Manufacture of hard contact lenses. Hygiene and contraindications
We work with various types hard contact lenses (Wohlk, Boston, Rose-K, SoClear, etc.).
Our specialists can choose exactly those contact lenses that will provide the highest quality of vision in your case.
What are rigid gas permeable contact lenses?
Sounds kind of intimidating.
Soft contact lenses are a much more pleasant name. However, you will be surprised that hard contact lenses allow much more oxygen to pass to the cornea than conventional soft contact lenses and even the newest silicone hydrogel lenses, which are now the safest and most advanced among soft lenses. contact lenses. And this indicator is almost the most important for those who constantly wear contact lenses.
Besides hard contact lenses provide better vision clarity, 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 doesn't everyone wear hard contact lenses then?
First - You need adaptation, i.e. It takes some 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.
Second, in order to successfully wear hard lenses, you must be worn every day(with a few exceptions), because if you do not wear them for a while, then you will need some time to adapt again
Rigid contact lenses - an excellent option for those people who cannot achieve perfect vision in soft contact lenses. This is possible in several cases:
- those people who make higher demands on the quality of vision, such as shooters, operating surgeons, pilots, jewelers, etc.;
- those. who have astigmatism, especially a high degree, and due to this, 100% vision is not achieved in soft contact lenses;
- patients with keratoconus (irregular shape of the cornea);
- patients who need correction after previous corneal surgeries (laser surgeries to eliminate myopia, corneal transplantation, lens removal).
- patients with problems when wearing soft contact lenses (corneal vascularization, recurrent eye inflammation, excess accumulation deposits)
If you already wear hard contact lenses and would like to purchase a new set, please note:
You can order or purchase hard lenses from us if the selection of lenses was made in our office. Rigid lenses can not be ordered in absentia, prescription glasses / soft lenses or the parameters of old hard lenses. To purchase lenses in our office, you need to make an appointment, take a break from wearing your lenses for a few days, and bring all the data you have with you (from examination data to old glasses and contact lenses).
You can sign up for a consultation and selection of hard contact lenses…
Ask a doctor about hard lenses online right now ... or by phone. 730-52-60, 730-53-35.
30-11-2011, 12:33
Description
In specialized laboratories of the country, both domestic and imported equipment is used for the manufacture of contact lenses.
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 laboratories contact correction view 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 inner walls cylinder 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 the design features of the lens. 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 manufacture of HPLC is carried out according to the same scheme, but less intensive processing modes and special compositions for cleaning and polishing these materials are used.
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 a special fixture (“toric fork”) of the 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.
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 when active classes 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 in 1888 described a glass lens with optical power. And made optical lens and introduced its use into medical practice by ophthalmologist August Müller 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 let oxygen through 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, as a rule, are used to correct complex cases of vision pathologies (for example, with high astigmatism and keratoconus), in addition, they are used only 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 means of correction.
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 the increase percentage 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. With prolonged wear of lenses with a smaller radius of curvature, corneal hypoxia often occurs without oxygen, which increases the risk of infectious processes, since infectious agents do not survive with a sufficient amount of oxygen.
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 a low 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. In this regard, in order to avoid infection with eye infections, along with the purchase of a new pair of lenses, it is worth buying a container for their storage, 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 an affordable daily disposable option. 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 of myopia and, as well as change the tone, color and even the appearance of the eyes completely. In the production of colored lenses, an innovative coloring technology is used. 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 disposable contact lenses are a prime example 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. In fact, this is what makes silicone hydrogel disposable lenses so reliable and comfortable.
Contact lenses are a medical product that allows you to correct various deviations that are a consequence of eye diseases. Most often, on sale you can find products made with the expectation of people suffering from myopia (myopia), that is, those who see poorly in the distance. For patients with farsightedness (hypermetropia), there are also models of their own, just there are much fewer people with such a visual defect. Yes, and short-sighted in fact have to large quantity time to spend in glasses / lenses, so as not to experience inconvenience in everyday life. There are also options for correcting astigmatism.
You can choose lenses for yourself only after visiting a specialist who will conduct a full examination and write out an appointment. Even if you have been a user for many years, do not be too lazy to visit an ophthalmologist before changing one brand to another. Contact lenses different manufacturers and different lines differ from each other in “design”. This concept usually includes parameters for the shape of the front and back surfaces, diameter, center thickness, base radius, and so on. It is also incorrect to select lenses according to a prescription for glasses, since their optical power is different. Our rating will tell you about the best contact lenses in their categories.
The best disposable contact lenses
Currently, daily disposable contact lenses are considered the safest. They are made from the most breathable and comfortable materials. These lenses are retailed in boxes of 10 to 180 lenses. Every day in the morning, the user puts on a fresh pair, and throws it away in the evening. This guarantees better protection of the eyes from infection, simplifies the process of wearing, since the need for care is eliminated. The use of disposable lenses significantly reduces the risk of complications due to more comfortable and modern materials.
4 Dailies (Alcon) Total1 (30 lenses)
The most comfortable feeling
Country: USA
Average price: 1,590 rubles.
