الفهرس 
Lacrimal functional unitOnly 14 pages are availabe for public view
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Abstract
Dry eye is a multifactorial disease of the tears and the ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. Estimates of the prevalence of dry eye in the general population range from 11 to 22%, depending on the parameters and populations studied. Dry eye is divided into two subgroups, tear-deficient and evaporative. Each form calls for a different therapeutic approach and it is therefore essential to apply a combination of diagnostic tests in order to establish the exact diagnosis. The diagnosis of DED is based in part on the patient’s history, symptoms and in part on the application of specific tests. Several noninvasive tests exist (e.g. slit-lamp examination, meniscometry, interferometry). Mildly invasive tests are the fluorescein tests, staining with lishamine green. Markedly invasive tests include the Schirmer test and staining with rose bengal. Additional histological procedure which is the impression cytology. Dry eye disease is generally not curable and management is structured around the control of symptoms and the prevention of surface damage. Fortunately, in the great majority of patients the disease is not sight-threatening. General measures for management of DED include life style modifications, eyelid hygiene and identification and treatment of associated conditions. Artificial tears are the mainstay of DED treatment. They are used in all stages of DED, either alone (in mild to moderate disease) or in combination with other treatments (in moderate to severe disease). Most tear supplements act as lubricants; other actions may include replacement of deficient tear constituents, dilution of proinflammatory substances, reduction of tear osmolarity and protection against osmotic stress. Other therapeutic options include tear retention by moisture spectacles/goggles, therapeutic contact lenses, tear stimulation by systemic secretagogues e.g. pilocarpine, cevimeline, and topical secretagogues. Anti-inflammatory agents may be helpful. These include topical corticosteroids, oral tetracyclines, topical cyclosporine and topical azithromycin. Other options include mucolytics, topical vitamin a (retinol), antivascular endothelial growth factor antibodies, omega-3 and omega-6 fatty acid and hormone therapy Severe dry eye that does not respond to clinical treatment may require a surgical approach. The most used procedure for DED is punctual occlusion. Lateral tarsorrhaphy may be of help as it diminishes the evaporation of the tear film by reducing the palpebral fissure. Surgical interventions for severe cases of dry eye may be one of the following, punctal patch technique for long lasting punctalocclusion,cisternoplasty, tarsorrhaphy, microvascular submandibular transplantation, conjunctival graft of the minor salivary gland, limbal stem cells, conjunctival stem cells transplantationand amniotic membranetransplantation.