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Normal vision requires a moist healthy ocular surface. A sufficient quality of tears, a normal composition of the tear film, normal lid closure, and regular blinking are among the prerequisites to maintain a healthy ocular surface. What is Dry Eye? Dry eye is a disorder of the tear film due to tear deficiency or excessive tear evaporation which causes damage to the interpalpebral ocular surface (i.e. exposed eye surface) and is associated with symptoms of ocular discomfort. This definition of dry eyes was adopted by the National Eye Institute workshop on dry eyes. The eye becomes dry either because there is not enough tears being produced or because there is abnormally high rate of evaporation of tears. In the light of new knowledge about the roles of tear hyperosmolarity and ocular surface inflammation in dry eye and the effects of dry eye on visual function, The Dry Eye Workshop (DEWS) in 2007 adopted a revised definition of dry eyes. According to the DEWS definition, Dry eye is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. Dry eye is recognized as a disturbance of the Lacrimal Functional Unit (LFU), an integrated system comprising the lacrimal glands, ocular surface (cornea, conjunctiva and meibomian glands) and lids, and the sensory and motor nerves that connect them (Link fo DEWS Report). According to the DEWS report, prevalence of dry eye ranges from 5%-30% in people aged 50 years and older. Prevalence of moderate- to-severe dry eye lies closer to the lower estimate of the range, whereas prevalence of mild dry eyes lies closer to the higher estimate of the range. It is estimated that about 3.2 million women and 1.7 million men, for a total of 4.9 million Americans 50 years and older have dry eye. Tens of millions more have mild dry eyes that may be notable only when some adverse contributing factor is present, such as low humidity or contact lens wear. Dry Eyes Evaporative Dry Eye Environmental factors Central heating (forced air dry heat), hair dryer, car windscreen demisting, air travel, dry climates, wind, air pollution (cigarette smoke), contact lens wear (Reduced blinking) Driving, watching TV, computer work, reading Eyelid Inflammation Blepharitis, Rosacea & MGD (Meibomian gland dysfunction) are major cause of this form of dry eyes. Ocular rosacea has been suggested to be present in upto 75% of perimenopausal women with facial Rosacea. Lid surfacing anomalies Tears are not spread adequately over the eye surface due to Proptosis, Ectropion, Entropion, Nocturnal lagophthalmos, Bell's palsy, Pterygium/Pingecula, Conjunctivalchalsis Tear-Deficient Dry Eye Sjogren Syndrome (dry eye + dry mouth + arthritis) Patients with Sjogrens syndrome not only have dry eyes but also have dry mouth. Blood tests show the presence of several antibodies (SS-A or SS-B, ANA and RF). Connective tissue diseases (Rheumatoid arthritis, lupus etc) may also be present. non-Sjogren syndrome Patients with non-Sjogren dry eyes do not produce tears because of a disease of the tear gland. Examples of diseases that can cause dry eye in this fashion include: Sarcoidosis, Vitamin A deficiency, Trachoma, Atopy and Trauma. Chronic contact lens wear, past herpes eye infection, diabetes and aging are other causes. (Hover the cursor over the diagram to pop-up descriptions and photos) Dry Eye Overview in videoDial-up modemBroadband-cable/DSL Although most people equate dry eye disease with uncomfortable eyes, serious vision complications are a distinct possibility. If untreated severe dry eye disease may lead to desiccation of the corneal epithelium, ulceration and perforation of the cornea, an increased incidence of infectious disease, and, potentially, serious visual impairment and blindness. Therefore the diagnosis and adequate treatment of dry eyes is important. There have been several recent developments of significance. It is now being realized that part of the problem in dry eye disease is a low grade (subclinical) inflammation. The use of anti-inflammatory agents (mild steroids or cyclosporine eye drops) may help these patients. The effect of androgen deficiency is also being studied since majority of dry eye disease suffers are females. 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