The conditions of tear film formation and stability are governed by the surface chemical characteristics of the tear film system and by the proper functioning of the lacrimal apparatus. The tear film has to remain continuous between blinks in order to fulfill it function. The presence of an abnormal tear film results in dry eye states that can be detrimental to vision. The diagnostic tests presently available are limited mainly to approximately determining tear secretion rate and estimating epithelial damage by staining techniques. The only test that directly measures tear film stability is one which determines tear film breakup time. The treatment modalities depend on the type of irregularity causing the dry eye state and range from the application of artificial tear substitutes or the obstruction of the puncta to surgical alterations of the lacrimal system.

Contact Lenses↗

PubMedDate not supplied

Meibomian gland dysfunction.

Blepharitis is probably the most common disease entity seen in the general ophthalmologist's office. A significant proportion of these cases are secondary to meibomian gland disease. This review outlines our knowledge of the histopathology, lipid abnormalities and role of microorganisms in meibomian gland dysfunction. We will also review the physiology of meibomian gland secretion and present models of meibomian gland dysfunction which have enhanced our knowledge of this condition. The importance of diagnosing associated conditions such as aqueous tear deficiency, contact lens intolerance, rosacea, and seborrheic dermatitis is emphasized. Although this condition causes significant morbidity in the population, there are effective treatments available and these will be discussed.

Animals↗

PubMedDate not supplied

The blood-vitreous barrier in corneal surgery.

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Aphakia↗