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Temporary corneal stem cell dysfunction after radiation therapy

Authors:
Hiroshi Fujishima at Tsurumi University
Hiroshi Fujishima
J Shimazaki
J Shimazaki
J Shimazaki
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K Tsubota
K Tsubota
K Tsubota
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Abstract and Figures

Radiation therapy can cause corneal and conjunctival abnormalities that sometimes require surgical treatment. Corneal stem cell dysfunction is described, which recovered after the cessation of radiation. A 44-year-old man developed a corneal epithelial abnormality associated with conjunctival and corneal inflammation following radiation therapy for maxillary cancer. He experienced ocular pain and loss of vision followed by conjunctival epithelialisation of the upper and lower parts of the cornea. Examination of brush cytology samples showed goblet cells in the upper and lower parts of the cornea, which showed increased fluorescein permeability, and intraepithelial lymphocytes. Impression cytology showed goblet cells in the same part of the cornea. Specular microscopy revealed spindle type epithelial cells. Patient follow up included artificial tears and an antibiotic ophthalmic ointment. The corneal abnormalities resolved after 4 months with improved visual acuity without any surgical intervention, but the disappearance of the palisades of Vogt did not recover at 1 year after radiation. Radiation therapy in this patient caused temporary stem cell dysfunction which resulted in conjunctivalisation in a part of the cornea. Although limbal stem cell function did not fully recover, this rare case suggested that medical options should be considered before surgery.
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British
J7ournal
of
Ophthalmology
1996;80:911-914
Temporary
corneal
stem
cell
dysfunction
after
radiation
therapy
Hiroshi
Fujishima,
Jun
Shimazaki,
Kazuo
Tsubota
Abstract
Background-Radiation
therapy
can
cause
corneal
and
conjunctival
abnor-
malities
that
sometimes
require
surgical
treatment.
Corneal
stem
cell
dysfunction
is
described,
which
recovered
after
the
cessation
of
radiation.
Methods-A
44-year-old
man
developed
a
corneal
epithelial
abnormality
associated
with
conjunctival
and
corneal
inflamma-
tion
following
radiation
therapy
for
maxil-
lary
cancer.
He
experienced
ocular
pain
and
loss
of
vision
followed
by
conjunctival
epithelialisation
of
the
upper
and
lower
parts
of
the
cornea.
Results-Examination
of
brush
cytology
samples
showed
goblet
cells
in
the
upper
and
lower
parts
of
the
cornea,
which
showed
increased
fluorescein
permeabil-
ity,
and
intraepithelial
lymphocytes.
Im-
pression
cytology
showed
goblet
cells
in
the
same
part
of
the
cornea.
Specular
microscopy
revealed
spindle
type
epithe-
lial
cells.
Patient
follow
up
included
artifi-
cial
tears
and
an
antibiotic
ophthalmic
ointment.
The
corneal
abnormalities
re-
solved
after
4
months
with
improved
visual
acuity
without
any
surgical
inter-
vention,
but
the
disappearance
of
the
pali-
sades
of
Vogt
did
not
recover
at
1
year
after
radiation.
Conclusion-Radiation
therapy
in
this
patient
caused
temporary
stem
cell
dys-
function
which
resulted
in
conjunctivali-
sation
in
a
part
of
the
cornea.
Although
limbal
stem
cell
function
did
not
fully
recover,
this
rare
case
suggested
that
medical
options
should
be
considered
before
surgery.
(Br_J
Ophthalmol
1996;80:911-914)
Radiation
induced
corneal
epitheliopathy
is
one
of
the
serious
complications
of
radiation
therapy.'
Manifestations
of
radiation
induced
keratopathy
include
superficial
keratitis,
stro-
mal
clouding,
cell
infiltration,
and
oedema
of
the
cornea,'
and
in
severe
cases
perforation
of
the
cornea'
can
occur.
Degeneration
of
the
corneal
epithelium,
probably
due
to
an
irre-
versible
inhibition
of
corneal
mitosis
after
radiation
therapy,
was
reported
in
experimen-
tal
models.45
Corneal
stem
cells
are
essential
to
maintain
the
epithelial
organisation
by
undergoing
continuous
turnover
throughout
adult
life.6
7
The
number
of
cells
are
maintained
via
the
proliferation
of
a
distinct
subpopulation
of
stem
cells.8
When
the
stem
cells
are
severely
injured,
the
conjunctival
epithelium
extends
across
the
cor-
neal
scleral
limbus,
creating
a
thin
and
irregu-
lar
surface
over
the
cornea.9
Transdifferentia-
tion
of
the
conjunctiva
to
phenotypically
normal
corneal
epithelium
has
been
observed
in
some
animal
models
and
patients.1'°
Limbal
transplantation
(corneal
stem
cell
transplanta-
tion)
should
be
considered""
when
the
stem
cell
deficiency
is
thought
to
be
permanent.
We
describe
here
a
patient
with
radiation
induced
corneal
epitheliopathy
which
resolved
sponta-
neously
within
4
months.
Clinical
course
and
change
in
tear
function
and
ocular
surface
condition
are
reported.
Patient
and
methods
A
44-year-old
Japanese
man
with
advanced
maxillary
cancer
of
the
left
parasinus
was
treated
with
radiation
from
May
to
June
1993.
A
total
dose
of
61
Gy
over
44
days
(maximum
dosage
3
Gy/day)
was
administrated
via
a
right
angled
pair
of
wedge
filtered
portals.
Three
days
after
completion
of
the
radiation
therapy
he
complained
of
blurred
vision
and
ocular
surface
pain
in
the
left
eye.
The
cornea
and
conjunctiva
were
evaluated
using
slit-lamp
examination,
including
fluores-
cein
and
rose
bengal
staining.
Schirmer's
test,
the
cotton
thread
test,"5
and
the
clearance
test'6
were
performed
to
evaluate
the
tear
dynamics.
Central
corneal
sensation
was
measured
with
a
Cochet
and
Bonnet
aesthesiometer
(Luneau
Ophtalmologie,
France).'7
Conjunctival
cells
were
also
evaluated
by
the
brush
cytology
method.'8
Smears
containing
cellular
material
were
spread
on
glass
slides
in
the
usual
manner,
and
then
stained
and
fixed
with
a
May-Grunwald
stain
solution
(eosin-
methylene
blue
solution;
Muto
Pure
Chemi-
cals
Ltd,
Tokyo,
Japan).
Impression
cytology
Figure
1
Corneal
stem
cell
dysfunction
3
days
after
completion
of
radiation
therapy.
Upper
and
lower
corneal
epithelial
cells
showed
damage,
and
epithelial
opacity
was
apparent.
The
upper
and
lower
parts
of
the
cornea
showed
fluorescein
staining.
Department
of
Ophthalmology,
Tokyo
Dental
College,
Chiba,
Japan
H
Fujishimna
J
Shimazaki
K
Tsubota
Department
of
Ophthalmology,
Keio
University
School
of
Medicine,
Tokyo,
Japan
H
Fujishima
K
Tsubota
Correspondence
to:
Hiroshi
Fujishima,
MD,
Department
of
Ophthalmology,
Tokyo
Dental
College,
5-11-13
Sugano,
Ichikawa,
Chiba,
Japan
272.
