Dry eye syndrome

Example of irritation caused by dry eye syndrome.

Dry eye syndrome is a multifactorial disease of the ocular surface due to a loss of the tear film. It is a common form of ocular surface disease and may overlap with other causes of ocular surface disease, such as limbal steam insufficiency. Dry eye syndrome occurs when an individual is unable to produce enough tears or maintain a normal layer of tears to coat their eyes. It can result in ocular symptoms and visual disturbance due to the underlying tear film instability, ocular surface inflammation and damage, and neurosensory abnormalities.

The following are common symptoms of dry eye syndrome:

• A stinging or burning feeling in the eyes
• A feeling of pressure in the eyes, or a feeling that something is in them
• Redness
• Blurred vision or sensitivity to light
• Difficulty or discomfort when opening the eyes
• Watery tearing
• Difficulty reading at a computer or book for long periods

When a person blinks, a film of tears spreads over the eye, which works to keep the eye's surface smooth and clear. The tear film is important for good vision and is made of three layers: an oily layer, a watery layer, and a mucus layer. Each layer serves a specific purpose:

• The oily layer is outside of the tear film. This layer makes the tear surface smooth and keeps the tear film from evaporating too quickly. The oily layer is made in the eye's meibomian glands.
• The watery layer is the middle layer of the tear film. This is the layer that makes the majority of the tears and is responsible for cleaning the eyes and washing away foreign particles from the eyes. This layer comes from the lacrimal glands in the eyelids.
• The mucus layer is the inner layer of the tear film, which helps spread the watery layer over the eye's surface to help keep it moist and help the tears stick to the eye. The mucus is made in the conjunctiva, a membrane of clear tissue covering the white of the eye and the inside of the eyelids.

The breakdown of the different glands and structures in the production of tears.

There are several factors that cause dry eye:

The evaporation of water from the tear film can increase due to a dysfunction in the meibomian gland or blepharitis. This dysfunction can cause decreased production or an altered composition of oil and is a common condition associated with rosacea, Demodex mites, graft versus host disease, and other conditions. When the layers of the tears are changed, this creates a poor quality to the tears, which can cause the tears to evaporate too quickly or to not spread evenly due to deficiencies in the layers. This can happen in any of the layers, which can cause the tears to present differently. For example, a deficiency in the oil layer can cause tears to evaporate too quickly, leaving a mucus-like scum on the eyes. While a deficiency in the mucus layer can cause a person to tear up often, but the tear film will not properly stick to and protect the eye.

A decreased tear production is often associated with an autoimmune or inflammatory systemic condition, such as Sjögren's, sarcoidosis, lupus, and rheumatoid arthritis, which can damage the tear glands. Discomfort, dryness, and the pain sensation are part of the creation of tears, so an individual suffering from dry eye syndrome will not tear appropriately to this pain sensation. This becomes detrimental to the health of the cornea, as the pain sensation is part of the corneal surface cell regeneration, and the reduction of tear production leads to a loss of the pain sensation for the cornea. Decreased corneal sensation can be caused by chronic dry eye, long-term contact lens wear, or a viral infection such as shingles. Decreased tears can also be caused by age, as a side effect of some medications, and environmental conditions, which can lead to symptoms of dry eye.

Several health conditions, such as diabetes and rosacea, can impact the glands associated with tear production and lead to dry eye syndrome. The following are the most common health conditions associated with dry eye:

Dry eyes can develop for other reasons, besides those listed above:

• Age—Dry eyes are a part of the aging process, with the majority of people over sixty-five experiencing some symptoms of dry eyes.
• Gender—Women are more likely to develop dry eyes due to hormonal changes caused by pregnancy, oral contraceptives, and menopause.
• Medications—Some medicines, such as antihistamines, decongestants, blood pressure medications, and antidepressants, can reduce tear production.
• Environmental conditions—Exposure to smoke, wind, and dry climates can lead to increased tear evaporation and result in dry eye symptoms. Failure to blink regularly, such as when staring at a computer screen for long periods, can contribute to the drying of the eyes.
• Other factors—Long-term use of contact lenses can lead to dry eyes, and refractive eye surgeries such as LASIK can decrease tear production and lead to dry eye syndrome.

