Dry eye disease in patients with metabolic syndrome

Methods

The study was conducted in the Ophthalmology and Endocrinology Department of Bagcilar Education and Research Hospital, a tertiary care center in Istanbul, Turkey, between January and December 2015. The study design was a prospective cross-sectional. We prospectively enrolled 44 consecutive newly diagnosed patients with MetS and 43 healthy controls. All procedures performed with humans were in compliance with the Institutional Research Committee’s ethical standards, the World Medical Association Declaration of Helsinki developed in 1964 and its amendments and other comparable ethical standards. Before conducting any procedure, permission was obtained from all the participants.

Laboratory evaluations and physical examinations were performed for each subject. Participants who had >3 of the following criteria, based on the guidelines of the National Cholesterol Education Program Adult Treatment Panel (NCEP ATP III) 2005, were defined as having MetS:11 1) Abdominal obesity: waist circumference >102 cm in men or >88 cm in women. 2) Hypertriglyceridemia: >150 mg/dl. 3) Low high-density lipoprotein (HDL) cholesterol: <40 mg/dl in men and <50 mg/dl in women. 4) High blood pressure: >130/85 mm Hg, or using antihypertensive drugs. 5) High fasting glucose: >100 mg/dl.

Individuals with known diabetes were excluded due to the confusion risk posed by diabetic eye complications. The use of medications, or any other systemic or ocular disease that could affect tear quality or production, the use of ocular medications, a history of anterior segment surgery, refractive procedures, contact lens wear, ocular allergy, glaucoma, diabetic or hypertensive retinopathy, ocular trauma, eyelid pathologies, nasolachrymal drainage obstruction, pregnancy, and lactation were the exclusion criteria. All of the participants also underwent thorough ophthalmological examinations. Snellen’s chart was used to measure the visual acuity of both eyes. A biomicroscopic anterior segment examination was performed to observe the tear film, cornea, conjunctiva, and adnexa. A biomicroscopic posterior segment examination was carried out to exclude any posterior segment pathology. The study population completed McMonnies&Ho questionnaire, a tear osmolarity test, a tear film break-up time test (TFBUT), and the Schirmer I; all were performed on the same day by a single ophthalmologist. All tests were performed using a randomization table for one eye, and all examinations were performed daily between 15:00 and 16:00 under the same physical conditions to provide diagnostic accuracy.

The dry eye symptoms of the patients were evaluated with McMonnies&Ho questionnaire. Any score over 14.5 indicated a strong likelihood of dry eye disease.12 Tear osmolarity was measured using laboratory on-a-chip technology, a TearLab™ Osmolarity System (TearLab Corporation, 9980 Huennekens St., Ste 100, San Diego, CA 92121, 1-855-832-7522, USA). The measurements were performed at a stable room temperature of 25-25.5°C, and the room humidity was 50-55%. At the beginning of each day of patient testing, reusable electronic check cards, which were provided by the manufacturer to confirm the calibration and functioning of the TearLab™ Osmolarity System, were used to perform quality control checks. The participants were asked not to wear any makeup on their eyelids. From the inferior lateral tear meniscus of the ocular surface, a tear sample of approximately 50 nl was collected. The cut-off score was 308 mOsm/L. The diagnostic value showed 75% sensitivity and 88% specificity for tear osmolarity in cases of mild/moderate disease, while it was 95% sensitive in cases of severe disease.13 The TFBUT is the standard test for estimating tear film stability. The TFBUT was performed by installing an impregnated fluorescein strip moistened with non-preserved saline into the lower fornix. The patient was asked to blink several times for 10-30 seconds and then stare straight ahead. The TFBUT measures the interval between the patient’s last blink and the first appearance of a random dry spot.14,15 The TFBUT values of more than 10 seconds were considered normal, <10 seconds was considered moderate, and <5 seconds was considered severe dry eye disease.16 The Schirmer I test is commonly used to measure the basal and reflex volume of aqueous tears. The filter paper was inserted at the junction of the medium and lateral third of the lower lid for 5 minutes. Less than 10 mm of wetting is considered mild, while less than 5mm of wetting is considered to indicate severe DED.1

Statistical Package for the Social Sciences (SPSS, SPSS Inc., Chicago, IL, USA) Version 21.0 was used to perform the statistical analyses. Descriptive statistics were summarized as means ± SDs or percentages. A student’s independent t-test was used to compare the MetS and normal groups. A p-value of <0.05 was regarded as statistically significant.