Accepted
for
publication
24
May
1996
911
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Fujishima,
Shimazaki,
Tsubota
Table
1
Clinicalfindings
First
day
4
weeks
8
weeks
4
months
6
months
I
_w
Visual
acuity
(left
eye)
20/500
20/250
20/100
20/100
20/40
20/
Pain
+++
++
+
-
-
-
Fluorescein
stain
+++ +++
++
+
Rose
bengalstain
+++
+++
++
+
±
+
Epithelial
opacity
+++
+++
+
+
Corneal
sensitivity
(g/mm2)
>17.68
17.68
12.
Goblet
cell
+
Palisade
of
Vogt
-
Spindle
type
cell
+
Figwre
2
Examination
of
brush
cytology
samples.
Goblet
ceJls
were
detected
in
the
upper
and
lower
areas
of
the
corneal
surace.
was
also
performed
using
the
method
of
Nelson
et
al
(Schiffs
Reagent;
Muto
Pure
Chemicals
Ltd,
Tokyo,
Japan)."9
Specular
microscopy
(Kowa;
Tokyo,
Japan)
was
per-
formed
during
the
initial
evaluation
for
blurred
vision
and
again
12
months
later.
Results
The
previous
examination,
6
months
before
initiation,
showed
no
ophthalmic
abnormalities
of
radiation
therapy.
At
the
initial
examination,
the
patient's
visual
acuity
was
20/40
in
his
right
eye
and
20/500
in
the
left
eye.
A
slit-lamp
examination
of
the
left
eye
showed
corneal
epi-
thelial
opacity,
extending
from
the
upper
and
lower
limbus
to
the
central
cornea.
Increased
fluorescein
permeability
was
detected
in
the
area
(Fig
1).
Rose
bengal
stining
was
difffusely
positive
on
the
cornea.
The
palisades
of
Vogt
*
..~~~~~~~.
.o
mm
g
.
.
..
.
Figre
3
Periodic
acid
Schiff
saining
in
pressn
cytoloy
at
dt
onset
of
complicatioL
The
mucin
was
stained
red
(POV)`0
were
not
observed.
Corneal
sensation
showed
1.84
g/mm'
in
the
right
eye
and
greater
than
17.68
g/mm2
in
the
left.
Schirmer's
test,
the
clearance
test,
and
the
tear
function
index
(T1FI)
were
9
mm,
8
x,
and
72
(right
eye)
and
17
mm,
1
x,
and
17
(left
eye).
Results
of
the
cotton
thread
test
were
32
mm
(right
eye)
and
40
mm
(left
eye).
The
results
indicated
that
tear
flow
was
increased
by
the
irritation
but
its
drainage
was
poor
in
the
left
eye.
Brush
cytol-
ogy
samples
in
the
upper
and
lower bulbar
conjunctiva
showed
a
few
goblet
cells
including
lymphocytes
from
inflammatory
cells
(Fig
2).
Impression
cytology
also
revealed
goblet
cells
on
the
entire
cornea
(Fig
3).
Specular
micros-
copy
in
the
central
corneal
epithelium
revealed
spindle-shaped
and
enlarged
cells
(Fig
4).
The
patient
was
treated
with
preservative-
free
artificial
tears
(10
times
a
day)
(Soft
Santear
eye
drop;
Santen
Pharmaceutical
Co,
Osaka,
Japan)
and
antibiotic
ophthalmic
oint-
ment
(twice
a
day)
(Tarivid
eye
ointment;
Santen
Pharmaceutical
Co,
Osaka,
Japan).
After
4
weeks
of
follow
up,
epithelial
opacity
and
vital
stainings
did
not
improve,
and
visual
acuity
remained
at
20/250
(Fig
5).
The
patient
still
had
ocular
pain
at
this
time.
After
8
weeks
of
follow
up,
epithelial
opacity
as
well
as
vital
staining
gradually
decreased.
The
visual
acuity
of
the
left
eye
improved
to
20/100,
and
ocular
pain
was
markedly
de-
creased.
Four
months
after
radiation
therapy,
scattered
punctate
epithelial
staining
was
seen
in
the
lower
part
of
the
cornea
(Fig
6).
Rose
bengal
staining
was
also
decreased.
Six
months
after
the
therapy,
the
patient
no
longer
had
ocular
pain
and
his
visual
acuity
recovered
to
20/30
in
the
right
eye
and
20/40
in
the
left.
Epithelial
opacities
and
fluorescein
staining
had
completely
disappeared;
however,
slight
rose
bengal
staining
in
the
lower
part
of
the
cornea
remained.
The
results
of
tear
function
tests
performed
1
year
after
radiation
therapy
were
as
follows:
Schirmer's
test,
clearance
test,
and
TFI
were
9
mm,
16
x,
and
144
(right
eye)
and
29
mm,
1
x,
and
29
(left
eye),
and
cotton
thread
test
was
35
mm
(right
eye)
and
30
mm
(left
eye).
Visual
acuity
recovered
to
20/25
in
the
left
eye.
Corneal
sensation
was
1.84
g/mm'
(right
eye)
and
it
slightly
recovered
but
still
was
12.84
g/mm'
(left
eye).
No
goblet
cells
were
detected
by
either
brush
cytology
or
impres-
sion
cytology.
Specular
microscopy
showed
no
spindle-shaped
cells
and
cell
configuration
was
normal
(Fig
7).
There
was
no
complaint
of
ocular
pain;
however,
the
disappearance
of
the
palisades
of
Vogt
remained
(Fig
8)
(Table
1).
Discussion
X
ray
treatment
for
parasinus
carcinoma
deliv-
ers
a
tumour
lethal
dose
to
the
eyeball,
which
may
lead
to
changes
in
the
cornea
and
conjunctiva.
Acute
radiation
reactions
include
temporary
corneal
punctate
epithelial
erosions.
Delayed
corneal
complications
may
result
directly
from
the
effect
of
radiation
or
develop
in
association
with
the
dry
eye
syndrome
as
a
result
of
reduced
or
absent
lacrimal
secretions.'
A
decrease
in
corneal
sensitivity
is
a
typical
early
sign
of
radiation
keratopathy.
Corneal
912
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Temporary
corneal
stem
cell
dysfunction
after
radiation
therapy
.|s_
...
...
...~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~......
Figure
4
Specular
microscopy
performed
at
the
onset
of
complicatons
of
radiation
therapy.
Spindle-type
epitheial
cells
and
large
cells
were
seen.
"-'VJ~
Figure
5
Corneal
stem
cell
dysfunction
60
days
after
complication
of
radiation
therapy.
Slit-lamp
examination
showed
a
decrease
in
epithelial
opacity.
Fluorescein
staining
had
largely
disappeared.
k
......~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~....
W~~~~~~~~~~~~~~~~~~~~~
..
...._i
Figure
6
Slit-lamp
examination
4
months
after
complication
of
radiation
therapy.
Only
corneal
epithelialitis
was
seen
in
lower
part
of
the
cornea.
keratopathy,
characterised
by
epithelial
and
stromal
oedema,'
has
also
been
observed
after
radiation
therapy.