Those with dry eye syndrome can experience complications. These can include infections, in which the lack of tear production, which protects the eye from infection, increases the risk of an eye infection. It can lead to damage to the surface of the eyes where, if left untreated, dry eyes may lead to eye inflammation, abrasion of the corneal surface, corneal ulcers, and vision loss. And dry eye syndrome can lead to a decreased quality of life, in which dry eyes make it difficult to perform everyday activities such as reading.

Dry eye syndrome can be diagnosed with various methods. These include:

• A routine eye exam by an eye doctor or specialist
• The Schirmer's test, in which the volume of tears is measured by a slip of paper placed under each eye to absorb the water released for five minutes
• Tear film breakup time, a test that uses dyes on the ocular surface to observe the tear film breakup time
• A fluorescein dye test, which uses an orange dye and a blue light to observe microabrasions of the tissue covering the corneal epithelium
• A tear film osmolarity test which determines the number of solutes in tear film versus solvent, also known as the tear composition
• Blood tests and other work-ups can be ordered in some cases to uncover an underlying rheumatological disorder

For milder cases of dry eye syndrome, especially those caused by environmental factors or lifestyle factors, the best treatment may be the frequent use of artificial tears or other lubricating eye drops. There are various brands available without a prescription, and these eye drops, either prescription or over-the-counter (OTC) tend to have different ingredients and viscosity based on the time of application or the individual needs. There are two main types of eye drops:

• Low viscosity artificial tears, which are "thin" and watery to provide quick relief with little to no blurring of vision when they are applied. Often the soothing effect of low viscosity artificial tears is short-lived and may be used frequently to receive adequate relief
• High viscosity artificial tears, which are more gel-like and provide longer-lasting lubrication. Typically these drops cause significant blurring of vision for several minutes after they are applied, and these types of drops are not considered a good choice for use during a workday or when an individual needs to quickly clear their vision for certain tasks; often high viscosity artificial tears are recommended for overnight use.

The ingredients in certain brands of artificial tears may determine the type of dry eye condition they are better suited for. One brand might work better for an individual if they do not produce enough tears, whereas an individual who produces low-quality tears that evaporate too quickly may benefit more from another eye drop.

Sample drops of dry eye treatment Restasis.

Instead of over-the-counter artificial tears eye drops, or in addition to them, an eye doctor may recommend daily use of a prescription eye drop called Restasis. Restasis does more than lubricate the surface of the eye; it includes an agent to reduce inflammation associated with dry eye syndrome and helps the body produce more natural tears to keep eyes moist, comfortable, and healthy. The therapeutic effect of Restasis is not immediate, with the drops often requiring ninety days to experience the full benefits.

Example of drops of Xiidra.

Xiidra is another prescription eye drop for dry eye treatment. Similar to Restasis, Xiidra aims to reduce the inflammation associated with the signs and symptoms of dry eyes. The safety and efficacy of Xiidra was studied in four placebo-controlled, twelve-week clinical trial that included 1,181 people with dry eyes. Participants were evaluated for dry eye signs and symptoms prior to use of the drops, and then they were evaluated again at two weeks, six weeks, and twelve weeks of use with Xiidra.

In two of the four studies, Xiidra was associated with a significant reduction in dry eye symptoms after two weeks. In all four studies, participants noticed a reduction in dryness symptoms at six and twelve weeks of Xiidra use. The twelve-week mark was also associated with a statistically significant reduction in signs of dry eye symptoms compared to those participants given a placebo. The most common side effects of Xiidra reported in the studies were eye irritation, altered taste sensation, and reduced visual acuity, which occurred in 5 to 25 percent of participants.

Lacrisert application under the lower eyelid.

