Many people associate hard gas permeable lenses with optical instruments that were used several years ago. They were difficult to wear and often caused red eyes. However, technology has stepped far forward, and modern hard lenses have several advantages, compared with more familiar soft options.
Concept and types
Contact lenses are small optical instruments made of transparent materials, which are used to correct vision, as well as to give an additional decorative and cosmetic effect. Compared to glasses, they provide clearer peripheral vision. In addition, lenses can correct diseases such as keratoconus and aniseikonia, which cannot be done using other methods.
There are several classifications of such optical products. They are divided into groups, depending on the material from which they are made, on the service life, frequency of replacement, design, degree of transparency, etc. In general, the following types are distinguished:
The first type is preferred by 90% of all contact lens users. Recently, however, thanks to new technologies, the second type is gaining popularity. In the presence of severe myopia, as well as a high degree of astigmatism, hard contact lenses will be the most optimal option, because, due to their shape and density, they not only more accurately correct vision, but also hinder the progression of myopia. This is especially important for children and adolescents. Also, hard lenses are often preferred by people of the older generation, since such products are more durable and they are better to feel when putting on, in comparison with soft options.
Features
Rigid gas-permeable lenses are made of special silicones and polymers that provide optimal strength to the optical product, but at the same time oxygen passes through them well. Most often they are used in situations where accurate vision correction is needed, as well as to eliminate vision problems in especially difficult cases, such as astigmatism, keratoconus, orthokeratology, etc.
Given the features of this option, each lens should ideally suit a person, so such products are made individually. In this case, usually the patient first comes to the specialist and is diagnosed, after that the optical instruments themselves are made, and only then the doctor can put them on. The procedure for selecting hard contact lenses takes longer, compared with the same for soft options, since it requires individual calculations.
Technology
There are several features that hard lenses have. The description of the technologies allows us to more accurately characterize this. Since the term “hard lenses” is associated with certain negative memories in many middle-aged people, the World Association of Contact Lens Manufacturers has proposed abandoning the term. Instead, the concept of "gas permeable lenses" is proposed. The fact is that, despite the word "hard", this option differs from those lenses that were used earlier, since completely different methods are now used to manufacture them.
Modern technology allows you to accurately adjust 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 to the main characteristics. For this, accurate computer diagnostics, digital turning control are used, and the highest quality and modern materials are used.
Benefits
Comparison of hard gas permeable contact lenses with traditional soft ones allows you to see a number of advantages that the former possess.
- The cornea has no blood vessels, therefore it can receive oxygen only from the atmosphere. A soft optical lens completely covers it, which stops the flow of oxygen. Modern hard products are made from special materials based on silicones and polymers, which have a high rate of gas permeability. That is why they let in more oxygen, compared to thinner and softer options.
- Rigid hard contact lenses also provide the greatest possible visual acuity. Other correction methods do not give such a result. This is due to the fact that almost any cornea has certain irregularities. A soft lens follows the shape of the eye, including all of its bulges and hollows. Rigid options create a perfectly flat optical surface. This allows the correction as accurately as possible.
- Such lenses do not dry out and do not need to be moisturized.
- 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, which fall on them from the tear film. These proteins can serve as a source of allergies, as well as impair gas exchange.
Despite the fact that comfort when using is a clear advantage of soft optical devices, modern technologies allow you to create a rigid lens that most closely follows the shape of the cornea and is also convenient to use.
disadvantages
Despite the advantages of rigid gas permeable lenses, some negative aspects of their application stand out.
- Such products require a longer period of adaptation and addiction.
- The price of such options is much higher than that of soft ones.
- Care requires special solutions for gas permeable hard lenses.
In addition, the process of selecting optical instruments is quite complicated, since they are made individually for each eye.
Astigmatism
Hard lenses are ideal for correcting astigmatism. Due to their strength and hardness, such options hold and form a tear film on the front surface of the eye in the shape of a sphere. Between the cornea and the rear surface of the lens an additional space is formed, which allows you to compensate for the manifestations of this visual impairment.
A similar effect, however, is possible in the presence of a small degree of astigmatism. If the level is greater, then the possibility of correction using spherical optical devices is reduced. To do this, you can use parts of a different shape. The best option for this will be toric lenses.
Selection
Rigid gas-permeable lenses are very popular in Moscow, however, the process of their selection is more complicated than for soft options. The optical product should almost perfectly match the front surface of the human cornea. This can be checked with a special fluorescent type paint. That is why for the right selection, you need to contact the appropriate doctor who will use special equipment.
Unlike soft, hard lenses require a certain period of adaptation. It usually takes 5-7 days, and in some cases more. Over time, the cornea of the eye adapts, and wearing comfort increases significantly.
The production of hard lenses is handled by many specialized companies. 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 (multinational company), Avizor (Spain) ) and other customer reviews indicate that each option has its positive and negative sides, however, all corporations offer high-quality and reliable materials and a high level of efficiency and safety of finished products.
Care and regular monitoring
Hard lenses provide high quality vision, but they require more responsibility from the person. Firstly, they need to be properly and regularly looked after, and secondly, you need to visit an ophthalmologist often. Safety rules for using hard contact lenses deserve special attention. This applies to the features of removal and donning, as well as hygiene rules.
Hard gas permeable lenses are the best option for those who need 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 ones in terms of comfort, they have other indisputable advantages. Modern technologies allow you to create options that will not only accurately perform all their functions, but also will be as convenient and comfortable for humans as possible.