The lacrimal apparatus consists of the lacrimal gland, accessory lacrimal glands, puncta, canaliculi, lacrimal sac, and nasolacrimal duct. The lacrimal gland develops from ectodermal buds and secretes tears. Tears drain through the puncta and canaliculi into the lacrimal sac, then through the nasolacrimal duct into the nose. Contraction of the orbicularis oculi muscle aids in tear drainage by creating pressure changes in the lacrimal sac.

1. LACRIMAL APPARATUS
12/MAY/2021
Dr Shayri Pillai
2ND Year Ophthalmology Resident
Liberia Eye Centre
JFK Memorial Medical Center
L V Prasad Eye Institute

2. EMBROYOLOGY
 Lacrimal gland -Starts to develop from multiple
solid ectodermal buds arising from the basal cells of
conjunctiva in the superotemporal region of fornix at
6th-7th weeks
 Mesenchyme surrounds these buds and proliferates
to form the parenchyma of the lacrimal gland
 Buds branch and canalize to form ducts and alveoli

3.  At 5th month of gestation lateral horn of levator
aponeurosis divides it into palpebral and orbital
part
 Lacrimal glands do not function fully until
approximately 6th week of life
 Accessory lacrimal glands are formed from
ectodermal invagination of conjunctiva which
detected at 6 to 7 months

4. Lacrimal apparatus comprises
Structures concerned with formation of tears i.e the
main lacrimal gland and accessory lacrimal glands and
its transport

6. Components of lacrimal apparatus
Lacrimal gland Lacrimal puncta Lacrimal
cannaliculi Lacrimal sac Nasolacrimal duct

7. LACRIMAL GLAND
Situated in the fossa for lacrimal gland,formed by the
orbital part of frontal bone,in the anterolateral part of orbit
Gland is divided in its anterior aspect by the lateral horn of
aponeurosis of the levator muscle into two parts:
1. Superior Orbital
2. Inferior Palpebral,which are continuous with each
posteriorly

9. PARTS OF THE LACRIMAL GLAND
The larger Orbital part is in a depression, the lacrimal
in the frontal
bone
The smaller Palpebral part is inferior to levator palpebrae
superioris ,in
the superolateral part of the eyelid
Gland is compressed from above downwards - seen through
the conjunctiva when the lid is everted

10. Lacrimal gland is drained by a series of 8-12 small ducts
 Ducts open into the lateral part of the superior
conjunctival fornix
 1-2 ducts also open into the lateral part of the inferior
fornix
 Secretions from the gland is spread over the surface of
the eye by the action of the lids

11. Structure of the lacrimal gland- Tubuloalveolar
Consists of 3 parts- GLANDULAR
STROMA
SEPTA
Glandular tissue: consists of acini and ducts arranged
in lobes and lobules
This lobules joins to form intralobular ducts which
finally joins to form extralobular ducts

13. Stroma: connective tissue, elastic tissue, lymphoid tissue,
plasma cell, nerve terminals and blood vessels
Septa: fibrovascular in nature and separates lobes and
lobules from each other

14. Ducts are lined by 2 layers of epithelium- Inner cylindrical
cells
Flattened
layer of cells
 Nucleus is central
 Accessory lacrimal glands – these are glands of Krause
glands of wolfing rudimentary accessory glands

15.  Blood supply Arterial- lacrimal artery - branch of
ophthalmic artery
 Venous – lacrimal vein which joins the ophthalmic
vein
Lymphatic drainage- they drain along the
conjunctival drainage and then into preoricular lymph
nodes
Nervous supply –
Sensory – lacrimal
Sympathetic- carotid plexes of cervical sympathetics
Secretomotor – superior salivatory nucleus

18. Puncta
 Two small rounded or oval openings one on each
upper and lower eyelid, at the junction of ciliary and
lacrimal portion of the lid margin
SITUATION: situated upon a slight elevation called
lacrimal papilla
 Upper puncta is 6mm and lower puncta is 6.5mm
lateral to the inner canthus
 Puncta are surrounded by a ring of dense fibrous
tissue which keeps them patent

19. Structure of lacrimal canaliculi- Lined by Stratified
squamous epithelium
 Corium rich in elastic tissue
 Fibers of orbicularis which surround the corium are
called pars lacrimalis
 Lacrimal sac- lies in lacrimal fossa, formed by lacrimal
bone and frontal process of maxilla
 Bounded anteriorly and posteriorly by lacrimal crests.
it is enclosed by lacrimal fascia It is 15mm in length, 5-
6mm breadth, capacity of 20cmm.

