What is a good DK T?
Papas found that a Dk/t of 125 was necessary to avoid limbal injection. Morgan and Efron stated that Dk/t levels need to be approximately 20 and 33 for the central and peripheral portions of a soft lens, respectively, in order to avoid edema with daily wear. These Dk/t levels are summarized in figure 1.
What is a good DK T for contacts?
Today’s silicone hydrogel lenses feature oxygen permeability levels of around 150 Dk/t. A high oxygen permeability ensures that your cornea will receive a lot of oxygen, which it needs to keep your eyes as healthy as possible.
What is the minimum DK t required for silicone hydrogel lenses?
In none of these studies was there a difference reported. This suggests that, not only is the criterion of 125 of little relevance in the clinical world, but that a figure of 37, the minimum peripheral Dk/t found in DW silicone-hydrogel lenses, is adequate to avoid clinically important open-eye limbal redness.
What is good oxygen permeability for contacts?
These days, typical values of oxygen permeability for hydrogel contact lenses range from 25 to 50.
What does DK and Dk / t value mean?
The Dk value measures oxygen permeability, the Dk/t value measures oxygen transmissibility of a contact lens. Dk/t is calculated from the oxygen permeability (Dk) of the material and the thickness (t) of the contact lens.
What’s the Dk / t value of a contact lens?
The contact lens specification sheets on Optix-now usually show the Dk/t value for a lens at -3.00D. Most manufacturers provide a Dk/t value for the -3.00D version of a lens. That way it is easier to compare lenses from different manufacturers.
How does Dk / t work in the laboratory?
But while Dk/t tells us exactly how much oxygen passes through a contact lens on the laboratory bench, that does not replicate the on-eye situa- tion. Many people also used equivalent oxygen potential or percentage (EOP), which predicts the partial pressure of oxygen at the front surface of the cornea.
What is the Dk value of Nelfilcon A?
Oxygen permeability. For example, Nelfilcon A has a Dk value of 26, and the Omafilcon A has a Dk of 25. While those numbers are typical of hydrogel contact lenses, many contact lenses are made of silicone hydrogel, which has a much higher oxygen permeability. For example, the Dk value of Lotrafilcon B and Comfilcon A, two silicone hydrogels,…
