How to choose contact lenses for your eyes. How to choose the right contact lenses for myopia? Quality indicator of the described products
Which lenses are better, daytime or traditional, corrective or toric, colored or clear? To some extent it is a matter of taste, but in most cases it is a matter of eye health and the prescription written by an ophthalmologist.
The EYETOP online store offers the widest range of lenses:
- one-day (Bauch & Lomb, Ciba Vision, Coopervision and Johnson & Johnson);
- for 2 weeks (Johnson & Johnson);
- for 1 month (Bauch & Lomb, Ciba Vision, Clear Lab, Coopervision and Maxima);
- for 3 months (Bauch & Lomb, Interojo, OKVision and Ophthalm Renaissance);
- traditional (Coopervision and Maxima).
In this review, we will tell you everything about contact lenses: which ones are better to choose, how they differ and which brand you should give preference to. We will talk about the features of each type of optics and analyze their features and disadvantages in detail.
If our review helped you understand which contact lenses are better and decide on the type of optics, you can find it in our online store. All you need to do to do this is follow the link to the appropriate catalog page.
What lenses are best to wear?
Today, most ophthalmologists recommend wearing daily contact lenses. They require no maintenance and do not cause dry eyes or allergic reactions. In addition, daily lenses are the best option for tourism and travel: if you drop a lens, you can always throw it away and instantly replace it with a spare one from the package. The main thing is to always have several lenses in stock.
Which contact lenses to choose from the assortment of the EYETOP online store?
The lenses presented in the catalog of our store differ in the following parameters:
- by type: corrective, toric, colored and crazy extraordinary;
- by wearing time: from one day to several months;
- by manufacturer.
If the color of the lenses, their shape, design and even the brand largely depend on the preferences of a particular person, then the wearing period and type of lenses are usually determined by the ophthalmologist. From our review you will find out what contact lenses are sold in the EYETOP online store and understand which ones are right for you.
Daily lenses: which ones are better?
In the EYETOP online store you will find manufacturers such as Bauch & Lomb, Ciba Vision, Coopervision and Johnson & Johnson.
Soft contact lenses produced by the American company Johnson & Johnson Vision Care are perhaps the most popular. Which contact lenses are best to choose depends on your doctor's prescription and how often you use them:
Particularly noteworthy is the new product from Johnson & Johnson - 1-Day Acuvue Moist lenses. They are manufactured using patented Lacreon Technology, which combines the time-tested Etafilcon A material with a special component inside the lens that retains moisture in and around it. If you don't know which lenses are best for dry eyes, feel free to choose these.
Lenses manufactured by CibaVision are also available in packs of 30 or 90 pieces. They contain AquaComfort moisturizing component and polyvinyl alcohol (PVA), so the lenses remain constantly moisturized. They are made of Nelfilcon A - a non-ionic material with a moisture content of almost 70%. Consult with your doctor which lens material is best for you - this or silicone hydrogel.
German lenses from Bauch & Lomb, as well as Dailies Aqua Comfort Plus, are made from non-ionic material hilafilcon A. As a result, the resistance of the contact lens surface to protein deposits is significantly increased, and dehydration is reduced. In addition, hilafilcon A perfectly transmits oxygen, which means the risk of developing hypoxic complications is reduced to zero. An ophthalmologist will determine which lenses are best for you, silicone or hydrogel.
CooperVision is manufactured using patented PC Technology. PC is an abbreviation for phosphorylcholine, a component that contains hydrophilic molecules that are biologically compatible with the cells of the human body. As a result, a protective screen accumulates on the surface of the lens, which retains moisture and ensures the cleanliness of the lens. Which lenses are the best of all those listed, only a doctor can say after an examination.
By the way, if you don’t know which lenses are best for children and whether it’s worth buying them for your child at all, choose daily ones and don’t forget to consult your doctor. Only a pediatric ophthalmologist can select suitable optics for children's eyes.
What lens material is best for two-week optics?
In addition, the manufacturer offers not only clear lenses, but also Acuvue-2 Colors Enhancer tint lenses. Whatever Acuvue contact lenses for 2 weeks you choose, you can wear them without removing them at night for one week or for 2 weeks - only during the day.
Which monthly lenses are best?
