Contact lenses are a good and convenient way to quickly correct any degree of visual impairment. Compared with other ways of adjusting vision (glasses, LASIK), this is the most practical, simple and safe for the eyes. The main advantage of any lenses is that they, covering the entire surface of the optical apparatus of the eye, provide the same correction of both direct and lateral vision, so that the vision does not impair, and for several years remains unchanged. Choosing a contact lens that is comfortable must be done so with your ophthalmologist.
General approach to the choice of lenses
Contact lenses, which is most comfortable? day, night, one-day, two-week, etc. It is impossible to say unequivocally, since contact lenses depend on individual cases.
Soft Contact Lenses
Soft contact lenses are made of plastic polymers. These lenses are flexible and when they are well adjusted, they mold to the cornea (the anterior surface of the eye). They are the most common type of contact lens. These lenses are generally more comfortable compared to hard lenses with shorter adaptation period for new users. Soft contact lenses are less sensitive to light than hard or rigid gas-permeable lenses.
Rigid Gas Permeable Lenses
Rigid gas-permeable contact lenses are made from more rigid polymers than soft contact lenses (hydrogel and silicone-hydrogel). Although these contact lenses are called rigid, they should not be confused with the previously existing hard contact lenses made from PMMA (Polymethyl methacrylate). PMMA contact lenses were uncomfortable and did not allow oxygen to the cornea of the eye, which it needed to maintain a healthy state. Compared with soft contact lenses, rigid gas-permeable contact lenses are considered to provide better vision. Due to the higher stiffness, rigid gas-permeable contact lenses retain their shape during blinking (soft contact lenses are slightly crushed when the eyelids are closed), and therefore the image remains stable and not “floating”, as sometimes happens with soft contact lenses.
So why are rigid gas permeable contact lenses much less popular than soft contact lenses, and they are less and less prescribed? The fact is that in order to get used to rigid gas-permeable contact lenses a period of adaptation is required (up to a month or longer). And soft contact lenses become comfortable right after putting on. This disadvantage is caused by the higher stiffness of rigid gas-permeable contact lenses and the lack of water in them.
Silicone-hydrogel contact lenses appeared on the market about 10 years ago. Their main advantage over traditional hydrogel contact lenses is that silicone hydrogel contact lenses allow much more oxygen to the cornea, which is necessary to maintain a healthy eye condition.
The cornea of the eye does not contain blood vessels through which oxygen along with the blood enters all human organs. Oxygen, which is necessary for the vital activity of corneal cells, enters it from the atmosphere of air (oxygen diffuses from the atmosphere through the tear fluid to the surface of the cornea and further into it). When the eye is closed by the eyelids (during sleep), the oxygen supply decreases, but it is quite enough for the normal functioning of the cornea. This level of oxygen (when the eyes are closed) is considered the minimum acceptable for maintaining cornea health.
Silicone-hydrogel contact lenses provide higher comfort during long-term work at the computer, while in adverse environmental conditions (dryness, dust, etc.). They eliminate the symptoms of dry eye that occur when ordinary hydrogel contact lenses are worn under these conditions.
Daily contact lenses
The tear fluid contains various substances: proteins, fats, calcium and other substances that are products of the functioning of various structures of the eye. With repeated use of the same contact lenses, these substances, as well as dust particles and other external contaminants (for example, mascaras), gradually accumulate on the surfaces of the contact lenses, which leads to a deterioration in the quality of vision and makes wearing contact lenses less comfortable than with new contact lenses. In addition, deposits accumulated on contact lenses increase the risk of an allergic reaction of the eye.
Therefore, it is necessary to regularly clean and disinfect reusable contact lenses. However, even with regular care of contact lenses, it is impossible to remove all surface deposits that have accumulated on them. Part of the deposits remains, they are attached to the surface of the contact lens, and to remove them already requires a deeper enzyme cleaning, which still does not provide 100% removal of all deposits. Daily contact lenses are a great option considering these issues.