Electron
microscopy
has
Figure
7
Specular
microscopy
performed
1
year
after
complication
of
radiation
therapy.
No
specific
changes
were
seen.
Figure
8
Slit-lamp
examination
1
year
after
complication
of
radiation
therapy.
Cornea
and
conjunctiva
were
normal.
shown
degeneration
of
the
corneal
epithelium
probably
due
to
irreversible
inhibition
of
mito-
Sis."
We
have
shown
here
a
case
of
spontaneous
recovery
of
radiation
induced
corneal
epithe-
liopathy,
with
the
presence
of
goblet
cells
whose
permeability
to
fluorescein
remarkably
improved
within
6
months.
Since
the
corneal
sensation, tear
function,
and
disappearance
of
POV
did
not
fully
recover
during
the
follow
up,
the
improvement
of
the
corneal
epithelium
was
not
due
to
the
recovery
of
the
sensation
or
tear
function.
Thus,
we
present
this
case
as
a
'tem-
porary
corneal
stem
cell
dysfunction',
which
recovered
gradually
after
the
cessation
of
radiation.
Stem
cells
are
a
distinct
subpopulation
of
basal
cells
located
in
various
epithelial
tissues.
Corneal
epithelial
stem
cells
are
believed
to
be
located
in
the
basal
cell
layer
of
the
periphery
of
the
cornea,
the
transition
zone
between
the
corneal
and
conjunctival
epithelium,
and
the
corneal
limbus.212'
Evaluation
of
POV'0
21
is
a
hallmark
of
the
presence
of
stem
cells.
Under
normal
conditions
stem
cells,
conjunctival
epi-
thelial
cells,
and
vessels
do
not
penetrate
the
cornea
and
corneal
clarity
is
maintained.
When
the
cornea
is
injured,
active
cellular
renewal
and
differentiation
can
contribute
to
wound
healing.24
The
concept
that
limbal
stem
cell
dysfunction
includes
conjunctivalisation
was
first
proved
by
Tseng
et
al
in
serial
experimen-
tal
studies,
and
has
been
further
confirmed
by
impression
cytology
in
a
recent
report."
11
24
25
Corneal
stem
cell
dysfunction
leads
to
corneal
epithelial
cell
dysfunction.
Conjunctival
cell
invasion
leads
to
a
decrease
in
visual
acuity.
In
the
present
case,
the
presence
of
goblet
cells
in
the
cornea
indicated
that
conjunctival
cells
had
invaded
the
cornea
and
that
epithelial
cells
had
become
dysfunctional.
The
recovery
was
thought
to
be
due
to
the
residual
stem
cells.
As
the
temporal
and
nasal
cornea
were
still
clear
and
stem
cells
in
these
parts
of
the
cornea
still
remained
and
functioned,
this
keratopathy
could
recover
spontaneously.
Other
conditions,
such
as
thermal
burns,
alkaline
burns,
chemi-
cal
burns,
contact
lens
injury,
vernal
conjuncti-
vitis
and
radiation,
may
damage
entire
limbal
stem
cells
so
that
the
corneal
epithelium
cannot
be
repopulated.
Radiation
may
also
affect
the
mitotic
rate
of
undifferentiated
stem
cells.
The
corneal
abnormalities
in
the
present
case
may
have
been
related
to
temporary
stem
913
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cell
dysfunction,
inhibition
of
epithelial
mito-
sis,
goblet
cell
hyperplasia,
or
a
combination
of
these
factors.25
After
8
weeks
to
6
months
of
follow
up,
cor-
neal
epithelial
cells
covered
the
entire
cornea.
No
spindle-type
cells
were
present,
suggesting
that
the
rate
of
mitosis
of
corneal
epithelial
cells
or
stem
cells
may
have
recovered.
A
total
daily
dose
of
3
Gy,
with
a
standard
fractiona-
tion
of
10
Gy
per
week
in
five
fractions
(2
Gy
per
treatment
session),
is
considered
safe
for
external
beam
radiation.
For
malignant
tu-
mours
of
the
maxilla,
a
megavoltage
dose
of
60
Gy
or
more
is
performed.22
However,
these
doses
were
determined
using
a
low
energy
220
kV
machine,
which
has
still
a
higher
incidence
of
complications
than
contemporary
radio-
therapeutic
machines.26
The
onset
of
corneal
changes
after
radiation
therapy
varies
from
a
few
days
to
a
year.'
27
Initial
treatment
of
radiation
related
corneal
abnormalities
aims
to
remove
any
noxious
ele-
ments
that
may
cause
further
tissue
damage.
Specific
treatment
depends
on
the
seriousness
of
the
condition.
Preservative-free
eyedrops
may
be
useful
because
tear
dysfunction
brings
about
these
cases.
Also,
ointment
and/or
medi-
cal
use
contact
lenses
may
be
appropriate
for
a
mild
case.
In
a
serious
advanced
case,
limbal
allo-
or
autograft
transplantation
must
be
considered.`2-4
While
the
limbal
stem
cell
function
did
not
fully
recover
at
1
year
after
radiation,
the
present
case
showed
clinical
recovery
of
corneal
and
conjunctival
abnor-
malities
within
several
months,
suggesting
that
medical
options
should
be
explored
before
sur-
gery
is
considered.
The
authors
thank
Ms
Yukiko
Yagi
for
performing
the
brush
cytology,
Ms
Saori
Nishijima
for
taking
slit
photographs,
and
Ke-Ping
Xu,
MD,
for
performing
impression
cytology.
1
Magfaul
PA,
Bedford
MA.
Ocular
complications
after
therapeutic
irradiation.
BrJ
Ophthalmol
1970;54:237-47.
2
Scheie
HG,
Dennis
RH,
Ripple
RC,
Calkins
1I,
Buesseler
JA.
The
effect
of
low
voltage
roentgen
rays
on
the
normal
and
vascularized
cornea
of
the
rabbit.
Am
J
Ophthalmol
1950;33:549-7
1.
3
Kadota
Y,
Okisaka
S,
Mizukawa
A,
Takahashi
A.
A
case
of
corneal
perforation
and
retinopathy
followed
by
external
radiotherapy
for
maxillary
carcinoma.
Folia
OphthalmolJpn
1988;39:2466-71.
4
Oinaka
M.
Experimental
investigations
of
the
late
effects
of
ionizing
radiation
on
the
cornea.
Jpn
J
Ophthalmol
1980;84:224-39.
5
Oinaka
M.
Experimental
investigation
of
the
late
effects
of
ionizing
radiation
on
the
cornea.
II.
Folia
Ophthalmol
Jpn
1981;32:1298-300.
6
Tseng
S.
Concept
and
application
of
limbal
stem
cells.
Eye
1989;3:421-57.
7
Thoft
RA,
Friend
J.
The
X,
Y,
Z
hypothesis
of
corneal
epi-
thelial
maintenance.
Invest
Ophthalmol
Vis
Sci
1983;24:
1422.
8
Hall
PA,
Watt
FM.
Stem
cells:
the
generation
and
maintenance
of
cellular
diversity.
Development
1989;106:
619-33.
9
Dua
HS,
Forrester
JV.
