Since they began to be studied, biomarkers constituted a quantifiable and useful instrument to identify pathogenic processes, biological processes, and the effectiveness of a treatment 15; therefore, they could be used to prevent, identify or measure a risk 16, as well as diagnose, understand mechanisms, assess the severity of a pathology 17 and monitor the disease 18; that is, in the presence, absence or high concentration of a biomarker, a pathological state can be detected even before it begins, or it will allow recognizing the effectiveness of treatment from the first stages of its application. Consequently, a biomarker will reduce the uncertainty of pathology by identifying the diagnostic tests that will allow it to detect a clinical condition to separate healthy people from sick ones adequately. 19; in this sense, the biomarker will have sensitivity and specificity to detect a disease 20.
Similarly, biomarkers should be easily evaluated in clinical practice; these correspond to measurable proteins in biological fluids 22) such as blood, urine, tears, among others. In the field of the ocular surface, biomarkers constitute an alternative tool to diagnose diseases of the ocular surface, such as occurs with dry eye syndrome; the advantage of this fluid is that it can be easily collected, and it can use samples of tear or conjunctiva to assess eye tissue; Consequently, thanks to its emergence, the subtypes of the disease have been explained with greater precision, 29 and it has made the treatment increasingly specific to each patient, 12 allowing the response to treatment to be evaluated since its application. However, its viability has been questioned due to its difficult access, high costs27, and the need for highly qualified personnel to take and analyze the samples for each procedure 28.
The first studies of biological samples for the diagnosis of dry eye date back to 1990, the “pre-proteomic era” was called; However, due to the limited techniques of the time, only a little more than 10 tear proteins were reliably recognized 29, among them are lactoferrin, lysozyme, secretory immunoglobulin A, Zinc alpha2 glycoprotein, albumin, immunoglobulin G, and transferrin; those who were directly involved with dry eye syndrome 23. Based on these findings, more markers were identified that could be linked in one way or another with the pathophysiology of the disease 24), (25, so that, Various ways were developed to quantify and categorize the ocular surface proteins 26.
Currently, the difficulty in diagnosing and controlling patients with dry eye syndrome persists due to the variability of the symptoms, the absence of highly reliable tests, weak correlations between clinical tests, and, therefore, impact on the quality of life of patients 17 Therefore, the clinical value of developing specific biomarkers for diagnosis becomes evident. It has even been shown that the tear has a complex composition of proteins, lipids, mucins, water, and salts, of which 1526 proteins have been identified thanks to proteomic analysis; these are considered less complex than plasma fluid or serum 20. Therefore, biomarkers are vital indicators that allow the study of disease activity and decision-making.
Therefore, the scientific evidence supports the analysis of the tear proteome as promising, since it allows to expand the knowledge to dry eye syndrome, since changes in tear proteins may reflect the state of the ocular surface and the disease 29, that is, they would help with the process of early diagnosis, follow-up of the disease and treatment options 30. However, the procedures about tear biomarkers in clinical activity are still in progress. For their part, authors such as Bohem 12) suggest that protein profiles should not be taken as a diagnostic alternative without considering the different pathological or etiological aspects of dry eye disease. For this reason, it is relevant to investigate the information provided by biomarkers about eye damage, since they can diagnose the impact of tear dysfunction on the ocular surface, 21 showing signs of early inflammation and allowing early assessment of those cases where traditional staining tests do not show obvious damage to the surface, although there are reports of symptoms.
About lysozyme, it is the first recognized tear protein 47), (48, it is reduced in patients with idiopathic dry eye and with yes Sjögren’s syndrome compared to controls; while other authors 49) indicate that its concentration does not differ in dry eyes due to Sjögren’s syndrome or in dry eye syndromes not related to Sjögren’s versus controls. They have indicated that lipocalin is lower in patients with dry eye, Sjögren’s syndrome, in patients with hyperevaportive early dry eye but not in patients with non-Sjögren dry eye, 49 its has also presented an inverse correlation with tear film breakdown fifty.
For its part, lactoferrin (transferrin) is one of the most abundant components in the healthy tear film, contributes to iron retention mechanisms against pathogens 49) and mitigates oxidative stress 51; while, serum albumin has one of the lowest contents of tear proteins; However, both derive from plasma, through a passive filtration in the vessels 52) in patients with healthy tears, however, albumin is an indicator of subclinical inflammation due to the filtration of inflamed conjunctival vessels 53. In a study of one hundred and sixty patients with suspected mild to moderate dry eye, in 2013, a significant increase in albumin was found in the absence of clinical signs or conjunctival lesions, which would indicate that albumin is an objective indicator to evaluate inflammatory states of the ocular surface when symptoms are not evident; While the same study showed a significant decrease in transferrin in patients with early dry eye compared to controls, 29 therefore, when there is a decrease in transferrin, an iron imbalance will occur in tears, leading to cellular damage due to nonbinding to iron, 54 a decrease that has also been seen in patients with water-deficient dry eye.
Your doctor may change the type of contact lenses you wear. You may need to stop wearing contact lenses. Your doctor may tell you to stop using or change medications that cause dry eyes. You may also need any of the following treatments:
Medicines to relieve pain or inflammation or treat an eye infection. You may also be given medicine to make your eyes make more tears. These medications are given in the form of eye drops.
Tear plugs Your tear glands may be plugged. Tears flow from the tear glands of the eyes into the nose. The plugs prevent tears from coming out of the eyes. This can also prevent dry eye.
Surgery may be used if other treatments don't work. Surgery may be done to close the tear glands permanently. This will prevent tears from coming out of your eyes. This can also prevent dry eye.