Dry eye syndrome (SOS) is a disease of the ocular surface produced by a heterogeneous group of diseases with a common denominator in a functional deficit of the tear. It has been modified over the years until reaching the current name, lacrimal keratoconjunctivitis, agreed in April 2007 by the international working group on the dry eye: multifactorial disease of tears and the ocular surface that causes symptoms of discomfort or discomfort, altered visual acuity, and tear film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear and inflammation of the ocular surface1.
Its prevalence ranges between 10 and 20% of the population, although in some eastern countries, it can reach 33% 2. It is common in the European adult population, more frequent in older people, with acne rosacea being the only factor associated with dry eye, while autoimmune diseases and the use of data display screens (PVD) have been considered significantly associated with the signs, but not with symptoms 3.
A large combined population study carried out in the United States (USA) in 2009 in 2 groups concluded estimating that the standardized age of prevalence of SOS is 4.34% (1.68 million) in men 50 years of age or older, with expectations that it will affect more than 2.79 million men in the US in 2030. The comparison in the prevalence of SOS in men and women, adjusted for different age groups, shows a significantly higher prevalence rate in women and all age groups, especially those over 50 years of age, with a 70% higher prevalence in women compared to men4.
Already in the US population, a population study in women had been carried out in 2003, which concluded in the same way, estimating a prevalence of SOS of 5.7% in women over 50 years of age, reaching 9.8% from the age of 50. 75 years. Globally considering the figures, this study estimates an affectation of 3.23 million women over 50 years of age in the United States, the prevalence and symptoms being more severe with increasing age5.
As a disease, it implies a wide repercussion in the general population and, especially in the workplace, where, together with the general risk factors6, occupational risks7 have to be considered7 and, in a complementary way, the indirect costs linked to decreased productivity and absenteeism due to SOS, with a significant reduction in costs after effective ergonomic interventions at work.
Causes of dry eye syndrome
At present, dry eye is one of the most frequent causes or the most common reason for urgency in an ophthalmological service due to the discomfort generated since it affects, depending on the severity, the quality of life of the patients who suffer from it.
Along these lines, multiple factors cause Meibomian Gland Dysfunction (MGD) in people with dry eyes, causing the tear film to break and be exposed to the air.
Therefore, you can influence its appearance in the following scenarios:
Skin disorders: acne rosacea.
Intake of antidepressants, antihistamines, or contraceptives, among others.
Hormonal changes: menopause.
It has undergone previous eye surgery, such as Lasik surgery, for the treatment of myopia, hyperopia, and astigmatism, since it can cause a decrease in the sensitivity of the cornea.
The abuse of contact lenses can even cause a corneal ulcer.
Read for long periods as the frequency of blinking is reduced and the tear evaporates faster.
Using an electronic device too frequently can lead to increased evaporation of the tear duct.
Aging, especially after 50 years.
Indoor environments (air conditioning, heating systems) and outdoor environments (mainly arid climates with low levels of humidity and high wind)
Taking the plane a lot: the air in the cockpits of the plane is very dry.
Certain diseases such as diabetes, lupus, rheumatoid arthritis, or Sjögren’s syndrome can contribute to dry eye.
Eyelid problems: such as blepharitis, the inability to close the eyelid, a disease caused by aging or, after blepharoplasty surgery, called lagophthalmos, can cause severe dry eye.
A laser eye operation or corneal refractive surgery, in general, can also cause dry eye.
Pollution also affects dry eyes.
High levels of air pollution are related to health problems, mainly of the respiratory type. According to the World Health Organization (WHO), this high concentration of pollution in the air contains particulate matter, ozone, nitrogen dioxide, and sulfur dioxide.
Consequently, the lack of humidity and the increase in air pollution due to car smoke and chemical compounds from factories contribute to the growth of eye inflammations and the appearance of dry eyes.
Dry eye symptoms
Some of the symptoms that may indicate a case of dry eye, in addition to dry eye, are:
Burning: burning sensation.
Itching: itchy sensation in the eyes.
Discomfort when performing daily tasks such as reading, driving, staring at a television screen, and intolerance to contact lenses.
Blurred vision or excessive sensitivity to light may also be noted.
Heaviness in the eyelids.
Photophobia (hypersensitivity to light)
Watery eyes, since the dryness of the eye’s surface, overstimulates the production of the aqueous component of tears as a protection mechanism.
Dry eye also causes inflammation and pain.
Occupational risk factors related to dry eye syndrome
There are multiple work factors involved in SOS, but those repeatedly referred to in the medical literature derive from work carried out with PVD in what some authors have called “computer vision syndrome” 9 and in-office work and related to indoor environmental conditions 7. To better understand and understand the issues involved in this area, it is necessary to combine industrial hygiene approaches based on indoor air quality, occupational health approaches, and ophthalmology support.
SOS is related to the loss of the homeostatic mechanism of the tear functional unit (UFL) 10. A stable tear film allows the health and functionality of the ocular surface to be preserved (DEWS, 2007). This stability is achieved thanks to a set of anatomical structures, called Stern Lacrimal Functional Unit (UFL) 11, formed by the main lacrimal gland, cornea, conjunctiva, and Meibomian glands, the eyelids, and the motor and sensory nerves that connect these structures. The UFL must also preserve corneal transparency and the quality of the retinal.
The tear film is composed of 3 layers, which from the inside out are: mucosa, produced by goblet cells, and aqueous itself, which is secreted by the lacrimal glands, and the outermost oily layer, produced by the meibomian glands. This last layer prevents the evaporation of the tear, maintaining the necessary moisture on the ocular surface. Tears contain proteins, enzymes, and immunoglobulins, which, when decreased, can lead to certain eye diseases and infections.