anatomy and physiology of eye, general introduction

DONE BY,S. ARYA DAS

1 ST YEAR,BACHELOR OF OPTOMETRY

BHARTIMAIYA COLLEGE OF OPTOMETRY

ANATOMY AND PHYSIOLOGY OF EYE

CONJUCTIVAL GLANDS

• There are mainly three types of glands. They are :-

(i) Mucin secretory glands (ii) Acessory lacrimal glands

THE MUCIN GLAND

• Globlet cells• Henle’s glands• Glands of manz

GOBLET CELLS

• These are unicellular mucous glands located within the epithelium of all the regions of the conjunctiva except the marginal in epithelial xerosis

• This leads to the desication of the conjuctiva. NOTE:- The number of globlet cells is incresed

greatly in the inflammatory conditions.

HENLE’S GLANDS

• They are not true glands.• Folds of mucous membrane are present in

between the tarsal plate and the fornices.• They are tuburular structure.• They contain few globlet cells.

GLANS OF MANZ

• These are found in the limbal conjunctiva.• They are found in animals like pig,ox,calf,etc.• There existence in human beings is

controversial.

ACESSORY LACRIMAL GLANDS

• Glands of krause• Glands of wolfring• Rudimentary acessory lacrimal glands

GLANDS OF KRAUSE

• These are microscopic glands found in the sub conjunctival tissue of the fornices.

• These are about 40-42 in the upper fornix.• 6-8 in the lower fornix .• Their ducts unites to form a long duct which

opens in the fornix.

GLANDS OF WOLFRING

• These are microscopic glands.• They are present in the upper border of

superior tarsus(2-5 in numbers).• Present in the lower border of inferior

tarsus(2-3 in numbers).

RUDIMENTARY ACCESSORY LACRIMAL GLANDS

• These are present in the caruncle,plica semilunaris and infraorbital region.

THE CARUNCLE

• It is a small, soft, pinkish mass situated in the inner canthus.

• In reality it is a piece of modified skin , hence is covered by the stratified squamous epithelium.

• It contains sweat glands, sebaceous glands and hair follicles.

• It differs from the skin by the presence of the accessory glands of krause.

BLOOD SUPPLY OF CONJUNCTIVA

• The marginal arterial arcades• The peripheral arterial arcades• The anterior ciliary arteries

THE MARGINAL ARTERIAL ARCADE

• It is formed by the anastomosis of medial and lateral palpebral arteries.

• It lies in the submascular plane in front of the tarsal plate.

• it is 2mm away from the lid margin, in each lid.• This branch reach the conjunctiva where, they

divide into marginal and tarsal branches.

THE PERIPHERAL ARTERIAL ARCADE

• It is situated at the upper border of the tarsus in the upper lid.

• It has two branches. (i) The ascending branches (ii) The descending branches.

THE DESCENDING BRANCHES

• The descending branches supply the tarsal conjunctiva

• It anastomose with branches of the marginal arterial arcade at the level of sulcus subtarsalis.

THE ASCENDING BRANCHES

• The ascending branches pass upward and then bend down the superior fornix.

• It descend under the bulbar conjunctiva as the posterior conjunctival artery.

• It is at about 4mm from the limbus.• The posterior conjunctival artery anastomose

with the anterior conjunctival artery.• It forms the pericorneal plexus.

THE ANTERIOR CILIARY ARTERIES

• These are branches of muscular arteries.• These arteries give off anterior conjunctival

arteries at about 4mm from the limbus. NOTE:- The anterior conjunctival arteries

moves forward towards the limbus at a plane deeper than the posterior conjunctival arteries.

VENOUS DRAINAGE OF CONJUNCTIVA

• The veins from the conjunctiva drain into the venous plexus of eyelid.

• It in turn drains into the superior or inferior opthalmic veins.

• A circumcorneal zone of vein about 5-6mm from the limbus drains into the anterior ciliary veins.

LYMPHATICS OF THE CONJUNCTIVA

• Conjunctival lymphatics are arranged in two layers.

• They are the superficial and the deep.• Lympatics from the lateral side drains into the

perauricular lymph nodes.• Lymphatics from the medial side drains into

the submandibular lymph nodes.

NERVE SUPPLY OF CONJUNCTIVA

• It is supplied by the branches from the long ciliary nerves.

• It supplies the cornea.• The rest is supplied by the branches of

lacrimal, infratrochlear, supratrochlear, supraorbital and frontal nerves.

• These nerves donot posses the myelin sheath.

REFERENCE

• TEXTBOOK OF ANATOMY AND PHYSIOLOGY OF EYE

• INTERNET

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