The EYETOP online store offers a wide range of:
- Bausch & Lomb: Pure Vision 2HD, Pure Vision, Softlens 59;
- Ciba Vision: Air Optix Night & Day Aqua, Air Optix Aqua, Air Optix Aqua Multifocal;
- Clear Lab: Clear 58 UV;
- Coopervision: Avaira, Proclear, Biomedics 55 Evolution;
- Maxima: Maxima 55 Comfort+, Maxima 55 UV;
- Biomedics Color Premium and FreshLook colored lenses.
What are the best contact lenses from the Bausch & Lomb range? If we compare productions, the advantage of the former is obvious: better image in low light conditions thanks to High Definition Optix technology. Softlens are also slightly inferior to them, despite the fact that they have a high degree of hydrophilicity (59%).
Eye lenses: which are the best from the Ciba Vision range? out of competition. Firstly, you can wear them without taking them off for a month (both day and night). Secondly, they allow oxygen to pass through and do not dry out the eyes: wearing them is not only comfortable, but also useful. Other lenses in this series are suitable for daytime wear only.
Which contact lenses from Clear Lab are better? Clear 58 UV with an ultraviolet filter is perhaps the most popular and comfortable model from this manufacturer. They are very thin, thanks to which they allow oxygen to pass through well and are not felt at all while wearing.
What are the best lenses from the Coopervision series? All lenses from this manufacturer are of high quality and ideal compatibility with human tissue due to the content of phosphorylcholine, a substance that is part of the cornea. The lenses are highly elastic and easily mold to the user's cornea.
Which lenses are best to choose from the Maxima line? If it is necessary to correct vision defects caused by a small degree of astigmatism, preference should be given to the model, and to protect the eyes from UV radiation, Maxima 55 UV is suitable. In any case, the decision to prescribe certain lenses is made by the doctor: only in this case will vision correction be effective.
Colored monthly lenses for eyes: which ones are better? All products of the EYETOP online store are of high quality, and therefore the choice depends only on the initial eye color and preferences of a particular person. For example, for light eyes, tinted lenses are suitable to enhance the natural color, and for dark eyes - or. If you decide to experiment with eye color, feel free to choose.
What three-month lenses are sold in our store?
Most of the assortment of the EYETOP online store is colored:
- Interojo: Adria Color 3 Tone, Adria Color 3 Tone, Adria Crazy;
- OKVision Fusion and Crazy;
- Ophthalm Renaissance: Ophthalmix Colors;
- the exception is lenses manufactured by Bauch & Lomb.
It is impossible to say which contact lenses are the best among colored ones: the choice depends solely on the taste preferences of the buyer. For example, lenses marked Crazy change the size and shape of the pupils and give the iris an unusual color. They can be called extreme: such models are great for parties and theatrical performances.
Which lenses are better to choose for six months?
Such optics are called traditional and, as a rule, are purchased for six months or even a year. The EYETOP online store is represented by such manufacturers as Maxima and Cooper Vision. It is better to buy such optics with a doctor's prescription, because they help correct vision defects and even compensate for corneal astigmatism (for example, LUNELLE ES70 UV).
An ophthalmologist will advise which lenses to choose, colored or clear. The color on tint lenses is applied thinly and clearly: it is not recommended to wear them on very rare occasions.
How to choose which lenses are best?
This is not as difficult as it seems, especially if you have decided on the time to wear them. When choosing lenses, you need to pay attention to the following parameters:
- hydrophilicity;
- airtightness;
- soft or hard lenses;
- lens material.
Hydrophilicity is the moisture content of the lens. It is a common belief that the more, the better, but this is not true. Optics containing too much water causes dry eyes, too little causes discomfort. The best option is silicone hydrogel lenses for the eyes, which are better than others for sensitive eyes and contain a sufficient amount of moisture (more than 50%).
The breathability of a lens is the amount of oxygen that it allows through itself. The higher this indicator, the better it is for the eyes. The oxygen transmittance coefficient is denoted DK/t (Dk is oxygen permeability, t is the thickness of the lens at the center). Accordingly, the thinner the lens, the more oxygen will flow to the eyes.
Which contact lenses are the best for this parameter? Just a few years ago, lenses with an oxygen transmittance coefficient of 20-30 Dk/t were considered such, but today this figure is considered very small. For example, the coefficient of hydrogel lenses is on average 130-140 DK/t, and silicone hydrogel lenses with a coefficient of up to 170 DK/t are considered the best in terms of breathability.
