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Soledad Benlloch-Navarro, Violeta Sanchez-vallejo, Inmaculada Almansa, Emma Arnal, Dolores Silvestre, Maria Miranda; Cigarrete Smoking And Diabetes But Not Increased Levels Of Cholesterol, Increase Lipid Peroxidation In Human Tears. Invest. Ophthalmol. Vis. Sci. 2013;54(15):6014. doi: https://doi.org/.
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Oxidative stress can be defined as an increase in the formation of reactive oxygen species and/or a decrease in antioxidants and is an important factor in many ocular disorders. The ocular surface is chronically exposed to oxidative stress because of ultraviolet light, oxygen in the air, and changes in oxygen pressure due to blinking. Tears protect the cornea against oxidative damage from radiation, atmospheric oxygen, and pollutants. Schirmer strips are routinely used to measure tear volume in order to diagnose dry eye. The main purpose of this study was to measure and compare the concentration of a marker of lipid peroxidation (malondialdehyde, MDA) in tears that were obtained from Schirmer strips in different groups of patients (patients who usually smoke, diabetic patients and patients with increased cholesterol levels).
The experiment was approved by the Ethics Committee of the institution, all participants signed an informed consent form. A Schirmer strip placed onto the outer canthus of the eye of each subject, and reflex tears were collected for 5 minutes. The Schirmer strips were removed and placed into an Eppendorf tube and 400 µl of phosphate buffered saline (PBS) were added. The samples were stored at −20 °C until processed. MDA was assayed in tears by HPLC with a method where the complex formed between MDA and thiobarbituric acid was detected.
MDA in tears from patients that smoke more than 10 cigarretes/day was significantly increased than MDA in tears from control subjects. Diabetes increased slightly MDA tear concentration and increased cholesterol levels did not modify tear’s MDA.
The lipid peroxidation status of tear fluid is of interest, because tears constitute the first barrier protecting the cornea against oxidative damage and it is altered in patients who smoke and diabetic subjects.
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