Rating (2018): 4.5
High-quality and expensive silicone hydrogel lenses, extremely comfortable for constant wear. Correct both myopia up to -12 and hyperopia up to +6. The model received an excellent oxygen permeability of 156 Dk / t, which will ensure the flow of oxygen to the eyes at almost the same level as in ordinary glasses. With a moisture content of 80%, the lenses become comfortable for those suffering from dry eye syndrome. Judging by the reviews, some buyers are uncomfortable with very thin lens material, but this is a matter of habit. A significant disadvantage is the high cost - these are the most expensive lenses in the section. However, with such characteristics, such a price is not surprising.
Advantages:
- high level of moisture content;
- are not felt when worn.
Flaws:
- very high price.
3 CooperVision Proclear 1 Day (30 lenses)
Good level of moisture retention
Country: USA
Average price: 1,199 rubles.
Rating (2018): 4.6
Good one-day lenses - Proclear 1 Day from CooperVision. Each lens is molded from a hydrogel material and has an excellent moisture content of 60%, which is very convenient due to its good ability to retain moisture. They are perfect for people who often suffer from the feeling of "sand" or redness of the eyes while wearing lenses. The retention of water molecules occurs through the use of a patented technology - PC Technology ™. These lenses are recognized by experts as providing increased comfort for those users who previously often experienced the discomfort caused by dryness. Even after many hours spent in them, hydration remains at 96%.
Advantages:
- correct nearsightedness and farsightedness;
- high level of moisture content;
- no need to buy storage solution.
Flaws:
- price.
2 Acuvue 1-Day Moist (30 lenses)
Astigmatic
Country: USA/Ireland
Average price: 1,406 rubles.
Rating (2018): 4.7
Acuvue 1-Day Moist Daily Contact Lenses are designed for 15 days and come in a pack of 30. These lenses are suitable not only for people with farsightedness or nearsightedness, but also for people with astigmatism. Throughout the day, they provide not only vision correction, but also wearing comfort. The moisture level of the lenses is 58%. Thanks to a special formula that retains moisture inside, from morning until evening, the eyes do not experience fatigue and irritation. Flexibility and thinness allow more oxygen to be carried. These lenses are perfect for people with sensitive corneas and those with allergies.
Advantages:
- correct astigmatism;
- are not felt on the eyes;
- invisible;
- comfortable to wear;
- do not require care.
Flaws:
- price.
1 Acuvue 1-Day TruEye (30 lenses)
Best Breathable Lenses
Country: USA/Ireland
Average price: 1,330 rubles.
Rating (2018): 4.8
Acuvue's 1-Day TruEye contact lenses are the best breathable lenses in their category. Made from a modern material, silicone hydrogel, they provide up to 100% oxygen to the eyes when worn, almost as much as they get without them. Their softness and imperceptibility give comfort throughout the day. Moisturizing components allow you to forget about dryness and redness. Acuvue 1-Day TruEye also boasts the most possible level UV protection. Daily lenses are sold in packs of 30. Thanks to this, they are very convenient and hygienic, because they do not need to be stored in a solution, and also cleaned.
Advantages:
- high level of hydration;
- good UV protection;
- there is no need for care and storage.
Flaws:
- price.
The best contact lenses for a month
Contact lenses for a month are slightly inferior to daily ones. Their service life is longer, but the responsibility for care is also added. It is important to clean the lenses in time and apply a quality lens “preservation” solution at night. If a pair, designed for 30 days, is worn longer than the allotted time, pain, burning and itching in the eyes will most likely appear. Even with the right care. It is better not to experiment and wear lenses by the expiration date.
4 Bausch & Lomb PureVision (6 lenses)
Country: USA
Average price: 1,100 rubles.
Rating (2018): 4.5
Quite popular silicone hydrogel lenses with a long history. The lineup offers optical power from -12 to +6 - quite standard. I am glad that there are two radii of curvature - 8.3 and 8.6, so that the lenses will suit people with different eyes. The moisture content is low - only 36%, but due to the good oxygen permeability of 112 Dk / t, they are comfortable on the eyes, do not dry out and do not rub the cornea. In reviews, buyers write that the lenses are very comfortable and breathable, despite the characteristics. At the same time, one box with lenses for three months will cost less than 1,500 rubles, which is very economical.
Advantages:
- two radii of curvature;
- high oxygen permeability;
- good feedback.
Flaws:
- low moisture content.
3 CooperVision Biofinity (6 lenses)
Flexible wearing mode
A country: US/UK
Average price: 2 340 rubles.
Rating (2018): 4.6
Biofinity - contact lenses for a month from CooperVision can be used, like the previous ones, not only in the daily mode, but also in flexible mode. This allows you to wear them at any time of the day, depending on what each specific user needs. They are made of the same silicone hydrogel, which has excellent characteristics. The lenses correct nearsightedness and farsightedness while still providing comfort even when worn for up to seven consecutive days. Adequate hydration and oxygen permeability is ensured by Aquaform® Comfort Science™ technology.
Advantages:
- flexible wearing mode;
- material with natural moisture;
- you can not use special drops;
- high rate of oxygen permeability.
Flaws:
- high price.
2 Maxima 55 UV (6 lenses)
Best affordability
Country: UK
Average price: 931 rubles.
Rating (2018): 4.7
Contact lenses Maxima 55 UV have the best affordability. Offers for their sale start at a cost of 750 rubles. They provide good vision by correcting farsightedness and nearsightedness. They are UV protected and easy to use. Despite the protection from UV radiation, it is impossible to refuse full-fledged sunglasses. The lenses are processed using a special technology, so they are produced in a thinner profile. This guarantees better oxygen permeability to the eye cornea. The smooth surface makes the wearing process comfortable, preventing dryness and redness. Contact lenses are lightly colored so that they are easy to see in solution.