Which lenses are best to choose, soft or hard, is usually determined by your doctor. Hard ones are prescribed for eye diseases such as severe astigmatism, keratoconus, presbyopia, as well as if orthokeratological correction is necessary. Soft lenses are presented on the market, and in particular in the EYETOP online store, in a wider range and are more popular. Not only are they better for the eyes, as they contain moisture and allow air to pass through, but they are also more comfortable to wear.
Which lens material is better? Most ophthalmologists recommend silicone hydrogel lenses. Why? Firstly, they perfectly transmit oxygen and do not dry out the eyes due to their high water content, and the silicone in the lens transfers oxygen from the air to the eye. In addition, silicone hydrogel lenses are very thin and are practically not felt.
Which contact lenses are best for sports?
One-day. It's not just about convenience, but also about safety. Firstly, in the gym, due to physical activity, people sweat and often wipe their face with a towel. If you snag or drop a traditional lens, you will not be able to continue working, but simply replace your daily lens with a new one. If you want to exercise in comfort, don’t even think about which lenses are best to wear to the gym: definitely, daily ones.
Secondly, over time, colonies of fungi form on shower curtains, walls and door handles, which, if they come into contact with a soft lens, are absorbed and can lead to complications. In the case of a one-day lens, this is not a problem: you will throw it away at home anyway, but on a traditional lens, the fungus can take weeks to develop and cause serious vision problems. There are two options: either never, under any circumstances, touch your eyes with your hands, or simply buy daily lenses.
Which contact lenses are better: reviews
Olga Eremina, Moscow:
For a long time I could not determine for myself which lenses were the best; reviews on optics websites did not give a clear idea about this or that model. The first year I wore hard ones, I remember with horror the sensation of having a piece of glass in my eye. Now I wear two-week Acuvue Oasis tinted lenses, for me this is the ideal choice: firstly, you can leave them on at night, and secondly, they gently and naturally change the color of your eyes.
Mikhail Sternin, Moscow
My ideal lenses are daily lenses from Bausch & Lomb. I spent a long time comparing manufacturers and deciding which lenses were best to choose: the reviews did their job: I didn’t come across a single negative one about the German company Bausch & Lomb, everyone wrote that they were very comfortable.
Ivan Malinin, Krasnodar
If you don't know which contact lenses are best, reviews are unlikely to help you make the right choice. I only found mine with the help of an ophthalmologist and it is Proclear 1 Day by Cooper Vision. They never make your eyes dry and there is no discomfort. An excellent choice for those who value convenience and care about their vision!
Contact lenses are an excellent replacement for glasses. Not only will they help correct your vision, but with the help of colored and patterned models you can also change your appearance. Unlike glasses, they provide a good view and do not collect water when it rains. This makes them very comfortable and ideal for sports. The main thing is to know how to choose the right model for yourself.
Modern views
Form
They are in form:
- spherical: have a round shape;
- aspherical: they have an ellipse-shaped surface, unlike spherical models, they do not produce distortions even at high diopters, have a large viewing radius, they are thinner, flatter and lighter;
- toric: designed to simultaneously correct myopia and farsightedness;
- multifocal: have three zones that provide a clear picture at different distances - near, medium and far.
Depending on the material, they can be hard or soft. The latter are made from hydrogel or silicone hydrogel. Another important characteristic is color: they can be colorless or colored. There are also models with drawings, which allow you to give your eyes a completely unusual look.
Diameter and curvature
All models vary in size (diameter). It must be selected individually to ensure a good fit and comfort while wearing. If this is not done, discomfort is guaranteed. In addition, wearing models of the wrong size can lead to worsening eye condition.
The second most important geometric parameter, along with diameter, is curvature. It must correspond to the curvature of the cornea, in this case the fit will be perfect. A lens with an incorrectly selected diameter and radius of curvature causes discomfort, and this may cause refusal to wear it.
Material
They can be hard or soft, and nine out of ten users choose the second option.
Soft ones have a higher water content, they are more comfortable, but their service life is shorter.
Depending on the material of manufacture, they are divided into two types:
- hydrogel: thin, soft, comfortable;
- silicone hydrogel: characterized by the presence of a silicone frame, they are more rigid and hold their shape well.
Rigid models are worn mainly for severe visual impairments- high degrees of astigmatism, keratoconus and others. They are made from special breathable polymers.
Colored or transparent
You can distinguish by color four main options:
- unpainted;
- tinted;
- translucent;
- colored.
Tinted lenses are more convenient to use: they are much better visible on any surface, so they are easy to handle- take off, put on and care for.
Translucent models allow you to add expressiveness to your eyes, emphasizing and enhancing the natural color of the iris. They are often worn by those with light eyes.
Colored models are completely opaque except for the pupil area. They can be used to change the color of both light and dark eyes. radically.
You can learn how to choose the color of contact lenses yourself from this video:
One-day and long-term wear
According to the wearing mode, the most popular are:
- daytime, or DW: they must be removed at night;
- flexible wearing, or FW: can be left on for two to three days, can be removed every time before going to bed;
- extended, or EW: such models can be worn for up to 7 days;
- long-term wear, or CW: they can be worn continuously for a month.
Which type to choose depends mainly on personal preference. EW and CW models are more convenient.
At the same time, as a result of wearing them, the risk of developing microbial keratitis and decreased visual acuity slightly increases.
For sensitive eyes
There are people with very sensitive corneas for whom glasses are the only option. However, most of those who wish can still choose “contacts” for themselves. Models suitable for sensitive eyes made of soft materials - hydrogel, silicone hydrogel- with the inclusion of hydrophilic particles.
They are highly compatible with the human eye and usually do not cause discomfort. It is worth paying attention to materials with medium and high water content.
Another important parameter is thickness: the smaller it is, the less likely it is to feel discomfort when wearing it. For this reason there may be aspherical options are preferred.
An ophthalmologist can give precise recommendations on the choice of specific models after an examination. If wearing it still causes discomfort, additional moisturizing of the eyes with the help of special drops, which a specialist will also prescribe for you, will help relieve it.
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For farsightedness and myopia
Each major manufacturer produces models for both the correction of farsightedness and myopia.
The most popular models are those designed to correct myopia, which have the number of diopters with a minus sign. They are usually needed by young people who, if possible, prefer to avoid wearing glasses.
You can opt for spherical or toric options.
To correct age-related farsightedness Multifocal models are most often used- both one-day and long-term wear. They provide a clear picture at different distances. Also popular options include spherical and toric.
How to choose the right model for yourself
In order to select a model, you need to contact an ophthalmologist. After conducting the necessary examinations, he will explain which ones are best to choose and prescribe contact lenses for the eyes that are best suited for you. He will indicate all the necessary parameters, after which you will only have to purchase one of the suitable options.
Trying to make a choice on your own can lead to unpleasant consequences - discomfort when wearing and deterioration of vision due to eye hypoxia.
It is better to prefer products from a trusted manufacturer, which guarantees the quality of the products. There are plenty of inexpensive options of dubious brands on the market, primarily they are presented in online stores.
However, when it comes to health, the desire to save money by purchasing the cheapest option available is completely inappropriate. Usually choosing the first set is difficult. However, after you try models from different manufacturers with similar characteristics, you can settle on the option that turns out to be the most convenient and practical for you.
Watch the video in which an ophthalmologist gives his feedback on how and which ones are best to choose contact lenses for vision:
Review of popular manufacturers, average prices
Perhaps the most widely advertised and popular brand of lenses today. The brand belongs to the famous American manufacturer of medical equipment and body care products - the company Johnson&Johnson. A wide range of models for all occasions, in which almost everyone can find something for themselves.
A pack of five pairs costs from 240 rubles.
Bausch&Lomb
This American company was founded in the mid-19th century. It has been producing contact lenses for over forty years. Its popular product lines include lenses PureVision, 1 Day Biotrue, Optima, SofLens.
The cost of a package of five pairs starts from 150 rubles.
Ciba Vision
The head office of this company is located in Basel, Switzerland. Ciba is one of the world's leading manufacturers of contact lenses, lens care products and eye treatment products. Popular lines - Focus Dailies, AIR OPTIX, as well as colored lenses
FreshLook.
The price of a package of five pairs is from 500 rubles.
The very first contact lenses were made from glass. Despite the rather high optical characteristics for those times, wearing them comfortably was not possible. Modern manufacturers use polymer materials to create lenses. We will talk about which of them are considered to be of higher quality in this article.
When choosing contact optics, many users pay attention to the material from which the lenses are made. Etafilkon, Balafilkon, Polimakon, Nelfilkon... These names of manufacturing materials remain unclear to many users. Most people concerned about the health of their eyes would like more information about what models are made from. However, unfortunately, neither the packaging nor the instructions supplied with the goods provide detailed information about this or that material, with the exception of indicators of oxygen permeability and moisture content. What polymer are the best lenses based on?
What were the very first contact lenses?
It is known that the very first means of contact correction were made from glass by grinding. The polishing process was quite long and lasted at least ten hours. They were rather poorly tolerated by users due to the characteristics of the material. The glass had a lot of weight, and therefore, when worn, contact lenses put pressure on the sensitive eye tissues. For a long time, attempts by scientists to develop a more comfortable material, the manufacture of optical products based on which could solve the problem of many visually impaired people, ended in failure. Progress in the development of contact lenses came at the end of the 30s of the last century, when manufacturers began to use polymethyl methacrylate, a type of acrylic resin, to create them, which could later be tinted and dyed. It was patented under the brand name Plexiglas in 1933 by German chemist Otto Roehm, an employee of Rohm and Haas. The first sales of vision correction products began in 1936.
Despite the many advantages of polymethyl methacrylate compared to conventional glass, it also could not be called an ideal raw material for the production of lenses. The optical products developed on its basis were quite rigid in their structure, and therefore required a long period of adaptation. In addition, due to low oxygen permeability, not all users could wear them. Often, the use of contact correction products made from polymethyl methacrylate led to tragic consequences for the eyes, causing swelling of the cornea. Today, this type of acrylic resin, also called plexiglass, is not used for the production of optical products in most developed countries. However, in some countries the demand for models developed based on this material still does not decrease. The production of such lenses is carried out by the well-known ophthalmological corporation Contamac. Thus, in 2003, a record production of these products was recorded - 1 million contact lenses, the order for which came from partners from India.
Attempts to develop lenses from a material with more advanced characteristics have been made by scientists constantly. In the mid-70s of the last century, optical products were created that were distinguished by improved surface properties. Manufacturers subsequently focused on making products from gas-permeable materials, which were proven to be more suitable for ocular tissue. In 1977, specialists in the field of ophthalmology developed cellulose acetobutyrate, capable of transmitting oxygen to the cornea at a level of 8 to 11 Dk/t. Considering the characteristics of modern hydrogel and silicone hydrogel polymers used in the production of contact lenses, such parameters are not very impressive. However, compared to polymethyl methacrylate, which had been used for a long time, they were a real breakthrough in the field of optometry. In addition, the advantages of this material included hydrophilicity and resistance to protein deposits. The disadvantage was considered to be the instability of the parameters due to the production technology used, due to which scratches often formed on the surface of the lenses.
How do lens makers obtain materials?
Users who are interested in developments in the field of optometry and contactology will certainly be interested in reading about how new materials are created. The production and assessment of the production qualities of a particular raw material, which in the future can presumably be used to create lenses, requires certain knowledge in many scientific fields. For example, a specialist developing such materials must have a good understanding of polymer chemistry and physics, and know the basics of visual physiology and toxicology. It is believed that only an interdisciplinary approach makes it possible to create high-quality materials, the production of contact lenses based on which becomes widespread and productive.
As a rule, specialists obtain lens material by polymerizing monomers when placed under certain conditions. Simply put, many molecules attach to the active sites of low molecular weight substances, resulting in the formation of a liquid prepolymer. After this, it is placed at a certain temperature in which it hardens better, forming the polymer itself. In the production of soft lenses by modern companies, developers often use weakly cross-linked polymers, also called gels. They are distinguished by the properties inherent in superabsorbents (they can absorb large volumes of water when swelling).
Criteria for materials used to create good lenses
In order to answer the question of which lens material is better, it is necessary to have a general understanding of what criteria are used to evaluate the suitability of a particular raw material for the production of optical products. Experts who have been developing contact lenses for many years believe that it is almost impossible to single out one or two parameters. In their work, they usually focus on the overall balance of such characteristics as:
- optical transparency necessary to provide bright and contrasting vision;
- biological inertness, ensuring physiological compatibility with the tissues of the eyeball;
- chemical stability, manifested in the ability of raw materials to retain their original properties;
- mechanical stability, which affects the ability of the introduced lubricant to maintain its qualities;
- hydrophilicity, the level of which indicates the ability to absorb moisture;
- oxygen permeability, providing oxygen access to the cornea of the eye;
- elasticity, guaranteeing an accurate “fit” of contact lenses on the cornea.
In general, this is still not a complete list of criteria by which modern developers determine which material is best used for the production of optical products and which is not. The main parameter, according to many of them, is chemical stability. It is this indicator that affects the number of days of operation, mode of use and shelf life of the model. Particular attention is paid to the non-toxicity and non-carcinogenicity of materials. Modern equipment makes it possible to test the resulting raw materials for the presence of various impurities, for example: residual stabilizers, plasticizers or monomers, which can move into the tear fluid and have a toxic effect on the retina.
Lenses made of hard polymers. Why are they better?
Based on the polymers from which they are made, contact lenses are divided into two groups that are familiar to experienced users, namely hard and soft. Rigid ones can be either gas-permeable or gas-tight. Both varieties are called GPL in the language of ophthalmologists. Soft ones include models of lenses developed on the basis of hydrogel, designated both Hg, and those based on silicone hydrogel, designated by specialists as Si-Hg.
Although polymers used as a basis for the production of hard lenses have been used less frequently lately, they have a number of advantages. Ophthalmologists recommend that their patients suffering from high degrees of astigmatism or keratoconus choose hard contact lenses. An excellent effect is ensured by their use for deformations of the cornea, both traumatic and postoperative. It is believed that the combination of material and manufacturing method allows for the creation of models that are resistant to scratches and tears, and therefore are recommended for long-term wear.
The disadvantages of rigid polymers include the need for adaptation. According to user reviews left on the Internet, most of them were able to get used to wearing the presented lenses only after a week. Some took longer. In addition, these optical products are smaller in size, which increases the risk of falling out or becoming dislodged during sports activities.
Contact lenses made of soft polymers
The very first material on the basis of which soft contact lenses began to be developed was called hydroxyethyl methacrylate. It is well known to many modern users who prefer wearing decorative optical products under the name HEMA. Many manufacturers believe that it is best suited for the production of color and tint models. It was first synthesized in 1960 in the Czech Republic. News about the development of innovative raw materials quickly spread throughout Europe. Soon, the headlines of newspapers and specialized magazines were full of news that a unique material had been developed, which had no analogues in the whole world, on the basis of which specialists would finally be able to develop good lenses suitable for the majority of users. Its uniqueness lay in its hydrophobicity - the ability to absorb water up to 38% of its own weight.
At the end of the 60s, specialists from the American brand Bausch & Lomb acquired a license to produce HEMA lenses and patented the casting technology. Having learned about which materials transmit oxygen well to the cornea through moisture evaporation, many brands sought to obtain a patent for the production of optical products based on them. Soon, models developed from hydroxyethyl methacrylate took first place in the optics market, displacing rigid ones into the background. In 1998, the first elective replacement contact lenses were released by Johnson & Johnson. A year later, this company introduced the first continuous wear model. Around the same time, the first ephemera appeared, occupying a special niche in the optics market today.
FDA classification. What lenses does it include?
To simplify the understanding of the optical characteristics of certain polymers and make a preliminary conclusion about which lens material is better, FDA specialists have developed a certain classification. It involves dividing all currently existing contact lens models into several groups. It’s very easy to understand which ones are good, although the definition itself is not entirely correct. The first group, as a rule, includes models characterized by low moisture content and insufficient oxygen permeability. Such optical products are practically not prescribed today due to the unsatisfactory optical properties for most users. The most modern means of correction belong to the fourth group of the FDA.
First FDA Group
FDA specialists included in the first group optical products made on the basis of nonionic polymers with a low water content of less than 50%. Such contact lenses are characterized by stable optical parameters, high strength and resistance to various types of deposits. Polymers of the first group include:
- Tefilcon;
- Polimakon;
- Lotrafilcon;
- Galifilcon;
- Senofilkon.
