Self-Retained Cryopreserved Amniotic Membrane for the Management of Corneal Ulcers

Abstract

Purpose
To evaluate the clinical outcomes of self-retained cryopreserved amniotic membrane (cAM) for the treatment of corneal ulcers.

Methods
This was a single-center, retrospective review of consecutive patients with non-healing corneal ulcers that underwent treatment with self-retained cAM (PROKERA® Slim). The primary outcome measure was time to complete corneal epithelialization. Ocular discomfort, corneal staining, corneal signs, and visual acuity were assessed at 1 week, 1 month, 3 months, and 6 months. Complications, adverse events, and ulcer recurrence were also recorded.

Results
A total of 13 eyes (13 patients) with recalcitrant corneal ulcers were included for analysis, 9 (69%) of which progressed from neurotrophic keratitis (NK). Prior to cAM application, patients used conventional treatments such as artificial tears (n = 11), antibiotics (n = 11), ointment (n = 11), steroids (n = 6), and antivirals (n = 3). Self-retained cAMs (n = 1.5 ± 0.8) were placed for 6.8 ± 3.4 days, during which time antibiotics were continued. Four cases (31%) were subsequently treated with bandage contact lens (n = 3) and tarsorrhaphy (n = 1). All corneal ulcers healed in a median of 14 days (range: 4–43). This was accompanied by a significant improvement in ocular discomfort, corneal staining, and corneal signs at 1 week, 1 month, 3 months, and 6 months (P<.05). Recurrence was noted in one case. No adverse events were observed.

Conclusion
Self-retained cAM may be a valuable, in-office treatment option for healing recalcitrant corneal ulcers of various etiologies, especially those with underlying NK. Further prospective, controlled studies are warranted.

Full text

ORIGINAL RESEARCH
Self-Retained Cryopreserved Amniotic Membrane
for the Management of Corneal Ulcers
This article was published in the following Dove Press journal:
Clinical Ophthalmology
Daniel Brocks
1
Olivia G Mead
2
Sean Tighe
3,4
Scheffer CG Tseng
2
1
BostonSight, Needham, MA, USA;
2
Ocular Surface Center and TissueTech
Inc, Miami, FL, USA;
3
Department of
Ophthalmology, Florida International
University, Miami, FL, USA;
4
Department
of Biochemistry and Molecular Biology,
University of Miami, Miami, FL, USA
Purpose: To evaluate the clinical outcomes of self-retained cryopreserved amniotic mem-
brane (cAM) for the treatment of corneal ulcers.
Methods: This was a single-center, retrospective review of consecutive patients with non-
healing corneal ulcers that underwent treatment with self-retained cAM (PROKERA
®
Slim).
The primary outcome measure was time to complete corneal epithelialization. Ocular
discomfort, corneal staining, corneal signs, and visual acuity were assessed at 1 week, 1
month, 3 months, and 6 months. Complications, adverse events, and ulcer recurrence were
also recorded.
Results: A total of 13 eyes (13 patients) with recalcitrant corneal ulcers were included for
analysis, 9 (69%) of which progressed from neurotrophic keratitis (NK). Prior to cAM
application, patients used conventional treatments such as artificial tears (n = 11), antibiotics
(n = 11), ointment (n = 11), steroids (n = 6), and antivirals (n = 3). Self-retained cAMs (n =
1.5 ± 0.8) were placed for 6.8 ± 3.4 days, during which time antibiotics were continued. Four
cases (31%) were subsequently treated with bandage contact lens (n = 3) and tarsorrhaphy (n
= 1). All corneal ulcers healed in a median of 14 days (range: 4–43). This was accompanied
by a significant improvement in ocular discomfort, corneal staining, and corneal signs at 1
week, 1 month, 3 months, and 6 months (P<.05). Recurrence was noted in one case. No
adverse events were observed.
Conclusion: Self-retained cAM may be a valuable, in-office treatment option for healing
recalcitrant corneal ulcers of various etiologies, especially those with underlying NK. Further
prospective, controlled studies are warranted.
