Eye Therapies, LLC v. Slayback Pharma, LLC

United States Court of Appeals
for the Federal Circuit
______________________
EYE THERAPIES, LLC,
Appellant
v.
SLAYBACK PHARMA, LLC,
Appellee
______________________
2023-2173
______________________
Appeal from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. IPR2022-
00142.
______________________
Decided: June 30, 2025
______________________
JAMES R. BARNEY, Finnegan, Henderson, Farabow,
Garrett & Dunner, LLP, Washington, DC, argued for ap-
pellant. Also represented by BRYAN DINER, JUSTIN JAMES
HASFORD, CHRISTINA JI-HYE YANG; CHARLES E. LIPSEY,
Reston, VA.
KEVIN P. MARTIN, Goodwin Procter LLP, Boston, MA,
argued for appellee. Also represented by ELAINE BLAIS,
WILLIAM EVANS, ROBERT FREDERICKSON, III; LINNEA P.
CIPRIANO, New York, NY.
______________________
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 2
Before TARANTO and STOLL, Circuit Judges, and SCARSI,
District Judge.1
SCARSI, District Judge.
Appellant Eye Therapies, LLC (“Eye Therapies”) ap-
peals from a final written decision of the Patent Trial and
Appeal Board (the “Board”) holding all claims of U.S. Pa-
tent No. 8,293,742 (“the ’742 patent”) unpatentable. Eye
Therapies challenges (1) the Board’s construction of the
phrase “consisting essentially of” and (2) the Board’s con-
clusion that all claims of the ’742 patent would have been
obvious over the prior art. For reasons explained below, we
reverse the Board’s claim construction of the “consisting es-
sentially of” limitation, vacate its obviousness finding, and
remand for further proceedings.
BACKGROUND
Eye Therapies owns and licenses the ’742 patent, which
teaches a method to reduce eye redness using a low-concen-
tration dose of brimonidine.2 ’742 patent col. 22 ll. 17–21,
25–32. As relevant to the appeal, independent claims 1 and
3 recite:
1. A method for reducing eye redness consisting es-
sentially of administering brimonidine to a patient
1 Honorable Mark C. Scarsi, District Judge, United
States District Court for the Central District of California,
sitting by designation.
2 Brimonidine is an alpha-adrenergic receptor ago-
nist, a category of compounds known to cause vasocon-
striction. ’742 patent col. 1 ll. 60–63. Vasoconstriction
counteracts vasodilation, or “[d]ilation of small blood ves-
sels,” a condition that “causes many clinically undesirable
events” including “surface hemorrhage and hyperemia fol-
lowing Lasik surgery” and “eye redness (conjunctival hy-
peremia).” Id. col. 1 ll. 6–9.
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 3
having an ocular condition, wherein brimonidine is
present at a concentration between about 0.001%
weight by volume and about 0.05% weight by vol-
ume.
3. A method for reducing eye redness consisting es-
sentially of topically administering to a patient
having an ocular condition a composition consisting
essentially of brimonidine into ocular tissue,
wherein pH of said composition is between about
5.5 and about 6.5, wherein said brimonidine con-
centration is between about 0.001% and about
0.025% weight by volume and wherein said compo-
sition is formulated as an ocular drop.
’742 patent col. 22 ll. 17–21, 25–32 (emphases added).
During patent prosecution, the examiner rejected prior
versions of these claims that used “comprising” instead of
“consisting essentially of.” The examiner found that the
claims that used “comprising” were anticipated by U.S. Pa-
tent No. 6,242,442 (“Dean”), which discloses the admin-
istration of brimonidine and brinzolamide to treat ocular
diseases. J.A. 1033–35. In response, the applicant re-
placed “comprising” with the phrase “consisting essentially
of,” among other amendments. J.A. 1049. The applicant
then argued that Dean only disclosed the use of brimoni-
dine in combination with brinzolamide. J.A. 1053.
Whereas Dean required brinzolamide as “an active ingre-
dient” in addition to brimonidine, the applicant explained
that the revised claims “do not require the use of any other
active ingredients (emphasis added) in addition to brimoni-
dine.” Id. The examiner allowed the amended claims, cit-
ing the applicant’s representation “that the presently
claimed methods do not require the use of any other active
ingredients (emphasis added) in addition to brimonidine.”
J.A. 1082.
On petition by Appellee Slayback Pharma, LLC (“Slay-
back”), the Board instituted an inter partes review of
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 4
claims 1–6 of the ’742 patent and entered a final written
decision determining all challenged claims were unpatent-
able. J.A. 2–3, 166. On claim construction, “the parties dis-
pute[d] whether the scope of the claims includes the use of
additional drugs along with low-dose brimonidine.” J.A.
