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 became widespread 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 moremodern and high quality materials. 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 produce an exact fit for a particular patient.
Indications for Rigid Lenses
Soft contact lenses have limitations in the range of optical 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 is not much different from the corresponding parameters of soft products for vision correction.
Hard 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 smallest dimensions areedge area. 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, 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 water-free, 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 quite 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 you need to wear special lenses. In the process of sleep, the cornea of the eye changes, its optical zone becomes flatter. This form is preserved for the next day. As a rule, the effect of such a correction can be maintainedtwo 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 of the eye, eyelids, all kinds of inflammatory processes, “dry eye” syndrome.
Negative aspects of using hard lenses
In addition to the above advantages, hard 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 acuitythe 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 for hard contact lenses
First of all, any lenses require 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. A daily cleaner for rigid gas permeable contact lenses is also needed. 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. To dateA widely used multifunctional cleaner for hard contact lenses. 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, hard lenses can be polished in a special laboratory.
Special requirements for hard 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 are an excellent option for correcting vision in many cases, but they require proper and thorough care.
