What are dry eyes and dry eye syndrome?

Dry eyes are a chronic lack of lubrication and moisture on the surface of the eye. An adequate and consistent layer of tears on the surface of the eye is essential to keep your eyes healthy, comfortable, and seeing well. Tears bathe the eye’s surface to keep it moist and wash away dust, debris and microorganisms that could damage the cornea and lead to an eye infection. A normal tear film consists of three important components:

  1. An oily (lipid) component produced by meibomian glandsin the eyelids
  2. A watery (aqueous) component produced by lacrimal glands located behind the outer aspect of the upper eyelids.
  3. A mucous-like (mucin) component produced by goblet cells in the conjunctiva that covers the white of the eye (sclera).

Each component of the tear film serves a critical purpose. For example, tear lipids help keep the tear film from evaporating too quickly and increase lubrication. Mucin helps anchor and spread the tears across the surface of the eye.

Dry eyes can become red and irritated, causing a feeling of scratchiness.

The results of dry eyes range from subtle but constant eye irritation to significant inflammation. It may even lead to scarring of the front surface of the eye. In addition to being called dry eye syndrome, dry eye disease or simply “dry eye,” alternative medical terms used to describe dry eyes include:

  • Keratitis sicca. Generally used to describe dryness and inflammation of the cornea.
  • Keratoconjunctivitis
    to describe dry eye that affects both the cornea and the conjunctiva.
  • Dysfunctional tear syndrome. Used
    to emphasize that poor quality of tears can be just as important as low

What causes dry eyes?

There are many potential causes of dry eyes:

  • Computer use – When working at a computer or using a smartphone or other portable digital device, we tend to blink our eyes less fully and less frequently. This leads to greater tear evaporation and increased risk of dry eye symptoms.
  • Contact lenses – It can be difficult to determine how much worse contact lenses can make dry eye problems. But dry eyes are a primary reason why people stop wearing contacts.
  • Aging – Dry eye syndrome can occur at any age, but it becomes more common as you age, especially after age 50.
  • Menopause – Post-menopausal women are at greater risk of dry eyes than men of the same age.
  • Indoor environment 
    Air conditioning, ceiling fans and forced air heating systems all can decrease indoor humidity. This can hasten tear evaporation, causing dry eye symptoms.
  • Outdoor environment 
    Dry climates, high altitudes and dry or windy conditions increase dry eyerisks.
  • Air travel – The air
    in the cabins of airplanes is extremely dry and can lead to dry eye problems, especially among frequent flyers.
  • Smoking – In addition to dry eyes, smoking has been linked to serious eye problems, including macular
    degeneration, cataracts and uveitis.
  • Health conditions – Certain diseases such as diabetes, thyroid-associated conditions, lupus,
    rheumatoid arthritis and Sjogren’s syndrome can contribute to dry eye problems.
  • Medications – Many prescription and nonprescription medicines increase the risk of dry eye
    symptoms, including antihistamines, antidepressants, certain blood pressure medications such as beta-blockers or diuretics and birth control pills.
  • Eyelid problems – Incomplete closure of the eyelids when blinking or sleeping (called lagophthalmos)
    can cause severe dry eyes. Severe dryness can lead to a corneal ulcer if left untreated. Lagophthalmos has many causes, including natural aging, eye infections and nerve damage from trauma or cosmetic blepharoplasty.
  • LASIK – LASIK and other corneal refractive surgery can sometimes cause dry eyes. In most cases, however, dry eye discomfort after LASIK is temporary and resolves within a few weeks of the procedure. If you have dry eyes prior to LASIK, your eye doctor may recommend dry eye treatment before your procedure to insure your best LASIK results.
  • Wearing a mask – Many masks, such as those worn to protect against the spread of COVID-19,
    can dry the eyes by forcing air out the top of the mask and over the surface of the eye. Wearing glasses with a mask can direct the air over the eyes even more.
  • Allergies – Allergies can cause dry eyes, and as noted above, taking antihistamines to relieve allergies can also cause dry eyes.

Dry eye symptoms

Symptoms of dry eyes and dry eye syndrome include:

  • Burning sensation
  • Itchy eyes
  • Aching sensation
  • Heavy eyes
  • Fatigued eyes
  • Sore eyes
  • Dryness sensation
  • Red eyes
  • Photophobia (light sensitivity)
  • Blurred vision
  • Feeling like something is in your eye (foreign body sensation)
  • Mucus in or around the eyes
  • Discomfort when wearing contact lenses

And as odd as it may sound, watery eyes also can be a symptom of dry eye syndrome.