Keywords: amniotic membrane, corneal ulcer, neurotrophic keratitis, ocular surface disease
Introduction
Like other epithelial barriers of the human body, the corneal epithelium is con-
tinuously self-renewing with a distinct stem cell niche in the limbal basal region.
1
When this protective barrier is subjected to physical, chemical, or biological insult,
corneal epithelial cells briskly undergo proliferation and migration to restore cor-
neal integrity and preserve the ocular surface.
2
While most epithelial defects heal
without complication, co-existing ocular surface conditions can compromise this
regenerative healing process and impair the cornea's ability to restore the epithe-
lium, leading to persistent corneal epithelial breakdown and ulceration. One such
condition, neurotrophic keratitis (NK), involves damage to the corneal nerves that
can diminish corneal epithelial viability and dampen the blinking and tearing
reflexes that maintain ocular surface health.
3,4
This is especially devastating as
corneal nerves and epithelial cells mutually support one another via neuropeptides
Correspondence: Daniel Brocks
BostonSight, 464 Hillside Ave Suite 205,
Needham, MA 02494, USA
Tel +1 781 726 7337
Email danielbrocks@yahoo.com
Clinical Ophthalmology Dovepress
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and growth factors to ensure corneal wound healing
5–8
and
nerve repair and survival.
9
Thus, early diagnosis and treat-
ment of underlying disease are essential in restoring the
ocular surface and preventing progressive ulceration,
imminent perforation, and irreversible vision loss.
Current therapies aim to promote healing of corneal
ulcers by maintaining a stable tear film and providing
mechanical protection of the cornea. Conservative treatments
include preservative-free artificial tears, ointments, autolo-
gous serum eyedrops, and bandage contact lens (BCL).
When corneal ulcers respond poorly to conservative meth-
ods, adjunctive procedures and surgical interventions are
commonly implemented including tarsorrhaphy, punctal
occlusion, conjunctival flap, and amniotic membrane trans-
plantation (AMT). Unfortunately, the cosmetic impact of
some surgical interventions such as tarsorrhaphy and con-
junctival flap may be undesirable to patients; in addition,
punctal occlusion with an underlying inflammatory disease
can lead to further damage by retention of pro-inflammatory
components in the tear film. In contrast, amniotic membrane
(AM) contains unique anti-inflammatory, anti-scarring, and
pro-regenerative properties
10,11
and has been shown to suc-
cessfully treat epithelial defects and corneal ulcers of various
etiologies, including NK.
12–14
While AMT with sutures has
been widely reported for the treatment of corneal ulcers, few
studies have assessed the use of self-retained cryopreserved
AM (cAM).
15–18
Therefore, the purpose of this study was to
assess the clinical outcomes following the treatment of cor-
neal ulcers with self-retained cAM.
Materials and Methods
Following approval and waiver of consent by the
Institutional Review Board at Vassar Brothers Medical
Center, a retrospective chart review was performed in
accordance with the tenets of the Declaration of Helsinki
on consecutive patients that were treated between 2016
and 2017 by the study author. Appropriate measures were
undertaken and maintained to protect the confidentiality of
study participants. Patients were included for analysis if
they (1) presented with a recalcitrant corneal ulcer, (2)
were treated with self-retained cAM (PROKERA
®
Slim
[PKS], Bio-Tissue, Miami, FL), and (3) had at least 6
months of follow-up data. Recalcitrant corneal ulcers
were defined as those that failed to display any tendency
of epithelial healing despite conventional treatments.
Medical histories and results from comprehensive ophthal-
mic examinations were obtained. Collected data included
demographic variables, corneal ulcer etiology, associated
signs and symptoms, concomitant therapies, time to com-
plete healing, and recurrence and/or complications.
Intervention
After PKS was thawed at room temperature for several
minutes, it was rinsed with saline and inserted under
topical anesthesia with 0.5% proparacaine hydrochloride
eye drops in the office. PKS was first placed into the
superior fornix while the patient looked down and was
then slid under the lower eyelid. Patients returned to the
office at 1 week (± 5 days) for PKS removal following the
dissolution of the AM and continued to follow-up at 1
month, 3 months, and 6 to 12 months. Slit-lamp examina-
tion with fluorescein staining was performed at baseline
and all follow-up visits.
Outcome Measures
The primary outcome measure was time to complete corneal
epithelialization. Ocular discomfort, corneal surface integ-
rity, and corneal signs were also assessed at 1 week, 1 month,
3 months, and 6 months following the application of cAM via
PKS. Corneal symptoms of discomfort, severity, and fre-
quency were graded as none (0), mild discomfort with inter-
mittent frequency (1), moderate discomfort with variable
frequency(2), and severe discomfort with constant frequency
(3). Corneal surface integrity was assessed using fluorescein
staining and was scored as clear (0), mild (1), moderate (2),
or severe (3). Corneal signs were graded as absent (0), mild
debris and reduced tear meniscus (1), filamentary keratitis
with mucus clumping and increased tear debris (2), super-
ficial punctate keratitis (SPK) (3), and defect/ulceration (4).
Snellen visual acuity (VA) was also assessed at 1 week, 1
month, 3 months, and 6 months. Change in the number of
Snellen lines was calculated by logMAR transformation, and
asignificant improvement in VA was considered 3 or more
lines. “Counting Fingers”(CF) and “hand motion”(HM)
were quantified as 0.014 and 0.005, respectively.
19
“Light
perception”(LP) was quantified as 0.002.
20
Statistical Analyses
All statistical analyses were carried out using SPSS
Software version 20.0 (IBM; Armonk, NY, USA).
Continuous data were reported as mean ± standard devia-
tion or median and range, and categorical data were
described using frequency and percentage. Ordinal vari-
ables including ocular discomfort, corneal staining, and
corneal signs were compared between timepoints using
the Wilcoxon Signed-Rank test. Correlations between
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parameters were assessed by the Spearman’s rank-order
correlation. A Pvalue less than 0.05 was considered
statistically significant.
Results
Thirteen eyes of 13 consecutive patients (6 females, 7 males)
with a mean age of 67.3 ± 11.8 were included in this study.
All patients presented with corneal ulcers despite prior con-
servative treatment with artificial tears (11/13, [85%]), anti-
biotics (11/13 [85%]), ointment (11/13 [85%]), steroids (6/13
[46%]), antivirals (3/13 [23%]), NSAIDs (3/13 [23%]), BCL
(1/13 [8%]), and mydriatics (1/13 [8%]). Ulcers were located
centrally (7/13 [54%]), peripherally (3/13 [23%]), or both
centrally and peripherally (3/13 [23%]) as evidenced by
corneal staining. The majority of corneal ulcers (9/13
[69%]) resulted from underlying neurotrophic keratitis
(NK) caused by acoustic neuroma removal (n = 1),
lagophthalmos (n = 3), herpetic infection (simplex or zoster)
(n = 3), and advanced diabetes mellitus (DM) (n = 2). The
etiologies of the remaining ulcers were autoimmune disease
(n = 2), chemical burn (n = 1), and dry eye (n = 1). Relevant
clinical data for each patient are summarized in Tabl e 1 .
Chief complaints at baseline visit included ocular pain
(3/13 [23%]), discomfort (4/13 [31%]), light sensitivity (2/
13 [15%]), blurred vision (11/13 [85%]), and redness (8/13
[62%]). While slit-lamp examination revealed severe cor-
neal staining in all patients, the median ocular discomfort
score was 0 out of 3 (mean score of 0.9 ± 1.1), which
further indicates that the majority of the study sample had
underlying NK.
Each patient received a median of 1 PKS application
(range: 1–3); eight eyes (62%) received a single applica-
tion, whereas a second and third PKS was placed in 3
(23%) and 2 (15%) eyes, respectively. Placement and
removal of PKS were uneventful in all patients, and PKS
was well tolerated by all patients. PKS was placed for
a duration of 6.8 ± 3.4 days (range: 2–15), during which
time antibiotics were continued and steroids discontinued.
The cAM fell out spontaneously in one eye prior to dis-
solution on day 4. Aside from this case, the cAM was
completely dissolved in all eyes upon removal of PKS.
Corneal ulcers healed in all eyes in a median of 14
days (range: 4–43); only one neurotrophic corneal ulcer in
a blind eye secondary to angle-closure glaucoma failed to
heal within the first month and required full-sutured tarsor-
rhaphy to complete epithelialization (Figure 1). Following
PKS removal, BCL was placed in 3 eyes (23%) to com-
plete corneal epithelialization.
Complete corneal epithelialization was accompanied by
significant improvements in clinical signs and symptoms at
all follow-up timepoints (Table 2). Ocular discomfort sig-
nificantly improved from 0.9 ± 1.1 at baseline to 0.2 ± 0.6 at
1 week (P= 0.04), 0.2 ± 0.4 at 1 month (P= 0.03), 0.1 ± 0.4
at 3 months (P= 0.02), and 0.1 ± 0.4 at 6 months (P= 0.04).
In addition, corneal staining improved from 3.0 ± 0.0 at
baseline to 1.5 ± 1.3 at 1 week (P= 0.01), 0.5 ± 0.9 at 1
month (P= 0.001), 0.2 ± 0.6 at 3 months (P< 0.001), and
0.3 ± 0.5 at 6 months (P= 0.001). This was accompanied by
a significant improvement in corneal signs from 4.0 ± 0.0 at
baseline to 2.7 ± 1.9 at 1 week (P= 0.03), 1.1 ± 1.7 at 1
month (P= 0.002), 0.3 ± 1.1 at 3 months (P= 0.001), and
0.8 ± 1.5 at 6 months (P= 0.001). When excluding 4 eyes
with poor visual potential due to underlying conditions or
treatment such as tarsorrhaphy or PKS, VA improved from
a median of 0.70 logMAR (20/100) at baseline to 0.48
logMAR (20/60) at 1 month, 0.48 logMAR (20/60) at 3
months, and 0.30 logMAR (20/40) at 6 months. None of
these improvements were statistically significant. At 1
month, 7 eyes (54%) demonstrated clinically significant
improvement in VA (≥3 lines) compared to baseline. This
improvement in VA remained relatively stable in 5 (38%)
and 6 eyes (46%) at 3 and 6 months, respectively.
No adverse events were reported throughout the study
period. Corneal ulcer recurrence was noted in one severely
diabetic patient with a neurotrophic cornea. The ulcer
initially healed in 14 days with PKS but recurred 3 months
later and was treated with tarsorrhaphy to complete heal-
ing. Furthermore, 2 patients with autoimmune diseases
presented with mild SPK at 6 months, and 6 patients
displayed signs of minimal stromal opacity.
Discussion
Over the last two decades, many studies have reported the
palliative benefits of AM in treating various ocular surface
diseases.
21,22
AM contains many growth factors such as
nerve growth factor (NGF), keratinocyte growth factor
(KGF), and hepatocyte growth factor (HGF), all of which
have been shown to promote healing of the corneal
epithelium.
23–25
The abundance of NGF in the AM
stroma
24,26-29
is especially important because NGF supports
and repairs corneal nerves,
9
which are essential in eliciting
protective reflexes that respond to corneal injury and help to
maintain a healthy epithelium.
30
Furthermore, mononuclear
cells such as lymphocytes and macrophages have been
shown to adhere to the cAM stroma and undergo rapid
apoptosis, significantly reducing corneal inflammation and
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Table 1 Demographic and Clinical Characteristics
Case Age Sex Eye Ulcer Etiology Previous
Surgery
Prior Management Comorbidities Additional
Treatment
PKS Placement
(Days)
Epithelial Healing
(Days)
1 52 F L Acoustic neuroma
removal
Antibiotics, Steroid, BCL NK 8 (x3) 24
2 58 F L Lagophthalmos Antibiotics, Ointment NK, Bell’s Palsy 7, 5 12
3 56 M R Chemical Burn Tears, Antibiotics, Steroid, Mydriatic 15 15
4 70 M R Dry Eye Tears, Antibiotics, Steroid, Ointment MGD 3, 2 5
5 47 F L Autoimmune PRK Tears, Antibiotics, Ointment, NSAIDs Thyroid disease 3 4
6 86 M L DM Cataract Tears, Antibiotics, Ointment, NSAIDs NK, Advanced DM Tarsorrhaphy
a
14 14
7 67 F L DM Cataract, PI Tears, Antibiotics, Ointment NK, Severe advanced glaucoma Tarsorrhaphy 10, 7 43
8 75 F L Autoimmune, HZV Tears, Antibiotics, Ointments Autoimmune disease
(Unspecified)
BCL 8, 5, 3 29
9 68 M L HSV Tears, Antiviral, Steroid, Ointment,
NSAIDs
NK, severe advanced
glaucoma, MGD
410
10 68 M R Lagophthalmos Cataract,
Tarsorrhaphy
Antibiotics, Ointment, Tears NK, MGD BCL 7 20
11 80 M L HZV Cataract Tears, Steroid, Ointment, Antiviral,
Antibiotics
NK, Ptosis 7 7
12 82 F L Lagophthalmos Cataract Tears, Ointment NK, DED, Bell’s Palsy 6 6
13 66 M R HSV Antibiotics, Antiviral, Ointment,
Steroid, Tears
NK, Leukemia, MGD BCL 6 24
Note:
a
Tarsorrhaphy was performed at month 3 following ulcer recurrence.
Abbreviations: BCL, bandage contact lens; DED, dry eye disease; DM, diabetes mellitus; F, female; HSV, herpes simplex virus; HZV, herpes zoster virus; L, left; M, male; MGD, meibomian gland dysfunction; NK, neurotrophic keratitis;
NSAIDs, nonsteroidal anti-inflammatory drugs; PI, peripheral iridotomy; PKS, PROKERA Slim; PRK, photorefractive keratectomy; R, right.
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promoting healing.
31–36
While a number of studies have
reported the benefits of AMT in treating corneal ulcers,
there is increased interest in utilizing a sutureless approach
to eliminate suture-induced inflammation and circumvent
surgical complications such as infection. Sutureless
application is highly beneficial as the cAM can be placed in-
office via PKS, facilitating timely intervention and evading
delays inherent to scheduling surgery.
Following placement of self-retained cAM, all corneal
ulcers in the present study exhibited rapid corneal
Figure 1 Time to complete corneal epithelialization. Kaplan–Meier survival analysis shows the days to complete corneal epithelialization in patients treated with self-
retained cryopreserved amniotic membrane (cAM) via PROKERA Slim for corneal ulcers.
Table 2 Clinical Outcomes
Visual Acuity Discomfort Severity &
Frequency
Corneal Staining Corneal Signs
T
0
T
1
T
2
T
3
T
4
T
0
T
1
T
2
T
3
T
4
T
0
T
1
T
2
T
3
T
4
T
0
T
1
T
2
T
3
T
4
1 CF 20/60 20/60 20/200 20/150 0 0 0 0 0 3100043000
2 20/300 20/400 N/A
a
20/400 20/300 0 0 0 0 0 3330044400
3 20/60 20/150
a
20/25 20/25 20/25 3 1 1 1 0 3110044300
4 20/50 20/50 20/25 20/25 20/25 1 0 1 0 1 3000040000
5 20/100 20/70 20/20 20/20 20/20 3 0 1 0 0 3000140003
6 CF HM 20/400 CF CF 2 0 0 1 1 3302144044
7HM
b
HM
b
HM
b
LP
b
LP
b
1 0 0 0 0 3310044400
8 20/60 CF
a
20/400 20/200 20/200 2 2 0 0 0 3300144003
9HM
b
HM
b
HM
b
HM
b
HM
b
0 0 0 0 0 3100044000
10 LP LP HM 20/400 20/400 0 0 0 0 0 3300044000
11 20/100 20/400
a
20/100 20/100 20/200 0 0 0 0 0 3000040000
12 20/50 20/100
a
CF
a
20/60 20/40 0 0 0 0 0 3010140300
13 20/100 20/400
a
20/50 20/60 20/20 0 0 0 0 0 3200044000
Notes:
a
Vision was obstructed from PKS, tarsorrhaphy, or thick ointment covering eye.
b
Poor visual potential due to severe advanced glaucoma.
Abbreviations: CF, counting fingers; HM, hand motion; LP, light perception; T
0
, Baseline; T
1
, Week 1; T
2
, Month 1; T
3
, Month 3; T
4
, Month 6.
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epithelialization without complication in a median of
14 days. Four (31%) severe cases underwent subsequent
interventional measures to complete epithelialization via
BCL or tarsorrhaphy. Tarsorrhaphy was performed in 2
cases (of which one case after recurrence), in which both
cases had underlying advanced diabetes, and one case also
had advanced glaucoma. The need for tarsorrhaphy may
be related to the severe nerve impairment in these patients.
Furthermore, 6 eyes (46%) with visual potential improved
by 3 or more Snellen lines by 6 months in the present
study. These findings are similar to what was reported in
a meta-analysis by Liu et al, which found a 2.3% (9/358)
complication rate and pooled vision improvement rate of
53%.
12
Schuerch et al recently published the largest retro-
spective analysis to date of patients who underwent AMT
for the treatment of corneal ulcers.
13
In that study,
Schuerch et al reported a 47% (7/15) healing rate of
neurotrophic corneal ulcers at 1 month following double-
layered AMT with adjunctive therapeutic contact lens
13
in
comparison to a 92% (12/13) healing rate in the present
study. These findings suggest sutureless application of
cAM via PKS may accelerate healing when compared to
traditional AMT with sutures. However, it is important to
note that their healing rate improved to 87% (13/15) at 3
months and 93% (14/15) at 6 months;
13
thus, it is possible
that double-layered AMT with sutures may take longer to
resorb, rendering it more difficult to monitor complete
epithelization at 1 month. Overall, these findings support
the use of AM in promoting complete epithelialization of
corneal ulcers caused by underlying NK.
Three retrospective case series
15–17
have reported
findings regarding the use of self-retained cAM for the
treatment of corneal ulcers. Cheng and Tseng found 4
herpetic corneal ulcers underwent rapid corneal epitheli-
zation within 5 ± 4 days of PKS placement along with
reduced ocular surface inflammation and improved VA
during 3–51 months of follow-up.
16
In another short-term
study, Suri et al described how 73% (8/11) of corneal
ulcers healed following PROKERA
®
placement despite
failure to heal with prior use of punctal plugs (n = 5),
BCL (n = 4), and tarsorrhaphy (n = 2);
15
remarkably, one
eye with descemetocele re-epithelialized and formed an
anterior chamber following treatment with PROKERA
®
despite failure to heal with BCL.
15
In a case series
involving corneal ulcers with bacterial keratitis, Sheha
et al found 2 of 3 corneal ulcers healed in 14 and 23
days.
17
Our similar results, with a larger sample size and
various etiologies, further support the current literature of
using self-retained cAM to promote corneal epithelializa-
tion. Furthermore, use of cAM for NK is further sup-
ported by two recent studies, in which PKS was shown to
promote corneal nerve regeneration in patients with
severe dry eye disease and concurrently reduce corneal
neuropathic pain.
37,38
These findings may shed light on
the successful outcomes observed in this retrospective
series, which predominantly comprised corneal ulcers
with underlying NK. Further prospective studies are war-
ranted to confirm our findings.
Disclosure
The development of PROKERA was supported in part with
Grant no. EY014768 from the National Institute of Health
(NIH) and National Eye Institute (NEI). The content is
solely the responsibility of the authors and does not neces-
sarily represent the opinion of the NIH or the NEI. OM, ST,
and SCGT are employees of TissueTech. Dr. Tseng has
obtained a patent for the method of preparation and clinical
uses of amniotic membrane and has licensed the rights to
TissueTech, Inc, which procures and processes, and to Bio-
Tissue, Inc, which is a subsidiary of TissueTech, Inc, to
distribute cryopreserved amniotic membrane for clinical
and research uses. Dr Daniel Brocks reports Consultant to
Biotissue (manufacturer of Prokera) from Aug 2015 to
Aug 2017. The authors report no other conflicts of interest
in this work.
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