Dry eye syndrome is one of the most common reasons people visit ophthalmologists. It is traditionally caused by a defect in the quality of the tear film that lubricates the ocular surface. The tear film covers the surface of the eye with a thin layer, serves as a lubricant between the eye and the eyelids during movements of the eyeball, protects it from drying out, contains substances that nourish the cornea and protect the eye from pathogenic viruses.
The tear film consists of three uneven layers. The mucous layer is in direct contact with the eye, creating the foundation for the entire film. The middle aqueous layer contains moisture that nourishes the cornea. This layer is 98% water, as well as salts, proteins and other substances. The outer fat layer is the thinnest layer of fat that covers the film and slows down its evaporation.
Tears are produced in several glands within the eye. The aqueous part is produced in the lacrimal gland located behind the upper eyelid. Several smaller glands in the thickness of the eyelids and conjunctiva secrete fatty and mucous layers. With each blinking movement, the eyelids distribute a tear along the plane of the eye. Its excess drains into 2 thinnest lacrimal canaliculi in the inner corner of the eye. The lacrimal ducts open into the lacrimal sac, which communicates with the nasal cavity through the nasolacrimal duct. This communication of the conjunctival and nasal cavities explains why liquid flows from the nose when crying.
Tearing can be triggered reflexively in response to extraocular stimuli, such as pain, emotions. However, such reflex tears do not soothe a dry eye, and therefore a person with wet eyes may be bothered by irritation.
Dry eye syndrome has many causes. One of the most common is the normal aging process. As we age, our body produces less fat secretion – at 65 years old, 40% of the level of an 18-year-old. This is more pronounced in women, whose skin is traditionally drier than in men. The lack of fatty secretion also affects the stability of the tear film. Without enough fat, the process of evaporation of the tear film is accelerated, which leads to the appearance of dry spots on the plane of the cornea.
Many other factors such as hot, dry or windy climates, high altitudes, air conditioning and cigarette smoke can cause/exacerbate dry eye syndrome. Many people begin to experience eye irritation while reading or working on a computer. Periodic distraction from work with frequent blinking brings more comfort.
Contact lens wearers may also experience discomfort due to dryness, as the lenses absorb the tear film, depositing the proteins that make up the tear film. Certain medications, thyroid disorders, vitamin A deficiency, and Parkinson’s and Sjögren’s diseases can also cause dryness. Women often begin to experience dry eye problems as menopause progresses due to hormonal changes.
- eye redness;
- blurry vision, which is restored after blinking;
- increased discomfort after reading, watching TV or working on a computer.
There are several methods for diagnosing dry eye syndrome. The doctor will first determine its cause by measuring the rate of tear formation, the rate of evaporation, and the quality of the tear film. Special drops that emphasize changes otherwise invisible, especially help to assess the presence and severity of dryness.
Treatment of dry eye syndrome is always individual. Many achieve symptom relief simply by regularly applying artificial tear drops. Some of these products are liquid and short-lived, others are thicker and stay on the plane of the eye longer. Preservative-free artificial tears are always preferred as they are the most soothing to the eyes and contain the fewest additional components that can irritate. Avoid drops that quickly relieve redness in the eyes. They achieve this by narrowing the conjunctival vessels, do not have sufficient wetting properties and only exacerbate the problem.
Another approach is to close the opening of the lacrimal canaliculus with a special plastic stopper. This reduces the loss of tear fluid by reducing its natural outflow. The cork can be worn temporarily if it is made of resorbable collagen, or for relatively permanent wear if it is made of silicone.
There are also simple lifestyle tips to help manage dry eyes. For example, drinking 8-10 glasses of fluid a day will keep your body well hydrated and speed up the elimination of waste. Consciously try to blink more often, especially when reading or watching TV. Avoid rubbing your eyes as this only increases the irritation.
Remember that treating dry eye syndrome is important not only in terms of achieving good health, but also in maintaining the health of the cornea.