Advantages:
- thin profile;
- UV protection;
- ease of use;
- price.
Flaws:
- the need for care;
- purchase of storage solution.
1 Air Optix (Alcon) Aqua (6 lenses)
Better oxygen permeability
Country: Switzerland
Average price: 1,350 rubles.
Rating (2018): 4.8
worldwide well-known manufacturer, the Alcon company, presents contact lenses for a month - Air Optix Aqua. They are made from Lotrafilcon B, developed from the proven silicone hydrogel material. This material is characterized by increased hydrophilicity and has better oxygen permeability. Such lenses are perfect for people with hypersensitivity eyes, as they provide an optimal level of hydration. Their surface is treated special composition enhancing the feeling of comfort while wearing. Due to the special treatment of the lenses, high protection against lipid and protein deposits, as well as against contact with decorative cosmetics, dust and other contaminants.
Advantages:
- fivefold increased oxygen permeability;
- protection against deposits and pollution;
- suitable for flexible and extended wear mode.
Flaws:
- during nighttime use, discomfort may occur.
The best colored contact lenses
Colored contact lenses can be with or without diopters. Their difference from the classic models is in the color of the lenses. It, in turn, can be of different intensity, density and may contain different patterns or patterns. Depending on this, such lenses are divided into tint, actually colored and carnival.
With brown and green natural shades, colored lenses will do well. They have a more intense color and a special reflective layer that does not allow the dark color of the eyes to break through the lens. Carnival lenses have a pattern that is completely different from natural - for example, a spiral or cobweb. They are used at parties and similar events where outrageousness is more important than naturalness.
4 Ophthalmic Butterfly Three-tone (2 lenses)
Bright and exotic colors
Country Russia
Average price: 800 rubles.
Rating (2018): 4.4
Domestic colored lenses that have taken a worthy position in the budget segment. They create a bright, unusual shade with any "native" eye color. Three tones are applied to each lens to create a natural iris pattern. Of course, there is no question of naturalness - Oftalmix, as a budget brand, is not capable of it. But this is not critical, since the exoticism and brightness of the look compensates for this. As for the characteristics - 15.8 Dk / t and a moisture content of 42% create a comfortable "union", so the lenses can be easily carried all day, and the eyes will only start to get tired in the evening. The optical power varies from 0 to -7.
Advantages:
- bright shades of lenses;
- low cost;
- can be worn for three months.
Flaws:
- unnatural colors;
- low oxygen permeability.
3 Air Optix (Alcon) Colors (2 lenses)
The first breathable colored lenses
Country: USA
Average price: 1,188 rubles.
Rating (2018): 4.6
Air Optix Colors from the American company Alcon - colored contact lenses, one of the first "breathable". Their material of manufacture is silicone hydrogel (Lotrafilcon B), which provides extraordinary comfort during use. Handsome and natural color they have thanks to a special technology of applying pigment inside the lens in three layers. Due to this, the shade on the overlap of the natural looks natural. The inner ring of pigment adds depth to the look, the middle one gives the main color, and the outer one emphasizes expressiveness. The high oxygen permeability and polished smooth surface guarantee clean lenses, and the eye health and comfort.
Advantages:
- high rate of oxygen permeability;
- correction of myopia and hyperopia;
- plasma surface treatment;
Flaws:
- daily wear only.
2 ADRIA Glamorous (2 lenses)
Wide color palette
Country: Korea
Average price: 1,036 rubles.
Rating (2018): 4.7
Adria Glamorous - colored contact lenses with the widest color palette, including 9 various shades. Many users note that these lenses visually enlarge the eyes, but do not look artificial. They also perfectly cover brown and green natural shades. Complex patterns make the look unusual, deep and expressive. Good UV protection, optimal oxygen permeability and moisture content keep the eyes healthy. Lenses correct nearsightedness and farsightedness. They can be used at night and for active sports activities.
Advantages:
- wide color palette;
- cover dark shades
- visually enlarge the eyes;
- protection from UV rays.
Flaws:
- not identified.
1 OKVision Fusion (2 lenses)
Better color depth and brightness
Country: USA
Average price: 850 rubles.
Rating (2018): 4.8
OKVision Fusion contact lenses have the best color depth and brightness among similar models. This is ensured by using unique technology layer-by-layer application of the coloring matter to the inner surface. Thanks to this method, the natural depth of the gaze is preserved, and overlap is guaranteed even dark color eye. In addition to changing the shade, lenses make it possible to correct farsightedness or nearsightedness. The high moisture content provides the wearer with comfort, relieving the eyes of dryness, fatigue and redness. Lenses are divided into two-tone ordinary, with a mix. effect and three-tone.
Advantages:
- high-quality overlap of the native eye color;
- look natural;
- optimal indicator of oxygen permeability;
- are not felt when worn.
Flaws:
- not identified.
The best astigmatic contact lenses
To correct astigmatism, there are special toric contact lenses. They have a special design, thanks to which they correct astigmatism. This type of visual impairment is characterized by the fact that it does not allow the rays entering the eye to converge, as a result of which the person lacks the clarity of the visible image. Such lenses must have a cylinder.