The
corneoscleral
limbus
in
human
corneal
epithelial
wound
healing.
Am
J7
Ophthalmol
1990;110:646-56.
10
Kruse
FE,
Chen
JJY,
Tsai
RJF,
Tseng
SCG.
Conjunctival
transdifferentiation
is
due
to
the
incomplete
removal
of
limbal
basal
epithelium.
Invest
Ophthalmol
Vis
Sci
1990;31:
1903-13.
11
Puangricharern
V,
Tseng
SCG.
Cytologic
evidence
of
corneal
diseases
with
limbal
stem
cell
deficiency.
Ophthal-
mology
1995;102:1476-85.
12
Kenyon
KR,
Tseng
SCG.
Limbal
autograft
transplantation
for
ocular
surface
disorders.
Ophthalmology
1989;96:
709-23.
13
Pfister
RR.
Corneal
stem
cell
disease:
concepts,
categoriza-
tion,
and
treatment
by
auto-
and
homotransplantation
of
limbal
stem
cells.
CLAO3'
1994;20:64-72.
14
Copeland
RA,
Char
DH.
Limbal
autograft
reconstruction
after
conjunctival
squamous
cell
carcinoma.
Am
J
Ophthal-
mol
1990;110:412-5.
15
Sakamoto
R,
Bennet
ES,
Henry
VA,
Paragina
S,
Narumi
T,
Izumi
Y,
et
al.
The
phenol
red
thread
tear
test:
a
cross-cultural
study.
Invest
Ophthalmol
Vis
Sci
1993;34:
3510-4.
16
Xu
K-P,
Yagi
Y,
Toda
I,
Tsubota
K.
Tear
function
index:
a
new
measure
of
dry
eye.
Arch
Ophthalmol
1995;113:
84-8.
17
Cochet
P,
Bonnet
R.
L'esthesiometrie
corneenne:
Realisa-
tion
et
interet
pratique.
Bull
Soc
Ophtalmol
Fr
1961;61:
541-50.
18
Tsubota
K,
Kajiwara
K,
Ugajin
S,
Hasegawa
T.
Conjuncti-
val
brush
cytology.
Acta
Cytol
1990;34:233-5.
19
Nelson
JD,
Havener
VR,
Cameron
JD.
Cellulose
acetate
impressions
of
the
ocular
surface.
Arch
Ophthalmol
1983;101:
1869-72.
20
Kinoshita
S,
Kiridoshi
A,
Ohji
M,
Ohashi
Y,
Manabe
R.
Disappearance
of
palisades
of
Vogt
in
ocular
surface
disease.
Jpn
J
Clin
Ophthalmol
1986;40:363-6.
21
Davanger
M,
Evensen
A.
Role
of
the
pericorneal
papillary
structure
in
renewal
of
corneal
epithelium.
Nature
1971;
229:560-1.
22
Takahashi
H,
Konno
A.
Ocular
complication
with
therapeu-
tic
irradiation
of
malignant
tumor
in
the
maxilla.
Folia
OphthalmolJ1pn
1983;34:320-4.
23
Zieske
JD,
Bukusoglu
G,
Yankauckas
MA.
Characterization
of
a
potential
marker
of
corneal
epithelial
stem
cells.
Invest
Ophthalmol
Vis
Sci
1992;33:143-52.
24
Huang
A,
Tseng
S.
Corneal
epithelial
wound
healing
in
the
absence
of
limbal
epithelium.
Invest
Ophthalmol
Vis
Sci
1991;32:96-105.
25
Chen
JJY,
Tseng
SCG.
Abnormal
corneal
epithelial
wound
healing
in
partial-thickness
removal
of
limbal
epithelium.
Invest
Ophthalmol
Vis
Sci
1991;32:2219-33.
26
Chako
DC.
Considerations
in
the
diagnosis
of
radiation
injury._JAMA
1981;245:1255-8.
27
Khaw
PT,
Ward
S,
Grierson
I,
Rice
NSC.
Effect
of
j
radia-
tion
on
proliferating
human
Tenon's
capsule
fibroblasts.
Br
J7
Ophthalmol
1991;75:580-3.
914
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1996 80: 911-914Br J Ophthalmol
H Fujishima, J Shimazaki and K Tsubota
radiation therapy.
Temporary corneal stem cell dysfunction after
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... 13 Clinically, chronic corneal inflammation and concurrent decreased corneal sensation have been described with the development of limbal stem cell deficiency in patients with radiation keratopathy. 14,15 Unfortunately, most patients are not referred to ophthalmologists for monitoring after receiving radiation therapy for cancers of the head and neck. Therefore, if damage to the cornea does occur, treatment may be started after the disease has advanced and the effects of radiation become irreversible and, thus, treatment options become more limited. ...
... They suggested to reduce the total dose and fraction size to all components of the lacrimal system to reduce the incidence of delayed severe DED. Further, Fujishima et al. 15 described a severe case of radiation keratopathy with temporary corneal stem cell dysfunction that developed after radiation therapy and resulted in ocular pain and loss of vision followed by partial conjunctivalization of the cornea. 15 Thus, radiation keratopathy can result in significant ocular surface disease, stem cell deficiency, vision loss, discomfort, and subsequent poor quality of life. ...
... Further, Fujishima et al. 15 described a severe case of radiation keratopathy with temporary corneal stem cell dysfunction that developed after radiation therapy and resulted in ocular pain and loss of vision followed by partial conjunctivalization of the cornea. 15 Thus, radiation keratopathy can result in significant ocular surface disease, stem cell deficiency, vision loss, discomfort, and subsequent poor quality of life. ...
A Novel Murine Model of Radiation Keratopathy
Article
Full-text available
  • Aug 2018
Purpose: Radiation therapy results in severe chronic keratopathy and dry eye disease. We developed a novel mouse model for radiation keratopathy to allow future mechanistic studies. Methods: Six to 8-week-old BALB/c mice underwent sublethal irradiation to the head only from a Cesium-137 irradiator, 2 × 550 rad, 3-hours apart. Irradiated mice were clinically evaluated by corneal fluorescein staining (CFS) at 1, 2, and 3 months, after which corneas were excised and immunofluorescence histochemistry performed with anti-CD45, anti-MHC class II, and anti-β-tubulin antibodies. Results: The survival rate after irradiation was 100%. Mice demonstrated significant CFS and hair loss around the eyes. Corneal nerve density decreased in the central and peripheral corneas (P < 0.01) at 2 and 3 months, respectively. CD45+ immune cell densities increased in the central and peripheral corneas (P < 0.005, P < 0.001) at 2 and 3 months, respectively. MHC class II, a sign of antigen presenting cell activation, significantly increased after irradiation in the central and peripheral corneas at 2 and 3 months (P = 0.02). A strong inverse correlation was noted between decreased corneal nerves and increase in CD45+ cells in the central cornea at 2 (P = 0.04, r = -0.89) and 3 months (P = 0.03, r = -0.91) after irradiation. Conclusions: We present a model of radiation keratopathy and demonstrate significant nerve loss and increase in immune cell influx and activation within months. This model will enable future investigations to understand the effects of radiation therapy on the eye, and to study mechanisms of neuro-immune crosstalk in the cornea.