This is because dryness on the eye’s surface can sometimes lead to overproduction of the watery part of your tears as a protective mechanism. But this “reflex tearing” does not stay on the eye long enough to correct the underlying dry eye condition.

In addition to these symptoms, dry eyes can cause inflammation and (sometimes permanent) damage to the surface of the eye.

Dry eye syndrome also can affect the outcomes of LASIK and cataract surgery.

Dry eye Categories

There are different categories of dry eyes,depending on which component is affected.

For example, if the meibomian glands don’t produce enough oil, the tear film may evaporate too quickly. This is a condition called “evaporative dry eye.” The underlying condition, called meibomian gland dysfunction, is now known to be a factor in many cases of dry eye syndrome. In other cases, the main cause of dry eye is a failure of the lacrimal glands to produce enough watery fluid to keep the eyes adequately moistened. This condition is called “aqueous deficiency dry eye.”

The specific type of dry eye often will determine the type of treatment your eye doctor recommends to give you relief from your dry eye symptoms.

Dry eye treatment and prevention

Dry eye syndrome is a chronic and typically progressive condition. Depending on its cause and severity, it may not be completely curable. But in most cases, dry eyes can be managed successfully. Treatment usually results in greater comfort, fewer dry eye symptoms and, sometimes, sharper vision. Dry eye disease can have a number of causes, and a variety of treatments are used. Some optometrists and ophthalmologists may have you complete a questionnaire about your symptoms prior to initiating dry eye treatment. Your answers to this survey are then  used as a baseline, and the questionnaire may be administered again after several weeks of treatment to evaluate the effectiveness of the treatment.

Successful treatment of dry eyes requires that you are willing to follow your eye doctor’s recommendations and that you use the products he or she recommends consistently.

The following is a list of dry eye treatments that are commonly used by eye doctors to reduce the signs and symptoms of dry eyes. Your eye doctor may recommend only one of these dry eye treatments or a combination of treatments, depending on the cause(s) and severity of your condition.

Eye drops for dry eyes

  1. Artificial tears eye drops

For mild cases of dry eyes caused by computer use, reading, schoolwork and other situational causes, the
best dry eye treatment may simply be frequent use of artificial tears or other lubricating eye drops.

Artificial tears usually are the first step in dry eye treatment.

There are many brands of artificial tears that are available without a prescription. The challenge with using artificial tears is not lack of product availability – it’s the confusing number of brands and formulations available to choose from.

Artificial tears and other over-the-counter (OTC) lubricating eye drops are available in a wide variety of ingredients and viscosity (“thickness”).

Artificial tears with low viscosity are “thin” and watery. They often provide quick relief with little or no
blurring of your vision when you apply them. But often their soothing effect is very short-lived, and sometimes you must use these drops very frequently to get adequate dry eye relief.

Artificial tears that have a high viscosity are more gel-like and can provide longer-lasting lubrication. But typically these drops cause significant blurring of your vision for several minutes immediately after you apply them. For this reason, these drops often are not a good choice for use during your work day or when you need immediate clear vision for tasks such as driving. Sometimes high-viscosity artificial tears are recommended for bedtime use only.

Also, the ingredients in certain brands of artificial tears may determine which type of dry eye condition they are better suited for. For example, one brand might work better if you don’t produce enough natural tears (aqueous-deficiency dry eye), while another brand may be more effective if your natural tears evaporate too quickly (evaporative dry eye).

If your eye doctor recommends that you use one or more brands or formulations of artificial tears, be sure to follow the directions he or she gives you concerning when and how often you use them. Also, do not substitute other brands from those your eye doctor recommends. Using a different brand or multiple brands of artificial tears will make it difficult to assess the success of the dry eye treatment your doctor recommended.

  1. Prescription eye drops

Instead of OTC artificial tears (or in addition to them), your eye doctor might recommend daily use of a prescription eye drop for dry eye treatment. It includes an agent that reduces inflammation associated with dry eye syndrome and helps your body produce more natural tears to keep your eyes moist, comfortable and healthy.

  1. Steroid eye drops

Over the past several years, inflammation has been recognized as a significant cause of dry eyes. Inflammation frequently causes the redness and burning associated with dry eye disease. Artificial tears usually do not adequately address these inflammatory changes, and your doctor may recommend steroid eye drops to better manage the underlying inflammation associated with dry eyes.

Steroid eye drops generally are used short-term to quickly manage symptoms. They often are used in onjunction with artificial tears as a complement to these more long-term dry eye treatment strategies.

