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INTRODUCTION: Human tears contain a number of agents which may play an important role in diagnosing local eye disorders as well as systemic diseases. The small amount of fluid obtained during the collection and the consequent difficulty in analysing it are the main problems encountered in the diagnostic process. AIM: We decided to investigate the practical usefulness of two simple methods of collecting tear fluid for chemical analysis, i.e., glass tubes and Schirmer's strips. The substance analyzed was vascular endothelial growth factor (VEGF), a compound commonly recognized in ophthalmology. METHODS: We used standard Schirmer's tear test and calibrated glass tubes for tear fluid collection in healthy volunteers. The standard ELISA assay was used to check the effectiveness of the tear sampling by estimating the VEGF level. RESULTS: The results of the study show that Schirmer's tear strip test is a more effective tool of the two. Moreover, using Schirmer's strips to obtain tear fluid was found to be more patient friendly and amounts of the tear fluid collected with that test were enough and better for the VEGF detection. CONCLUSIONS: Our study indicates that the widely used Schirmer tear test may be the best method of tear collection for chemical analysis. However, further studies on test calibration are needed.
RESUMEN
In this case study, the authors describe peculiar bilateral cotton wool-like retinal lesions associated with macular edema in a patient with COVID-19 who was vaccinated with a single dose of AstraZeneca one month earlier. This patient had no pulmonary or systemic cardiovascular complications from COVID-19, as reported in other papers that found retinal lesions. However, the patient was diagnosed with idiopathic myopathy when discovering the SARS-CoV-2 infection. The patient was a 22-year-old white female with no previous history of morbidity, complaining of blurred vision in both eyes seven days after testing positive for SARS-CoV-2 by PCR (using nasal and oral swab) and confirmed through ELISA blood test (IgM positive). There was no ancillary test revealing diabetes mellitus. The patient presented with scattered whitish cotton wool-like lesions and a few hemorrhages on the posterior pole in fundus examination. On spectral domain optical coherence tomography (SD-OCT), there were hyperreflective lesions in the nerve fiber layer, ganglion cell layer, inner nuclear layer, and inner and outer plexiform layers at the site corresponding to the whitish cotton wool-like lesions in the posterior fundus photos. Moreover, the macula of both eyes had intraretinal and subretinal fluid, reversible with corticosteroid therapy. In conclusion, COVID-19 has been associated with capillary disorders at different target sites such as retina, lungs, and central nervous system. Similarly, vaccination against SARS-CoV-2 has been linked to retinal complications in the literature; however, cotton wool-like lesions have not yet been reported. There are many questions yet to be answered about the implications of COVID-19 infection and its vaccines.