3 Bausch & Lomb SofLens 66 Toric (6 lenses)
High moisture content (66%)
Country: USA/Ireland
Average price: 1,321 rubles.
Rating (2018): 4.6
Astigmatic contact lenses Bausch & Lomb SofLens 66 Toric have quite high content moisture (66%) that lingers inside the lens, providing comfort from morning to evening. The special non-ionic material used in the manufacture reduces protein deposits. Lenses are easy to put on due to their special strength. They are also difficult to damage, tear, but at the same time they are lightweight and not felt by the user. Visual acuity is enhanced by the unique two-radius back surface design. The rounded edges of the lenses provide free sliding. The casting process used in the manufacture is computerized. This allows the lenses to have the widest range.
Advantages:
- astigmatism correction;
- high moisture content;
- comfort and accuracy of fit;
- reduction of accumulations on the surface;
- strength.
Flaws:
- price.
2 Air Optix (Alcon) For Astigmatism (3 lenses)
Best price
Country: USA
Average price: 960 rubles.
Rating (2018): 4.7
Contact astigmatic lenses. Air Optix For Astigmatism from Alcon has the best price among competitive models. Their manufacturing material is developed on the basis of silicone hydrogel, which amazed world scientists with its excellent characteristics. These lenses are designed specifically for people with astigmatism. They perfectly pass oxygen, give clear vision and provide ease of use and comfortable wearing throughout the day. The lenses are treated with a special patented technology that is responsible for reducing protein deposits on the surface.
Advantages:
- astigmatism correction;
- surface cleanliness for a long time;
- comfort during wearing;
- ease of handling and accuracy of fit;
- price.
Flaws:
- not identified.
1 Acuvue OASYS for Astigmatism with Hydraclear Plus (6 lenses)
Biweekly scheduled replacement
Country: USA/Ireland
Average price: 1,190 rubles.
Rating (2018): 4.8
Acuvue's OASYS for Astigmatism with Hydraclear Plus Contact Lenses are safer for eye health with a two-week scheduled replacement. As we know, the shorter the period of wearing, the greater the chance of avoiding infection and discomfort. These lenses have a very smooth surface, which has a positive effect on the movement of the eyelids. On the eyes of such lenses are almost not felt. Made from a material based on silicone hydrogel, they provide almost one hundred percent oxygen penetration to the iris, so you can forget about redness, burning and irritation of the mucosa. HYDRACLEAR ® PLUS is a technology responsible for moisturizing the eye throughout the day. Ultraviolet radiation is blocked by lenses, protecting the retina and lens.
Advantages:
- correction of farsightedness, myopia and astigmatism;
- two-week scheduled replacement;
- fatigue protection.
Flaws:
- not identified.
The best contact lenses for three months
quarter lenses prolonged wear- the option that is the most optimal in terms of price and convenience. The user does not need to look for a new pair of lenses for a long time and spend the budget on their purchase. They are more durable and, as a rule, of high quality. Therefore, the canvas of the lens can be thicker than that of monthly and even more so one-day models. Therefore, some users out of habit may feel discomfort. Three-month-old lenses require careful maintenance and occasional rinsing.
3 CooperVision Biomedics 38 (6 lenses)
Three pairs in a box
Country: USA
Average price: 900 rubles.
Rating (2018): 4.6
A very popular model of contact lenses, which has been on the market for many years. Despite not the best characteristics, these hydrogel lenses are almost not felt on the cornea and do not interfere in any way. Naturally, if you do not violate the mode of wearing. The optical power varies from -0.5 to -10. Moisture in the model is 38% at Dk / t 23.5, which is why it is not recommended to wear a pair for more than 8 hours without a break. But many users are happy to note that the lenses do not dry out and do not break. ahead of schedule- the material is quite thick and dense. With proper care, problems with irritation or damaged lenses should not occur. In addition, for a modest price, you will receive not 4 lenses in a box, like most manufacturers, but 6 at once, which will allow you not to go to stores for 9 months.
Advantages:
- good feedback;
- dense and reliable material;
- six lenses in a box.
Flaws:
- large thickness;
- not for sensitive eyes.
2 OKVision Season (2 lenses)
Excellent lens performance
Country: USA
Average price: 500 rubles.
Rating (2018): 4.7
Hydrogel lenses with high performance and excellent wearing comfort. The model can offer a moisture content of 45% and an oxygen permeability of 27.5 Dk/t. Due to this, contact lenses do not dry out and pass enough oxygen to the cornea to make them comfortable to wear. In reviews, many buyers write that they are comfortable to wear and do not interfere. On sale you can find optical power options from +12.5 to -15. But on the other hand, the radius of curvature is only one, so the kit is not suitable for every eye. Unfortunately, there is only one pair of lenses in the box, which, at a price of 400-500 rubles (compared to other options), is quite expensive.
Advantages:
- high moisture content and oxygen permeability;
- a large selection of optical power;
- comfortable to wear.
Flaws:
- high price;
- only two pairs included.
1 Bausch & Lomb Optima FW (4 lenses)
Outstanding lens durability
Country: USA
Average price: 700 rubles.
