Dry eye is a common and often chronic and benign problem that is characterized by a disturbance of the tear film. There are either insufficient tears or poor quality tears to lubricate and nourish the eyes or the tears evaporate too quickly. There can also be an improper balance of tear production to tear drainage. Tear deficiencies can cause a variety of signs and symptoms and can interfere with quality of life.
To help keep the eyes comfortable and vision optimal, a normal thin film of tears coats the eyes with every blink. Tears consist of salt water, fatty oils, protein, electrolytes, bacteria fighting substances and growth factors. There are three main layers that compose the tear film:
1. The thinnest layer is the innermost layer of mucin or mucus. The mucin is produced by cells in the conjunctiva, the clear vascular skin that lines the eyes. The function of the mucus is to help the overlying watery layer to evenly spread over the eye. A malfunction in this layer can lead to dry patches on the cornea, the front surface of the eye.
2. The largest and thickest middle layer is called the aqueous or water layer. It is composed of a dilute saltwater solution. The lacrimal glands, situated under the eyebrow bones, secrete the aqueous layer. This layer's function is to keep the eyes moist and comfortable, plus it helps to flush out any dust, debris, or foreign objects that may get into the eyes. If the water layer is too thin, the oil and mucus layers may touch each other, resulting in a stringy discharge, a hallmark sign of dry eyes. Deficiencies in this layer is the most common cause of dry eye symptoms.
3. The outermost layer is a thin layer of oil or lipids. These oils are produced by the meibomian glands and the glands of Zeis in the eyelids. The function of this layer is to help decrease evaporation of the middle aqueous layer.
The prevalence of dry eye increases with age. Post-menopausal women are twice as likely than men of the same age to develop dry eyes. Over three million women over 50 in the US have dry eyes, while less than 1.7 million men of the same age range have dry eyes. Many contact lens wearers experience dry eyes at some point leading to discontinuing or a decrease in contact lens wear. LASIK surgery often causes dry eyes, which can be a temporary or permanent sequelae.
The affect of dry eyes on ocular health is obvious, but the discomfort and irritation of dry eyes also deteriorates the general wellbeing, emotional health, and social functioning of those who suffer from it. Dry eye patients often have difficulty with reading, computer work, watching TV, and driving. There are also financial costs to those who suffer from dry eye, due to frequent eye exams, diagnostic tests, and charges for treatment. Decreased productivity and efficiency, as well as, lost work time are indirect costs of dry eye patients.
Tear deficiencies are caused by a decrease in tear production, excessive tear evaporation, an abnormality in the oil or mucus production, or a combination of these. Aqueous tear deficiency is caused by a poor production or excessive evaporation of the water layer, which may be a result of age, hormonal changes, side effects of medications, environmental conditions, smoking or various autoimmune diseases. After the age of 40, tear production tends to fall. When it drops to a certain point, the eyes can become dry and easily irritated and inflamed. Menopause can increase the risk of dry eye syndrome. Postmenopausal women on hormone therapy, especially estrogens alone, have a higher prevalence of dry eye than postmenopausal women taking no hormones. Sjogren's syndrome, rheumatoid arthritis, scleroderma and lupus are the most common culprits of autoimmune diseases that lead to a tear deficiency. Those with shingles, diabetes, Bell's palsy, vitamin A deficiency, radiation treatment and HIV infection can also experience dry eyes. Eyelid problems such as ectropion, where the eyelid flops outward, or entropion, where the eyelid curls inward, may also cause dry eyes. Lagophthalmos, or sleeping with the eyelids slightly open, dries out the exposed ocular surface. Contact lens wear and refractive surgery (LASIK) increases the risk of dry eyes. Irregularities of the conjunctival surface, such as with pinguecula or pterygia, can cause dry eye symptoms. Evaporative loss of the aqueous layer is usually due to an inadequate oil layer.
Some medications that may decrease tear production are: antihistamines, antidepressants, beta-blockers, dermatological agents, some diuretics, ACE inhibitors, decongestants, some sleeping pills, opiate-based painkillers and oral contraceptives.
If blinking is decreased or the eyes are unable to close completely, the tear layer may evaporate. Long hours on the computer decreases the blink rate, as well as, conditions like Bell's palsy or stroke.
Poor production of the mucus layer can be caused by chemical, specifically alkali, burns to the eye, autoimmune diseases such as Stevens-Johnson syndrome and cicatricial pemphigoid. The surface of the eye can dry out and become scarred, even with an adequate layer of aqueous present.
