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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 themconsidered as invasive and having a lowdegree of
standardization. Another negative factor is the lack of knowledge on the
pathophysiologyof thediseaseand theunclear symptomswhichcouldbeconfused
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 systemsubject tonumerous internal andenvironmental variations,
leading frequently tomisinterpretations of theobtained results (16). Inconclusion
the variety of causative agents and the high number of ocular conditions with
similar signs and symptoms make an accurate, differential diagnosis difficult,
especiallydue to lackof correlationbetweensigns andsymptoms. Accurate testing
anddiagnosis of dry eye is crucial to the correctmanagement of the conditionand
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 EyeWorkshop (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 commercializedmoreDED 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 eyewe couldmention 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 surfacemoistened and relieve discomfort. Another type of treatment is the
tear retention devices/implants also known as punctal plugs. They have been
