U.S. Patent 7,884,228: UV-absorbers for ophthalmic lens materials.

Texas Business reports:  A Fort Worth man received a patent for inventing a method for blocking harmful ultraviolet rays in contact lens and intraocular lens.

Walter R. Laredo of Fort Worth received U.S. Patent number 7,884,228 for “UV-absorbers for ophthalmic lens materials.”

He applied for the patent May 5, 2009.

Alcon Inc. was the assignee of the patent.

The  summary of the invention states:  The present invention provides UV absorbers that block not only UV light but also light in the 400-450 nm range. These UV absorbers are suitable for use in ophthalmic devices, including contact lenses, and are particularly useful in implantable lenses, such as intraocular lenses (IOLs). The UV absorbers of the present invention are copolymerizable with other ingredients in ophthalmic device formulations.

The UV absorbers of the present invention provide the following benefits. They absorb wavelengths of light between 400-450 nm in addition to UVA rays between 400-320 nm, UVB rays between 320-280 nm, and UVC rays below 280 nm.

They also contain reactive groups, which allow for covalent attachment of the UV absorber to the ophthalmic lens material. Finally, the UV absorbers of the present invention can be readily synthesized in relatively simple steps (e.g., 2-4) from relatively inexpensive starting materials.

The background of the patent states:  Many UV light absorbers are known as ingredients for polymeric materials used to make ophthalmic lenses. UV absorbers are preferably covalently bound to the polymeric network of the lens material instead of simply physically entrapped in the material to prevent the absorber from migrating, phase separating or leaching out of the lens material. Such stability is particularly important for implantable ophthalmic lenses where the leaching of the UV absorber may present both toxicological issues and lead to the loss of UV blocking activity in the implant.

Numerous copolymerizable benzatriazole, benzophenone and triazine UV absorbers are known. Many of these UV absorbers contain conventional olefinic polymerizable groups, such as methacrylate, acrylate, methacrylamide, acrylamide or styrene groups. Copolymerization with other ingredients in the lens materials, typically with a radical initiator, incorporates the UV absorbers into the resulting polymer chain. Incorporation of additional functional groups on a UV absorber may influence one or more of the UV absorber's UV absorbing properties, solubility or reactivity. If the UV absorber does not have sufficient solubility in the remainder of the ophthalmic lens material ingredients or polymeric lens material, the UV absorber may coalesce into domains that could interact with light and result in decreased optical clarity of the lens.

In addition to blocking UV light, some ophthalmic lenses also block blue light.  

There is a need for UV absorbers that are capable of blocking not only UV light (400 nm and below) but also blocking at least some light in the 400-450 nm range.