Court: U.S. Court of Appeals for the Federal Circuit

Docket: 23-2173

Opinion Date: June 30, 2025

Eye Therapies, LLC owns the ‘742 patent, which describes a method to reduce eye redness using a low-concentration dose of brimonidine. The independent claims of the patent specify that the method consists essentially of administering brimonidine at certain concentrations. During patent prosecution, the examiner initially rejected the claims for being anticipated by prior art, specifically U.S. Patent No. 6,242,442 (Dean), which disclosed the use of brimonidine in combination with another active ingredient, brinzolamide. The applicant amended the claims to replace “comprising” with “consisting essentially of” and argued that the claimed methods did not require any other active ingredients besides brimonidine. The examiner allowed the amended claims based on this representation.

The Patent Trial and Appeal Board (PTAB) instituted an inter partes review on petition by Slayback Pharma, LLC and concluded that all challenged claims were unpatentable. The Board interpreted the phrase “consisting essentially of” to allow the inclusion of additional active ingredients that do not materially affect the basic and novel properties of the invention. Based on this construction, the Board found that the prior art taught or suggested each limitation of the challenged claims and that a person of ordinary skill in the art would have had a reasonable expectation of success in combining the references.

The United States Court of Appeals for the Federal Circuit reviewed the case and reversed the Board’s claim construction. The court held that the phrase “consisting essentially of” in the ‘742 patent should be interpreted to exclude the use of active ingredients other than brimonidine, based on the prosecution history. The court vacated the Board’s obviousness finding and remanded the case for further proceedings consistent with the corrected claim construction.