Dry eyes syndrome

Ever had eyes that just tear freely or had a gritty feeling under your eyelid that you cannot get rid of? Then you probably have dry eye syndrome. Although the condition is not well known amongst the population, it is quite a common disease, mostly affecting people older than 40. The condition is called “keratoconjunctivitis sicca” in Latin which means “dryness of the cornea and conjunctiva”.

Other symptoms that can be experienced is blurred vision, irritation, redness, a watery discharge and eyes that tire easily. The symptoms can vary from mild and occasional to severe and continuous, often aggravated by seasonal allergies. If left untreated, permanent damage to the cornea may occur.

There are two main reasons for the condition: either the eye does not produce enough tears or the composition of the tears causes them to evaporate too quickly, leaving the surface of the eye unprotected. Dry eye syndrome can be caused by prolonged contact lens use, Meibomian gland dysfunction, allergies, auto-immune diseases and vitamin A deficiency. Medications such as antihistamines, blood pressure lowering agents and hormone replacement therapy can aggravate the symptoms. Chronic conjunctivitis from tobacco smoke exposure, air pollution or adenovirus infection may also lead to the condition.

Diagnosis is mainly based on the symptoms and treatment aims to address the underlying cause and improve eye comfort. Artificial tears or gel are usually the first option while wearing glasses instead of contact lenses may decrease tear evaporation.

Even when you are happy, your eyes are full of tears. They provide moisture and lubrication to help you see properly and to keep your eyes comfortable.

But what is in a tear? It is a mixture of

• Water, for moisture
• Oils, for lubrication
• Mucus, for even distribution and
• Antibodies and proteins that protect the eyes against infection.

Dry eyes syndrome is often an indication that your tears are in a state of imbalance. When your tears do not contain enough moisture or any of the other components, you start to experience discomfort.

The most common symptoms of keratoconjunctivitis sicca are dryness, a burning or stinging sensation in the eye and a gritty eye irritation that worsens throughout the day. You may feel that something, such as a grain of sand or a hair, is beneath the eyelid and you are unable to get rid of it. The resulting scratching or rubbing may damage the eye surface, causing inflammation, discomfort and sensitivity to light.

Although it does not make sense, dry eye syndrome can cause the eyes to water excessively because the eyes are irritated. These reflex tears are watery without much lubricating qualities and will not necessarily make the eyes feel better.

We normally blink about 10 times per minute, forcing a new tear from the tear gland and smearing it across the surface of the eye. Some activities, such as prolonged computer use, may reduce the rate of blinking. Symptoms are further aggravated in environmental conditions where the rate of evaporation is increased such as when an air conditioner is used for long periods, dry, windy and dusty weather or being in an aeroplane for a long flight.

Fortunately, symptoms can immediately improve when the weather changes to rainy and humid or after having a shower.

Keratoconjunctivitis sicca can normally be attributed to either insufficient tear production or as a result of excessive tear evaporation. The lacrimal gland does not produce enough tears to keep the entire conjunctiva and cornea covered by a complete layer of liquid. This is common amongst people who are otherwise healthy and is most commonly found in postmenopausal women.

Since tear production decreases with age, aging is considered one of the reasons for dry eyes. Several types of medications (both prescription and OTC) have been considered as a major cause of dry eye, especially amongst the elderly. Anticholinergic medications known to cause dry mouth are believed to aggravate dry eye syndrome. Diabetics are believed to be more susceptible to dry eye syndrome because the disease often compromises the eyes.

Many people who wear contact lenses suffer from the symptoms of dry eyes. New types of contact lenses have been developed to reduce dry eye discomfort, for example silicone hydrogel contact lenses. Another option is lenses with an innovative water gradient system for extended use (more than 16 hours). Sensitivity to preservatives in a multipurpose solution may mimic contact lens induced dry eyes. In such a case it would be advisable to switch to daily, disposable lenses.

Dry eyes also occur as a result of or may get worse after LASIK and other refractive surgeries. During these procedures the corneal nerves, which regulates tear secretion, are cut. Dry eyes as a result of eye surgery usually resolves after several months, but it can be permanent in isolated cases.

An eye injury or abnormality of the eyes or eyelids, such as bulging eyes or a drooping eyelid can cause dry eyes as the blinking motion required to spread tears might be impaired.

Various options can be considered as treatment: Avoidance of aggravating factors, tear stimulation and supplementation, increased tear retention, eyelid cleansing and treatment of eye inflammation.

We have a natural tendency to reduce our blink rate when concentrating. Some basic steps that can alleviate the problem is to blink purposefully, especially during computer use for long periods, and to rest your eyes frequently – close your eyes for a few seconds or focus on an object at least 5 meters away every 20 minutes. Rubbing your eyes can increase irritation and inflammation and should be avoided. Conditions such as blepharitis (infection, scaling and crusting of the eyelid) can often co-exist. The crusting and scaling prevent the effective distribution of the tear layer on the eye and worsens the condition. To relieve the discomfort, the eyelids can be cleaned in the morning and at night (and in between if necessary) with a mild soap and warm compresses. Not only will both conditions improve, but the eyes will feel clear and refreshed.

Factors in the environment that should be avoided include dry, dusty places with excessive smoke and wind flow caused by hairdryers, heaters, air conditioners or fans, especially when these devices are directed toward the eyes. It can be helpful to wear glasses or by keeping your computer screen at or below eye level. Moisture can be added to dry indoor air by using a humidifier.

Frequent supplemental lubrication is the most important part of treatment for mild and moderate cases. The application of artificial tears every few hours can provide relief and comfort, although it is only temporary.

Lubricating tear ointments are another option but due to the temporary vision disturbance after application, they are generally only used at bedtime. Depending on the severity of the condition, it may be applied hourly or just at bedtime as preferred but it should never be used simultaneously with contact lenses.

Inflammation and the histamine response in reaction to the imbalance in the tear film and the absence of the protective film on the eyes can be suppressed by taking anti-inflammatory drugs and antihistamines, in consultation with your healthcare practitioner.

In extreme cases alternative methods can be considered to allow both natural and artificial tears to stay on the eye a bit longer. Each eye has two openings, called puncta, that drain excess tears into the tear ducts. The tear ducts can be partially or completely blocked with punctal plugs so that the flow of tears into the nose are obstructed, and thus more tears become available to cover the surface of the eye.

Hot compresses and a gentle massage of the eyelid can provide relief in helping to unblock the oil glands in the eye. Even the heat of your hands can relieve some of the discomfort, albeit mostly briefly.

Without sufficient tears to form a protective film on the eye, a mild irritation can progress to permanent scratches on the cornea, the clear, dome-shaped surface in front of the iris. Over time and after repeated incidents, scratches on the cornea due to dry eye syndrome can cause scar tissue, resulting in impaired vision. Sometimes the result can even be blindness.

Most people with dry eyes experience mild irritation that respond well to treatment, without any long-term effects. The condition can be managed effectively if you know what to do, but it is a chronic, incurable disease. If left untreated or treated ineffectively, the complications can cause permanent eye damage. It is important to consult your doctor when dry eye symptoms persist for more than a couple of days or when symptoms worsen.

Sources:

https://www.nhs.uk/conditions/dry-eyes/
https://en.wikipedia.org/wiki/Dry_eye_syndrome
https://www.webmd.com/eye-health/eye-health-dry-eyes#1