes to the fact that the front surface comes out extremely smooth (and this is the convenience of wearing), and the back (adjacent directly to the cornea) - with any rather complex geometric shape.

As a result, this method produces contact lenses of the most complex shapes. Also a plus is the good oxygen permeability of the lenses. Of the minuses, one should name a longer manufacturing process (in time), and a higher cost of production.

Promising types of contact lenses

In our time, almost brought to the production of prototypes new type lenses called "Bionic Contact Lenses". Of course, this will be the next step in the evolution of contact lenses, because the lenses will include ultra-small electronic circuits. But also as with modern lenses, bionic lenses will be both medical in nature (vision correction) and entertainment and professional in nature (electronic display in the eye). In the case of the medical nature of the application, it will even be possible to “correct” lens defects with electronics (say, due to inaccurate topography of the patient’s eye).

But the production of bionic lenses will also require a fundamentally new approach to their production. If the production methods have already been worked out with the lenses themselves, then with the electronic filling it is more difficult. At the first stage, electronic circuits are assembled from metal plates a few nanometers thick (1 millimeter is 1 million nanometers). On the other hand, the LEDs are planned to be only one third of a millimeter thick, and it will obviously not be easy to apply them with tweezers, so they are sprayed onto the surface of the lens with their “powder”. To accommodate such miniature components, a method called microfabrication or self-organizing assembly is used.

Finally

Unfortunately up to end result still far. Now the stage of searching for materials that will not irritate the user's eye has been completed, and the very fact of the direct location of the emitting LED on the surface of the eye is being studied. It is also too early to talk about the cost of such a “novelty”, but it is clear that the first prototypes will be very expensive.

Rigid contact lenses

Today's rigid contact lenses are made from gas-permeable materials that contain silicone, which makes them more flexible than previous gas-tight lenses made of polymethymethacrylate, and is also breathable. a large number of oxygen through the lens to the cornea. This allows rigid gas permeable contact lenses to provide a significantly more comfortable and healthier wear than their gas permeable predecessors, which are now largely non-prescribed.

Advantages hard contact lenses

Compared to soft contact lenses, rigid gas permeable contact lenses provide significantly better vision because, due to their higher rigidity, they retain their shape during blinking and therefore the image remains permanently stable. Soft contact lenses are slightly wrinkled when the eyelids are closed, 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, as their surface is less porous and easier to clean than the surface of soft contact lenses. In addition, they are 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 to the shape of the cornea, that is, it fits perfectly. The mobility of a rigid contact lens is 2-4 times greater than that of a soft one. All this provides a much better exchange of tear fluid in the sublens space and a much greater supply of oxygen to the cornea, and, consequently, a less frequent development of hypoxic (associated with a lack of oxygen) complications.

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

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

The range of optical power (diopters) of most modern soft contact lenses does not go beyond -12.00 D - +8.00 D. And the properties of the materials of those contact lenses that will provide high-quality vision with higher degrees of myopia and hyperopia ( 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, it should be understood that the higher the degree of myopia, the thicker the soft contact lens along the periphery, and the higher the degree of hypermetropia, the thicker it is in the center, which, given 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 is left for these unfortunate people to do? Or be content with incomplete insufficient correction, depriving yourself of the opportunity to see well and enjoy full life, or use soft contact lenses, the wearing of which will almost inevitably lead to the development of complications. They, of course, can be offered spectacle correction, but in glasses with such diopters, peripheral aberrations (distortions) will be very pronounced, which will make their use very uncomfortable, and their aesthetic properties will be very doubtful ( spectacle lenses will be thick and the eyes behind them will either be very large in high degrees of farsightedness or very small in nearsightedness).
But in fact, there is a choice! Rigid contact lenses tend to have a wider refractive range ( -25.00 D to +25.00 D), but through the use of materials with high coefficient refractions remain quite thin even at high diopters. In addition, due to the better exchange of tear fluid in the sublens space, they provide an adequate supply of oxygen 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 high-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.

