Link to Case: Haag-Streit AG v. Eidolon Optical, LLC

In Haag-Streit AG v. Eidolon Optical, LLC, the United States Court of Appeals for the Federal Circuit affirmed the validity of claims of U.S. Patent No. 6,547,394 ('394 Patent) challenged in an inter partes review.

The challenged claims recited a device that illuminates a patient's eye while examining it for epithelial defects. Specifically, the device uses a blue LED instead of an incandescent lamp with a halogen bulb to achieve greater fluorescence at a lower power. Claim 1 of the '394 patent recites:

  1. An ophthalmic illuminator, comprising:

    a battery;
    an electrical resistor in circuit with the battery;
    an electrical switch in circuit with the resistor;
    at least one light emitting diode, in circuit with the switch, for generating blue light energy in response to activation of the switch; and a fluorescin dye administered to a patient's eye, the dye being responsive to the energy to fluoresce.

The IPR Decision

As part of its IPR petition, Haag-Streit argued that the challenged claims were obvious based on European Patent Application 0 554 643 A1 (Longobardi), which discloses "an apparatus for visualizing an object and/or recording images of said object under low lighting conditions." The Longobardi reference also mentions the advantages of using the blue light spectrum (465 and 490 nm) in conjunction with fluorescin dye.

Longobard also discloses using LEDs in place of a continuous light source. But the Patent Trial and Appeal Board (PTAB) rejected Haag-Streit's argument that Longobardi implicitly disclosed a blue LED with sufficient power output to cause sodium fluorescein to fluoresce. Therefore, they found the '394 patent valid as nonobvious. They found the limitations of Longobardi sufficient to the point where the two embodiments did not depict "identical embodiments of the same invention with different light sources." The PTAB also looked to Haag-Streit's expert testimony, finding it unsupportive of Longobardi implicitly disclosing a blue LED. Finally, it noted that Haag-Streit had not proven that a blue LED with sufficient power output existed when Longobardi was filed.

CAFC Analysis

The CAFC began its analysis by citing In re Burckel, noting that a prior art reference "must be considered not only for what it expressly teaches, but also for what it fairly suggests." It reiterated that determining whether a person of ordinary skill in the art (POSITA) would view a prior art reference as containing an implicit disclosure is a fact question.

Not Identical Embodiments

The PTAB believed, and the CAFC agreed, that Longobardi was more limited than the '394 embodiment. Specifically, it noted that Longobardi teaches an embodiment with three LEDs, but not the same functionality is inherent. Namely, "the presence of blue light to cause sodium fluorescence to fluoresce."

The CAFC declined to reweigh the evidence, finding that the PTAB's decision was supported by substantial evidence.

Expert Testimony does not Support Obviousness

The CAFC also agreed with the PTAB that the expert testimony did not support the position that a POSITA would find implicit disclosure of a blue LED in Longobardi. It noted that none of the expert, Dr. Jiao's, expert testimony "actually addresses the state of the art of blue LEDs in 1992," which Haag-Streit had acknowledged being relevant in the determination of implicit disclosure.

Haag-Streit argued that this determination that "none of Dr. Jiao's testimony supports the contention that Longobardi implicitly discloses a blue LED" was inconsistent with findings in the PTAB's Institution Decision. But the CAFC noted that "the Board is not bound by any findings made in its Institution Decision." Even so, it also disagreed with the premise, finding that the decision only mentions Dr. Jiao "[taking] the position that one of ordinary skill in the art would view Longobardi as at least implicitly teaching or suggesting the use of a blue LED to generate blue light energy," but that Eidolon's expert created an issue of material fact a POSITA would not have used a blue LED for medical use.

Haag-Streit did not Carry its Burden to Establish the Existence of Capable Blue LEDs

The CAFC also agreed with the PTAB's final finding that Haag-Streit had not carried its burden in establishing that "a blue LED with sufficient power output to cause sodium fluorescein to fluoresce existed as of February 5, 1992." On the other hand, Eidolon presented expert testimony conveying that "blue light energy suitable for diagnostic medical applications such as retinal angiography simply did not exist."

While Haag-Streit pointed to three different references to challenge Eidolon's expert testimony, the CAFC noted that the relevant inquiry was whether blue LED with sufficient power output to cause sodium fluorescein to fluoresce existed. It looked to the PTAB's observation that Dr. Jiao admitted that he did not know the specific amount of power output needed for an LED to cause sodium fluorescein to fluoresce and that without knowing the power requirement, Haag-Streit could not have carried its burden in proving the existence of the blue LED from the '394 patent.


Haag-Streit is an interesting nonobviousness case because it involves material from a reference that may not have been a focus of the drafter's mind when they drafted the utility application. While the Longobardi reference disclosed the use of LEDs, the main Figure 1 did not include LEDs, and it appears that the PTAB saw them as a kind of "covering bases" strategy. It is important for drafters broadening beyond the inventor's specific embodiment to think about the current POSITA to determine if they would be enabled to practice the invention. That means that if the alternative embodiment employs non-industry standard techniques, the detailed description should provide details on how the alternative embodiment would be able to function, in this case, receive sufficient power from a blue LED to perform the fluorescence.