الفهرس 
Introduction and Aim of the workOnly 14 pages are availabe for public view
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Abstract
It has been known for many years that Dry Eye Syndrome (DES) is a common clinical problem. Surveys over the last 20 years have estimated the prevalence of DES to be between excessive exposure to wind , sunlight , high temperature and air pollution , other factors may increase the risk of DES, such as, autoimmune diseases and post menopausal estrogen therapy which has been associated with a 70 percent increase in risk of dry eye. Other risk factors may include chronic diseases such as diabetes mellitus, a diet rich in high fatty acids and use of certain medications such as steroids.
DES is a multifactorial disorder of the tear film and ocular surface that results in eye discomfort, visual disturbance, and possible ocular surface damage. Dysfunction of any Lacrimal Functional Unit (LFU) component can lead to DES by altering the volume, composition, distribution, and/or clearance of the tear film. There are two major etiologic categories of DES: aqueous deficient and evaporative. However, regardless of etiology, tear hyperosmolarity and tear film instability have been identified as global, mutually reinforcing mechanisms. In addition, inflammation is a key factor in perpetuating DES.
Clinical features of DES include an unstable tear film, ocular surface inflammation, and epitheliopathy, resulting in symptoms ranging from discomfort to blindness.
Currently there are no uniform diagnostic criteria. DES is considered a symptomatic disease; assessment of symptoms is considered of primary importance, and may be aided by use of a validated symptom questionnaire. Combinations of various diagnostic tests (including measurements of tear film instability, ocular surface damage, and aqueous tear flow) have been used to evaluate clinical signs, but although diagnostic tests are useful for confirming the diagnosis, they often correlate poorly with symptoms. Measurement of tear osmolarity might provide a “gold standard” of diagnosis, but a practical tear osmolarity test is not yet widely available. Measurement of tear film instability by means of a TBUT test has good overall accuracy and may be more repeatable than many other diagnostic tests.
An established sequence of diagnostic tests is desirable to prevent one test from interfering with another. They include clinical diagnostic tests such as Grading ocular surface staining, Tear break up time, and Schimer’s test. Histopathological tests such as impression cytology, conjunctival and labial salivary gland biopsy. Laboratory tests include Tear flourescein clearance, tear function index, tear osmolarity, analysis of protein, lactoferrin, tear lysozyme and leukocyte esterase in tears. Study of lipid layer that involves meibometry, lipid layer thickness, and lipid layer appearance.
The management ofDES encompasses both pharmacologic and nonpharmacologic approaches, including avoidance of exacerbating factors, eyelid hygiene, tear supplementation, tear retention, tear stimulation, anti-inflammatory agents and surgery as mucus membrane, salivary gland, amniotic membrane, limbal stem cell transplantation, lid surgery and tarsorrhaphy.
This study include all patients attended to the Beni-suif university ophthalmology outpatients clinic between December 2015 and april 2016 done on 5622 patients showed prevalence of dry eye syndrome in 8.8 % of all people 20-40year
With outdoor occupation are more exposed to extraneous influences of environment factors .