Various factors are capable of progressively increasing the evaporation of water from the corneal surface and causing a faster thinning of the PTF (precorneal tears film): thermal factors (low relative humidity, high temperature); task-related demands (excessive attention decreases blinking and enlarges the exposed ocular surface), and individual characteristics (gland dysfunctions and use of contact lenses), which causes dryness and formation of a dry spot on the cornea, possibly followed by corneal alterations and epithelial alterations of the conjunctiva. Also, exposure to some irritating chemical compounds or oxidation mixtures formed in the reactions between ozone and unsaturated organic compounds (alkenes) alters the TFP, which can exacerbate this effect of low relative humidity in the air15.
Studies carried out in the workplace show a higher prevalence of symptoms of fatigue, heaviness of the head, eye irritation, dry skin on the face in workers with allergies, and that this clinic is exacerbated in workers using PVD. Passive smoking and psychosocial burden also acted as predictors of SOS, while improved cleaning conditions in the ventilation system and local temperature improved eye discomfort16.
Among the environmental conditions of the offices that influence the appearance of SOS are those related to indoor air quality, valued based on measurements of oxidative stress indicated by urinary 8-hydroxydeoxyguanosine (8-OHG). The increase in the mean value of 8-OHdG is related to greater symptomatology of sick building syndrome (SBS), which includes among its characteristic nonspecific symptoms dry eyes together with respiratory distress syndrome, itchy nose, sneezing, dry throat, of skin, and dizziness 17.
It is worth highlighting the priority role in this pathology of using data display screens (PVD) since it is considered a specific risk in the appearance of SOS. Ocular symptoms related to the use of computers are frequent, including visual fatigue, tired eyes, irritation, redness, blurred vision, and diplopia, and to which are added ergonomic factors associated with the use of PVD, such as reflections, poor screen quality, low frequency of breaks, radiation, poor lighting intensity and flickering of the screens18. The gaze angle concerning the monitor stands out as the main culprit in the appearance of dry eyes, with improvement in symptoms if the gaze is directed downward at an angle of 14 degrees or greater19.
SOS is the main condition related to the use of PVD, but not the only one, since anomalies of the ocular surface or accommodative spasms can also occur.
Ocular involvement with symptoms of SOS has been highlighted in some studies carried out in professional risk groups and related to various factors. Thus, in airline workers, it has been observed that conditions of low relative humidity during the flight in the cabins lead to increased evaporation of aqueous tears and the appearance of dry eyes20. In workers in the TFT-LCD (thin-film transistor liquid crystal display) industry, the prevalence of tear secretion dysfunction in working women performing light tests is high and increases with age in the position, the use of contact lenses being an increasing risk factor. In this specific light test process to detect product defects, the worker-operator is exposed to low humidity environments, intermittent light, and low ambient lighting during long working hours, which undoubtedly favors the appearance of symptoms. ocular21. Finally, it is worth highlighting the group of radiologists, in which the higher incidence of SOS compared to the control group of non-radiologists seems to be linked to the working conditions and circumstances associated with it: working in air-conditioned rooms, the use of X-ray scanners. And radiation exposure as a diagnostic technique22.
Dry eye diagnosis
Until now, the diagnosis of dry eye was relatively complex since there was no diagnostic test to help detect, identify and measure the severity of this annoying pathology.
Until then, some tests performed in ophthalmology consultations were staining the ocular surface with fluorescein for more detailed visualization of the cornea and the presence or absence of possible corneal ulcers. A Schirmer test has also been used to place small strips of filter paper on the para lower sides of both eyes to quantify the patient’s tear production.
At Oftalvist, we have acquired an advanced technology called DX Analyzer to take a qualitative leap in diagnosis and obtain greater control, monitoring, and prevention of dry eye.
DX Analyzer is a useful, effective, and highly accurate tool for analyzing the quality of the tear film that offers us important data to know the objective changes of the tear film and the visual quality of the patient at all times.
Thanks to this information, the specialist ophthalmologist will assess the best treatment to apply to the patient.
The OSDI test is used to establish the severity and classification of a dry eye according to its symptoms. It gives us a clue, therefore, of the type of dry eye that the patient has and the treatment.
Dry eye treatment
As it is generally a chronic and progressive ocular pathology, the treatment used to be long-term until now.
The most widespread classic treatment consisted of the application of preservative-free artificial tears to help retain moisture. Composed of water, they are an isotonic or hypotonic saline solution that helps lengthen the permanence of the artificial tear on the ocular surface and prevent any contamination and eye irritation.
In more complex cases, eye drops with growth factors obtained from the patient’s serum and immunosuppressive drugs have been used to fight inflammation, such as cyclosporine A.
Probing the meibomian glands
It is a non-invasive surgical procedure that aims to open the outlet duct of the meibomian glands, extract the fat content from its interior and apply an antibiotic to normalize the microbial flora. It is performed with superficial sedation and is painless.
Exfoliation of the free edge of the eyelids and glandular drainage
It is one of the least invasive techniques. It is about removing the membrane that clogs the meibomian glands through exfoliation. Next, a massage is performed to empty the contents of the glands by applying cold and antioxidants to reduce inflammation of the eyelids and improve lymphatic drainage.
Other treatments that have been used, prescribed only by an ophthalmologist, are topical corticosteroids, sodium hyaluronate, autologous serum tears, pilocarpine, or hyaluronic acid in combination with other products such as xanthan gum or HP-guar, among others.