The document discusses the anatomy, development and physiology of the lacrimal secretory and drainage systems. It describes the embryological development of the lacrimal system from ectodermal tissue. It details the anatomy of the lacrimal gland, puncta, canaliculi, sac, duct and nasolacrimal drainage system. It explains the physiology of tear secretion, composition of the tear film layers, and the role of nerves, blood vessels and muscles in lacrimal secretion and drainage.

1. ANATOMY,DEVELOPMENT AND PHYDIOLOGY OF
THE LACRIMAL SECRETORY AND DRAINAGE
SYSTEMS
PRESENTER: DR. MUGABI BARNABAS MUKAABYA
MODULATOR: DR. NAGAWA ELIZABETH
DEPARTMENT OF OPHTHALMOLOGY
MAKCHS

2. The following components of the lacrimal apparatus are discussed :
 Embryology
 Osteology
 Secretory system
 Excretory system
 Physiology

3. Anatomy and physiology of lacrimal secretion
and outflow

4. Lacrimal
gland
Conjunctival
sac
Lacrimal
puncta
Lacrimal
canaliculi
Lacrimal
sac
Nasolacrimal
duct

6. Ectodermal origin
Solid epithelial buds(first 2 months)
Superolateral conjunctival fornix

7. • Lacrimal sac and nasolacrimal duct : ectoderm of the naso-optic
furrow or nasolacrimal furrow
• The ectoderm of the furrow buries and forms a solid cord .
• Canalization : begins at 4 months and may continue after birth.

9. • The lacrimal sac fossa is a depression in the inferomedial orbital rim,
• Maxillary and lacrimal bones.
• Bordered by the anterior lacrimal crest (maxillary bone) & posterior
lacrimal crest (lacrimal bone).
• The fossa is approximately 16-mm high, 4- to 9mm wide, and 2-mm
deep.

11. • The medial orbital wall : Frontal process of maxilla, lacrimal , ethmoid
, lesser wing of sphenoid bone.
• The frontoethmoidal suture is important in lacrimal surgery
• It marks the roof of the ethmoid sinus. Bony dissection superior to
this suture may expose the dura of the cranial cavity.

12. • The nasolacrimal canal originates at base of lacrimal fossa.
• Formed by the maxillary bone laterally and the lacrimal and inferior
turbinate bones medially.
• The width of superior opening is 4–6 mm.
• The duct courses posteriorly and laterally in the bone for 12 mm to
drain into the inferior meatus of the nasal cavity.

13. • It includes lacrimal gland, accessory glands
• Lacrimal gland is above & anterolateral to globe.
• Secretes tears into superior fornix.
• Tears moisten & lubricates the : cornea , conjunctiva.
• It contributes 43D of 50D of refractive power of eye .

14. • It consists of
• Large Orbital Part
• Smaller Palpebral Part
• Lateral expansion of levator separates the parts

15. Paired almond-shapedglands.
It is present in a fossa on the anterolateral area of orbit
It has 2 surfaces, 2 borders, 2 extremities
• Superior surface
• Frontal bone
• Inferior surface
• Levator palpebrae superioris & lateral rectus

16. • Anterior border
• Septum orbitale
• Posterior border
• Contact with orbital fat , level with posterior pole.
• Lateral extremity
• Rest on lateral rectus
• Medial extremity
• On levator

17. • 1/3rd size of orbital part
• Superior fornix , seen on lid eversion.
• It is situated upon the course of ducts
• Related to levator superiorly, inferiorly to superior fornix
• Posteriorly it continues with orbital part.

18. • Are small, compound, branched, tubular glands
• Located in the middle of lid (Wolfring glands) or superior & inferior
fornices (Krause glands).
• Ectopic portions of lacrimal gland tissue.

19. • It is with connective tissue coat and excretory duct.
• The excretory duct splits & form intralobular ducts, connected to
secretory glandular epithelia.
• Secretory epithelia have elongated tubules.
• True acini are absent.

22. • Tubuloacinar with short,
branched tubules
• Acini are pyramidal secretory
cells with apex towards a central
lumen
• Myoepithelial cells., contractile
& aid the secretion

23. • In acinus, secretory cells are joined by junctional complexes
• Apical microvilli extend into the lumen
• Nucleus and rough endoplasmic reticulum are basal in the cells.
• Abundant secretory granules, at apex .

25. • The ducts have two or three cell layers and microvilli at luminal
surface.
• Plasma cells of the interstitial space are an important source of
immunoglobulins secrete IgA(and fewer lgG, lgM, IgE)

27. • Artery supply : Lacrimal artery , branch of ophthalmic artery.
• Venous drainages : Ophthalmic Vein.
• Lymphatic drainage : Joins that of conjunctiva & drain into the
preauricular lymph nodes.

28. • Sensory nerve supply : lacrimal nerve , branch of ophthalmic division
of Vth nerve
• Sympathetic nerve supply : carotid plexus
• Secretomotor fibers : superior salivary nucleus

31. • A small, round or oval orifice on the elevation, the papilla lacrimalis.
• At medial end of lid margin at the junction of its ciliated and non-ciliated
parts.
• Upper punctum medial to lower, from the medial canthus being 6 and 6.5
mm.
• The upper punctum opens inferoposteriorly, the lower superoposteriorly.

33. • First vertical and then horizontal
• Vertical part is 2 mm & turns medially at right-angle to become horizontal 8 mm
• At angle -dilatation or ampulla.
• The canaliculi pierce the fascia (i.e. the periorbita covering the lacrimal sac)
separately,
• Uniting to enter lacrimal sac.
• Stratified squamous epithelium supported by elastic tissue.