Rating (2018): 4.9
Hydrogel lenses from a well-known company, designed for long-term wear with comfort. They have a low moisture content - only 38.6%. But for a hydrogel, this is absolutely normal. Comfortable oxygen permeability – 24 Dk/t. Buyers in the reviews write that the lenses are much more durable than stated - with quality care and good solution for storage, one pair instead of three months can last six months and even a year! Naturally, we do not recommend experiments, but such quality is already an indicator. Three radii of curvature are available at once - 8.4, 8.7 and 9. It is inconvenient that in model range few diopters - from +4 to -9. In addition, sensitive eyes may not have enough oxygen to pass through the lens.
Advantages:
- durability;
- high quality material;
- three radii of curvature.
Flaws:
- few diopters;
- not for sensitive eyes.
The best contact lenses for six months
Semi-annual long-wear lenses are indispensable when the user does not have the opportunity to constantly buy new sets. They are convenient for their durability and strength - it is convenient to take such models with you on long business trips, on a watch or to other places where there are not very many ophthalmic stores. In addition, they are the most cost-effective.
Naturally, such models are not as convenient as daily lenses - they need to be looked after very well and rinsed from protein deposits in time. And you also need to get used to them - a durable hydrogel is not suitable for everyone.
2 Interojo Morning Q55 vial (1 lens)
Low price per pair
Country: South Korea
Average price: 350 rubles.
Rating (2018): 4.7
Semi-annual dense lenses created with an aspherical design using PolyVue technology. They are as comfortable as possible for constant wear and strong enough to withstand six months of "work". The model offers optical power from -20 to +12. There are also two radii of curvature - 8.6 and 8.8, which allows you to choose a lens for your eye. The moisture content of 55% and the oxygen permeability of 24 Dk/t ensure quite comfortable wearing throughout the day. But in the reviews, some users write that in the evening the eyes begin to get tired, and the problem needs to be solved with drops. The lenses are quite cheap - a pair for six months will cost only 700 rubles.
Advantages:
- two radii of curvature;
- low price.
Flaws:
- may tire your eyes from wearing.
1 OKVision Infinity (1 lens)
Good value for money
Country: USA
Average price: 370 rubles.
Rating (2018): 4.8
High-quality and quite popular long-wear lenses for a variety of users. Comfortable to wear and affordable. The characteristics of the model are 55% moisture content and oxygen permeability 32.5 Dk/t. Users note that the lenses are thick and hard, as they are made of a hydrogel thermopolymer, but they do not cause discomfort in wearing. The optical power of the model varies from -20 to +20. The radius of curvature is 8.4 and 8.7, which makes the lenses universal and very comfortable for non-standard eyes. And then there are the same lenses, but colored and acting as tint. But they have a very bright color, which is not suitable for every eye.
Advantages:
- two radii of curvature;
- many options for optical power;
- low price.
Flaws:
- The lenses are thick and not for everyone.
Contact lenses have long established themselves as a reliable method of vision correction. They are as relevant as possible in the case of myopia. farsightedness or astigmatism. Due to the fact that in their manufacture are used latest materials and technology, they adequately replace glasses. We will talk about the features of different types of lenses, their characteristics and disadvantages further.
Features of the selection of contact lenses
When choosing, you need to take into account various criteria, especially take into account the optical power, the radius of curvature and of course the material from which they are made. The right choice allows you to get good sharpness vision and feel comfortable during use. Undoubtedly, the quality of vision that is provided by contact lenses is much higher than the quality that a person receives when wearing glasses. This is due to the fact that the lenses are capable of forming a harmonious system with the surface of the eye. What's more, it doesn't have any restrictions on fields of view or the possibility of damage due to bad weather conditions.
Lenses have become popular, because they are distinguished not only by their ease of use, but also by their relatively low cost, and most importantly, they are able to protect the eyes from operations to restore vision. All surgical interventions create the possibility of complications, so it is better not to risk eye health.
Contact lenses are indispensable for those people whose occupation is different from the usual. Agree, it is unlikely that an athlete, race car driver or diver will find time to take care of his glasses. By the way, lenses are great option for people with different visual acuity of the left and right eyes. The modern range of such devices is represented by a wide optical range and different types: toric, aspherical, multifocal, as well as colored lenses of various shades.
Classification of modern contact lenses
Today, contact lenses can be divided into subgroups, guided by several parameters.
So, according to the time criterion, they distinguish:
According to the nature of wearing, they distinguish:
They can also have a special design and all sorts of colors:
Depending on what material served as the basis for manufacturing, soft and hard contact lenses are distinguished, which we will discuss in more detail.
Benefits of soft contact lenses
Such devices are used by almost all people today. Doctors warn that it is impossible to violate the prescribed regimen, it is necessary to remove them for the night period. Of course, it is much more convenient to wear lenses without removing them, but such an action can provoke corneal edema. This condition can occur due to the fact that the cornea does not receive an adequate supply of oxygen, and this, in turn, is fraught with very serious consequences.
The structure of the cornea of the human eye is specific, since it is devoid of blood vessels, so it is forced to receive oxygen and elements for nutrition from the air. environment, as well as from the lacrimal fluid. Moreover, when the cornea is covered with a contact lens, then it is completely deprived of oxygen and other nutrients. Sometimes attempts to compensate for the lack of oxygen provoke the formation of new vessels, which eventually grow into the corneal tissue. This process may result in a deterioration in the transparency of visibility and the creation of visual interference, which in combination leads to sharp decline vision. But soft lenses can prevent the possibility oxygen starvation cornea and solve the problem of vision correction.
