The cause of dry eyes and blocked tear ducts
The everyday notion of “tears” refers to transparent liquid flowing from the eyes in sadness, pain or joy. But when it comes to tears (as produced by the body’s lacrimal systems) and health, there is much more going on than you think.
How do the lacrimal and lacrimal drainage systems work, and what happens when they malfunction?
Dr. Nattawut Wanumkarng, an ophthalmologist specializing in
oculoplastic and reconstructive surgery explains how the eyes’ tear systems work, in this edition of Better Health.
Lacrimal system and lacrimal drainage system
Lacrimal glands in the eyelid produce tears – similar to a faucet that delivers water – to lubricate the conjunctiva and reduce friction when the eye blinks. Tears also wash out dirt and foreign bodies that irritate the eyes.
“Normally, lubricating tears flow and drain via small ducts at the inner canthus,” Dr. Nattawut explains. “The tear duct has two openings, which are on the edge of the upper eyelid and the edge of the lower eyelid on the inside. These two openings are joined to the lacrimal sac, passing down within the zygomatic bone to an opening in the nose that then flows down to the throat. These components together are called the
lacrimal drainage system.”
When functioning normally,
the lacrimal system and lacrimal drainage system brings comfort to the eyes. If they malfunction, various eye discomforts result such as irritation, sore eye, dry eye, or constant welling up of tears.
Tear-related diseases
Often, eye diseases that result from abnormal lacrimal glands have two characteristics: too few tears such as dry eyes and ocular surface diseases, and too many tears, such as nasolacrimal duct obstruction. Detecting and treating them early slows possible damage to the lacrimal glands, eyeballs, and tear ducts.
+ Dry eyes
Dry eyes are a symptom commonly found in patients with eye diseases. “Seventy to eighty percent of an ophthalmologist’s outpatients likely have eye irritation or discomfort; when diagnosed, we find they often suffer from dry eyes disease,” says Dr. Nattawut.
Several factors cause dry eyes. These include age-related degeneration of lacrimal glands; hormonal imbalances, which decrease the quality of tears, especially in females; wearing contact lenses; and environmental pollution-related eye allergies. A new and growing cause is technology-related lifestyle behaviors such as staring at computer or smartphone screens for excessive periods.
Symptoms of Dry eyes
Patients with dry eyes often complain of irritation, as if they have sand in their eyes. Redness from inflammation in the whites of the eyes and eyelids, allergies to light and wind, transient loss of vision, and eye discomfort after waking up are common symptoms. If these symptoms are left untreated, over time, the eye irritation increases, causing serious inflammation and eyelid retraction where eyelashes rub against the eye. In severe cases, the irritation can wound the cornea, which could require eye surgery to correct it.
“Some compare dry eyes symptoms to those of ischemic heart disease (constant chest pain) because dry eyes often occur 24 hours a day. Continual symptoms can result in decreased work efficiency and eye endurance, where a person has difficulty reading and performing work tasks,” Dr. Nattawut says.
Eight weapons to fight dry eyes
Traditionally, ophthalmologists preferred to use artificial tears or steroid drops to relieve dry eyes, but this treatment loses efficacy in the long run. Today’s treatments focus on diagnosis to find the underlying cause of symptoms. New lacrimal gland diagnostic technologies reveal the severity of the condition and the importance of patient self-care treatments to reduce symptoms to the possible minimum.
Dr. Nattawut highlights eight diagnostic weapons to fight dry eyes:
- Examination of the meibomian gland in the eyelid using a special camera process called “meibography” to see damage to the lacrimal gland;
- Using artificial tears to moisturize the eyes;
- Using steroid eye drops which actively depress and reduce the inflammation of eye surface or conjunctiva, and help to relieve itchiness and irritation (use of medication must be under a doctor’s care);
- Eyelid hygiene, which involves cleaning the eyelid with a special solution that kills germs or mites (Demodex blepharitis);
- Warm compression at 42 degrees Celsius at night and day;
- Adjusting lifestyle behaviors, such as reducing time staring at computer or smartphone screens, to allow the eyes to rest;
- Getting nutrients to enhance eyesight by eating deep-sea fish such as salmon and tuna in appropriate portions to increase tear quality;
- Treat meibomian gland inflammation with anti-inflammation antibiotics such as doxycycline or azithromycin.
“If a dry eyes sufferer adopts all these treatments, his chances of success increases eighty to ninety percent, except for age-related lacrimal gland degeneration, for which there’s no cure.”