Steroid eye drops (especially if used for relatively long periods) have the potential of causing side effects. So, it’s important to make your eye doctor aware of your full medical history before starting steroid eye drops.

For example, steroid eye drops can increase the risk of developing high eye pressure or even cataracts if used for extended periods of time. But these risks are low when the drops are used only on a short-term basis for dry eye treatment.

Slow release lubricant

Slow-release lubricant that is placed under the lower eyelid where the conjunctiva of the inside of the eyelid meets the conjunctiva of the eyeball.

It is a solid insert composed of a preservative-free lubricating agent (hydroxypropyl cellulose) that slowly
liquefies over time, providing an all-day moistening effect.

Other dry eye treatments

  1. Punctal plugs

Punctal plugs sometimes are used in dry eye treatment to help tears remain on the surface of the eye longer.

A punctal plug inserted in the tear duct of the lower eyelid to keep the eye’s tear film from draining away too quickly.

A punctal plug is a small, sterile device that is inserted into one of the small openings (puncta) of tear drainage ducts that are located in the inner corner of the upper and lower eyelids.

After these openings have been plugged, tears can no longer drain away from the eye through the ducts. This results in the tear film remaining intact longer on the surface of the eye, relieving dry eye symptoms.

So where do the tears go? Usually they will simply evaporate from the eye surface without symptoms. But if insertion of punctal plugs causes watery eyes, one or more of the plugs can be removed.

  1. Meibomian gland expression

A very significant percentage of dry eye cases are caused by inadequate oil (meibum) being secreted from meibomian glands located along the margin of the eyelids.

The openings of these glands are near the base of the eyelashes. If these openings get clogged, the oil that’s critical to keeping the tear film from evaporating too quickly cannot do its job. This is called meibomian gland dysfunction (MGD), which is a significant cause of evaporative dry eye symptoms.

To treat meibomian gland dysfunction and evaporative dry eye, your eye doctor may perform an in-office procedure called meibomian gland expression. In this procedure, warm compresses may or may not first be applied to your eyelids; then a forceps-type device is used to squeeze the clogged contents (hardened meibum and possibly other substances) from the meibomian glands.

To fully express the contents of the meibomian glands and get them functioning properly, significant pressure must be applied to the eyelids, which can be uncomfortable. But the results usually make any short-term discomfort from the procedure worth it.

  1. Warm compresses

An alternative (and potentially more comfortable) way to help open clogged meibomian glands to treat dry eyes is to simply apply warm compresses to the closed eyelids to soften the hardened meibum. Unfortunately, for warm compresses to work well, some researchers say you have to use a compress that can maintain a temperature of 108 degrees Fahrenheit for more than 10 minutes, and the compresses have to be applied for this length of time at least twice a day.

Most people are unable or unwilling to perform this type of dry eye treatment correctly, and shorter and less frequent use of variable-temperature warm compresses typically is ineffective.

  1. LipiFlow

The LipiFlow Thermal Pulsation System (TearScience) is an automated, in-office dry eye treatment that combines the best features of warm compress therapy and meibomian gland expression.

The patented device fits over the eyelids and applies precisely controlled heat to the lids to soften hardened meibum trapped in the meibomian glands. At the same time, the LipiFlow system applies pulsed pressure to the eyelids to open and express the clogged glands, thereby restoring the correct balance of oils in the tear film to relieve dry eye syndrome.

Lipiflow treatment takes approximately 12 minutes per eye.

  1. Intense pulsed light

Intense pulsed light (IPL) has long been used to treat rosacea on the skin. Rosacea on the skin and eyelid often occur together. Ocular rosacea is characterized by dilated blood vessels coursing along the eyelash margin in patients suffering from blepharitis and may contribute to dry eye symptoms. In IPL treatment, a hand-held device flashes bright light onto the skin. The light is filtered to allow only wavelengths that can be absorbed by the dilated blood vessels. The effect of this treatment may be the resolution of the dilated vessels and associated inflammation that contributes to dry eye symptoms.

  1. Nutritional supplements

Doctors sometimes recommend nutritional supplements as part of a holistic dry eye treatment plan. Studies have found that supplements containing omega-3 fatty acids can help dry eyes. Good sources of omega-3s include
cold-water fish such as salmon, sardines, herring and cod. For a vegetarian source of omega-3s, some eye doctors recommend flaxseed oil to relieve dry eye.

Also, simply drinking more water might help relieve dry eye symptoms. Mild dehydration often makes dry eye problems worse. This is especially true during hot, dry and windy weather.