Soft lenses can be made from a hydrogel polymer. Similar material has already been confirmed good compatibility with eye tissues, but sometimes it can cause ocular hypoxia, that is, lack of air. After the implants are placed, air is delivered to the cornea using the water contained in the lens. That is, the more water is in the optics, the more oxygen it can receive. But water tends to evaporate quickly. A person will instantly feel discomfort when wearing, which indicates the drying of the lens. When the water content in it exceeds the norm, it will no longer be able to keep its shape well.
The maximum possible oxygen transmission capacity of hydrogel lenses is no more than forty conventional units. But ophthalmologists assure that in order to prevent chronic hypoxia, the cornea must receive more intense doses of oxygen, which make up a coefficient of eighty units or more.
Soft models can also be made from silicone hydrogel. Due to the two components of the lens, it is ideally compatible with the eye tissue and, most importantly, does not interfere with the normal supply of oxygen to the cornea. Silicone is such a versatile material that it can easily deliver high oxygen throughputs of up to 150 conventional units. This fact completely eliminates the possibility of insufficient nutrition of the cornea. The hydrogel also contributes to the hydration of the cornea and the comfortable use of lenses.
This type of lens contains less water, so evaporation of the liquid is not a problem for them. Their worthy prerogative is the ability to use for a long time, without discomfort or excessive dryness. This can be explained by the fact that in finished goods the manufacturer introduces special additives for moisturizing. In addition, the optical mirror passes strict methods processing using plasma materials. The similar properties of these contact lenses make it possible to use them without interruption for removal during the sleep period.
Due to the high density, soft lenses are easier to put on and take off, because they can perfectly keep their shape for a long time. The next advantage is also that lipid and protein deposits do not appear in them over time, and this, in turn, continues the period of their comfortable operation.
Your ophthalmologist can offer you two types of silicone hydrogel contact lenses. The first can be safely worn for a week in a row (without being distracted by nightly removal), and especially durable allow you to use them for a month. They are perfect for those people who work. long time in non-stop mode, such as on duty or in a security environment.
Modern silicone hydrogel lenses help to correct not only the manifestations of myopia or hyperopia. but even forget about astigmatism.
Features of hard contact lenses
Innovative models have such an important characteristic as gas permeability. This contributes to the normal ability of the cornea to receive air and nutrients from the environment. Like soft lenses, hard lenses have silicone as their main component. This material was not chosen by chance, because, despite its strength, it does not protect the surface of the cornea from air supply. Some lens designs may exceed the gas permeability characteristics of their soft material counterparts. Although soft silicone options boast a high breathability coefficient, they are still inferior to hard silicone models. No matter how paradoxical it may sound, but rigid gas-permeable contact lenses have a more gentle effect on eye health than the option with soft counterparts.
In addition, there are many problems associated with hard contact lenses. good points, such as:
Of course, rigid lenses cannot be ideal in use, as they have several negative points. As a rule, patients need some time to adapt and this period lasts at least a week on average. But after that, patients noted the disappearance discomfort if there was no break when wearing lenses for a couple of days. In this case, you need to be prepared for a new addiction to the lenses.
Some people have noted that after they used hard lenses, they no longer corrected with glasses. That is, when using glasses, vision did not improve, it remained at the same level, and the image was devoid of clarity. This is often due to the fact that rigid lenses can actually change the shape of the cornea. But if you take breaks for a while, the shape of the cornea and visual acuity are gradually restored. Therefore, do not rush and prematurely abandon the use of hard lenses.
In truth, the process of fitting lenses based on rigid silicone is complicated, because the doctor must ensure the ideal ratio of the rigid lens to the surface of the cornea.
Contact lenses are an excellent option not only for correction, but also for preserving vision in a person of any age. The most important step towards good vision is choosing the best possible option. To do this, you will need to undergo a qualified examination by an ophthalmologist, as well as follow all his recommendations and prescriptions. In no case should you violate the mode of wearing lenses, regardless of their type.
Rigid gas permeable contact lenses: reviews, manufacturing. Rigid Contact Lens Care: Daily Cleaner for Rigid Gas Permeable Contact Lenses
December 8, 2015
Today, there are many ways to correct vision. Very often, contact lenses are used to improve its sharpness and eliminate other problems. Depending on the type of material, soft and hard gas permeable contact lenses are distinguished. Of course, the first type is most often used, but the latter have many advantages.
Rigid Lens Materials
Rigid lenses purchased wide use at the end of the twentieth century. Then the main material for their manufacture was polymethyl methacrylate. The lens itself was relatively small. The disadvantage of such lenses was the lack of gas exchange. Access of oxygen to the cornea was carried out only due to the mobility and small size of such a correction tool. However, today more modern and high-quality materials are used. Rigid gas permeable Contact lenses are made from fluoro-silicone compounds. Due to this, the lenses have good oxygen permeability. It is worth noting that they are quite comfortable, they are made individually, they make an exact fit for a particular patient.
Indications for the use of rigid lenses
Soft contact lenses have limitations in the range of refractive power. Often they are prescribed for myopia up to -12 diopters, myopia not higher than 8 diopters. A stronger degree of myopia requires specific correction. Soft lenses with high optical power will have a considerable thickness in this case. This, in turn, increases the risk of complications (tight fit can lead to hypoxia of the eye). You can, of course, use glasses, but today experts offer modern rigid gas-permeable contact lenses. They have a wide range of refraction - from -25 diopters to +25 diopters. The use of modern material ensures sufficient supply of oxygen to the eye. At the same time, the thickness of such lenses differs little from the corresponding parameters of soft products for vision correction. 
