- What is dry eye syndrome?
- What do we know about tears?
- What causes dry eye syndrome?
- Who is affected?
- What are the warning signs and how is it detected?
- Can dry eye syndrome come and go?
- Is dry eye affected by dust, pollen, or tobacco smoke?
- The white of my eye stings most of the time and is red.
Could this be dry eye?
- My eyes continually produce excessive tears. Could
this be related to dry eye?
- How is dry eye treated?
- What new treatments are coming for dry eye?
- What is dry eye
Dry eye syndrome is a condition caused by loss of water
from the tear film. When the tear film loses water
the concentration of salts and proteins, relative to the amount
of water, increases--the tear film concentration increases.
When tear film concentration increases scientists say
that its "osmolarity" increases. This increase
in tear film osmolarity causes the characteristic irritation
and changes on the eye surface known as dry eye syndrome.
People with dry eye typically experience sandy-gritty
irritated eyes or burning eyes that get worse
as the day goes on.
- What do we know
We know an enormous amount about tears and we are learning
more every day. Although it is a bit of a simplification,
the tear film can be considered to consist of three layers.
The most superficial layer is the oil layer produced by the
oil glands in the lids. These oil glands are called meibomian
glands. This oil layer coats the tear film retarding
evaporation like a biological Saran Wrap. The middle layer
is the aqueous layer. Scientists used to believe that
the purpose of this layer was to wash away debris, but we now
know it performs a much more important function. It turns
out that the living cells on the surface of the eye have no
blood supply. Instead these cells are dependent upon the aqueous
"tear supply" for two requirements necessary for life:
oxygen and a special mixture and balance of electrolytes.
The base layer or foundation of the tear film is the
mucous layer, and this layer provides the natural lubrication
for the eye surface. This layer is produced by "goblet
cells"--specialized cells on the eye surface that produce
and secrete mucus.
What causes dry
Jeffrey Gilbard, MD, conducting research sponsored by the
National Eye Institute, has proven that dry eye is caused
by any condition that increases tear film evaporation,
or by any condition that decreases tear production.
These conditions, in turn, may be caused by a dietary deficiency
of omega-3 essential fatty acids.
Evaporation can increase from chronic eye lid inflammation
or "blepharitis," specifically posterior
blepharitis or meibomitis. In this condition
the oil glands in the eye lid become damaged as a result of
inflammation, and oil production decreases. With decreased
oil on the tear film there is increased evaporation.
Evaporation can also increase from having large
eyes either on a hereditary basis (as in "my, you have big beautiful eyes"), or
from thyroid eye disease. The larger the eyes, the larger the surface
area for evaporation, the greater the evaporation and the greater the loss of
Tear production can decrease from any condition that damages
the lacrimal gland. The most common cause of lacrimal
gland damage is Sjögren's syndrome.
Patients with primary Sjögren's syndrome also have
dry mouth. Patients with secondary Sjögren's
syndrome have an associated autoimmune condition such as
Tear production can also decrease from any condition that
decreases corneal sensation. Just as irritated eyes tear
more, eyes that lose sensation tear less. This is because
intact corneal sensation partially drives tear production.
Causes for decreased corneal sensation include long-term contact
lens wear, LASIK eye surgery, trauma to the 5th nerve,
and certain viral infections.
Omega-3 essential fatty acids are provided primarily by the
consumption of salmon, herring, sardines and mackeral. For
those who can't, won't or don't eat these on a regular basis,
there is TheraTears Nutrition an omega-3 supplement developed
for dry eyes and blepharitis.
- Who is affected?
While dry eye is seen in young adults, its prevalence increases
with age. About 14% of adults over the age of 40 have
dry eye. Based on the 2000 US Census, this translates
into over 20 million Americans. This does not include the
many people under age 40 who also have dry eye. Women are
affected about 1.5 times more frequently than men. The prevalence
of dry eye increases to as high as 19% in people over 80.
About 3 million people have dry eye as a result of Sjögren's
syndrome, and 90% of Sjögren's patients are women.
These cases are frequently the most severe. And dry eye
is very common in diabetics, affecting about half over
the age of 20 (about 7 million Americans). Other risk factors
for dry eye include hyperthyroidism (1.9% of females),
long-term contact lens wear, and people who have had LASIK
- What are the warning
signs and how is it detected?
People with dry eye have sandy-gritty irritation
or burning in their eyes. Initially people may
have symptoms only after particularly long days, or when driving,
or with contact lens wear, or when exposed to extremely dry
environments such as that seen in airplane cabins.
Eventually symptoms become more consistent, and if someone
has sandy-gritty irritation or burning that gets worse as the
day goes on, and if they have had these symptoms for more than
6 months, dry eye should be ruled out by an eye doctor.
The eye doctor will review your history and examine your eyes
to make sure you do not have any other problems, and determine
the cause for your dry eyes.
