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Evaporative Dry Eye Disease
Reports from researchers in the field of dry eye
disease, suggest that evaporative dry eye may
be being under-reported and underdiagnosed.1
The authors indicate that incorrect treatment can
result in an exacerbation of the pain, inflammation
and visual disturbance associated with dry eye
and consequently that correct diagnosis is critical
to receiving the correct treatment.1 “The reports
expose a greater need to re-evaluate the way
that evaporative dry eye disease is currently
diagnosed and treated”, says Dan Alalouff,
Medical Information Executive at Moorfields
Dry eye, a general term, which collectively
describes aqueous deficient and evaporative dry
eye, is estimated to affect as many as 17% of
women and 11.1% of men 2,3,5 . As a
multi-faceted disease of the lacrimal functional
unit, the two types of dry eye are characterized by
a range of, often overlapping, signs and symptoms
including; incorrect tear composition, discomfort,
visual disturbance, tear film instability and
potential damage to the ocular surface resulting
in decreased tear production, increased tear
evaporation and inadequate lubrication of the
eyes 1-5.
Chronic dry eye is particularly prevalent among
women, ranging from 5.7% to 9.8%, and this
prevalence is thought to increase with age 2,3.
Few epidemiological studies to gauge the specific
incidence of evaporative dry eye have been
conducted, however one study of 224 patients
diagnosed with dry eye disease determined that
86% of these exhibited signs of meibomian gland
Different causes of evaporative and
aqueous deficient dry eye
Both aqueous deficient and evaporative dry eye
subtypes present with very similar symptoms and in
the case of moderate to severe dry eye, aqueous
deficient dry eye may take on the features of
evaporative dry eye 2,3. However, the causes of
these two types of dry eye are distinct and relate to
dysfunction of different components of the lacrimal
Whilst, aqueous dry eye arises from chronic
tear deficiency and dysfunction of the lacrimal
glands, evaporative dry eye is primarily caused by
dysfunction of the meibomian glands, embedded
in the eyelids or extrinsic factors such as contact
lense use, vitamin A deficiency and the effects
of chronically applied topical anaesthetics and
preservatives1-3. Meibomian gland dysfunction
(MGD) produces abnormalities in the secreted
lipids resulting in impaired tear film lipid layer
(TFLL) integrity and the increased evaporation of
tears1-3. Further details and diagrams of the major
etiological causes of dry eye can be found on our
educational website -
The tear film layer is composed of three layers; an
inner mucin layer, a central aqueous layer and an
outer lipid layer.
The superficial lipid layer of the tear film is derived
from the meibomian glands, which serve to
regulate the lipid content and quality of the layer.
An intact functional lipid layer allows smooth
movement of the eyelid over the eye, reducing the
surface tension thus promoting the integrity of the
aqueous portion and acting to reduce evaporation
of underlying aqueous fluid in the open eye. Tear
film instability is one of the primary reasons in
developing dry eye and may be the initiating event
in the onset of dry eye syndrome.
The aqueous layer of the tear film is produced by
the lacrimal gland, beneath the upper eyelid. This
layer provides moisture, oxygen and electrolytes
to the cornea. In aqueous deficient dry eye, where
tear production is impaired, the aqueous layer
can become more concentrated (hypertonic) and
can lead to increased tear osmolarity. In severe
dry eyes the tear hypertonicity may result in the
development of ocular surface disease.
Diagnosis of evaporative dry eye
Schirmer’s testing may be used as a first step in
identifying dry eye syndrome, as represented on
blotting paper by a reduced level of tear secretion
. However, if tear secretion levels are normal,
but the patient still shows signs and symptoms of
dry eye, then assessment of Tear Break Up Time
(TBUT) using fluorescein strips can be used to
distinguish evaporative from aqueous deficient dry
eye. A low TBUT suggests the lipid layer has been
compromised, and therefore indicates meibomian
gland dysfunction and the presence of evaporative
dry eye3.
Soybean Oil 7%
+ Natural Phospholipids 3%
20 x 0.3 ml
Use with
contact lenses
Treatment of evaporative dry eye
Mild to moderate cases of dry eye syndrome
are often treated using lubricant eye treatments
based on hydroxypropylmethylcellulose (HPMC)
or sodium hyaluronate that serve to maintain
the aqueous tear film layer but do not treat the
underlying reduced tear film integrity associated
with evaporative dry eye3.
However, Emustil, a preservative free, natural
eye drop emulsion which has been specifically
formulated for treating evaporative dry eye, has
been shown to significantly reduce the frequency
and severity of symptoms in moderate to severe
evaporative dry eye compared to other lubricant
based treatments for dry eye5.
Emustil is based on soy bean extracts and the
same phospholipids that occur in natural tears,
allowing the drops to integrate with and restore
the tear lipid layer to reduce evaporation and
osmolarity. Research from the Caledonian
University has demonstrated Emustil to be as
effective as meibomian lipids in reducing tear film
1) The International Workshop on Meibomian Gland
Dysfunction: Report of the Subcommittee on Management
and Treatment of Meibomian Gland Dysfunction
Geerling G, Tauber T, Baudouin C, Goto E, Matsumoto
Y, O’Brien T, Rolando M, Tsubota K, and Nichols K
Investigative Ophthalmology & Visual Science, Special Issue 2011,
Vol. 52, No. 4
2)The International Workshop on Meibomian Gland
Dysfunction: Report of the Diagnosis Subcommittee
Alan Tomlinson, Anthony J. Bron, Donald R. Korb,
Shiro Amano, Jerry R. Paugh, E. Ian Pearce, Richard
Yee, Norihiko Yokoi, Reiko Arita, and Murat Dogru
Investigative Ophthalmology & Visual Science, Special Issue 2011,
Vol. 52, No. 4
3)2007 Report of the International Dry Eye WorkShop (DEWS)
The Ocular Surface, 2007, Vol 5, No. 2 .
Available from
4)Distribution of aqueous-deficient and evaporative dry
eye in a clinic-based patient cohort: a retrospective study.
Lemp MA, Crews LA, Bron AJ, Foulks GN, Sullivan BD.
Cornea. 2012 May;31(5):472-8.
5)Effectiveness of Artificial Tears in the
Management of Evaporative Dry Eye
McCann L.C, Tomlinson A, Pearce E.I., and Papa, V.
Cornea, 2012, Volume 31, No.1
6) State of the art management of chronic dry eye
Proceedings from a scientific roundtable, 2006
A division of

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