What is a rigid silicone-hydrogel?

A rigid silicone-hydrogel is a copolymer of a silicone monomer (like TRIS), a hydrophilic monomer (like HEMA) and a crosslinker. Other modifying monomers may also be present. By varying the monomer ratios, polymers can be made with water contents from 0% to 60%. At low water contents, the polymers are rigid. Increasing the crosslink density prevents the polymer from expanding. Thus the polymer cannot absorb water into the interior of the lens, but the surface can hydrate like a soft silicone-hydrogel lens.

How is a rigid silicone-hydrogel lens different from an ordinary RGP lens?

Standard rigid oxygen permeable lenses contain methacrylic acid (MAA) as a wetting agent to produce low wetting angles; however comfort does not approach that of a hydrogel lens. This is because the surface remains rigid while ionized acid groups attract water to the surface. In a hydrogel lens, water is actually absorbed into the polymer creating a comfortable soft and supple surface. This surface is created in rigid silicone-hydrogel lenses - lenses that approach the comfort of hydrogel lenses because the surface is similar.

How does ONSI-56 compare to hydrophilic surface RGP lenses?

ONSI-56 (onsifocon A) has a higher oxygen permeability (Dk) than the other hydrophilic surface lenses available in the US.

How does ONSI-56 compare to soft silicone-hydrogel lenses?

ONSI-56 (onsifocon A) has a comparable Dk to the most popular daily wear soft silicone-hydrogel lens. Also, ONSI-56 can be custom made in all parameters and lens designs including torics and bifocals.

Are there any special lens care requirements?

Treat ONSI-56 (onsifocon A) lenses like standard RGP lenses – we recommend Lobob Optimum solutions.

Are there any special fitting requirements, recommendations or suggestions?

ONSI-56 (onsifocon A) lenses are fit like standard mid- to high-Dk RGP lenses. Check with your custom lens laboratory fitting consultant for details.

What does the name ONSI signify?

ONSI is named after our black lab mix, Onslow Gehund.