Tips of Contact Lens
Date:2021.09.18 Views:1164
Tips of Contact Lens
Contact lens replacement methods and materials
Annual disposable ≠ good quality
Annual disposable = worst
Traditional annual contact lenses are made of HEMA, which is the oldest and most traditional material with a water content of 38%. It is true that annual contact lenses are easy to wear, but this is at the expense of water content and oxygen permeability, and they are prone to protein precipitation, which affects corneal health. Contact lens wear is the shorter the time the healthier.
Corneal hypoxia is very common, and redness and dryness of the eyes with oxygen are signs of hypoxia. If the phenomenon is severe, it is best to use lenses made of silicone hydrogel. Many brands now also have silicone hydrogel lenses, but silicone hydrogel is not available in color.
Lenses with too much water also tend to suck water back out of the eyes. So this has always limited the amount of oxygen permeability of contact lenses.
But silicone hydrogel material breaks this limitation by adding silicon to the material, which directly transmits oxygen from the air without relying on the excess of water, making the Dk/t value (oxygen permeability) of the lenses a significant leap forward, resulting in ultra-long continuous wear.
Silicone hydrogel is basically a monthly disposable, and Johnson & Johnson's Advance is a bi-weekly disposable. If you stay up late working, or overnight entertainment, going out to travel or something, is very convenient choice, with sleep that is healthy, care solution is also saved.
Daily Disposable
The market for daily disposable is very big, although daily disposable is old material, not as healthy as silicone hydrogel material. (Because silicone hydrogel is very expensive, made into a daily throw will not be bought) but now generally add from short chain to medium and long chain of water lubrication molecules (such as PVA), can guarantee 14-20 hours of non-drying.