12. The Board noted that “the use of ‘consisting essentially
of’ ‘signals that the invention necessarily includes the
listed ingredients [but] is open to unlisted ingredients that
do not materially affect the basic and novel properties of
the invention,’” in accordance with the phrase’s typical
meaning. Id. (alteration in original) (quoting PPG Indus.
v. Guardian Indus. Corp., 156 F.3d 1351, 1354 (Fed. Cir.
1998)). The Board rejected Eye Therapies’ arguments that
the prosecution history demonstrated that “consisting es-
sentially of” in this context should be read to claim a
method for administering brimonidine as the sole active in-
gredient, reasoning:
During prosecution, the patentee asserted that
“[o]ne of the basic and novel characteristics of the
presently claimed methods is that they do not re-
quire the use of any other active ingredients (em-
phasis added) in addition to brimonidine.” But,
unlike Patent Owner, we do not read the prosecu-
tion history as prohibiting the use of any other ac-
tive ingredients besides brimonidine. To do so
would construe the semi-open-ended transition
phrase “consisting essentially of” to have the same
scope as the closed transition phrase “consisting
of.”
J.A. 14 (alteration in original) (citations omitted). Instead,
the Board concluded that “under the proper scope of the
claims and consistent with the prosecution history, the
claimed methods cannot include additional active ingredi-
ents that are required to perform the method.” Id. (empha-
sis added).
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 5
Applying our decision in Ecolab, Inc. v. FMC Corp., 569
F.3d 1335 (Fed. Cir. 2009), the Board reasoned that “be-
cause the Specification states that low-dose brimonidine
alone can significantly reduce hyperemia, if there are addi-
tional agents beyond low-dose brimonidine administered to
a patient that may also reduce eye redness . . . those addi-
tional agents would not materially affect the basic and
novel characteristics of the invention.” J.A. 15. Accord-
ingly, the Board held that “the transitional phrase ‘consist-
ing essentially of’ does not preclude the use of additional
active agents that may also cause vasoconstriction and re-
duction of hyperemia along with low-dose brimonidine.”
J.A. 15–16.
Applying this construction, the Board concluded “that
the combination of [the prior art] teach[es] or suggest[s]
each limitation of the challenged claims and a [person of
ordinary skill in the art] would have had a reason to com-
bine the references with a reasonable expectation of suc-
cess.” J.A. 52–53.3
Eye Therapies timely filed this appeal. We have juris-
diction pursuant to 28 U.S.C. § 1295(a)(4)(A).
STANDARD OF REVIEW
“We review de novo the Board’s ultimate claim con-
structions and any supporting determinations based on in-
trinsic evidence,” and “[w]e review any subsidiary factual
findings involving extrinsic evidence for substantial evi-
dence.” Personalized Media Commc’ns, LLC v. Apple Inc.,
952 F.3d 1336, 1339 (Fed. Cir. 2020).
Obviousness is a “mixed question of law and fact.” Ho-
logic, Inc. v. Smith & Nephew, Inc., 884 F.3d 1357, 1361
(Fed. Cir. 2018). We review the Board’s ultimate
3 The Board also resolved other issues not relevant
to this appeal. J.A. 16–40.
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 6
obviousness determination de novo and its underlying find-
ings of fact for substantial evidence. Id.
DISCUSSION
We conclude the Board erred in its construction of the
phrase “consisting essentially of” as allowing the coadmin-
istration of active ingredients other than brimonidine.
Given the prosecution history, we interpret the phrase as
used in the ’742 patent to preclude the use of active ingre-
dients other than brimonidine. Because the Board’s obvi-
ousness analysis materially relied on its erroneous claim
construction, we cannot affirm the Board’s unpatentability
determination. We reverse the Board’s claim construction,
vacate the Board’s decision, and remand the matter to the
Board.
A. Claim Construction
The central dispute on appeal is the meaning of limit-
ing claim language “consisting essentially of.” Eye Thera-
pies contends that this transition phrase “should be
construed to exclude active ingredients other than brimoni-
dine in the claimed method.” Appellant’s Br. 29. Slayback
argues that the Board properly construed “consisting es-
sentially of” in line with our caselaw interpreting the
phrase and the patent prosecution history. Appellee’s Br.
25.
Claim terms “are generally given their ordinary and
customary meaning” as understood by “a person of ordi-
nary skill in the art in question at the time of the inven-
tion.” Phillips v. AWH Corp., 415 F.3d 1303, 1312–13 (Fed.