20. Its has 3 parts-
fundus 3-5mm
body 10-12mm
neck
Middle part of lateral wall of sac has diverticulum
called lacrimal sinus of maier into which the
common canaliculli open
Relations of lacrimal sac
Medially- related to anterior ethamoidal sinus in
upper part,middle meatus in lower part.

22. Nasolacrimal duct
 It is 18mm in length and 3mm in diameter
 Upper end is narrowest part and it is a continuation of
neck of lacrimal sac
 Direction is downwards,backwards and laterally
 Externally it is represented by line joining the inner
canthus to the ala of the nose
 It consists of 2 parts- intraosseous part 12.5mm
intranasal part 5.5mm

23.  Intraosseous part lies in bony lacrimal canal formed
anterolaterally by maxilla and posteromedially by
lacrimal bone and inferior nasal concha
 Nasolacrimal canal lies lateral to middle
meatus,produce ridge in maxillary antrum
 Therefore lesions in maxillary sinus often cause
epiphora
 Intranasal part lies in the mucous membrane of lateral
part of nose and open into inferior meatus
 Valve of hasner situated at lower end of nasolacrimal
duct and prevents entry of air into sac when air is
blown out of closed nose

24. Blood supply of lacrimal passage-
Arterial- superior ,inferior palpeberal arteries, angular
ar, infraorbital ar,nasal br of sphenopalatine ar
Venous drainage- angular vein and infraorbital vein
from above and nasal vein from below
Lymphatics- submandibular and deep cervical glands
Nervous supply –infra trocheolar and antero superior
alveolar nerve

26. THE ACCESSORY LACRIMAL GLAND INCLUDES:
GLAND OF KRAUSE: these are microscopic glands lying
in the sub-conjuctival tissue of the fornices
These are 40-42 in number in the upper fornix and
about 6-8 in lower fornix
GLANDS OF WOLFRING: these are microscopic glands
present along the upper border of superior tarsus 2-5 in
number and in lower border of inferior tarsus 2-3 in
number
RUDIMENTARY ACCESSORY GLANDS: these are present
in caruncle, plica semilunaris and infraorbital region

29. Secretion of tears
Continously secreted through out the day by main
&accessory lacrimal gland
Rate of tear production -1.2microl/min
tear vol.-7 micro litres
2 Components: Basic Secretors and Reflex Secretors

31. Reflex secretion due to irritation of 5th cranial nerve in
response to sensation from cornea and conjunctiva.(mainly
by lacrimal gland)

32. PHYSIOLOGY
Tear drainage: Tears are drained from conjunctival sac
by two mechanisms:
1. Gravity
2. Active pump mechanism
By Gravity: Gravity plays a small part and most of the
tears are drained by active pump

33. Active pump (Suction):
70% of the tears are drained through the lower
punctum and 30% through the upper punctum
Upper and lower marginal strips of tears go medially
The tears enter the puncta by capillary action and
suction
Pretarsal orbicularis oculi splits into superficial and
deep heads around the ampulae and some fibres are
attached to the sac

34. During closure of the eye:
 Ampulae is compressed
 Horizontal canaliculus shortens
 Puncta move medially
 Deep head of the orbicularis (attached to sac) causes
dilatation of the sac
All these causes a negative pressure in the sac and tears
are sucked into the sac
When the eye closes, the sac goes to its original volume,
forcing the tears into the nasolacrimal duct, and the
puncta move laterally sucking tear into it.

35.  Contraction of the lacrimal part of the orbicularis oculi
creates a positive pressure
 Forces tears down the nasolacrimal duct and into the
nose, mediated by helically arranged connective tissue
fibres around the lacrimal sac
 When the eyes open, the canaliculi and sac expand,
creating negative pressure that draws tears from the
canaliculi into the sac

37. Thank you!
Excellence Equity Efficiency
L V Prasad Eye Institute