Hydrogel or silicone-hydrogel: What lenses are better?
Nowadays leading manufacturing companies in the sphere of eyesight contact correction, produce a vast number of contact lenses with various designs, properties and wearing schedules.
In some cases patients do not agree with the type of contact lenses, that was prescribed by professional ophthalmologist. For example, the doctor recommend to use hydrogel contact lenses, but the patient insists on silicone-hydrogel, as he believes that if they are newer then they are better. Is he true? Let's try to understand.
According to statistics, in 2011 refractionists prescribed hydrogel lenses for about quarter of their patients. The others were recommended to use lenses, manufactured from silicone-hydrogel material. However, disposable daily lenses were not even included in the statistics.
The large popularity of silicone-hydrogel lenses is explained by the fact that the assortment of these lenses have significantly more new models and it constantly continues to increase. In addition, many of these lenses can be worn in extended schedule and do not require daily care. These doubtless advantages make silicone-hydrogel lenses incredibly famous among all users of contact lenses worldwide.
Fidelity to traditions or popularity?
The growth in demand for silicone-hydrogel lenses is largely due to the high index of oxygen permeability, that makes them breathable and completely excludes the risk of hypoxic damage of eye cornea. The most popular brands and series of contact lenses in this segment are:
- Pure Vision 2HD and Pure Vision 2HD for Astigmatism. These lenses have high definition optical system and their oxygen transmission coefficient is 130 units.
- Air Optix Aqua. These lenses have high value of the coefficient Dk/t - 138 units. In addition, they are distinguished by special moisturizing system. It includes three components: smooth surface with excellent wettability (resistant to protein deposits), lens material (resistant to dehydration) and moisturizing component in the solution, that is poured in blister.
- Biofinity. These lenses are perfectly balanced by all the basic indices. They have high index of oxygen permeability – 125 units, high wettability and a low modulus of elasticity.
It would seem that if there are contact lenses with such outstanding qualities, the hydrogel lenses should become a thing of the past. But it does not happens, because there are many users that prefer to use hydrogel lenses and highly appreciate their significant advantages.
The material of these lenses is a special polymeric frame, filled with water. It is called as hydrogel. It differs by unsurpassed softness, that ensures increased wearing comfort of contact lenses. However, hydrogel lenses has lower degree of oxygen permeability than silicone-hydrogel. For this reason they can be worn only during the daytime and should be removed before going to bed.
Hydrogel monthly lenses IQlens All-Day Comfort are in great demand nowadays. Their distinctive features are high stability to protein and lipid deposits and the ability to maintain a sufficient amount of moisture on the lens surface during the whole period of use (lenses lose not more than 1% of water even in unfavourable conditions).
ProClear 1-Day is another model of hydrogel lenses, that is very convenient and safe in wearing. It is manufactured on the basis of biocompatible polymeric material, that can perfectly maintain the stability of the tear film. The index of oxygen permeability of these lenses is 28 units, moisture content – 60%.
As you can see, the modern market of contact lenses offers a wide range of products. They differ from each other not only by the production material, but also by many other characteristics, that should be considered in the process of selection of contact lenses. It is worth noting that only the professional ophthalmologist can help you to select the most suitable contact lenses according to your personal characteristics.