Causes of Dry Eyes
Tears are made up of more than just water. They're a complex mixture of
water, fatty oils, proteins, electrolytes, bacteria-fighting
substances and growth factors that regulate various cell processes.
This mixture helps make the surface of your eyes smooth and clear.
Without tears, good vision is impossible.
For some people, the cause of dry eyes is an imbalance in the
composition of their tears. Other people don't produce enough tears
to keep their eyes comfortably lubricated. Eyelid problems,
medications and other causes, such as environmental factors, also
can lead to dry eyes.
Poor tear quality
The tear film has three basic layers:
oil, water and
mucus. Problems with any
of these layers can cause dry eye symptoms.
The outer layer, produced by small glands on the edge of your
eyelids (meibomian glands), contains fatty oils called lipids. These
smooth the tear surface and slow evaporation of the middle watery
layer. When the oil layer is abnormal, the watery layer evaporates
too quickly. Dry eye problems are common in people whose meibomian
glands are clogged. Meibomian dysfunction is more common in people
with inflammation along the edge of their eyelids (blepharitis),
rosacea and other skin disorders.
middle layer, which is by far the thickest layer, is mostly water with a
little bit of salt. This layer, produced by the tear glands (lacrimal
glands), cleanses your eyes and washes away foreign particles or
irritants. A shallow water layer can predispose you to tear film
instability. If your eye produces only small, inadequate amounts of
water, the oil and mucus layers can touch and cause the stringy
discharge familiar to people with dry eyes.
Mucus. The inner
layer of mucus allows tears to spread evenly over the surface of your
eyes. Dry spots form easily in any part of the front surface of the eye
(cornea) that has patchy loss of the mucus layer.
Decreased tear production.
Dry eyes are common, especially for
people older than 40. Tear production tends to diminish as you get
older. When you're unable to produce enough tears, your eyes become
dry and easily irritated. The medical term for this condition is
keratoconjunctivitis sicca (ker-uh-to-kun-junk-ti-VIE-tis sik-uh).
Although dry eyes can affect both men and women at any age, the
condition is more common among women, especially after menopause.
This may be due in part to hormonal changes. Damage to the tear
glands from inflammation or radiation can hamper tear production.
Dry eyes are also associated with some medical conditions such as
diabetes, rheumatoid arthritis, lupus, scleroderma, Sjogren's
syndrome and vitamin A deficiency.
Refractive eye surgeries such as laser-assisted in-situ keratomileusis (LASIK)
also may cause decreased tear production and dry eyes. Symptoms of
dry eyes related to these procedures are usually temporary.
Poor lid function.
Through blinking — normally at a
rate of about once every 12 seconds — your eyelids spread a
continuous thin film of tears across the surface of your eyes.
Problems with your eyelids can impair the complex blinking motion
required to spread these tears, resulting in dry eyes. Eyelid
problems that may develop as you age include an out-turning of the
lids (ectropion) or an in-turning of the lids (entropion).
Blepharitis, an inflammation along the edge of the eyelids, also may
cause your eyes to feel dry and scratchy.
Medications. The types
of common medications, both prescription and over-the-counter (OTC),
that can be the causes of dry eyes include:
Diuretics, drugs commonly
used to treat high blood pressure
Angiotensin-converting enzyme (ACE) inhibitors used to treat high blood pressure
Birth control pills
for treatment of acne
relievers, such as morphine
Other causes of dry eyes.
Dry eyes can be worsened by
exposure to many environmental conditions that has a drying effect,
such as sun, wind, high altitude, a dry climate, hot blowing air and
the dry air that commonly occurs in the cabins of commercial
In addition, tasks that require intense visual concentration — such as
working at a computer, driving or reading — tend to decrease your
blink rate, thereby increasing tear evaporation.
Often times under diagnosed or not addressed by patients’
optometrists or ophthalmologists, Dry Eyes Syndrome plays a
significant role when treating other ocular conditions. Dr.
Azizi believes when Dry Eyes is appropriately addressed and treated,
outcomes for ocular surgeries such as Cataracts, LASIK,
Blepharoplasty to name a few is much improved. Dry Eyes
Syndrome plays a large role at West Florida Eye. Dr. Azizi’s
expertise in this field has allowed him to help thousands of
individuals suffering from this disease, at times debilitating for
many individuals. Dr. Azizi has made Dry Eyes Syndrome a focal
point of his practice and career; and he will continue to be in the
forefront of research and treatment.
Symptoms of dry eyes
Signs and symptoms of
dry eyes, which usually affect both eyes, may include:
A stinging, burning or
scratchy sensation in your eyes
Stringy mucus in or
around your eyes
irritation from smoke or wind
Eye fatigue after
short periods of reading
Sensitivity to light
Difficulty wearing contact lenses
Blurred vision, often
worsening at the end of the day or after visually focusing for
prolonged period on a nearby task.