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Basilio
Colligris,
Jesús
Pintor

the
disease
is
contributing
to
the
difficulty
of
a
precise
diagnosis
(14).

Conventional
tests
include
Schirmer
test,
tear
break-­-up
time
(TBUT)
and
ocular

surface
staining,
some
of
them
considered
as
invasive
and
having
a
low
degree
of

standardization.
Another
negative
factor
is
the
lack
of
knowledge
on
the

pathophysiology
of
the
disease
and
the
unclear
symptoms
which
could
be
confused

with
the
symptoms
of
other
conditions
,
such
as
conjunctivochalasis
(which
can

easily
induce
an
unstable
tear
film)
or
delayed
tear
clearance
(which
is
a
frequent

cause
of
ocular
irritation)
(15).
Other
negative
factors
are
the
invasive
nature
of

some
of
the
diagnostic
tests,
which
can
make
the
interpretation
of
the
results

challenging
or
the
use
of
the
individual
tests
in
very
dissimilar
scenarios,

suggesting
the
application
of
different
protocols.
Nevertheless,
tear
film
is
a

dynamic,
open
system
subject
to
numerous
internal
and
environmental
variations,

leading
frequently
to
misinterpretations
of
the
obtained
results
(16).
In
conclusion

the
variety
of
causative
agents
and
the
high
number
of
ocular
conditions
with

similar
signs
and
symptoms
make
an
accurate,
differential
diagnosis
difficult,

especially
due
to
lack
of
correlation
between
signs
and
symptoms.
Accurate
testing

and
diagnosis
of
dry
eye
is
crucial
to
the
correct
management
of
the
condition
and

it
is
advisable
the
use
of
combinations
of
tests
and
sequences.
Consequently,
the

creation
of
objective
tests
with
precise
diagnostic
value
is
essential.
The

International
Dry
Eye
Workshop
(DEWS)
diagnosis
subcommittee
classifies
tests

into
five
fundamental
functional
groups:
Questionnaires,
ocular
surface
staining

tests,
tear
film
stability
tests,
tear
volume
tests
and
tests
to
measure
biological

components
(2).

Currently
there
are
only
a
few
pharmaceutical
treatments
for
dry
eye.
In

some
countries
like
Japan,
are
commercialized
more
DED
treatment
drugs
than
in

Europe
and
the
USA
as
the
approval
rules
are
not
so
rigorous.
Another
important

factor
concerning
DED
treatment
is
that
in
most
of
the
cases,
the
biotechnology

companies
are
trying
to
sort
out
the
problem
based
on
“over
the
counter”

strategies,
trying
to
relieve
symptoms
rather
than
getting
to
the
cause
of
the

disease.
Consequently,
for
the
symptomatic
relief
of
dry
eye
we
could
mention
the

following
treatments
currently
used:
Supplements
called
“artificial
tears”
which

are
synthetic
lubricants,
characterized
by
hypotonic
or
isotonic
buffered
solutions

containing
electrolytes,
surfactants
and
several
types
of
viscosity
agents
(17).
The

“artificial
tears”
permit
not
only
the
increase
of
tear
quantity,
but
also
to
keep
the

ocular
surface
moistened
and
relieve
discomfort.
Another
type
of
treatment
is
the

tear
retention
devices/implants
also
known
as
punctal
plugs.
They
have
been

154