Cir. 2005) (en banc) (internal quotation marks and citation
omitted). “Claim construction requires a determination as
to how a person of ordinary skill in the art would under-
stand a claim term ‘in the context of the entire patent, in-
cluding the specification.’” Trs. of Columbia Univ. v.
Symantec Corp., 811 F.3d 1359, 1362 (Fed. Cir. 2016)
(quoting Phillips, 415 F.3d at 1313).
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 7
Generally, the term “comprising” is an open-ended
transitional term that allows for additional steps. Invitro-
gen Corp. v. Biocrest Mfg., L.P., 327 F.3d 1364, 1368 (Fed.
Cir. 2003). On the other hand, the transitional phrase
“consisting essentially of” generally “has long been under-
stood to permit inclusion of components not listed in the
claim, provided that they do not ‘materially affect the basic
and novel properties of the invention.’” AK Steel Corp. v.
Sollac, 344 F.3d 1234, 1239 (Fed. Cir. 2003) (quoting PPG
Indus., 156 F.3d at 1354). However, “a patentee can alter
that typical meaning”; for example, the patentee can make
the intended meaning clear in the specification or disclaim
an alternative meaning in the prosecution history. Ecolab,
569 F.3d at 1343–44. Limiting statements in the patent
prosecution history can “inform the meaning of the claim
language by demonstrating how the inventor understood
the invention and whether the inventor limited the inven-
tion in the course of prosecution, making the claim scope
narrower than it would otherwise be.” Phillips, 415 F.3d
at 1317.
Eye Therapies contends the prosecution history sup-
ports an atypical meaning of “consisting essentially of,” as
the applicant “expressly argued that the amended claims
preclude the use of other active ingredients and that a basic
and novel property of the invention is the administration
of brimonidine without other therapeutic drugs.” Appel-
lant’s Br. 30. We agree with Eye Therapies that the pros-
ecution history informs an atypical meaning of “consisting
essentially of” in the ’742 patent.
Following the examiner’s rejection of the ’742 patent
over Dean, the applicant amended the claims, replacing
“comprising” with “consisting essentially of.” J.A. 1049.
The applicant explained that the amendment distin-
guished the claims from Dean, which “does not disclose a
method . . . which consists essentially of administering to a
patient with an ocular condition brimonidine . . . or a phar-
maceutical composition consisting essentially of
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 8
brimonidine.” J.A. 1053. The applicant explained that the
innovation in the “claimed methods is that they do not re-
quire the use of any other active ingredients (emphasis
added) in addition to brimonidine.” Id. In allowing the
claims, the patent examiner echoed the applicant’s repre-
sentation “that the presently claimed methods do not re-
quire the use of any other active ingredients (emphasis
added) in addition to brimonidine, thereby instating the
‘consisting essentially of’ language.” J.A. 1082 (citation
omitted).
Even if these representations to the examiner “do not
rise to the level of unmistakable disavowal, they do inform
the claim construction.” Shire Dev., LLC v. Watson
Pharms., Inc., 787 F.3d 1359, 1366 (Fed. Cir. 2015). “[A]n
applicant’s amendment accompanied by explanatory re-
marks can define a claim term by demonstrating what the
applicant meant by the amendment.” Personalized Media
Commc’ns, 952 F.3d at 1340. For example, arguments ad-
vanced in prosecution “to convince the examiner that the
claimed invention meets the statutory requirements of nov-
elty, utility, and nonobviousness” can limit claim interpre-
tation. Standard Oil Co. v. Am. Cyanamid Co., 774 F.2d
448, 452 (Fed. Cir. 1985).
The only material difference in the language circum-
scribing the scope of the rejected claims and the allowed
amended claims is the replacement of the open-ended term
“comprising” with the less-open phrase “consisting essen-
tially of.” As confirmed by the examiner’s repetition of and
maintained emphasis on the applicant’s representations,
the applicant secured allowance of the amended claims by
arguing that the claimed methods were novel because they
“do not require the use of any other active ingredients.” This
promotes a more restrictive interpretation of “consisting
essentially of” than our precedents interpreting the typical
use of the phrase would prescribe. Whereas an interpreta-
tion applying the standard meaning might permit addi-
tional unlisted active ingredients, the applicant persuaded
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 9
the examiner of the novelty of the claims by underscoring
the absence of other active ingredients in the claimed meth-
ods.
The strongest indicators of a more-restrictive-than-typ-
ical interpretation of the phrase “consisting essentially of”
are the applicant’s arguments on amendment contrasting
the claimed methods and Dean’s:
Dean is directed to the combinational use of
brimonidine and brinzolamide, and there is noth-
ing in the reference that would lead a person hav-
ing ordinary skill in the art to omit one of the two
essential components of the Dean’s compositions to
arrive at the claimed methods. Moreover, Dean
teaches away from methods consisting essentially
of administering brimonidine (i.e., methods which
do not include administering other active agents).
J.A. 1061–62 (second emphasis added); see also J.A. 1055
(“Thus, Dean . . . does not teach any methods of treating
any conditions by administering a pharmaceutical compo-
sition consisting essentially of brimonidine (i.e., a pharma-
ceutical composition which does not include any other
active agents).” (emphasis added)). “[U]se of ‘i.e.’ signals an
intent to define the word to which it refers.” Edwards
Lifesciences LLC v. Cook Inc., 582 F.3d 1322, 1334 (Fed.
Cir. 2009); see also Rembrandt Wireless Techs., LP v. Sam-
sung Elecs. Co., Ltd., 853 F.3d 1370, 1376 (Fed. Cir. 2017)
(“A patentee’s use of ‘i.e.,’ in the intrinsic record . . . is often
definitional.”). The applicant’s use of “i.e.” here indicates
an intent to define the claimed “methods consisting essen-
tially of brimonidine” as “methods which do not include ad-
ministering other active agents.” In this way, the standard
meaning of “consisting essentially of” is incompatible with
the more restrictive meaning the applicant ascribed to the
phrase.
Ecolab, which the Board analogized to reach a different
result, is consistent with our conclusion. In Ecolab, we
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 10
interpreted a method for sanitizing fowl using a solution
“which consists essentially of . . . peracetic acid” not to be
limited to compositions containing peracetic acid as the
sole antimicrobial agent. 569 F.3d at 1342–44. We rejected
a party’s argument for departing from the typical interpre-
tation of “consisting essentially of,” reasoning that the pa-
tent specification provided examples describing
compositions that contain antimicrobial agents other than
peracetic acid. Id. at 1343–44. In other words, we found
that the intrinsic evidence was irreconcilable with the al-
ternative meaning the party advanced.4 In contrast, the
prosecution history here strongly evinces a restrictive
meaning of “consisting essentially of.” Admittedly, other
aspects of the intrinsic record are less conducive to the con-
struction. Our construction would not embrace some em-
bodiments in the ’742 patent specification that describe
compositions containing active ingredients other than
brimonidine. E.g., ’742 patent col. 9 ll. 35–42. But an atyp-
ically restrictive construction of “consisting essentially of”
remains compatible with other embodiments that describe
compositions in which brimonidine is the only active ingre-
dient. E.g., id. col. 10 ll. 3–8. And it is hardly surprising
or unusual that a specification written with broader claim
language (“comprising”) would contain embodiments no
longer compatible with narrowed claim language adopted
4 The Board rested its Ecolab analogy on the specifi-
cation’s statement “that low-dose brimonidine alone can
significantly reduce hyperemia,” reasoning that “if there
are additional agents . . . those additional agents would not
materially affect the basic and novel characteristics of the
invention.” J.A. 15 (emphasis added). The contingency the
Board identifies extends well beyond the text of the speci-
fication. And while the Board’s logic is consistent with the
typical meaning of “consisting essentially of,” it does not
foreclose the more restrictive meaning the prosecution his-
tory supports.
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 11
during prosecution (“consisting essentially of”) accompa-
nied by a clear narrowing explanation, as here. Such ac-
tions, post-dating the filing of the specification, naturally
can and often do result in claims that do not cover all em-
bodiments in the specification. The fact that our construc-
tion does not encompass all alternative embodiments does
not foreclose its application, especially given its compelling
support in the prosecution history. TIP Sys., LLC v. Phil-
lips & Brooks/Gladwin, Inc., 529 F.3d 1364, 1373 (Fed.
Cir. 2008); see also Pacing Techs., LLC v. Garmin Int’l, Inc.,
778 F.3d 1021, 1026 (Fed. Cir. 2015) (“[W]here the patent
describes multiple embodiments, every claim does not need
to cover every embodiment.”).
Slayback argues that the applicant told the examiner
only that the amended claims do not require the use of any
other active ingredients, not that they preclude the use of
such ingredients. Appellee’s Br. 29. We rejected a similar
argument in Aylus Networks, Inc. v. Apple Inc., 856 F.3d
1353 (Fed. Cir. 2017). There, a patentee made “repeated
statements” in an inter partes review proceeding that its
claims “require that . . . only the [CPP logic] be invoked.”
856 F.3d at 1363 (ellipsis in original). We dismissed the
patentee’s argument that these statements could “reason-
ably be interpreted to mean that ‘only’ the CPP logic is re-
quired to be invoked in those claims—not that the
[conceptually distinct] CP logic is precluded from being in-
voked.” Id. We found the patentee’s interpretation unrea-
sonable given the context in which it made its concessions,
which did “not change the plain meaning of [the] disavow-
ing statements.” Id.5 So too here. Given the applicant’s
5 We applied prosecution history estoppel in Aylus,
856 F.3d at 1362–64. We do not apply that doctrine here,
even as we employ the prosecution history to inform the
claim construction. See Shire Dev., 787 F.3d at 1366 (dis-
tinguishing between prosecution history statements that
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 12
arguments distinguishing Dean and definitional use of
“i.e.” to equate its claimed “methods consisting essentially
of administering brimonidine” with “methods which do not
include administering other active agents,” J.A. 1055,
1061–62 (emphasis added), the appropriate interpretation
of the applicant’s representation that the claimed methods
“do not require” agents other than brimonidine, J.A. 1053,
1082, is that its claimed methods preclude the use of such
agents.
Accordingly, we reverse the Board’s claim construction.
We read the transition phrase “consisting essentially of” as
used in claims 1 and 3 of the ’742 patent to exclude use of
active ingredients other than brimonidine.
B. Obviousness
The Board’s erroneous claim construction infected its
consideration of facts in its obviousness analysis. For ex-
ample, the Board considered Dean and two other prior art
references—Richard A. Norden, Effect of Prophylactic
Brimonidine on Bleeding Complications and Flap Adher-
ence after Laser in situ Keratomileusis, 18 J. REFRACTIVE
SURGERY 468 (July/Aug. 2002) (“Norden”), and U.S. Patent
No. 6,294,553 (“Gil”)—all of which involved compositions
including active agents other than brimonidine, as teach-
ing toward the use of brimonidine alone. J.A. 42, 54. The
Board reasoned that “[a]lthough Norden and Gil may also
teach the possibility of co-administering pain medication,
steroids, and antibiotics, . . . the claims—when properly
construed—do not preclude administering other drugs that
do not materially affect the basic and novel characteristics
of the claims.” J.A. 54. Under the appropriate construction
of “consisting essentially of,” the claimed methods exclude
constitute “unmistakable disavowal” and those that “in-
form the claim construction”). Notwithstanding, our rea-
soning in Aylus is helpful to address Slayback’s argument.
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 13
compositions that contain active agents other than
brimonidine, undermining the Board’s conclusion.
One final point bears discussion. As Slayback points
out, the Board was careful to note that “even if the claim
term ‘consisting essentially of’ were construed to preclude
agents that reduced eye redness, Norden suggests that
those additional agents do not affect brimonidine’s redness-
reducing action and, would therefore, still satisfy the ‘con-
sisting essentially of’ limitation.” J.A. 54 n.24. But this
fallback position still relies upon a construction of “consist-
ing essentially of” inconsistent with the prosecution his-
tory. After all, Dean teaches co-administration of
brimonidine with an active ingredient that does not reduce
redness, brinzolamide. Dean col. 2 ll. 21–29, col. 3 ll. 26–
43. By amending the claims to include the phrase “consist-
ing essentially of” to overcome Dean, the applicant inten-
tionally sought to limit the claims to exclude applications
with any other active agent, whether or not the agent ad-
dresses eye redness.
We do not prejudge whether the correct claim construc-
tion permits the same factual findings or obviousness con-
clusion. We do note, however, that because the Board
applied an erroneous claim construction, it had no occasion
to consider whether, under the prior art, a person of ordi-
nary skill in the art would have been motivated to employ
a method with the properly understood limitation signified
by the ’742 patent’s use of “consisting essentially of.” “We
conclude that the appropriate course in this case, as in so
many others involving a reversal of a Board claim construc-
tion, is to vacate the Board’s decision and remand the mat-
ter.” Kaken Pharma. Co., Ltd. v. Iancu, 952 F.3d 1346,
1355 (Fed. Cir. 2020).
CONCLUSION
For the foregoing reasons, we reverse the Board’s claim
construction, vacate the Board’s final written decision, and
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EYE THERAPIES, LLC v. SLAYBACK PHARMA LLC 14
remand the matter to the Board for further proceedings
consistent with the construction provided above.
Costs awarded to appellant.
REVERSED IN PART, VACATED, AND
REMANDED
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