Rigid lens design
Modern rigid lenses have an optical zone, which is located in the center of the product. Its diameter does not exceed 8 mm. Thanks to the sliding zone, which has a specific structure, the lens is securely fixed on the eyeball. The marginal area has the smallest dimensions. It is she who is responsible for the comfortable wearing of the product, ensures the normal exchange of tear fluid under the lens.
The main advantages of these lenses
Many patients note that rigid gas-permeable rigid lenses are less prone to deformation and creasing. Due to the fact that their diameter is somewhat smaller than that of soft lenses, such products leave the peripheral zone of the cornea open. This, in turn, does not disrupt the process of tear exchange. They are also more resistant to protein deposits, so the period of safe operation increases. Since the composition is completely free of water, hard lenses cannot dry out, the patient does not need to use special moisturizing drops. It is also important to note their cost-effectiveness: only a change in visual acuity serves as an indication for replacement. Rigid contact lenses are also indicated for astigmatism. Patient reviews indicate that correction with soft lenses in this case is rather difficult, the only option is to use hard products. Orthokeratology correction is also widespread. It involves the use of hard lenses only at night. 
Orthokeratology. What is the essence of the technique
This type of vision correction allows you to maintain its sharpness during the daytime, but at night it is necessary to wear special lenses. In the process of sleep, the cornea of the eye changes, its optical zone becomes flatter. This form persists throughout the next day. As a rule, the effect of such a correction can last two days. Night lenses are good for children, patients with a progressive form of myopia, in the presence of contraindications for an operation to restore vision. Also, this method is often chosen by people of certain professions: athletes, military, builders, etc. Contraindications to orthokeratological therapy are diseases of the cornea, eyelids, all kinds inflammatory processes, dry eye syndrome. 
Negative aspects of using hard lenses
In addition to the above advantages, rigid lenses have their drawbacks. First of all, a certain period of adaptation (about a week) is necessary. After getting used to, the discomfort disappears, but even a short break in wearing requires a new habituation to the products. There is some degree of corneal deformation if rigid gas permeable contact lenses have been used. Patients' feedback suggests that the use of glasses after such lenses does not bring the desired result: the image becomes blurry, the sharpness decreases. However, this is a temporary effect. After the restoration of the cornea, you can safely use glasses without losing the quality of vision. Also, the process of selecting products is quite lengthy, their initial cost will also be an order of magnitude higher than that of soft lenses. 
How to choose the right gas permeable lenses
In order to correctly choose hard lenses, first of all, you need to contact a specialist. It determines visual acuity, the maximum degree of correction. With the help of special equipment, the ophthalmologist measures the necessary parameters of the patient's cornea. Next up is trying on a few pairs. All these manipulations are necessary for a perfect lens fit. The manufacture of hard contact lenses is carried out purely individually, taking into account more than 20 parameters of the eye. The engineer models the required design (optical zone, slip zone, edge region). Further, on a special machine, the product is machined in full accordance with the layout. The most famous manufacturer in this area is the German company Wohlk. This manufacturer provides high quality products. As a rule, after 14 days you can get a ready-made set of lenses. 
Daily care of hard contact lenses
First of all, any lenses require compliance with the rules of personal hygiene. Hands should be washed with soap and water before putting on or taking off. It is best to wipe them with a waffle towel to avoid getting various villi on the lens. Storage containers must be kept clean. There are special rules for women. Makeup should only be applied after the lens is worn. Accordingly, and remove it after removing the product from the eye. It is also necessary and daily cleaner for rigid gas permeable contact lenses. With its help, impurities, lacrimal fluid are removed. Once a week, a deeper cleaning is carried out. It is worth noting that it is impossible to rub the lenses strongly so as not to violate the optical properties. Today, a multifunctional cleaner for hard contact lenses is widely used. It allows you to effectively remove protein deposits (for example, Boston Simplus solution), does not require additional enzymatic purification. It also perfectly disinfects and softens the contact lens. Over time, the product becomes more difficult to clean. In this case, rigid lenses can be polished in a special laboratory. 
Special Requirements for Rigid Lens Wearers
Wearing hard lenses imposes certain responsibilities on the patient. Visits to the ophthalmologist should be regular. This will enable the specialist to assess the condition of the eyes. At the slightest change in the condition of the eyes, you should seek the advice of a specialist. Timely treatment will avoid conditions such as corneal edema, microbial keratitis, conjunctivitis, corneal ulcer, allergic reactions. Rigid gas permeable contact lenses - excellent tool for vision correction in many cases, however, they require proper and thorough care.
Rigid contact lenses
Yashina Olga Nikolaevna
Candidate medical sciences, head of the department of pathology of refraction
In the world of contact correction, leadership, of course, is occupied by soft contact lenses.
In the mind of the average person, rigid lenses are associated with the very first contact lenses, which were made first from glass, then from polymethyl methacrylate (PMMA). These lenses were very uncomfortable to wear, did not pass oxygen at all, they had to be boiled, special cleaners were used, etc.
Rigid lenses are commonly referred to as gas permeable contact lenses (GP lenses).
What is special about hard lenses?
