Silicone hydrogel contact lenses — what it is, what are their characteristics (feedback, price)
For many people a new generation of contact lenses has become a real discovery. Soft hydrogel and silicone hydrogel contact lenses create the Foundation of this innovative ophthalmic industry. But those and other lenses have advantages and disadvantages; and it is worth noting that silicone hydrogel definitely win some points.
What can silicone hydrogel contact lenses?
Hydrogel lenses are designed exclusively for daily wear and is designed for a two-week lifespan. In structure these lenses is polymer frame, gel filled, water-based. This design increases the amount of oxygen passing through the lens, but also moisturizes the surface of the cornea.
Important! Even the degree of hydration and the amount of oxygen does not allow you to carry such a lens around the clock.
Silicone hydrogel lenses — an improved and strengthened design fragile gel lenses. The silicone creates a more dense structure, better pervious to oxygen and moisture preserving quality eye. Thanks to the rigid, elastic and hydrophilic silicone, the rate of oxygen permeability is increased by 4 times, and the water retention increased to 80 %.
Such impressive performance allowed to create a new class of lenses for extended wear. According to manufacturers, Silicone hydrogel can be worn without removing up to 30 days. Giving such recommendations, attention was drawn to the level of corneal edema after a day of wear. It is believed that it should not exceed the figure of 8%, only in this case, after a night of wearing eye will recover quickly. A new type of optics coped with almost all the necessary requirements with good margin of safety.
How does silicone hydrogel contact lenses?
And still what it is — silicone hydrogel contact lenses? How they achieve such outstanding results?
In the lenses of the latest generation of silicone acts as a kind of reinforcement creates a durable and very elastic base to the hydrogel. If no silicone soft lenses may consist of water without loss of strength of approximately 50 %, with the maximum concentration, 80% water, they become overly fragile and rarely survive put two weeks of wear. By the way, that water is responsible for the supply of oxygen to the cornea.
The silicone adhesive is allowed to retain strength at 80 % water, this allowed to increase the amount of oxygen that passes through the lens several times. And time recommended wearing extend from several hours to several days.
Thus it was possible to achieve a breakthrough in several important evolutionary results in the development of optics contact:
- significant increase in wear time;
- the value of the supply the cornea with oxygen is close to natural;
- significant increase in wearing comfort.
These three major benefits are the main achievement of the creators of the silicone hydrogel contact lenses.
Who will benefit from the invention of silicone hydrogel lenses?
The most important and long-awaited breakthrough – the opportunity for several days to remove the lens. And even given the fact that many ophthalmologists recommend to not abuse this opportunity — reviews that receive silicone hydrogel contact lenses, mostly only positive.
First, the lenses are useful to people with non-standard work schedule. Is both sellers and managers of sales areas, service workers, security guards and many other occupations. And also for people working under the schedule days through three, etc.. These lenses are and conventional transparent, colored, astigmatic, so the circle of people who can use them is quite wide.
It is worth noting the advantages for students, especially during the sessions, and people leading an active lifestyle.
Important! Particularly useful lenses for extended wear people whose life is connected with frequent travel. As you know, the road is not always there are conditions to change lenses and because it is not always possible to use only daily lenses.
Otherwise, the choice of the type of lens is the taste. However, there is no argument that would not speak in favor of a more modern and progressive solutions.
A little criticism
Of course, the disadvantages are not deprived and the most modern contact optics.
The main drawback, which have yet to have a silicone hydrogel contact lens – the price is 4 times higher than that of its predecessors, does not contain silicone, and therefore wearing lenses will cost twice as much.
The second problem is the relatively long habituation of the eye to the lens. It is associated with greater elasticity of the material.
Next is that the lens is not enough water for the whole life, and it starts to dry out, which leads to deterioration of the supply the cornea with oxygen. At least this issue can be found on the first generations of these lenses.
And finally, there is a certain percentage of people with sensitivities to silicone, and if this intolerance is not installed in advance, the use of lenses can lead to dangerous allergic reactions.
To reassure potential buyers, it is worth noting that this is the shortest list of faults in the entire history of contact lenses.
Another feature is a small circle manufacturers in the world, few firms produce silicone hydrogel contact lenses. But among them big names such as Johnson & Johnson, Biomedics, PureVision, Air Optix VizoTeque Supreme and some others. And this dear part of the producers, perhaps, is the best guarantee that quality so useful to high-tech product.