Rigid contact lenses for presbyopia (age-related farsightedness)

In addition to glasses, special multifocal soft contact lenses can be used to correct vision in patients over 40 years of age. But all multifocal soft lenses presented on the domestic market have limitations in 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.
Rigid contact lenses have no such restrictions: they can be selected for patients after 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 the selection of hard contact lenses?
This procedure is carried out on the basis of examination data on an autorefractometer and visometry. After performing these studies, lenses from the diagnostic kit are installed on the patient's eyes, the "landing" of which after 20 minutes is evaluated by the doctor when examined with a slit lamp and stained with fluorescein. The visual acuity obtained in hard contact lenses is also checked. As a rule, in most cases, for a successful fitting, it is required to try on from 1 to 3 diagnostic hard contact lenses for each eye. This is necessary in order to achieve a complete ideal correspondence of the shape of the inner surface of a hard contact lens to the 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 determined the parameters of the hard contact lenses required by the patient, we can already send an order for their individual production.

Making hard contact lenses

In order to offer our patients the very best, we have partnered with the German company Wöhlk, which has 60 years of experience in the production of premium hard contact lenses. The level of this company is evidenced by the fact that such an optical giant with a worldwide reputation and an excellent reputation as Carl Zeiss entrusted the production of its soft contact lenses to it. The Wöhlk plant is located in the north of Germany in the town of Schenkirchen, and each product manufactured there is subjected to the strictest control and has a guarantee of the highest quality. All orders for hard contact lenses are made on 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 surveillance

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

Contact lenses are small clear lenses that are placed directly on the iris of the eye. The main purpose of such lenses is the correction of refractive errors (improving its sharpness). The exception is decorative and cosmetic contact lenses, which are mainly used as decoration, although they often perform a dual 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.

People apply contact lenses by optical or functional reasons. Lenses, compared to glasses, are usually able to provide better peripheral vision and do not "fog" in extreme weather (rain, snow, humidity). This makes them more suitable for outdoor use, especially during active sports. There is also a number ophthalmic diseases(e.g. aniseicoria, etc.) which are more effective to correct when wearing contact lenses rather than glasses.

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

A bit of history

Incredibly, the first idea to apply contact correction came to Leonardo da Vinci back in 1508. While sorting through the archive of his works, scientists came across drawings of a ball filled with water, through which a visually impaired person could look at surrounding objects. In addition, in his notes, schemes of lenses were found, which can be safely called the prototype of modern ones.

In 1637, the work of Rene Descartes was published, with drawings of an optical instrument. The device was a glass tube filled with water, to the end of which a magnifying glass was attached, while the other end was attached to 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. optical power. And the ophthalmologist August Müller made an optical lens and introduced its use into medical practice in 1889. His lens became a new method of correction and the subject of his doctoral dissertation.

Until the second half of the last century, organic glass (PMMA) served as the material for the manufacture of contact lenses. Such lenses were stiff and uncomfortable to wear, causing a sensation of a foreign body in the eye. In addition, they absolutely did not allow oxygen to pass to the cornea, which is necessary for its normal functioning. In 1960, the Czech scientist Otto Wichterle synthesized the new kind 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. As recently as 10 years ago, a new generation of contact lenses was created - silicone hydrogel. These soft lenses provide even more comfort and absolute safety when worn.

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

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

Rigid contact lenses are usually used to correct difficult cases pathologies of vision (for example, with high astigmatism and keratoconus), in addition, only they are used in orthokeratology, a relatively new direction in ophthalmology. The new generation of rigid lenses not only keep their shape perfectly, which makes them more comfortable to use, but also provide a high degree of oxygen transmission to the cornea. Such lenses are called rigid gas permeable contact lenses.

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

Colored and tinted lenses do not affect the color perception of visible objects, since they are transparent in the center. True, such lenses are not recommended for use in low light (at dusk and darkness), because the human pupil expands with a lack of light and then the colored part of the lens will fall into the visibility zone, which will cause visual difficulties. Such lenses should not be worn while driving or engaging in activities that require high attention.

Designation of parameters of contact lenses

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

• Manufacturing material.
• Lens diameter (D, BCR).
• Radius of curvature (BC, BCR).
• The optical power of the lens.
• The thickness of the center of the lens.
• Axes of the cylinder.
• Construction (design).
• Optimal mode wearing.
• replacement frequency.

Lenses with a long wearing period (6-12 months) are usually packaged in special bottles. For more frequent replacement lenses, blisters are used as packaging.

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

• Day (put on in the morning, removed before bedtime).
• Prolonged (worn for 7 days, not removed at night).
• Flexible (worn 1-2 days, not removed at night).
• Continuous (worn up to 30 days continuously, not removed at night). A similar regimen is possible for some types of silicone hydrogel lenses and requires the consultation of an ophthalmologist.

