The human precorneal tear film is a special body fluid, since it is a complex mixture of proteins, lipids, small bioactive molecules, and their concentrations and relative distribution represent not only the metabolic state of the ocular surface but also the systemic and local homeostasis of the outer eye and the human body. This suggests that biochemical analysis of the precorneal tear film composition may provide a non-invasive tool for diagnosis and monitoring of disease progression or treatment efficacy in human medicine. However, collecting tears is demanding, and obtaining reproducible and unaltered samples is challenging because of the small sample volumes of tears. Several methods are available for tear collection as a preparatory step of precorneal tear film analysis, and the collection method used has to be assessed since it has a critical impact on the effectiveness of the assays and on the quality of the results. Each sampling method has advantages and disadvantages; therefore, it is not easy to choose the appropriate collecting method for tear collection. To overcome these limitations various methods have been recommended by different authors for special aspects of specific tests. The aim of our review was to evaluate tear sampling methods with regard to our ongoing biochemical analysis. *Contributed equally.

The aim of this study was to evaluate the association between clinical signs and symptoms of dry eye disease (DED) in patients with systemic sclerosis (SSc). This cross-sectional observational study included 19 SSc patients and 19 normal subjects with no ocular symptoms or ocular surface disorders. Clinical parameters included tear film break-up time (tBUT), Schirmer I, lissamine green (LG) dye, and tear film osmolarity tests, tear production, and tear secretion flow. For assessment of the dry eye symptoms, the Ocular Surface Disease Index (OSDI) questionnaire was administered to all patients. The following mean values were found in SSc patients: OSDI 33.6 ± 19.86; osmolarity of the tear fluid 310.8 mOsmol/l ± 14.47; tBUT time 5.158 ± 2.328 s; Schirmer I test 5.395 mm/5 min; LG grading score 2.026 ± 0.8893; collected tear fluid volume 6.397 ± 2.761 µl. The calculated average tear velocity was 4.654 ± 1.963 µl/min. A significant correlation was found between the OSDI as a subjective parameter and disease duration. Early recognition of dry eye symptoms, a possible extra-intestinal manifestation of SSc, should be included in the check up of the disease to reduce ocular complications. The objective tear functional tests were strongly influenced by individual factors like age and disease duration.

Purpose: To evaluate detailed corneal parameters of inflammatory bowel disease (IBD) patients, including Crohn's disease (CD) and ulcerative colitis (UC) patients, and to assess associations between anterior segment values and other clinical variables. Methods: This prospective cross-sectional case-control study at a tertiary referral center included 30 CD patients, 36 UC patients and 80 age-and gender-matched controls with no ocular symptoms or ocular surface disorders. All study participants underwent a comprehensive ophthalmological evaluation with special interest in dry eye disease (DED). Corneal parameters were evaluated by Pentacam. Results: The mean age of CD patients, UC patients, and controls was 45.80 ± 11.55 years, 52.00 ± 16.05, and 50.68 ± 14.62, respectively. The average disease duration was 12.72 ± 5.83 years for CD patients and 15.94 ± 10.09 years for UC patients. All pachymetric (center, apex and thinnest) and corneal volume (CV) measurements were significantly decreased, while anterior chamber angle width (ACA) values were significantly increased on both sides in all IBD patients compared to those in controls (p < .05). In addition, several anterior segment parameters were altered unilaterally in CD or UC patients. Negative correlations were found between corneal parameters and Schirmer I test values. Conclusions: Our investigations suggest that IBD patients have thinner corneas compared to that of controls. The coexistence of reduced tear quantity seems to have an additional impact on the thinning of the cornea in IBD patients. Early recognition of corneal impairments, a possible extraintestinal manifestation of IBD, should be included in the disease checkup to reduce vision-threatening developments.

Background. Systemic sclerosis is an autoimmune disease, characterized by widespread small vessel vasculopathy, immune dysregulation with production of autoantibodies, and progressive fibrosis. Changes in levels of proangiogenic cytokines had already been determined largely in serum. Our aim was to assess the levels of VEGF in human tears of patients with SSC. Patients and methods. Forty-three patients (40 female and 3 men, mean (SD) age 61 (48–74) years) with SSc and 27 healthy controls were enrolled in this study. Basal tear sample collection and tear velocity investigations were carried out followed by an ophthalmological examination. Total protein concentrations and VEGF levels were determined in tear samples. Results. The average collected tear fluid volume developed 10.4 μL (1.6–31.2) in patients and 15.63 μL (3.68–34.5) in control subjects. The average total protein level was 6.9 μg/μL (1.8–12.3) in tears of patients and control tears contained an average of 4.132 μg/μL (0.1–14.1) protein. In patients with SSc the average concentration of VEGF was 4.9 pg/μL (3.5–8.1) and 6.15 pg/μL (3.84–12.3) in healthy samples. Conclusions. Total protein production was increased because of the smaller tear volume. Decreased VEGF in tear of SSc patients can be explained also by the decreased tear secretion of patients.

Early recognition of corneal impairment, a possible extraintestinal manifestation of SSc, should be included in the check-up of the disease in order to reduce sight-threatening complications.