Home remedies for dry eyes

If you have mild dry eye symptoms, there are several things you can try to get relief before going to the doctor:

Blink more often. Research has shown that people tend to blink much less frequently than normal when viewing a computer, Smartphone or other digital display. This decreased blink rate can cause or worsen dry eye symptoms. Make a conscious effort to blink more often when using these devices. Also, perform full blinks, gently squeezing your eyelids together, to fully spread a fresh layer of tears over your eyes.

Wraparound-style eyewear with side shields can protect your eyes from moisture-robbing wind and irritating debris.

  • Take frequent breaks during computer use. A good rule of thumb here is to look away from your screen at least every 20 minutes and look at something that is at least 20 feet from your eyes
    for at least 20 seconds. Eye doctors call this the “20-20-20 rule,” and abiding by it can help relieve dry eyes and computer eye strain.
  • Thoroughly remove eye makeup. Eyeliner and other eye makeup can clog the openings of the glands at the base of  the eyelashes, leading to meibomian gland dysfunction and evaporative dry eye. At the end of the day, be diligent about removing all makeup from your eyelids and eyelashes.
  • Clean your eyelids. When washing your face before bedtime, gently wash your eyelids to remove
    bacteria that can cause blepharitis and meibomian gland problems that lead to dry eye symptoms. Apply a warm, moist washcloth to your closed lids for at least 20 seconds. Then gently wash your lids and lashes with a mild cleanser, such as diluted baby shampoo or pre-moistened eyelid wipes sold in drugstores.
  • Wear quality sunglasses. When outdoors in daylight hours, always wear sunglasses that block 100% of the sun’s UV rays. For the best protection, choose sunglasses that also feature a wrap-style frame to protect your eyes from wind, dust and other irritants that can cause or worsen dry eye symptoms.
  • Use a humidifier. Dry air inside your home, particularly in dry climates, or in cold climates in
    winter, can contribute to making your eyes dry. Consider adding a humidifier to increase the relative humidity inside your home.
  • Other dry eye treatment considerations In addition to the dry eye treatments listed above, your eye doctor may recommend one or more of the following measures if any of the conditions below apply to you:
  • Medication adjustment. Many medicines — including antihistamines, antidepressants, birth control
    pills, certain blood pressure medications and more — can cause or worsen dry eye symptoms. Even over-the-counter (nonprescription) medications for allergies and other conditions can cause dry eyes. Be sure to discuss all medications you are taking with your doctor if you are experiencing dry eye problems. However, never discontinue a prescription medication without first discussing it with your physician.
  • Treating eyelid conditions. If you have blepharitis, meibomian gland dysfunction or other eyelid
    conditions, these often are associated with dry eye disease and should be addressed as part of your overall dry eye treatment regimen. For example, if you have blepharitis, your eye doctor may recommend use of an antibiotic and/or steroid ointment or eye drop in addition to daily eyelid cleansing with a non-irritating shampoo.
  • Discontinuing or reducing contact lens wear. If you wear contact lenses, it can be difficult to tell if an underlying dry eye condition is causing contact lens discomfort or if your contact lenses are causing dry eye symptoms. If you wear contacts, it’s often best to discontinue wearing them (or perhaps switch to daily disposable contact lenses) while your dry eye treatment is in progress.

Prevalence of dry eye Dry eye syndrome, also called dry eye disease (DED), is one of the most common eye conditions worldwide and a primary reason for visits to the eye doctor. In a review published in the Journal of Global Health, researchers reported that studies have shown the prevalence of dry eyes ranges from 5 percent to as high as 50 percent in different populations across the world. (The researchers felt the large variation may be due to disparities in diagnostic criteria of different studies, unique characteristics of the investigated populations and other factors.)

Dry eye tests and diagnosis

The only way to know for sure if you’ve got chronic dry eye syndrome is to have your eye doctor perform one or more dry eye tests, such as the Schirmer’s test, during an eye exam. Symptoms alone are poor signs of the presence and severity of dry eye disease. Symptoms can vary from person to person and may even be affected by personality type. Part of the testing focuses on the quality and quantity of tears your eyes can produce. Your doctor will also examine your eyelids, how you blink and how often you blink. The testing may also  involve dyes to help observe how and where your tears flow.  Some people with only mild dry eyes may feel
their eyes are very bothersome, while others may have significant dry eye problems and not consider their symptoms bad enough to see an eye doctor (or they may not experience dry eye symptoms at all).

Only a careful examination of your eyes by an eye doctor can reveal the presence and severity of dry eye yndrome and help your doctor determine the best type https://en.wikipedia.org/wiki/Dry_eye_syndrome