Contact Lens Material

Correction of vision using contact lenses is not an operational method and allows you to adjust astigmatism, myopia and hyperopia.

Contact lenses are smaller, so they are more comfortable to wear and have several advantages, for example, they are smaller and provide peripheral vision. Lenses are more convenient with an active lifestyle or adverse working conditions.

Today, all contact lenses on the market are subdivided into two large groups contact lens composition: hard and soft. A number of properties and characteristics differ from each other depending on the materials from which they are made.

Composition of hard contact lenses

Hard lenses can be made of gas permeable and gas tight materials.

Important! Gas permeable lenses are more modern, as they are made from innovative materials.

Gas permeable contact lens material

The main materials for their production is excellent breathability silicone. They provide the maximum flow of oxygen and other important nutrients to the surface of the cornea. However, the lens is a foreign body, so the eye must get used to them.

Important! Be prepared for tearing, redness and other phenomena that can last from several hours to several days.

The difference between gas-permeable hard lenses is the lower water content, however, this allows them to maintain the necessary shape and rigidity.

Material for gas tight contact lenses

The main material for the manufacture is organic glass or polymethyl methacryolate. However, it does not allow oxygen to pass through in the required amount. Therefore, more modern gas-tight lenses are made of silicone, which is more convenient than polymethyl methacryolate (PMMA). Concerning PMMA is no longer prescribed by doctors.

Water content in hard contact lenses

The water content in the composition of the lenses is determined by determining the ratio of the weight of the entire lens and the weight of the water itself as a percentage. This indicator is designated as Dk. The higher the water content in the composition of the lens, the higher their sensitivity to various mechanical influences. Also, those lenses that have a large Dk contribute to dry eyes, as the liquid gradually dries out during socks, and the optical parameters change accordingly.

The composition of soft contact lenses

Soft lenses can be made of hydrogel and silicone-hydrogel, both of which use a hydrogel.

Material for silicone hydrogel lenses

The main materials for the production of silicone-hydrogel lenses are silicone and hydrogel. Silicone is distinguished by its hydrophobicity, which means that the content of the lens already contains water.

pros silicone hydrogel lens material:

  • high level of breathability and the possibility of prolonged wear, that is, without taking off at night and a feeling of lack of oxygen.

By cons Silicone hydrogel lenses include:

  • individual intolerance, some patients cannot use such lenses;
  • the presence of a period for getting used to the lens;
  • relatively high cost.

Material for hydrogel lenses

For the first time, hydrogel material became known in the sixties of the last century.

Pros:

  • the main quality of these materials is hydrophilicity, that is, they attract water. They perfectly carry oxygen to the cornea of ​​the eye, since they are more than 35% water;
  • the advantages include easy selection and lack of addiction, as well as a relatively low price.

Minuses:

  • to the disadvantages, the ability to wear only during the day and low gas transmission.

Water content in soft contact lenses

According to the water content, soft contact lenses are divided into three types:

  • with a high moisture content - more than 60%;
  • with an average moisture content of about 50-60%;
  • low moisture content - less than 40%.

Important! The higher the percentage of water content, the more comfortable the lenses are in the sock, therefore, the more comfortable they are to wear.

What material to choose contact lenses from?

There is no definite answer to this question. It all depends on the individual characteristics of the body, tolerance, disease, and so on. Therefore, in order to choose the right lenses that will provide the maximum level of comfort for you, need to contact a specialist and consult with him.

Most often, specialists prescribe silicone hydrogel lenses., since they combine a sufficient level of moisture content, breathability, the necessary model of elasticity, comfortable wearing and excellent optical performance. However, it is important to consider the personal preferences of the consumer, his wishes, portability.

Watch the video: History of contact lens materials (March 2024).

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