View
... Damage to the ocular surface from radiation therapy utilized in treating many systemic cancers has been documented to reduce the functioning of LSCs [59]. Fujishima et al. report on a case of corneal epithelial abnormality associated with conjunctival and corneal inflammation after radiation therapy for maxillary cancer in a 44-year-old male. ...
... Conjunctival epithelialization and goblet cells were identified in the superior and inferior areas of the cornea, resulting in stem cell dysfunction and loss of vision. The course of treatment, in this case, alongside standard therapies, included artificial tears and an antibiotic ophthalmic ointment resulting in the resolution of lost visual acuity and corneal abnormalities [59]. ...
The Multifold Etiologies of Limbal Stem Cell Deficiency: A Comprehensive Review on the Etiologies and Additional Treatment Options for Limbal Stem Cell Deficiency
Article
Full-text available
  • Jun 2023
Given the various ocular manifestations of limbal stem cell insufficiency, an awareness of the genetic, acquired, and immunological causes and associated additional treatments of limbal stem cell deficiency (LSCD) is essential for providers. We performed a comprehensive review of the literature on the various etiologies and specific therapies for LSCD. The resources utilized in this review included Medline (PubMed), Embase, and Google Scholar. All English-language articles and case reports published from November 1986 through to October 2022 were reviewed in this study. There were collectively 99 articles on these topics. No other exclusion criteria were applied. Depending on the etiology, ocular manifestations of limbal stem cell deficiency range from dry eye syndrome and redness to more severe outcomes, including corneal ulceration, ocular surface failure, and vision loss. Identifying the source of damage for LSCD is critical in the treatment process, given that therapy may extend beyond the scope of the standard protocol, including artificial tears, refractive surgery, and allogeneic stem cell transplants. This comprehensive review of the literature demonstrates the various genetic, acquired, and immunological causes of LSCD and the spectrum of supplemental therapies available.
View
... A 44-year-old-man developed a corneal epithelial abnormality associated with conjunctival and corneal inflammation after radiation therapy for maxillary cancer. He experienced pain, loss of vision, and eventual conjunctival epithelialization of the upper and lower cornea [59]. ...
Ultrasound Biomicroscopy as a Novel, Potential Modality to Evaluate Anterior Segment Ophthalmic Structures during Spaceflight: An Analysis of Current Technology
Article
Full-text available
  • Mar 2024
Ocular health is currently a major concern for astronauts on current and future long-duration spaceflight missions. Spaceflight-associated neuro-ocular syndrome (SANS) is a collection of ophthalmic and neurologic findings that is one potential physiologic barrier to interplanetary spaceflight. Since its initial report in 2011, our understanding of SANS has advanced considerably, with a primary focus on posterior ocular imaging including fundus photography and optical coherence tomography. However, there may be changes to the anterior segment that have not been identified. Additional concerns to ocular health in space include corneal damage and radiation-induced cataract formation. Given these concerns, precision anterior segment imaging of the eye would be a valuable addition to future long-duration spaceflights. The purpose of this paper is to review ultrasound biomicroscopy (UBM) and its potential as a noninvasive, efficient imaging modality for spaceflight. The analysis of UBM for spaceflight is not well defined in the literature, and such technology may help to provide further insights into the overall anatomical changes in the eye in microgravity.
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... In addition to the etiologies of LSCD above, there is a range of acquired and hereditary LSCD. Inflammatory ocular surface diseases involve Stevens-Johnson syndrome, microbial infection, mucous membrane pemphigoid, and chronic vernal keratoconjunctivitis. Congenital diseases include aniridia, dyskeratosis congenita, epidermolysis bullosa, and epidermal dysplasia, whereas acquired LSCD contain chemotherapy, iatrogenic injury, and ultraviolet irradiation [104][105][106][107][108][109]. One of the most common causes of congenital LSCD is aniridia [104]. ...
Corneal Epithelial Stem Cells–Physiology, Pathophysiology and Therapeutic Options
Article
Full-text available
  • Sep 2021
In the human cornea, regeneration of the epithelium is regulated by the stem cell reservoir of the limbus, which is the marginal region of the cornea representing the anatomical and functional border between the corneal and conjunctival epithelium. In support of this concept, extensive limbal damage, e.g., by chemical or thermal injury, inflammation, or surgery, may induce limbal stem cell deficiency (LSCD) leading to vascularization and opacification of the cornea and eventually vision loss. These acquired forms of limbal stem cell deficiency may occur uni- or bilaterally, which is important for the choice of treatment. Moreover, a variety of inherited diseases, such as congenital aniridia or dyskeratosis congenita, are characterized by LSCD typically occurring bilaterally. Several techniques of autologous and allogenic stem cell transplantation have been established. The limbus can be restored by transplantation of whole limbal grafts, small limbal biopsies or by ex vivo-expanded limbal cells. In this review, the physiology of the corneal epithelium, the pathophysiology of LSCD, and the therapeutic options will be presented.
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... De nombreux autres actes thérapeutiques utilisés par les ophtalmologistes impliquent un risque iatrogène sur la surface oculaire. Ainsi, la radiothérapie [74] peut induire une blépharoconjonctivite, régressant en quelques mois, plus ou moins associée à un syndrome sec par atrophie des glandes lacrymales (décrite à par-tir d'une dose de 20 Gy), voire d'une dysfonction transitoire des cellules limbiques cornéennes [75] . ...
Pathologies iatrogènes de la surface oculaire
Article
  • Aug 2021
Ocular surface involvement related to both topical and systemic treatments is frequently encountered by ophthalmologists. Most often, the symptoms and signs are non-specific, but some clinical entities have to be well characterized and diagnosed in order to withdraw the treatment causing harm. The diagnosis of drug-induced adverse events remains a diagnosis of elimination, especially after ruling out other infectious and neoplastic diseases. In most cases, withdrawal of the causal therapy leads to the reversibility of symptoms and signs. Hereinafter, we discuss the mechanisms and clinical manifestations of ocular surface drug-induced adverse events by topical and systemic treatments and briefly describe other therapeutic actions, which can lead to the alteration of the ocular surface.
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... These include several major procedures, such as various chemotherapies: hydroxyurea (Ellies, Anderson, Topuhami, & Tseng, 2001), S-1 (K. H. Kim & Kim, 2015), hydroxycarbamide (Ding, Bishop, Herzlich, Patel, & Chan, 2009), Mitomycin C (Lichtinger, Pe'er, Frucht-Pery, & Solomon, 2010); Radiation therapies (Fujishima, Shimazaki, & Tsubota, 1996); eye surgeries such as surgery for pterygium (Atallah, Palioura, Perez, & Amescua, 2016), the use of 5-fluorouracil in glaucoma surgeries (Pires, Chokshi, & Tseng, 2000); and something as common as the use of preservatives (e.g., benzalkonium chloride) in widely used eye medications (Lin et al., 2013;Pisella, Pouliquen, & Baudouin, 2002). ...
Understanding cornea epithelial stem cells and stem cell deficiency: Lessons learned using vertebrate model systems
Article
  • Feb 2021
  • GENESIS
Animal models have contributed greatly to our understanding of human diseases. Here, we focus on cornea epithelial stem cell (CESC) deficiency (commonly called limbal stem cell deficiency, LSCD). Corneal development, homeostasis and wound healing are supported by specific stem cells, that include the CESCs. Damage to or loss of these cells results in blindness and other debilitating ocular conditions. Here we describe the contributions from several vertebrate models toward understanding CESCs and LSCD treatments. These include both mammalian models, as well as two aquatic models, Zebrafish and the amphibian, Xenopus. Pioneering developments have been made using stem cell transplants to restore normal vision in patients with LSCD, but questions still remain about the basic biology of CESCs, including their precise cell lineages and behavior in the cornea. We describe various cell lineage tracing studies to follow their patterns of division, and the fates of their progeny during development, homeostasis, and wound healing. In addition, we present some preliminary results using the Xenopus model system. Ultimately, a more thorough understanding of these cornea cells will advance our knowledge of stem cell biology and lead to better cornea disease therapeutics.
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... (Holland and Schwartz, 1997;Puangsricharen and Tseng, 1995;Sridhar et al., 2001) Radiation Rare, < 5% of all causes. (Fujishima et al., 1996) ...
Limbal stem cell diseases
Article
  • Feb 2021
The function of limbal stem/progenitor cells (LSCs) is critical to maintain corneal epithelial homeostasis. Many external insults and intrinsic defects can be deleterious to LSCs and their niche microenvironment, resulting in limbal stem cell dysfunction or deficiency (LSCD). Ocular comorbidities, frequent in eyes with LSCD, can exacerbate the dysfunction of residual LSCs, and limit the survival of transplanted LSCs. Clinical presentation and disease evolution vary among different etiologies of LSCD. New ocular imaging modalities and molecular markers are now available to standardize the diagnosis criteria and stage the severity of the disease. Medical therapies may be sufficient to reverse the disease if residual LSCs are present. A stepwise approach should be followed to optimize the ocular surface, eliminate the causative factors and treat comorbid conditions, before considering surgical interventions. Furthermore, surgical options are selected depending on the severity and laterality of the disease. The standardized diagnostic criteria to stage the disease is necessary to objectively evaluate and compare the efficacy of the emerging customized therapies.
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... Radiotherapy is widely used in the field of ophthalmology for thyroid eye disease, choroidal melanoma, retinoblastoma, lacrimal gland carcinoma, and orbital tumors, amongst others [9,10]. The ophthalmic and adnexal complications of radiotherapy for various benign and malignant ocular and periocular diseases have been described in the literature [9][10][11]; however, there are only limited reports on the ophthalmic complications following radiotherapy to the maxillary sinus region [12]. With improvements in radiotherapy technology, patients with advanced inoperable maxillary sinus-involving tumors (MMST) are now more likely to survive with preservation of the eye. ...
Clinical Spectrum and Outcomes of Ocular and Periocular Complications following External-Beam Radiotherapy for Inoperable Malignant Maxillary Sinus Tumors
Article
Full-text available
  • Nov 2020
Purpose: To highlight the clinical spectrum, management, and outcomes of ocular/periocular complications following high-dose external-beam radiotherapy (EBRT) for inoperable malignant maxillary sinus-involving tumors (MMST). Methods: A retrospective, interventional case series. All patients who were diagnosed with inoperable MMST (with orbital involvement) and treated with high-dose fractionated EBRT (65 Gy in 30 fractions) at James Cook University Hospital, UK, were included. Results: Seven patients with advanced MMST (T4aN0M0-T4bN2cM0) were included and were followed up for 23.8 ± 10.2 months. Severe lid margin disease, dry eye, and neurotrophic keratopathy were universally observed. Other complications included cicatricial conjunctivitis (71%), corneal perforation (57%), limbal stem cell deficiency (LSCD; 43%), glaucoma (29%), and superimposed candida keratitis (14%). Amniotic membrane transplant (AMT; 71%), tarsorrhaphy (43%), tectonic keratoplasty (29%), and evisceration (14%) were warranted. Intact corneal epithelium was observed in all patients and good corrected-distance visual acuity (≥20/60) was observed in 3 (43%) patients at final follow-up. Conclusion: High-dose EBRT for inoperable MMST can lead to a wide array of severe ocular/periocular complications. AMT serves as a potentially useful treatment modality to restore the ocular surface integrity after severe radiation keratopathy. We advocate active monitoring for any evolving ophthalmic complications during and after EBRT to enable timely intervention.
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... Other possible causes of LSCD include severe chronic rosacea blepharoconjunctivitis often in the setting of other ocular surface diseases, advanced ocular surface squamous cell carcinoma, 44 and radiation. 45 These etiologies of LSCD each represent less than 5% of all etiologies. ...
Global Consensus on Definition, Classification, Diagnosis, and Staging of Limbal Stem Cell Deficiency
Article
  • Dec 2018
  • CORNEA
Purpose: Despite extensive knowledge gained over the last 3 decades regarding limbal stem cell deficiency (LSCD), the disease is not clearly defined, and there is lack of agreement on the diagnostic criteria, staging, and classification system among treating physicians and research scientists working on this field. There is therefore an unmet need to obtain global consensus on the definition, classification, diagnosis, and staging of LSCD. Methods: A Limbal Stem Cell Working Group was first established by The Cornea Society in 2012. The Working Group was divided into subcommittees. Four face-to-face meetings, frequent email discussions, and teleconferences were conducted since then to obtain agreement on a strategic plan and methodology from all participants after a comprehensive literature search, and final agreement was reached on the definition, classification, diagnosis, and staging of LSCD. A writing group was formed to draft the current manuscript, which has been extensively revised to reflect the consensus of the Working Group. Results: A consensus was reached on the definition, classification, diagnosis, and staging of LSCD. The clinical presentation and diagnostic criteria of LSCD were clarified, and a staging system of LSCD based on clinical presentation was established. Conclusions: This global consensus provides a comprehensive framework for the definition, classification, diagnosis, and staging of LSCD. The newly established criteria will aid in the correct diagnosis and formulation of an appropriate treatment for different stages of LSCD, which will facilitate a better understanding of the condition and help with clinical management, research, and clinical trials in this area.
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Corneal epithelial wound healing in the absence of limbal epithelium
Article
Full-text available
  • Feb 1991
  • INVEST OPHTH VIS SCI
Corneal epithelial stem cells are thought to be at the limbus. The limbal epithelium was surgically removed in 12 New Zealand white rabbits. After 6 months, four showed mild vascularization. To challenge the remaining proliferative reserve, two consecutive 7.5-mm epithelial woundings were created 3 weeks apart in 11 limbal-deficient corneas and 11 controls. After the first wounding, five of the limbal-deficient corneas showed delayed healing, and seven became moderately vascularized; the controls healed normally. After the second wounding, eight experimental corneas showed intense vascularization; the controls did not. Recurrent erosions with delays in healing were noted in nine experimental animals but not in controls. Flat-mount preparation and impression cytology revealed centripetal migration of conjunctival epithelium with goblet cells onto the experimental corneas. These results indicate that only limited proliferative capacity of corneal epithelium remains in the absence of limbus. The constellation of delayed healing with recurrent erosion, corneal vascularization, and conjunctival epithelial ingrowth can be considered possible signs of limbal stem cell dysfunction.
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Abnormal corneal epithelial wound healing in partial-thickness removal of limbal epithelium
Article
Full-text available
  • Aug 1991
  • INVEST OPHTH VIS SCI
Limbal basal epithelium is thought to possess corneal epithelial stem cells that are the ultimate source of corneal epithelial proliferation and differentiation during corneal epithelial wound healing. Destruction of the limbal epithelium results in corneal conjunctivalization and vascularization, suggesting that the limbal epithelium also may be a barrier between corneal and conjunctival epithelia. In this experiment, a total corneal epithelial debridement using combined n-heptanol and mechanical scraping was created immediately (one-step) or 5 weeks (two-step) after 15 or 30 sec n-heptanol treatment at the limbus. All defects healed in 1-2 weeks. The severity of corneal vascularization, as judged by external photography, followed the ascending order of 30-sec two-step and 15-sec two-step less than 15-sec one-step less than 30-sec one-step (P less than 0.005). Immunofluorescence studies using monoclonal antibodies AM-3 and AE-5 showed mixed expression of corneal and conjunctival epithelial phenotypes on the corneal surface in the one-step subgroups. By contrast, the two-step subgroups had a normal corneal epithelial phenotype. Impression cytology was used to map goblet-cell distribution on the perilimbal corneal surface. The specimens taken from superior, temporal, and inferior bulbar areas were evaluated by a scoring system at different times. The extent of goblet cells invading onto the corneal surface also followed the same ascending order (P = 0.005). A transient goblet-cell surge was noted, and the extent was related to the extent of corneal vascularization. It is thus evident that in vivo n-heptanol treatment for different durations can result in different extents of corneal conjunctivalization and vascularization. The authors concluded that the capability of the remaining limbal basal epithelium to recover its original full-thickness stratified layers determines the strength of the limbal barrier.
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Characterization of a potential marker of corneal epithelial stem cells
Article
Full-text available
  • Feb 1992
  • INVEST OPHTH VIS SCI
Corneal epithelial stem cells are thought to be localized in the basal cell layer of the limbus. We developed a monoclonal antibody designated 4G10.3 that immunolocalized to limbal basal cells in rat corneas. Western blot analysis demonstrated that 4G10.3 reacted with a single band of 50,000 molecular weight in rat and rabbit corneal epithelium and 48,000-49,000 in human epithelium. Following extraction of corneal epithelium in 20 mM Tris-HCl (pH 6.8) and ultracentrifugation at 100,000 x g, the 50-kD protein was detected in the soluble fraction. 4G10.3 also was used to examine the response of the limbal basal cells to epithelial debridement and thermal burn wounds in the rat. In unwounded control corneas, 40.8 +/- 12.0 (mean +/- standard deviation) cell per limbal area bound 4G10.3. Following a 3 mm debridement wound, the number of cells binding 4G10.3 increased to 77.0 +/- 16.9 two days post-injury and returned to control levels by three days. Following thermal burn, 36.2 +/- 11.2, 68.8 +/- 15.8, 85.4 +/- 15.4, 104.6 +/- 13.8, and 88.0 +/- 40.2 cells per limbal area bound 4G10.3 18 hours, and 1, 2, 3, and 7 days post-injury, respectively. The 50 kD protein and 4G10.3 antibody provided a biochemical and immunological marker of limbal basal cells, hypothesized to be corneal epithelial stem cells.
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Effect of beta radiation on proliferating human Tenon's capsule fibroblasts
Article
Full-text available
  • Nov 1991
The effects of different doses of beta radiation from a strontium-90 source on the proliferation of human Tenon's capsule fibroblasts were studied. The cultured fibroblasts were exposed to doses of 100, 250, 500, 750, 1000, 1500, and 3000 rads, and cell numbers were counted at days 3, 7, and 14. Treatment inhibited the proliferation of the fibroblasts. At seven days the cells exposed to 3000 rads showed a decrease relative to the starting cell numbers, and at 14 days the cells exposed to 1500 and 3000 rads showed a decrease in cell numbers. The doses of radiation which inhibited cell proliferation more than 50% (at day 7 and 14) and yet did not cause a decrease in the cell population were 500, 750, and 1000 rads. beta Radiation reduces the proliferation of human Tenon's capsule fibroblasts, and at higher doses this effect may be more pronounced one and two weeks after irradiation.
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Conjunctival transdifferentiations due to incomplete removal of limbal basal epithelium
Article
Full-text available
  • Oct 1990
  • INVEST OPHTH VIS SCI
Previous studies have shown that using n-heptanol to create a total corneal epithelial defect beyond the limbus results in two different healing patterns with an unpredictable incidence. Between 14-68% of these wounded rabbit corneas (n = 287, combining various reports) showed extensive vascularization and conjunctivalization, whereas the remaining were not vascularized and had conjunctival transdifferentiation with a cornea-like epithelium. To investigate the role of the limbal epithelium in these two healing patterns, the authors treated rabbit eyes for various durations with n-heptanol and additional scraping. Histology showed that treatment for up to 120 seconds removed both the corneal and conjunctival epithelia but left the limbal basal cells intact. To prove viability, they cultured the treated limbal explants on collagen gel. After 14 days of culture, increased stratification of the limbal epithelium and an epithelial outgrowth onto the corneal stroma was observed. The latter was proven to be of corneal origin (positive to AE-5 but negative to AM-3 monoclonal antibody staining). The authors then surgically removed the entire limbal zone including 2 mm of peripheral cornea and 3 mm of adjacent conjunctiva in addition to n-heptanol debridement of the entire corneal epithelium in 54 rabbit eyes and observed a high incidence (96%) of corneal vascularization and conjunctivalization of the resultant epithelial phenotype (positive to AM-3, but negative to AE-5 monoclonal antibody staining). These results support the hypothesis that corneal epithelial stem cells are located in the limbus and indicate that an incomplete removal of the basal limbal epithelium by n-heptanol leads to unvascularized corneas with conjunctival transdifferentiation. Conversely, complete removal of such cells results in corneal vascularization and conjunctivalization.
