New Developments In Contact Lenses
Contact Lens Care : Cleaning Contact Lenses After Wearing
There are continuous developments in the field of contact lenses. In 1999, silicon hydrogel contact lenses were introduced, which allow a higher oxygen permeability to the cornea. These lenses can be worn overnight and in some cases for 30-days. Now there is a rigid gas-permeable contact lens that can correct nearsightedness by temporarily reshaping the cornea.
Some optometrists have used conventional daily-wear rigid lenses to reshape corneas, for several decades. This is systemized with the Ortho-K contact lens, which are able to reshape the cornea by using a series of lenses that apply pressure to the cornea.
When the results are achieved, use of daily-wear maintenance lens is necessary to reshape the cornea, but you only need to wear them part of the day.
There are increased risks of corneal ulcers for contact lenses wearers who wear them overnight, though they are more convenient in other respects. When the eyes are open, tears carry adequate oxygen to the cornea to keep it healthy.
But during sleep, the eye produces fewer tears, which can cause the cornea to swell. Under rigid contact lens during sleep, the flow of tears and oxygen to the cornea is reduced.
This is less so in the case of soft extended-wear lenses, but they are porous and allow some tears through during sleep. Because they have so little form, their binding has little effect on the shape of the eye.
The FDA has approved the use of silicone hydro-gel contact lasers overnight, and in some cases for up to 30-days, since they are more permeable to oxygen.
It's easier to get used to soft lenses than rigid lenses, because they conform to the eye more easily. Rigid lenses generally give clearer vision. They don't rip or tear, so they're easy to handle. Both soft and rigid lenses can be made to fill a prescription for bifocal correction. In some models, each lens corrects for near and distance vision.
For patients who produce a higher level of protein in their eyes or don't take as good care of their lenses, it might be healthier to replace the lenses more frequently.
Different types of contact lenses are available for different patients. These include disposable contact lenses, and those that are cleaned several times and then disposed of. In the U.S. contact lens marketplace, 82 percent wear soft lenses, 16 percent wear rigid gas-permeable, and 2 percent wear the old-fashioned hard contact lenses.