34. • Lacrimal fossa, formed by lacrimal bone and frontal process of
maxilla.
• The sac, closed above and open below, is continuous with the
nasolacrimal duct.
• The sac is enclosed by a periorbita, splits &form the lacrimal fascia .

35. • Relations
• Medial : periorbita and bone, arc of ethmoid sinuses.
• Lateral : skin, orbicularis oculi, and lacrimal fascia.
• Anterior: medial palpebral ligament and angular vein.
• Posterior : lacrimal fascia and muscle

36. • The nasolacrimal duct, continuation of lacrimal sac to the inferior
meatus.
• 15 mm.
• It lies in a canal formed by the maxilla, lacrimal bone and lacrimal
process of inferior concha.
• It descends posterolaterally, a surface indication a line from medial
canthus to first upper molar.

37. • The valves
• They are folds of mucous
• membrane with no
• valvular function.
• The most constant is the
• 'valve' of Hasner at the lower
• end.
• It prevents sudden blast of air
• (when blowing the nose) from
• entenng the lacrimal sac.

38. • Structure
• Double-layered Epithelium
• The superficial layer composed of columnar cells, the deeper cells
being flatter.
• The membranous wall of the sac is of fibroelastic tissue, the elastic
element being continued around the canaliculi.

39. • Around the nasolacrimal duct is plexus of vessels, forming erectile
tissue like that on the inferior concha.
• Engorgement of these vessel obstruct the duct.
• The course of the lacrimal sac and duct can be demonstrated by
dacryocystography

40. • Vessels
• Artery supply : palpebral branches of the ophthalmic, angular and
infraorbital arteries and nasal branch of the sphenopalatine.
• Venous drainages : Angular and infraorbital vessels above, below into
the nasal veins
• Lymphatic drainage: submandibular and deep cervical nodes.
• Nerves
• Infratrochlear and anterior superior alveolar nerves.

41. • The tear film overlays corneal and conjunctival epithelia.
• Tears produced by the ocular surface epithelia and adnexa.
• Thickness of up to 40 µm,
• Volume of tears covering the ocular surface range from 2.74 ±2.0µL to
7 µL

42. • For mucous and aqueous layers, secretion is regulated by neural reflexes.
• For the lipid layer, the blink itself regulates release of pre-secreted
meibomian gland .
• Tear secretion is balanced by drainage and evaporation.
• Drainage is regulated by neural reflexes ,causing vasodilation and
vasoconstriction of blood sinus.
• Evaporation depends blink rate and temperature, humidity, and wind
speed.

43. • To maintain the refractive power of the cornea;
• To defend against eye infection;
• To allow gas to move between the air and the avascular cornea;
• To support corneal dehydration (assisted by the tear film
hyperosmolality).

44.  Glycocalyx Mucous
layer
 Aqueous layer.
 Lipid layers

46. • Structure
• The glycocalyx is a network of polysaccharides that project from cellular surfaces.
• Mucins are classified into secreted and membrane-spanning mucin.
• Secreted mucins are either gel-forming or small soluble
• Function
• The membrane-spanning mucins function to hydrate the ocular surface and serve
as a barrier to pathogens.
• Membrane-spanning mucins appear to be altered in dry eye

47. • Structure
• The mucous layer backbone is the gel-forming mucin , synthesized
and secreted by conjunctival goblet cells.
• Function
• To resistance of the eye to infection by providing protection against
microorganisms. Mucins serve as wetting agents that keep the
apical epithelia hydrated.

48. • Lacrimal gland produce aqueous layer.
• Other ocular surface epithelia also contribute to the aqueous layer, eg.
conjunctiva, accessory lacrimal glands
• 7µm thick.
• Without the lubrication , the shearing forces produced on blinking will
cause accumulative ocular surface damage.

49. • Composed of water, with many solutes, including dissolved mucins,
electrolyte sand proteins.
• The osmotic pressure : concentrations of sodium, potassium and chloride
ions.
• The tear film’s osmotic pressure is important in the control of cornea–tear
film water flux.
• Bicarbonate and carbonate : pH buffering, maintaining the pH at 7.3–7.6
when the eyes open & 6.8 eyes closed.

50. • Aqueous layer function
• Aqueous deficiency dry eye.
• Protection from bacterial infection
• Reflex secretion washes away noxious substances.
• Protects against changes in pH.

51. • Meibomian glands, modified sebaceous glands, that line the upper and
lower eyelids.
• Meibomian gland lipids are stored in vesicles.
• The secretory product contains a complex mixture of lipids and proteins
and is termed meibum.
• Meibum is released on to the ocular surface in small amounts with each
blink. 0.1m in thickness

52. • Function
• Hydrophobic barrier to prevent tear overflow.
• The meibomforms a water-tight seal of the apposed lid margins during
sleep.
• Reduce tear evaporation .
• Lipids enhance the stability of the tear film and provide a smooth optical.

54. • Conjunctival fornices, preocular tear film, and marginal tear strips.
• Marginal tear strips are wedge shaped tear menisci, borders of upper and
lower lids.
• Apposed lacrimal puncta dip into marginal strip of tears
• Anterior limit of the marginal strip is the mucocutaneousjunction of the lid,

56. • Tears are lost from the conjunctiva sac by absorption, evaporation,
and nasolacrimal system.
• This is related to the size of the palpebral aperture, the blink rate,
ambient temperature and humidity.

57. • Tears flow
• the upper and lower marginal strips →upper and lower canaliculi
(capillarity+suction)
• Eyes close
• Pretarsalorbicularis oculi compresses the ampullae+ shortens and
compresses canaliculi+punctamedially.
• Lacrimal part of the orbicularis oculi, contracts → compresses the
sac,(positive pressure) tears → nasolacrimal duct → nose.
• Eyes open
• