Rigid gas-permeable lenses: overview, manufacturers, advantages and feedback
Rigid gas-permeable lenses in many people are associated with those optical devices that were used several years ago. They were difficult to wear, and they often caused red eyes. However, the technology has moved far ahead, and modern hard lenses have a number of advantages, compared with the more familiar soft options.
Concept and types of
Contact lenses are small optical devices made of transparent materials that are used for vision correction, as well as for giving additional decorative and cosmetic effect. In comparison with the glasses, they provide a more precise peripheral vision. In addition, with the help of lenses can be corrected diseases such as keratoconus and aniseikonia, which can not be done by other methods.
There are several classifications of similar optical products. They are divided into groups, depending on the material from which they are made, on service life, frequency of replacement, design, degree of transparency, etc. In general, the following types are distinguished:
The first kind of preference is given by 90% of all users of contact lenses. Recently, however, thanks to new technologies, popularity is gaining and the second type. In the presence of severe myopia, as well as high degree of astigmatism, hard contact lenses will be the best option, because, due to their shape and density, they not only more accurately correct vision, but also prevent the progression of myopia. This is especially important for children and adolescents. Also, hard lenses are often preferred by older people, because such products are more durable and better to feel when dressing, compared with soft options.
Rigid gas-permeable lenses are made of special silicones and polymers that provide optimum strength of the optical product, but at the same time oxygen passes through them well. Most often they are used in those situations when exact vision correction is needed, as well as to eliminate vision problems in particularly complex cases such as astigmatism, keratoconus, orthokeratology, etc.
Given the peculiarities of this option, each lens should ideally fit the person, thereforesuch products are manufactured individually. In this case, usually the patient first comes to a specialist and is diagnosed, after that optical devices are manufactured, and only then the doctor can put them on. The procedure for selecting hard contact lenses takes more time, compared to the same for soft options, since it requires individual calculations.
There are several features that have hard lenses. The description of technologies allows more accurately to characterize this. Since many middle-aged people associate the term "hard lenses" with certain negative memories, the World Association of Contact Lens Manufacturers has proposed to abandon this term. In return, the concept of "gas permeable lenses" is proposed. The fact is that, despite the word "hard", this option differs from those used earlier, because for their manufacture now use very different methods.
Modern technologies allow accurate correction of the tear profile under the lens itself, as well as the profile of the thickening of the optical device. Particular attention is paid to the shape of the edges of the rigid part, as well as the main characteristics. To do this, accurate computer diagnostics, digital control of turning are used, and the highest quality and modern materials are used.
Comparison of rigid gas-permeable contact lenses with traditional soft lenses makes it possible to see a number of advantages that the former possess.
- The cornea has no blood vessels, so it can receive oxygen only from the atmosphere. A soft optical lens completely covers it, which stops the supply of oxygen. Modern rigid products are made of special materials based on silicones and polymers, which have a high gas permeability index. That's why they miss more oxygen, compared to thinner and milder options.
- Hard hard contact lenses also provide the greatest possible visual acuity. Other methods of correction do not give such a result. This is due to the fact that virtually any cornea has certain irregularities. A soft lens repeats the shape of the eye, including all its bulges and hollows. Hard variants create a perfectly flat optical surface. This allows you to make the correction as accurately as possible.
- These lenses do not dry out and do not need moisture.
- They have a longer service life due to their strength and hardness.
- Rigid gas-permeable lenses are more resistant to the formation of a variety of deposits that fall on them from the tear film. These proteins can be a source of allergy, and also worsen gas exchange.
Despite the fact that comfort in use is a clear advantage of soft optical devices, modern technologies allow creating a rigid lens that closely resembles the shape of the cornea and is as easy to use as possible.
Despite the advantages of rigid gas-permeable lenses, some negative aspects of their application are also highlighted.
- Such products require a longer period of adaptation and addiction.
- The price of such options is much higher than that of soft ones.
- Special solutions for gas permeable rigid lenses are required for maintenance.
In addition, the process of selecting optical devices is rather complicated, because they are made individually for each eye.
For the correction of astigmatism, rigid lenses fit perfectly. Due to strength and hardness, such variants hold and form a tear film on the front surface of the eye in the form of a sphere. Between the cornea and the back surface of the lens, an additional space is formed, which compensates for the manifestations of this visual defect.
A similar effect, however, is possible with a small degree of astigmatism. If the level is higher, the possibility of correction with the help of spherical optical devices decreases. To do this, you can use parts of another shape. Optimal options for this are toric lenses.
Rigid gas-permeable lenses in Moscow are very popular, but the selection process is more complex than for soft options. The optical product should ideally perfectly match the front surface of the human cornea. This can be checked with a special fluorescent paint. That is why for proper selection, you need to contact the appropriate doctor who will use special equipment.
Unlike it's soft, hard lenses require a certain period of adaptation. Usually it takes 5-7 days, and in some cases more. Over time, the cornea of the eye adapts, and the comfort of wearing significantly increases.
Many specialized companies are engaged in production of hard lenses. The most famous are such giants as CIBA Vision( Switzerland), Vistakon( USA), Sauflon( Great Britain), Cooper Vision( USA), Clearlab( Great Britain), Zeiss( Germany), Baush &Lomb( transnational company), Avizor( Spain), etc. Customers' testimonials indicate that each option has its positive and negative sides, but all corporations offer high-quality and reliable materials and a high level of efficiency and safety of finished products.
Care and Regular Surveillance
Rigid lenses provide high quality of vision, however they require more responsibility from the person. First, they need to be taken care of regularly and regularly, and secondly, you need to often visit an ophthalmologist. Separate attention should be given to the safety rules for the use of hard contact lenses. This applies to the removal and putting on, as well as the rules of hygiene.
Rigid gas-permeable lenses - this is the best option for those who are in need of accurate vision correction, as well as for those who suffer from astigmatism and other similar problems. Despite the fact that such products require more careful selection and are slightly inferior to soft comfort, they have other undeniable advantages. Modern technologies allow creating variants that will not only perform all their functions accurately, but will also prove to be most comfortable and comfortable for a person.