Lacrisert is a sterile, slow-release lubricant 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 liquefies over time to provide an all-day moistening effect. For people with dry eyes, Lacrisert is applied once daily. According to the manufacturer, Lacrisert has been proven to relieve dryness, burning, watery eyes, foreign body sensation, itching, light sensitivity, and blurred vision.

Lacrisert is typically recommended for patients with moderate to severe dry eye symptoms, especially if dry eye treatment with artificial tears alone proves unsuccessful. If placed under the eyelid improperly, it is possible Lacrisert can cause corneal abrasions. Lacrisert may also cause blurred vision, eye discomfort or irritation, matting or stickiness of eyelashes, red eyes, and sensitivity to light.

Dry eye can be in some cases related to a lack of testosterone in the oil glands in an individual's eyelids, leading to improper production of the oil needed in the tear layer. In these cases, some eye doctors may give an individual testosterone cream, which is applied to the eyelids to help the oil glands work better. Treatment is often done through transdermal creams, rather than androgenic artificial tears, which can result in irritation and poor patient compliance. Transdermal delivery is effective in treating dry eye and also improving patient comfort. The treatment was also shown to have the greatest effect on post-menopausal females, while males showed the least benefit of these treatments.

A look at the openings of the meibomian glands.

A percentage of dry eye cases can be caused by inadequate oil (meibum) being secreted from the meibomian glands. These glands are located along the margins of the eyelids. The openings of these glands are near the base of the eyelashes, and these openings can get clogged, which stops the oil necessary to keep the tear film from evaporating too quickly leading to dry eye symptoms. This is called meibomian gland dysfunction (MGD) and is a significant cause of evaporative dry eye symptoms.

Example of the meibomian glands being expressed.

To treat meibomian gland dysfunction and evaporative dry eye, an eye doctor may perform an in-office procedure called meibomian gland expression. In this procedure, warm compresses may or may not be first applied to their eyelids before a forceps-type device is used to squeeze the clogged contents (often hardened meibum, if not other substances) from the meibomian glands. To fully express the contents of the meibomian glands and get them functioning, significant pressure has to be applied to the eyelids, which can be uncomfortable for a patient. The results often make the short-term discomfort of the procedure worth it.

An alternative way to help open clogged meibomian glands to treat dry eyes is the application of a warm compress to the closed eyelids, which can help soften the hardened meibum. However, research into the use of warm compresses has found that for the compress to work well, an individual has to use a compress capable of maintaining a temperature of 108 degrees Fahrenheit for more than ten minutes, at least twice daily. Many people are or may be unable or unwilling to perform this type of dry eye treatment correctly, and shorter and less frequent use of variable-temperature warm compresses will be ineffective.

The LipiFlow Thermal Pulsation System is an automated, in-office dry eye treatment that combines the best features of warm compress therapy and meibomian gland expression. The device fits over the eyelids and applies precise and 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 clogged glands to restore the correct balance of oils in the tear film and thereby relieve dry eye symptoms.

The LipiFlow treatment takes approximately twelve minutes per eye, and in a clinical study of the effectiveness of the procedure, 76 percent of patients reported improvements in their dry eye symptoms within two weeks of treatment. Most patients also showed improvement in the quality and quantity of meibomian gland secretions and the duration of time the tear film remained before evaporating. In some cases, improvements from the LipiFlow procedure took months to become apparent. However, the benefits of the procedure are considered to last between one to three years. Potential side effects from the treatment can include corneal abrasion, eye pain, swollen eyelids, eyelid irritation or inflammation, chalazia, transient blurred vision, itching, and red eyes.

Punctal plugs are sometimes used in dry eye treatment to help tears remain on the surface of the eye longer. In this procedure, one of the small openings (puncta) of tear drainage ducts (located in the inner corner of the upper and lower eyelids) is plugged. Once plugged, tears can no longer drain away from the eye through the ducts, resulting in the film remaining intact with the surface of the eye for longer. In plugging the punctal, the first step is often to use a temporary or dissolving punctal plug. This allows both the patient and the doctor to know whether a punctal plug benefits the patient and whether a more permanent plug may be beneficial.