If the contact lens has low gas permeability, then the cornea under it "does not breathe".
Modern rigid gas permeable lenses are made from silicone-based materials. As you know, one of the most important characteristics of any contact lens is the oxygen transmittance (Dk/t).
The cornea receives oxygen from the surrounding air, and if the contact lens has a low gas permeability, then the cornea "does not breathe", develops chronic hypoxia, swelling of the cornea, ingrowth of blood vessels - all this leads to a decrease in the transparency of the cornea and in the long term to an irreversible deterioration in vision.
Silicone has a high gas permeability - many times higher than soft contact lenses. Silicone hydrogel contact lenses have enough high ratio oxygen transmission, but still this indicator inferior to hard lenses based on silicone.
By providing a high oxygen supply, rigid gas permeable lenses have minimal impact on corneal physiology and are the safest for your eye health.
Benefits of rigid gas permeable lenses
In addition to high oxygen transmission, rigid gas permeable contact lenses have other positive properties:
Most importantly, rigid gas permeable lenses can in some cases provide better visual acuity than soft contact lenses:
Disadvantages of rigid lenses
It will take you some time to get used to hard contact lenses.
Rigid contact lenses are naturally inferior soft lenses for wearing comfort. You will need some time to get used to them. Adaptation can reach 5-7 days, then most users stop feeling any discomfort, but if you take a break from wearing for at least a few days, you will have to get used to hard lenses again.
In some patients, after wearing hard lenses, spectacle correction ceases to work, i.e. if such patients removed their lenses and put on glasses, their vision is low, the image is blurry.
This is due to the fact that rigid lenses slightly change the shape of the cornea (the same principle, only to a greater extent, underlies orthokeratology). Gradually, the cornea regains its shape and vision is restored with glasses, but many wearers stop wearing hard lenses as a result.
Selection of hard gas permeable lenses more complex compared to soft contact lenses, since the hard lens must ideally fit the surface of the cornea, respectively, the time required to fit the lenses will be longer, and the cost will be higher.
Technologies for the production of rigid gas permeable lenses are constantly evolving. Manufacturers strive to create lenses that are as comfortable as soft contact lenses. But already today, many users first of all choose the safety and health of the eyes, giving preference to gas-permeable lenses.
Rigid contact lenses
Often hard contact lenses are perceived as outdated uncomfortable optics made of glass, polymethyl methacrylate. Such samples previously did not allow oxygen to pass through, required boiling, and the use of cleaners. Modern LCLs are gas permeable. The site obglaza.ru will acquaint you with the positive qualities of this "solid" optics.
Features of LCD
The Dk/t coefficient characterizing oxygen permeability is important for any contact lenses. The cornea of the eye will not receive oxygen from the atmosphere and will not breathe if the optic material has low gas permeability. Consequences &minus edema, hypoxia, vascular ingrowth. Vision is irreversibly impaired due to a decrease in the transparency of the cornea.
Today, rigid gas permeable lenses are made from silicone-based raw materials. The value of their Dk / t exceeds that of soft contact lenses (even silicone hydrogel). Therefore, LCLs have minimal effect on the cornea. A gentle effect on the eyes has a positive effect on their health.
Advantages and Disadvantages of Rigid HP Lenses
Advantages
- Due to the high density of the initial material, hard contact lenses retain their shape, they do not crumple when blinking, ensuring image stability.
- Attracts the user, especially the middle-aged, ease of handling. LCL cannot be accidentally torn, but it can be broken purely theoretically.
- From the lacrimal fluid, protein deposits enter the optics. The resistance to them of the surface of hard lenses increases comfort, prolongs the period of safe wearing.
- The peripheral outer zone of the cornea is accessible to oxygen, since its diameter is slightly larger than the diameter of the GCL. A tear without interference washes away dead cells, foreign particles.
- There is no water in the material for the manufacture of hard contact GP lenses. In adverse conditions ( strong wind, heat) they do not dry. There is no need to apply moisturizing drops.
- Economic benefit: the duration of the period of use is unlimited, except for changes in the patient's vision. Specialists obaglaza.ru advise only to properly care for optics.
Rigid gas permeable lenses sometimes provide better vision. Cases when correction with LCD is preferable:
Flaws
Wearing hard lenses takes some getting used to, compared to soft lenses, they are not as comfortable. Adaptation takes place within a week, the main &minus is not to interrupt wearing, otherwise you will have to adapt again.
Some patients wearing LCL experience a decrease in vision with glasses, the termination of the effect of spectacle correction. Rigid lenses act on the cornea, changing its shape. However, it is gradually restored with a pause in the use of LCL, visual acuity returns when wearing glasses. Obaglaza.ru recommends taking this nuance into account and not rushing to categorically exclude the use of such contact lenses.
It is difficult to choose hard GP lenses & minus the optics should ideally fit into the surface of the cornea. This also causes the high cost of LCL.
Selection of hard contact lenses
Continuous improvement in manufacturing technology is a priority for manufacturers of rigid gas permeable lenses. Hard optics are constantly approaching soft optics in terms of comfort, which encourages users to prefer safe hard GP lenses.
There are a large number of medical centers with detailed eye examination services, diagnostics, and the selection of optics suitable for a particular patient. The choice of the necessary treatment should be trusted only to professional ophthalmologists, specialists of obaglaza.ru are sure. Never neglect a comprehensive eye examination.