An insufficient oil layer may be caused by meibomian gland dysfunction, acne rosacea, or medications to treat acne, such as Accutane. If these oil glands in the eyelids become blocked or degenerate, then there may not be enough oil to cover the water layer to prevent its evaporation.
Blepharitis, an infection along the eyelids and eyelashes, may break down the oil layer leading to evaporative loss of tears and dry eyes. Blepharitis and meibomian gland disease are initially treated with hot compresses and eyelid scrubs.
Environmental factors that can exacerbate or cause dry eye issues include a dry climate, wind, sun, and other types of hot blowing air or dry air, including airplane cabins. High altitude, pollution, smoke and the use of contact lenses are other factors. Use of a computer monitor, reading, or driving a vehicle all cause an increase in visual concentration, which may slow down the blink rate causing dry eye problems.
A person with a tear deficiency may experience a range of symptoms, including:
- A stinging or burning sensation
- A feeling of dryness, grittiness and soreness
- Sensitivity to light
- Difficulty keeping the eyes open
- Stringy mucus in the eyes
- Eye fatigue after reading
- Discomfort when wearing contact lenses
- Blurred vision, especially toward the end of the day
- Eye sensitivity to smoke or wind
- Double vision
- Foreign body sensation
- Eyelids sticking together upon wakening
- Eye pain
- Burning sensation
Sometimes a symptom of a tear deficiency may actually be intermittent excessive tearing. When the eyes become slightly dry and irritated, reflex tearing may result with large amount of tears all at once. The eyes can only handle a certain amount of tears at any one time; the rest pouring over the eyelids and down the cheeks. This tear wasting process often repeats itself.
During an eye examination, the optometrist will be able to diagnose tear deficiency just by listening to the patient's symptoms. the doctor will do a physical examination and ask the patient about their symptoms, their medical history, any current medications, and information about their occupation and environmental circumstances. The doctor will confirm the diagnosis and determine the type of tear deficiency by seeing the signs of dry eyes. Part of the eye examination will include the following tests:
- A slitlamp biomicroscope will examine the front of the eye, or ocular surface
- The amount and thickness of the tear layers will be assessed
- The conjunctiva will be examined to determine if it is dry
- An assessment of the tear breakup time will determine the stability of the tear film
- A corneal inspection to see if there is dry patches or damage
- Different dyes are used to look for staining on the cornea, areas of dead or dying cells, and to differentiate between healthy and abnormal surface cells of the cornea and conjunctiva
- Schirmer test measures the amount of tears produced
- Osmolarity, or salt content, of the tears may be assessed.
Although no cure exists for dry eye syndrome, the primary approach to treat and manage dry eyes include conserving tears, adding tears, increasing tear production, and treating any inflammation of the eyelids or ocular surface that contributes to dry eyes. Treatment is dependent on the severity of the dry eye symptoms, with some people only requiring a humidifier or occasional artificial tear drops, while others may require prescription eye drops or surgery to help decrease dry eye symptoms. Three ways of keeping the eyes lubricated are:
- Using artificial tears
- Making the most of natural tears
- Reducing tear drainage
- Artificial Tears & other eye drops
Over the counter artificial tear drops can help lubricate mildly dry eyes. The optometrist can advise which artificial tear drop to use, depending on the cause of the tear deficiency. Eye drops without preservatives, usually dispensed in single-dose containers, can be used as often as necessary, but artificial tears with preservatives usually have a maximum dosage of four times per day. Artificial tear gel drops are more viscous, stay in the eye longer and are used for more severe dry eyes. Eye drops for removing redness, such as Visine, should not be used. It is advised to use the artificial tears before doing activiites that tend to exacerbate dry eye symptoms. Artificial tear ointments will blur vision and are recommended for night time use only. Lacriserts, an artificial tear insert, is used 1-2 times per day and acts to stabilize and thicken the tear layer.
Some optometrists provide homeopathic eye drops from their office or over-the-counter. Homeopathic drops use natural compounds to treat the eye. Larsson Optometry carries a range of homeopathic eye drops for treatment of dry eyes. They stimulate the production of all three tear film layers while supporting the health of the cornea, conjunctiva and eyelid.
Restasis (0.5% Cyclosporine) and Xiidra (5% Liftegrast) are prescription eye drop medications that help decrease any inflammation on the ocular surface and helps the lacrimal gland produce more natural tears on their own. Patients should not use these drugs if they have any eye infection or a history of herpes viral eye infections.