Example of a punctal plug being inserted.

If a temporary punctal plug has proved beneficial, an eye doctor may choose to add longer-lasting plugs. These plugs tend to be made of medical plastic, such as silicone or acrylic, and are designed to stay in the eye for years. They can be removed if and when needed by an ophthalmologist. Another type of semi-permanent punctal plug can be placed in the deeper part of the puncta called the canaliculus, which cannot be seen in the eye.

In some cases, a dry eye sufferer can choose a procedure called punctal cautery, which uses a special tool to burn the opening shut. The scar that forms over the burn makes a permanent plug, which increases an individual's tear level by blocking the drain. In some cases, after cautery, the puncta can open up—at which point it may need to be cauterized again.

Intense pulsed light (IPL) therapy has been used to treat conditions such as rosacea on the skin, which can occur in the eyelid at the same time. Ocular rosacea is characterized by dilated blood vessels coursing through the eyelash margin in patients suffering from blepharitis and can contribute to dry eye symptoms. In IPL treatment, a hand-held device flashes bright light on the skin. The light is filtered to allow only wavelengths that can be absorbed by the dilated blood vessels and the effect of the treatment may be the resolution of the dilated vessels and the associated inflammation contributing to dry eye symptoms.

Someone undergoing intense pulsed light therapy.

Many patients experience relief from dry eye symptoms after IPL treatment and become less dependent on artificial tears and other routine measures to keep their eyes comfortable. For this reason, IPL treatment may be well-suited for dry eye patients who do not want to be troubled by the frequent use of eye drops. Patients often require four to six monthly IPL treatments for optimum effects, and the treatments tend to be well-tolerated and are not associated with any downtime but can make an individual's eyelids more light-sensitive.

Often, especially in the case of plugged or inflamed oil glands in the eyelid, the onset of dry eye symptoms is due to poor or lacking eyelid hygiene, which can require an individual to pay more attention to this part of personal hygiene. Increased hygiene can involve applying warm compresses to open blocked glands, cleaning eyelids with over-the-counter eyelid scrubs, or cleaning eyelids with a mixture of baby shampoo and water with a cotton-tip applicator.

For patients with severe dry eye syndrome, a device called Prosthetic Rehabilitation of the Ocular Surface Ecosystem (PROSE) can be used. This device is highly customized for each patient, bathing the front of the eye in artificial tears. It is generally used for other corneal conditions and could be considered an extreme treatment for chronic dry eye.

While it may go without saying, eating healthy and ensuring an individual consumes enough good vitamins and minerals needed can help protect vision, improve overall eye health, and relieve dry eye symptoms. There are vital nutrients that can help that can be consumed through a healthy diet, and these nutrients can also be supplemented. These include the following:

• Water—Hydration levels help improve eye comfort.
• Omega-3 fatty acids—Omega-3 is an anti-inflammatory and a building block for meibomian gland oil.
• Vitamin D—vitamin D has been shown to positively affect an individual's bones and eyes, with newer studies suggesting sufficient vitamin D levels can also improve the effectiveness of artificial tears.
• Vitamin A—Vitamin A deficiency has been linked to an increase in dry eye symptoms, and eye drops with vitamin A have been found to be an effective treatment for dry eyes.
• Zinc—Zinc is responsible for moving vitamin A from the liver to the retina and producing melanin, a pigment that helps to protect an individual's eyes.
• Lutein and zeaxanthin—these antioxidants help keep cells healthy and functioning, and proper levels have been linked to helping prevent chronic eye diseases, such as dry eye syndrome.

Dry eye is usually chronic and cannot be cured, but different treatments can improve an individual's eye comfort and eye health. The most common and popular treatment tends to be artificial tears eye drops, especially if that category is stretched to include gels and ointments used for the overnight treatment of dry eyes. Treating an underlying systemic disease or a change of diet, can help relieve the symptoms of dry eye, especially if dry eye is a symptom of a larger underlying disease. New prescription medications are also available to help the body produce more tears.