Material Selection – based upon oxygen permeability – has been divided into three categories, all pertaining to fluoro-silicone/acrylate materials:¹

Low Dk (25 – 49). These materials have the benefit of rigidity and flexural resistance. They are a viable option for daily wear myopic patients.

High Dk (50 – 99). These materials are best indicated for daily wear hyperopic patients (i.e., a +3D lens has approximately twice the center thickness of a -3D lens; hence, a material with twice the Dk of a -3D lens is necessitated. Likewise, corneal multifocal and keratoconic/post-surgical patients benefit as well.

Hyper Dk (≥ 100). These materials are indicated for all extended wear – including overnight wear of orthokeratology designs – and scleral lenses.