Steroid drops, such as Lotemax, Alrex, or FML, are either used alone or in conjuction with Restasis, reduce the signs and symptoms of dry eye. These medications should only be used under an eye doctor's supervision, as they may have side effects.
Nonsteroidal anti-inflammatory drops, such as Voltaren, Acular, or Nevanac, will also reduce the inflammation associated with dry eye symptoms.
Antibiotic drops are used if the person has meibomian gland dysfunction or blepharitis. Antibiotic ointments are used at night to decrease the number of bacteria that break down the oil layer of the tear film. They also lubricate the eyes overnight. Oral antibiotics, most commonly doxycycline or tetracycline, not only help decrease the number of bacteria, but also helps make the oil more fluid, so it flows out of the meibomian glands more easily. This is especially helpful for people with acne rosacea.
2. Nutritional Supplements for Dry Eyes
Optometrists sometimes recommend nutritional supplements as part of a dry eye treatment plan. Omega-3 and omega-6 fatty acids, or fish oil, can decrease dry eye symptoms, studies have found. A diet rich in omega-3 fatty acids, which includes oily fish, canola oil, flaxseed oil, walnuts, hemp oil, olive oil, pumpkin seeds, chia seeds, and soybeans. Taking oral supplements of fish oil, flaxseed oil and vitamin E has been shown to help keep the tear film healthy. Mild dehydration often exacerbates dry eye problems. Simply drinking more water can reduce dry eye symptoms.
3. Using Natural Tears
Helpful tips for making the most of natural tears include:
- wearing wraparound sunglasses for protection from wind and hot air
- wearing moisture-chamber goggles
- keeping room temperature moderate
- avoiding smoking and smoky places
- consciously blinking more frequently when using the computer
- taking frequent breaks to allow the eyes to rest while on the computer
- closing the eyes for 10-20 seconds every 10-20 minutes will increase comfort on the computer
- using a humidifier in the home to add moisture to the air. Also, spraying the curtains with a fine water mist can help keep the air humid
- decreasing the speed of ceiling fans and/or oscillating fans
- adding an air filter to the home to reduce large amounts of dust or other particulate matter in the air
- for people who sleep with their eyes slightly open, taping the eyes shut at night or wearing a moisture chamber
4. Punctal Plugs
Near the inner corner of each eyelid are small openings, called punctae, that are the beginning of the normal tear drainage system. In more severe cases of dry eye, the tear ducts, which drain the tears to the nose, may be intentionally blocked partially or completely to conserve tears. Just like a stopper placed in the sink drain keeps water from flowing down the drain, punctal plugs keep the tears from flowing down the tear drainage system. Thus, the eyes stay more moist and comfortable, even if one produces fewer tears than normal. Silicone or dissolvable plugs can be placed in the tear ducts by an optometrist. This helps keep both natural and artificial tears from draining too quickly from the eye. These plugs can easily be removed, if necessary.
5. Surgical Treatments
In severe dry eye cases, the punctae can be permanently closed by using a cautery or laser. This does the same thing as punctal plugs, but it is very difficult to reverse.
If a person has difficulty closing the eye completely, such as Bell's palsy, the eyes may dry out due to tear evaporation. Lateral tarsorrhaphy is a procedure done by an ophthalmologist where the lateral one-third of the eyelids are sewn together to decrease the ability of the eye to open widely and to help the eye close more easily. If a stroke or nerve damage keeps the eyelids from closing completely, a small gold weight can be implanted into the upper eyelid to help it close.
Salivary gland transplantation is a surgical procedure for patients with persistant, severe dry eyes who are not responding to other treatments. Some of the salivary glands are removed from the lower lip area and grafted into the side of the eyes. The saliva they produce is a substitute for tears.
If there is a significant drying of the ocular surface, a thinning, scarring, an increased risk of infection and ultimately a perforation of the cornea may occur. As a result, vision, or the eyeball itself may be permanently lost.
6. Contact Lenses
A scleral contact lens that rests on the white part of the eye, creates a fluid-filled layer over the cornea, preventing it from drying out.
If you or someone you know is suffering from dry eye problems, get a thorough eye examination from your optometrist. Explain to the doctor the symptoms you are experiencing, your health history, including any medications, and any environmental conditions that make your symptoms worse. Your optometrist should be able to help alleviate or reduce the dry eyes symptoms with a combination of the above treatments. Larsson Optometry specializes in treating patients with dry eye problems. Call our office at 209-333-2020 to make an appointment.
Dry Eye Causes