3. Learning Objectives
Describe tears
Define Lacrimal apparatus
Explain the flow of tear secretion and drainage
Describe the secretion parts and its functions
Describe the drainage parts and its functions
At the end of the session the trainee will be able to:
4. Tears
• Lubricates the eye and keep
the eye moist
• Carries bacteria fighting
enzymes (Lysozymes and
leukocytes) to the eye
• Washes away waste products
and foreign debris.
• Provides a smooth refracting
surface to the cornea
Functions of tears:
Eyes are constantly covered by a thin layer of liquid called Tear
film.
5. Layers of Tears – 1. Lipid / Oil Layer
It is the outer layer secreted by
the Meibomian glands, glands of
Zeis and Moll
Function:
• Lubricates the eyelids
• Reduce evaporation of
tears
6. Consists - Water and other proteins
which are secreted by the lacrimal
gland and accessory lacrimal glands
Function:
• Supplies oxygen
• Fight against bacteria
• Provide smooth optical
surface
Layers of Tears
2. Lacrimal / Aqueous Layer
Lacrimal Gland
Gland of Wolfring
Gland of Krause
7. Layers of Tears
3. Mucous / Mucin Layer
Secreted by
Conjunctival Goblet cells, Glands
of Manz
Crypts of Henle
Function: Provide hydrophobic to
hydrophilic surface
Goblet Cells
Crypts of Henle
Glands of Manz
Goblet cells
10. A group of organs concerned with the production and drainage
of tears is called as Lacrimal Apparatus. Tears are produced and
regulated by the Lacrimal Apparatus.
Anatomy of Lacrimal System
Ducts of Lacrimal gland
12. Lacrimal Apparatus - Secretion Part
Lacrimal Gland
Ducts of Lacrimal Gland
Shape: Almond shape
Location: Bony orbit of
upper eyelid Function:
Secretes major tears
and conveys fluid to the
eye
Ducts in the gland: 10 –
12 ducts or tubes
emerging from the
gland
Blood supply: Supplied
by lacrimal artery which
is a branch of
ophthalmic artery
Nerve supply: Lacrimal
nerve - a branch of the
ophthalmic division of
5th Cranial Nerve
13. Glands of Krause
• Location: Situated in the
Palpebral conjunctival side (that
is underneath the eyelid)
Function: Secretes tears
Gland of Wolfring
• Location: Situated in the upper
border of the tarsus midway
between the ends of the tarsal
gland
• Function: Secretes tears
Lacrimal Apparatus - Tear Secretion
Part - Accessory Glands
14. Lacrimal Apparatus - Tear Distribution
Tear
• Tears secreted by Lacrimal gland will travel through 10 – 12 ducts
from the lacrimal gland which joins in upper fornix
• During blinking these tears will be distributed from upper fornix to
the other parts of eye (Cornea, Conjunctival sac, Punctum etc.)
18. Label the Parts of Lacrimal Apparatus
Lacrimal Sac
Lacrimal Gland
Lacrimal Punctum
Lacrimal Canaliculus
Nasolacrimal Duct
Inferior meatus of Nasal cavity
Ducts of Lacrimal Gland
Hasner Valve
19. Lacrimal punctum in upper
and lower eyelid of each
eye
Upper punctum is 6mm
from inner canthus and
Lower punctum is 6.5mm
from inner canthus
Each punctum is situated in
the lacrimal papilla
surrounded by fibrous
tissue
Lacrimal Apparatus - Drainage Part
Lacrimal Punctum
20. Lacrimal canaliculus
Connects Puncta & Nasolacrimal duct .
Otherwise known as lacrimal canals or
lacrimal ducts. It is 8 to 10mm horizontal part
(ampulla) and 2mm vertical part.
Superior Canaliculus
First ascends and then runs horizontal to the
lacrimal sac
Inferior Canaliculus
First descends and then runs horizontal to
the lacrimal sac
Lacrimal Apparatus - Drainage Part
Lacrimal Canaliculus
21. Lies in the lacrimal fossa (formed by lacrimal bone and frontal process
of maxilla) located in the anterior part of medial orbital wall
Shape Oval
Fundus
Portion above the opening of
canaliculi
Lower end
Continued into the naso
lacrimal duct
Body Middle part 10mm
Lacrimal Gland - Drainage Part
Lacrimal Sac
22. Lacrimal Gland - Drainage Part
Naso Lacrimal Duct
Hasner Valve
90% of the tears drains through nasolacrimal system. 10%
evaporates while blinking
Continuation of the Lacrimal Sac is called as
tear duct - carries tears from the lacrimal sac
into the inferior meatus of nasal cavity
Contains numerous membranous valves
Hasner valve : Present at the lower end of
the duct and prevents tear reflux from the
nose
23. Mind Map
Lacrimal System
Anatomy of tears
Layers
Lipid / Oil Layer
• Lubricates the eyelids
• Reduce evaporation
Lacrimal / Aqueous
Layer
• Supplies Oxygen
• Fight against bacteria
• Wash away dust and
debris
Mucous / Mucin Layer
• Convert epithelium from
hydrophobic to
hydrophilic surface
Secretion Drainage
Lacrimal Gland
Accessory Gland
Blood supply
Nerve supply
Gland of
Krause
Gland of
Wolfring
Lacrimal Puncta
Collect excess tears
Lacrimal Canaliculus
Bridge between punctum
Lacrimal sac
Drain Dirt and Germs
Nasolacrimal Duct
Tear drain into nose
Produce
Tears
Lacrimal Gland
Produce tear liquid External Cornea
Produce liquid that makes
tear film liquid
Eyelid
Spread tears over eye surface
Meibomian Gland
Produce fatty liquid
Hold tear film
Tear Production & Drainage System
