No description available.
TEARS: TEARS Protective layer Watery liquid-Bathes/Nourishes Three layers: Lipid, Aqueous and Mucin Tear – secreted by glands around the eyelid TEAR PRODUCTION: TEAR PRODUCTION Lipid layer – Meibomian glands & Glands of Zeis Aqueous layer – Lacrimal glands, Glands of Krause & Wolfring Mucin Layer Goblet cells PHYSICAL CHARACTERISTICS OF TEAR FILM: PHYSICAL CHARACTERISTICS OF TEAR FILM Surface tension :40-50 dynes/cm2 pH :6.9 -7.4 Osmolarity :290-310 mOsm/l Viscosity :1.9-2 centipoises FUNCTIONS OF TEAR FILM: FUNCTIONS OF TEAR FILM Lubricates and moistens eye surface Provides nutrients & oxygen to cornea Washes away foreign bodies Protects against bacteria and viruses (with help of enzyme Lysozyme)COMPOSITION OF TEAR FILM: COMPOSITION OF TEAR FILM Lipid layer Proteins (albumin, globulin) Lysozyme (antibacterial) Aqueous layer Nutrients (minerals,Vitamins, electrolytes) Mucin layer Glycoproteins make the corneal surface more hydrophilicFUNCTIONS OF THE TEAR FILM LAYERS: FUNCTIONS OF THE TEAR FILM LAYERS Lipid layer Prevents evaporation of aqueous layer. Aqueous layer Nourishes and moisturizes the cornea and sclera. Protects against micro-organisms Mucin layer Helps in the even spreading of the tear film over the ocular surfaceTEAR SECRETION : TEAR SECRETION Two types of secretors :- basic and reflex Basic secretors Supply tears at constant rate – gland of Krause and wolfring Reflex secretors Supply tears when there is a stimulus like foreign body, emotions, bright light.BLINKING: BLINKING Provides regular rewetting Ensures normal tear film function Tear Break Up Time (TBUT) – 10 seconds Compromised blinking – leads to SSS (Screen Stare Syndrome) TEAR DRAINAGE: TEAR DRAINAGE PUNCTA CANALICULI LACRIMAL SAC NASO LACRIMAL DUCT EVAPORATION
Tears of Woma..
By: Virtue_d..
Tears of a Wo..
By: vnlib
Tears
By: far_72
Tears Don't F..
By: GothicGi..
By: Fheeroz
tears
By: metropol..
The tears
By: pmhollin..
Hist12 f Muss..
By: Yuan
Funny animals
By: yanki
logging in or signing up