Any abnormality of any one of the three layers of tears produces an unstable tear film, resulting in symptoms of<unk>  eyes. Increased evaporation The most common cause of<unk>  eye is increased evaporation of the tear film, typically as a result of Meibomian gland dysfunction. The meibomian glands are two sets of oil glands that line the upper and lower eyelids and secrete the oily outer layer of the tear film--the lipid layer. These glands often become clogged due to inflammation caused by blepharitis and/or rosacea, preventing an even distribution of oil. The result is an unstable lipid layer that leads to increased evaporation of the tear film. In severe cases of MGD, the meibomiam glands can atrophy and cease producing oil entirely. Low humidity Low humidity may cause<unk> . Decreased tear production Keratoconjunctivitis sicca can be caused by inadequate tear production from lacrimal hyposecretion. The aqueous tear layer is affected, resulting in aqueous tear deficiency (ATD). The lacrimal gland does not produce sufficient tears to keep the entire conjunctiva and cornea covered by a complete layer. This usually occurs in people who are otherwise healthy. Increased age is associated with decreased tearing. This is the most common type found in postmenopausal women. In many cases, aqueous deficient<unk>  eye may have no apparent cause (idiopathic). Other causes include congenital alacrima, xerophthalmia, lacrimal gland ablation, and sensory denervation. In rare cases, it may be a symptom of collagen vascular diseases, including relapsing polychondritis, rheumatoid arthritis, granulomatosis with polyangiitis, and systemic lupus erythematosus. Sjögren syndrome and other autoimmune diseases are associated with aqueous tear deficiency. Drugs such as isotretinoin, sedatives, diuretics, tricyclic antidepressants, antihypertensives, oral contraceptives, antihistamines, nasal decongestants, beta-blockers, phenothiazines, atropine, and pain relieving opiates such as morphine can cause or worsen this condition. Infiltration of the lacrimal glands by sarcoidosis or tumors, or postradiation fibrosis of the lacrimal glands can also cause this condition. Recent attention has been paid to the composition of tears in normal or<unk>  eye individuals. Only a small fraction of the estimated 1543 proteins in tears are differentially deficient or upregulated in<unk>  eye, one of which is lacritin. Topical lacritin promotes tearing in rabbit preclinical studies. Also, topical treatment of eyes of<unk>  eye mice (Aire knockout mouse model of<unk>  eye) restored tearing, and suppressed both corneal staining and the size of inflammatory foci in lacrimal glands. Additional causes Aging is one of the most common causes of<unk>  eyes because tear production decreases with age. Several classes of medications (both prescription and OTC) have been hypothesized as a major cause of<unk>  eye, especially in the elderly. Particularly, anticholinergic medications that also cause<unk>  mouth are believed to promote<unk>  eye.<unk>  eye may also be caused by thermal or chemical burns, or (in epidemic cases) by adenoviruses. A number of studies have found that diabetics are at increased risk for the disease. About half of all people who wear contact lenses complain of<unk>  eyes. There are two potential connections between contact usage and<unk>  eye. Traditionally, it was believed that soft contact lenses, which float on the tear film that covers the cornea, absorb the tears in the eyes. The connection between a loss in nerve sensitivity and tear production is also the subject of current research.<unk>  eye also occurs or becomes worse after LASIK and other refractive surgeries, in which the corneal nerves which stimulate tear secretion are cut during the creation of a corneal flap.<unk>  eye caused by these procedures usually resolves after several months, but it can be permanent. Persons who are thinking about refractive surgery should consider this. An eye injury or other problem with the eyes or eyelids, such as bulging eyes or a drooping eyelid can cause keratoconjunctivitis sicca. Disorders of the eyelid can impair the complex blinking motion required to spread tears. Abnormalities of the mucin tear layer caused by vitamin A deficiency, trachoma, diphtheric keratoconjunctivitis, mucocutaneous disorders and certain topical medications are also causes of keratoconjunctivitis sicca. Persons with keratoconjunctivitis sicca have elevated levels of tear nerve growth factor (NGF). It is possible that this eye's surface NGF plays an important role in ocular surface inflammation associated with<unk>  eyes.
Dry eye syndrome
Cat eye syndrome
Ocular ischemic syndrome
Phacolytic glaucoma
Motion-induced blindness
Iridocorneal endothelial syndrome
Ghost cell glaucoma
Infiltrative ophthalmopathy