An example of good lenses is Biomedics 38, presented by CooperVision. Despite the fact that the intended wearing period is up to three months, their structure is very thin and elastic, and supplies the cornea of the eye to the required extent with all the beneficial nutrients contained in oxygen. In addition, the smooth surface of Biomedics 38 lenses is resistant to protein deposits.
FDA Group 2
The second group, like the first, includes nonionic polymers, but only those whose hydrophilicity level is more than 50%. Due to their higher moisture content, they are not as durable as those belonging to the first group. They have an increased tendency to dehydration. Such materials do not accumulate protein deposits, but are prone to lipid deposits. In addition, they are unstable during heat treatment. This category includes contact lenses made from materials such as:
- Alfafilcon;
- Omafilcon;
- Hilafilcon;
- Nelfilcon;
- Nezofilkon.
An example is the Focus Dailies All Day Comfort lens model, developed by the Alcon brand. The AquaComfort technology used at the production stages makes it possible to provide the user’s eyes with the necessary hydration, which is so important for healthy vision, throughout its service life. The ultra-thin structure of the correction products, created using the Light Technology technique, allows you to forget about wearing discomfort and enjoy clear vision.
FDA Group Three
The third group, like the subsequent fourth, includes ionic polymers characterized by a low level of hydrophilicity, usually less than 50%. Their strength is better than those previously listed by us, but they are less resistant to protein deposits and have rather low air permeability. Moreover, these polymers are resistant to heat treatment. The group includes the following materials:
- Femfilcon;
- Balafilcon.
What lenses are created based on them? A striking example is the PureVision 2 lens model, developed by specialists from the Bausch & Lomb brand. These ophthalmic products can be used both in daytime and in flexible or prolonged modes. When creating them, they were processed using the unique Performa technique, with the help of which a hydrophilic component is introduced into the structure, preventing the matrix from drying out and increasing the smoothness of the surface.
FDA Group Four
The last group represents ionic materials, the moisture content of which is more than 50%. Their strength, as a rule, is somewhat worse than that of those included in the first or third group. This is compensated by high oxygen permeability and resistance to the accumulation of lipid deposits. Lens models are made using casting technology. What polymers are included in this group?
- Etafilcon;
- Ocufilcon;
- Femfilcon;
- Metafilcon;
- Wilfilcon.
This group includes many popular contact lenses, for example, 1-Day Acuvue Moist, created by Johnson & Johnson brand specialists using innovative Lacreon technology, which minimizes the friction that occurs between the cornea and the optical product and increases comfort during use.
They differ from each other in buffering properties and various additives, for example, some are better moisturizing and suitable for sensitive eyes. The properties of solutions depend on the chemical composition. The best are considered soft solutions - in which the alkaline environment (pH) is close to the alkaline composition of tears - 7.4. Manufacturers must indicate this information on the packaging.
Solutions with hyaluronic acid - a substance that retains and fixes water molecules - have stronger moisturizing properties and are suitable for patients with sensitive eyes.
If you feel a burning sensation in your eyes after using a new solution, try a milder solution, and if there is no improvement, you may have an allergic reaction to the material or one of the components of the solution.
Sometimes, in addition to solutions, ophthalmologists recommend moisturizing drops or drops with hyaluronic acid, which help relieve the feeling of dryness and protect the cornea.
How to determine the diameter, radius and curvature of a lens? What are the consequences of improper use and purpose?
“Diameter” in lens parameters refers to the diameter of the cornea from edge to edge, and “radius of curvature” is the radius of the inner surface of the lens. These parameters are determined by an ophthalmologist using an autorefractometer when selecting lenses. During the procedure, the parameters of the cornea are taken into account, and all sizes are selected individually.
If the diameter is incorrectly selected, the lenses will slide when you look up or down. If the radius is too small (more curvature), the lens becomes more convex and a gap is created between the cornea and the lens, which can lead to abnormal refraction. If the curvature is less, the lens becomes too flat and begins to “float” on the surface of the eye, causing discomfort. The patient's eyes become red and there is a sensation of a foreign body. This is due to the fact that the only part of the eye where there are receptors - sensory nerve endings - is the cornea. It is with this surface that the lens comes into contact, and during any manipulation it is the cornea that suffers.
How to choose the right optical power of lenses and is it different from the optical power of glasses?
