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In eyewear science, the wet to dry ratio is a measurement used to determine the water content of a contact lens material. By comparing the weight of a fully hydrated lens to the weight of the lens after all moisture has been evaporated, scientists can calculate exactly how much of the lens is composed of water.
read more about wet-to-dry ratio ...The ratio determines how the lens interacts with the eye:
If the wet to dry ratio is not precisely managed, a lens may not expand to the correct size during hydration. This would cause the prescription power to be incorrect, leading to blurry vision for the patient once the lens is on the eye.
While RGP lenses have very low water content, the ratio is still monitored during the development of new polymers. It ensures that the material does not absorb too much tear fluid, which could cause the hard lens to warp or change shape over time.
The lens is placed in a laboratory oven at a controlled temperature until it reaches a constant mass. This ensures that 100 percent of the saline has been removed, providing a pure measurement of the polymer material itself.
A lens with a high wet to dry ratio (typically over 50 percent water) is considered high water content. These lenses are very soft but can dry out faster in windy air.
Yes. In older hydrogel lenses, the water is what carries the oxygen. Therefore, a higher wet to dry ratio meant more oxygen could reach your cornea.
Your eye doctor chooses a lens with a specific ratio based on your tear production. If your eyes are dry, a lens with a lower ratio might stay comfortable for longer.
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