However, Dr. Nattawut emphasizes that existing treatments cannot restore an already damaged lacrimal gland to its original healthy condition. In that case, treatment is to preserve the remaining healthy area. Thus, timely treatment is vital to slow lacrimal gland damage.
+ Blocked tear ducts
Blocked tear ducts prevent tears from draining. The defining symptoms are tears welling up or constantly flowing. Blocked tear ducts fall into three types, depending on the blockage’s location:
- Blockage at the valve in the tear duct, found mostly in newborn babies whose tear-duct valve is not yet open;
- Blockage in the middle of the tear duct, due to several causes, such as an injury or inflammation from a recurring infection;
- Blockage at the tear duct’s opening, which occurs in adults, especially those who have inflamed fascia from conjunctivitis. For example, redness in the eye, frequent eye irritation, or irritation from using eye drops for an extended period.
Symptoms of Blocked tear ducts
Besides having tears heavily produce or constantly flow, some patients’ eyes may produce excessive mucus. Pain or irritation may or may not accompany this symptom.
“Excessive tear flow is not only cosmetically undesirable, but also negatively impacts daily life,” says Dr. Nattawut. “If left untreated, blocked tear ducts cause dust and excretion to accumulate, which contacts the cornea and conjunctiva, causing irritation or chronic inflammation. The inflammation, if left untreated for a long time, can spread and could lead to blepharitis (inflammation of the eyelids) where the eyelashes stab the eye or pus occurs in the tear duct. In extreme cases, untreated blepharitis pus and severe swelling occur in the lacrimal drainage system and the infection can spread to the eyes or eye sockets.”
Treating blocked tear ducts
+ For newborns, the doctor will massage the blockage area to loosen and remove the tissue that blocks the valve in the tear duct. Ninety percent of these patients will recover in twelve to eighteen months. If symptoms persist throughout the first year, the doctor will open the obstruction surgically by passing a probe through the tear duct, which cures most cases. If there’s a recurrence, the doctor may repeat the probe procedure and insert a silicon tube in the tear drainage system. If these methods fail, when the child reaches three to four years old, the doctor might recommend surgery to open the pathway to allow waste drainage to prevent subsequent complications.
+ For adults, the probe procedure used for newborns is not possible because fascia in the tear drainage system is usually too thick. Thus, treating blocked tear ducts requires surgery using one of the following methods:
Traditional surgery for blocked tear ducts, which entails a small (approximately 1.5 centimeters) external incision on the side of the nose. From this, the surgeon creates a new channel from the tear sac. The wound often heals slowly and may leave a permanent scar. Endoscopic surgery, which employs a tiny camera (endoscope) inserted through the nostril, to create a new connection between tear ducts and a new channel for tear drainage. This method leaves no visible surgical wound and heals faster than traditional treatment. However, it requires a specialized ophthalmologist to perform it.
Another disorder of the lacrimal system is blocked tear ducts with concurrent dry eyes. The patient has severe dryness in the eyes, but with overflowing tears due to inflammation and irritation of the eyeball surface that provokes constant, excessive tearing.
“The dry-eye symptom of the underlying blocked tear duct condition is a complicated problem that requires continual treatment,” Dr. Nattawut says. “But for most cases, surgery to correct the blockage reduces eyeball surface inflammation. The waste matter drains out, which breaks the cycle of chronic inflammation. However, treatment of meibomian gland dysfunction calls for ongoing intervention.”
Lacrimal system conditions may not need urgent treatment, but if left untreated over a long period, it can result in serious problems.
Dr. Nattawut Wanumkarng
“Seventy to eighty percent of an ophthalmologist’s outpatients likely have eye irritation or discomfort; when diagnosed, we find they often suffer from dry eyes disease.” Dr. Nattawut Wanumkarng
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There are two species of mites living on human skin: mites found in hair follicles and mites found in sebaceous glands. They are invisible to the naked eye. Seen through a microscope, they resemble worms with a head, tail, and eight legs. People with dry eyes often have a high number of these mites on their eyelashes. It’s common to find three to five mites on one eyelash feeding on sebum caused by inflammation of the lacrimal glands on the edge of the eyelid. Over time, they increase in number, resulting in a cycle of continuous inflammation. Cleaning the eyelids help break this cycle and improves dry eyes.
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Facts about tears
- Tears are comprised of three layers: oil/lipid (fat) on the surface, water in the middle, and a mucus inner layer touching the cornea.
- There are three types of tears: lubricating tears, which are produced continually; reflexive tears, which flow when the eyes are irritated; and emotional tears.
- Emotional tears are made of different chemical components than the other types. Crying can help to purge stress-linked chemicals out of the body.
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