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The Effect of Low-Voltage Roentgen Rays on the Normal and Vascularized Cornea of the Rabbit*
Article
  • Apr 1950
The experimental work in this paper presented studies of the effect of low-voltage roentgen irradiation from the Philips apparatus (44 K.V.) upon the normal rabbit eye, as well as observations upon the inhibitory effect of such rays upon experimentally induced corneal vascularization. The need for such controlled experiments is obvious. Little experimental evidence has accumulated to support various claims as to the clinical effect of low-voltage X rays upon the eye. Although information is available for such beta irradiation, it cannot be accurately interpreted and applied to problems involving X-ray therapy of the eye. Furthermore, since beta irradiation with radon as a source can be used only where a radon emanation plant is available as a source of supply, it would be advantageous to use X ray which is more widely available. Radium-D applicators are expensive and their use is practically limited to the eye. Low-voltage X-ray therapy machines, on the other hand, possess the advantage of wide usefulness in other fields of therapy. X-ray therapy has been used about the eye with hesitation since the time of Birch-Hirschfeld, 1908, who first reported cataracts following X-ray therapy. His cases, however, as well as all of those reported since, followed X-ray therapy to the eye or the neighborhood of the eye with a machine operated on a very high kilovoltage which gives hard rays of great penetrating qualities. In recent years, the Philips and Bracke-Seib machines, which give off X rays of low kilovoltage that are very soft and penetrate tissues poorly, have become available. The factor of safety of such machines is relatively great. If a 100-r dosage is given to the surface of the eye with the 100-K.V. machine, 80 percent reaches the lens; with the Philips machine (44 K.V.) only 36 percent reaches the lens. Although this penetration is greater than beta irradiation, the Bracke-Seib apparatus (10 K.V.) emits still softer rays of which only 10 percent penetrate to the lens compared to 18 percent for beta irradiation. Almost no possibility of injury to the lens exists, therefore, with such a machine. Work is now in progress to determine its therapeutic effectiveness. The recent experimental work was done with a Philips (44 K.V.) machine, because at the time the work was started, two years ago, it was the only low-voltage machine available. The first two series of animal experiments, devoted to work with the normal eye of the rabbit, were undertaken to find the approximate limits of tolerance of the anterior segment of the eye, particularly the cornea and the lens. These experiments demonstrated that, if the irradiated area included the cornea, adjacent conjunctiva, and sclera, dosages up to 2,000 r could be given weekly for as long as five weeks with no apparent ill-effect occurring in the cornea or lens. When exposure was limited to the center of the cornea through a five-mm. portal, dosages up to 5,000 r weekly for as long as 21 weeks caused no permanent damage. Production of cataracts was observed only twice. This occurred in animals which received 5,000 r and 10,000 r respectively weekly for 21 weeks. Animals receiving smaller dosages showed no lens changes. The longest period of observation, however, was 14 months. This was a considerably larger dosage than Poppe had found, but his work had been done with a high K.V. machine. The second phase of the experimental work reported in this paper presents observations of the effect of low-voltage X rays upon experimentally induced corneal vascularization. Both eyes of rabbits were injected with sodium hydroxide which produced a dense corneal infiltrate about five-mm. in diameter. Within four days a rather heavy ingrowth of newly formed blood vessels began to invade the periphery of the cornea nearest the lesion and shortly vascularized the lesion itself. In the first experiment, the right eye was irradiated with varying dosages of X rays at the time of the sodium-hydroxide injection, the left eye being kept as a control. The results obtained were rather indecisive, although the smaller doses of 750 r and 1,000 r slightly inhibited the ingrowth of vessels into the lesion. In the final two sets of experiments, the first exposure was given only after ingrowth of new vessels had already become well established, about the 4th or 5th day following the NaOH injection. Two series of animals were treated, one given weekly exposures and the other daily. The eyes exposed weekly showed marked inhibition of vascularization with 750 r and 1,000 r. Smaller dosages down to 300 r had a less striking effect. Exposures up to 1,000 r given weekly for eight weeks caused no apparent ocular injury in any of these animals. The final experiment was similar. Irradiation was also started after the vessels had begun to invade the cornea, but exposures were given daily in dosages up to 1,000 r for 16 days. The results in this series of animals were striking. Ingrowth of the vessels into the lesion caused by sodium hydroxide was practically halted following the 3rd or 4th day of treatment. The vessels in the treated eye rarely extended beyond 1.5 mm. into the cornea, in comparison to 5.0 mm. in the untreated cornea. Of almost as great interest as the inhibiting effect itself was the fact that exposures of 300 r were as effective when given daily as exposures of 1,000 r. In none of the experiments, however, did we observe that X ray had any effect in eliminating vessels which had already grown into the cornea. At the end of eight months, ghost vessels could still be seen in both the treated and the untreated eye extending to about their original distance into the cornea. However, the scars at the site of the NaOH injection were almost invariably less dense in the treated than in the untreated eye. The consistency of this finding suggested that the ingrowth of blood vessels into this type of lesion was certainly not curative and, as judged by the resultant scar, was harmful. It is possible that irradiation of some type might be of benefit in the treatment of alkali burns of the cornea. Clinical investigations have been carried out during the past two-and-one-half years since the beginning of our experimental work. We have used irradiation for the following conditions: (1) Prevention of vascularization of corneal transplants, (2) prevention of vascularization following keratectomy, (3) recurrent pterygium following surgery, (4) certain types of vascularizing keratitis, (5) sclerosing keratitis, (6) conjunctival neoplasm, (7) vernal catarrh. The evaluation of clinical results following any type of irradiation, unless the results are spectacular, is extremely difficult. It is impossible to predict the normal course which any clinical condition might take in an individual patient. A condition that might become extremely severe and aggravated in one patient might clear very quickly with no treatment in another. We also know that corneal vascularization tends to regress spontaneously following the healing of any corneal lesion. Even in corneal transplantation, where we have an ideal place in which to observe the development of blood vessels, invasion of the graft might occur during the first few weeks following surgery and then clear spontaneously. In some patients this tendency to invade is very severe and in others practically does not exist. Evaluation of the effect of irradiation is therefore extremely difficult and uncertain. Clinically, we have employed two general methods of treatment. Until recently, 400 r to 500 r have been given to the treated area of the eye at 3- to 4-week intervals. The size of the portal has varied with the extent of the area to be treated. Localization of exposure is not difficult. Pontocaine is instilled into the eye and a speculum inserted. The patient fixes on an object with his other eye, directing his gaze in a manner which facilitates contact of the Philips tube with the area to be treated on the fellow eye. The procedure is painless except in photophobic patients. In our later clinical work, we have begun to utilize information derived from our experimental observations. Exposures of 200 r were given every other day for 3 or 4 days and more recently daily for 5 or 6 days. These amounts fall well within the limits of safety found in our experimental work and even that of Poppe. It is our impression that low-voltage irradiation given in this manner can, to a great extent, prevent vascularization of corneal transplants. This has been particularly true with repeated small exposures. The same is true in corneas following keratectomy. It is our clinical impression that very small blood vessels can be obliterated by X ray but not the larger ones, such as has been reported by men working with beta irradiation. We are not certain whether failure to close vessels may be due to dosage, for as yet we have kept our clinical dosages extremely small to protect against possible injury to the lens. We are hopeful that with the larger dosages, as can be safely given with the new Bracke-Seib (10 K.V.) machine, the same can be accomplished as with beta irradiation and that sufficiently large dosages will obliterate even the larger vessels. Certainly, with this newer apparatus, the limits of tolerance of exposure to the cornea can be reached with extremely slight danger to the lens.
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Limbal Autograft Reconstruction After Conjunctival Squamous Cell Carcinoma
Article
  • Nov 1990
  • AM J OPHTHALMOL
Two patients who had squamous cell carcinoma with extensive limbal and corneal involvement were treated with surgery and cryotherapy. Rarely large areas of the cornea are involved by this tumor. Visual prognosis in such patients is poor. In these two patients, autologous limbal transplants were effective in restoring an excellent corneal surface and good visual function. This technique may be useful in the reconstruction of eyes with extensive neoplastic involvement of the corneoscleral limbus and cornea.
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