Can dry eye syndrome
come and go?
Dry eye syndrome does not truly come and go, but in the
early stages of the condition, or with mild dry eye,
you may only have symptoms after long days, or with environmental
conditions that decrease your blink rate (i.e. computer use)
or under conditions that increase evaporation from your tear
film (i.e. wind, dry air, etc.). Some patients may
notice discomfort only when they wear their contact lenses.
Some people may develop symptoms only when they are dehydrated--just
like your mouth becomes dry, your eyes can become dry in this
eye affected by dust, pollen, or tobacco smoke?
When tear production decreases, dust and pollen stay in the
eye longer and are more likely to stimulate an allergic response.
In addition, anything that makes an eye more irritated, including
dry eye, will make an eye more sensitive to environmental
irritants such as tobacco smoke.
- The white of my
eye stings most of the time and is red. Could this be dry eye?
Chronic, longstanding redness of the eyes is most commonly caused by either
chronic meibomitis (inflammation of the oils glands in the eye
lid) or dry eye. If symptoms are worse upon awakening,
and especially if the eyes are their most red upon first eye
opening in the morning, the most likely cause of the redness
is posterior blepharitis or meibomitis. See your doctor and ask him if you would
benefit from TheraTears Nutrition, an omega-3 supplement
containing flaxseed and fish oils and vitamin E) or an oral tetracycline.
If your eyes become more red and irritated as the day goes on
the most likely cause is dry eye.
Some people may notice that their symptoms have two peaks--one
in the morning upon awakening, and a second that occurs late
in the day. This is usually caused by having meibomitis, resulting
in morning symptoms, and dry eye from dysfunction of
the oil glands in the eye lid, with the increase in tear evaporation
causing the symptoms late in the day.
- My eyes continually
produce excessive tears. Could this be related to dry eye?
It depends. If the tears roll out of you eye, down you cheek
for example, the most likely diagnosis is the blockage of the
tiny ducts that drain tear fluid out of your eye. Your
doctor can do a special test to see if this system is blocked.
On the other hand, people with dry eye from dysfunction
of the oil glands in their lids will "feel like" their
eyes are tearing. This is because the oil layer, in addition
to coating the tear film and retarding evaporation, helps hold
the tears tight to the eye surface. With a decrease
or loss of this layer the tears splash around more when
you blink, and it can feel like you eyes are tearing, even though
tears are not rolling down your cheek. Your eye
doctor can look at the openings of these oil glands and evaluate
their status when he examines you.
- How is dry eye
Artificial tears have been the mainstay of dry eye treatment.
Until recently, these used to be recommended like cigarette
brands--doctors would hand out whatever they had in the sample
closet, and patients would pick their brand. Patients
would find that no matter how long or how frequently they used
these drops their eyes would still be dry. Fortunately,
Jeffrey Gilbard, MD, working at Harvard Medical School's Schepens
Eye Research Institute, has developed an eye drop call TheraTears.
This eye drop has been shown in peer-reviewed published studies
to promote healing in dry eye. In addition,
doctors are now recommending patients start immediately on an
omega-3 dietary supplement called TheraTears Nutrition, taking 4
soft gels in the morning. TheraTears Nutrition improves
eye comfort in the upon awakening and throughout the day.
(lubricant eye drops) works two ways. As an eye becomes dry the
tear film loses water and becomes more concentrated.
TheraTears is hypotonic, having more water relative to salt,
and has been shown to rehdyrate the tear film.
This "takes the gas out of the engine" causing dry
eye irritation. Second, the electrolyte balance
of TheraTears matches that in the human tear film which has
been shown to be biologically active in keeping the eye surface
TheraTears comes in three dosage forms--preservative-free unit dose,in a
bottle with a special disappearing preserving ingredient that turns into
oxygen and water on eye contact and as a liquid gel. Doctors usually recommend starting
with the preservative-free form and using "saturation dosing"--splitting the
entire contents of a single container between both eyes within a five-minute
period. The idea is not just to wet the eye but to rehydrate it.
The typical starting dose is four vials a day. TheraTears Liquid Gel
is recommended at night or for use as a protective bandage between the use of
Then, as the eyes get better, doctors recommend graduating to TheraTears in
a bottle, using one or two drops at a time as needed.
For some patients, TheraTears treatment is not enough.
For these patients doctors typically insert "punctal
plugs." Punctal plugs are tiny plastic plugs that
block tear drainage out of the eye. They increase the
efficacy of TheraTears, and there are few dry eye patients
who are not helped by the combination of TheraTears and punctal
What new treatments are coming for dry eye?
Multiple groups are struggling to develop better treatments
for dry eye. As news comes in regarding these projects
you will see announcements and analysis on this site at Dry
Eye News. If you would like to get this news delivered
to your email address, subscribe to our Dry Eye Breaking