It differs by an average of half a diopter. If the patient wears glasses -1, then the lenses will have a lower refraction and diopter than with glasses. Lenses -0.75 or -0.5 will suit him. And if the patient has -9 vision, then the difference will be more significant - up to the diopter.
Sometimes patients are prescribed lenses that differ from their vision by 0.25, but they feel that they cannot see well. This is usually associated with heavy visual stress: working at a computer, driving a car. All this provokes a spasm of accommodation - a spasm of the intraocular muscles, which leads to narrowing of the pupil and disruption of the refractive ability of the intraocular lens - the crystalline lens. Spasm of accommodation requires treatment, so if such symptoms occur, you should consult an ophthalmologist. This is usually treated with special drops that train the intraocular muscles. The drops are instilled in the evening as they dilate the pupil and the patient has difficulty focusing at close range. The tension gradually decreases; treatment usually takes about two weeks. In addition, vitamins with antioxidants and lutein are prescribed. To improve blood flow, you can massage the collar area.
What does lens moisture and oxygen permeability mean?
Today, lenses are made from hydrogel and silicone hydrogel. Hydrogel and silicone hydrogel are common names for different materials, and each manufacturer is conducting its own developments in this area. The parameters of the material are indicated on the packaging of the lenses - these are water permeability and the ability of the lenses to transmit oxygen.
The cornea, like any living tissue, needs nutrition to maintain vital functions, trophic processes, metabolism, metabolic processes - in general, for normal functioning. Oxygen is needed for all living things, including the eyes. Each manufacturer has its own technologies that allow more oxygen to pass through the lens. Due to lack of oxygen, chronic hypoxia can occur. With it, blood vessels begin to grow, and the vessels with the conjunctiva grow into the cornea.
| Companies, online stores and optical salons that sell contact lenses in Minsk and other cities of Belarus: colored lenses, spherical lenses, soft lenses, hard lenses, silicone - hydrogel lenses,
delivery of contact lenses, contact lenses manufactured by Acuvue, Optima maxima, CIBA Vision, Johnson&Johnson, Bausch&Lomb. He will select the basic characteristics and give recommendations regarding other characteristics. Then, depending on how comfortable you feel wearing certain lenses, you can try something new that is more suitable for you.
They are as comfortable as possible and safe for the eyes. Besides, if you don’t like wearing them, you don’t have to worry. After all, the lenses are designed for only one day. After using them, you throw them away and forget about them. The best lenses for the month. These lenses are worn for one month, only during the day (removed at night).
One of the best monthly replacement lenses. They are made from silicone - a hydrogel material of the latest generation. Provide maximum eye comfort due to good hydration and high oxygen permeability. They are biocompatible and resistant to deposits. One of the thinnest ones produced today. Comfortable to handle and wear. Provide excellent oxygen access to the cornea. Thanks to this, they can be worn for 7 days without a break. Moreover, the eyes will retain an attractive, healthy appearance. Provide clear, bright images even in low light conditions. These lenses are of the highest quality, made from state-of-the-art materials, unrivaled in comfortable wear. They provide convenience when working at a computer, when watching TV, or when in a room with dry air. Excellent oxygen permeability. Designed to be worn for 2 weeks, with breaks at night. The best lenses for three months (quarter lenses).
Made from modern hydrogel material. Blocks 91% of harmful ultraviolet radiation. Suitable for those who lead an active lifestyle. Comfortable to wear, well thought out lenses for long wear. The best lenses day-night without removing. Our choice is:
They are characterized by optimal moisture content, composition (silicone - hydrogel), as well as a high oxygen transmission coefficient Dk/t, making them as comfortable as possible to wear for as long as 30 days. Designed for daily wear for 30 days, or two weeks of continuous wear. Made from silicone hydrogel materials, they have excellent moisture content and oxygen permeability. Today, these are the most comfortable lenses to wear made from the latest generation of material. All indicators are excellent! Intended for two weeks of daily wear, or for a week of continuous wear.  Remember, there are many subtleties in choosing contact lenses for your eyes. In addition, even the most expensive, seemingly most suitable ones can cause discomfort and may not be suitable in your particular case. Therefore, you may have to spend time searching for the optimal, comfortable lenses for you. Or maybe you will be lucky, and thanks to the advice of doctors and our humble article, you will immediately purchase the best lenses for your priceless eyes. |