Night (should be put on before going to bed, and removed 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 the correction of myopia and hypermetropia.
• Toric - for the correction of myopia and hypermetropia with concomitant 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 is made up 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 of its manufacture. The main characteristics of the material for contact lenses are considered to be: the content of water in it and the permeability of oxygen.

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

The more water the hydrogel lens contains, the more oxygen the cornea will receive, which has a positive effect on eye health. But increasing the percentage of water in the lens makes it softer, making it harder 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 has nothing to do with water content. Wherein:

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

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

The diameter of a 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 values ​​of the radii of curvature. If a contact lens does not fit properly due to a discrepancy between the radius of its curvature and the shape of the cornea, serious discomfort occurs that can lead to refusal to wear lenses.

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

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

Terms of use

Incorrect selection of contact lenses and their improper fit, interference and discomfort are inevitable. To eliminate it, you should contact an ophthalmologist. With a larger radius of curvature of the lens than necessary, they seem to “float” in the eye, and with a smaller one, on the contrary, they “get stuck” and this part of the cornea ceases to be supplied with oxygen. In both cases, such lenses should be replaced with lenses with the desired radius of curvature. Properly fitting lenses tend to move slightly when blinking (landing without rigid fixation) but, most of the time, they are in a central place. At prolonged wear lenses with a smaller radius of curvature, corneal hypoxia often occurs without oxygen, which increases the risk of infectious processes, because at enough oxygen, infectious agents do not survive.

You can swim with lenses only if you use special sealed goggles or a swimming mask. In lenses, you can not go to the sauna and bath. If unboiled water gets on them (shower, pool), it is necessary to replace them with a fresh pair. Contact lenses are designed to be worn in all ambient temperatures, including extreme heat and cold.

Wearers of contact lenses are required to undergo annual examinations by an ophthalmologist.

Possible Complications

The use of contact lenses can lead to some complications, including:

• Infectious diseases (, dry keratoconjunctivitis, etc.).
• Allergic reactions.
• Reactions of hypoxia with oxygen deficiency for the cornea.
• Mechanical damage cornea.

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

Manufacturing of contact lenses

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

• Turning. With it, "dry" polymerized blanks are processed on a lathe. Lenses of complex geometry are obtained through the use of computer control programs. After turning, the lenses are polished and saturated with water (hydrated) to the required parameters, then they undergo chemical cleaning. final stage manufacturing in this case, is the tinting of the lens, sterilization, testing, packaging and labeling.
• Casting. This is less labor intensive than the turning method. First, a special metal mold-matrix is ​​made for the lens. Then plastic molds-copies are cast on the matrix and liquid polymer is poured into them, which hardens under the influence of ultraviolet radiation. Finished lenses are polished, hydrated, tinted, sterilized and packaged.
• Rotation molding is the oldest method of manufacturing contact lenses. With it, a liquid polymer is injected into a mold rotating at a certain speed and exposed to it. high temperature and / or UV radiation, which is necessary for its hardening. Then the workpiece is taken out of the mold, saturated with water and subjected to processing identical to the turning method.

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

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

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

For the manufacture of contact lenses of the latest generation, highly sensitive soft materials are used, which are particularly smooth. In order to facilitate the manipulation of such lenses, to maintain 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 the solution poured into the container bath, as well as in the process of rinsing them with special disinfectants.

Everyone who uses contact lenses knows the need to keep them perfectly clean, because the health of their own eyes and the quality of vision depend on it. Therefore, in order to avoid infection eye infections, along with the purchase of a new pair of lenses, it is worth buying a container for storing them, as well as a special solution that is best suited for both the eyes themselves and the optics.

Baush + Lomb's new contact lenses, dubbed SofLens Daily Disposable, are affordable option daily lenses. They do not require everyday care and provide clear vision at any time and in any light thanks to improved optics.

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

Daily contact lenses are a prime example of convenience, comfort and safety. Their other name is “daily replacement lenses”, because they are designed to make the look rested and bright every new day. What distinguishes them from the lenses of planned replacement that have already become familiar is that every morning it is necessary to open new packaging, and every evening - dispose of lenses that have become unusable all day. Actually, this is what makes silicone hydrogel daily lenses so reliable and comfortable.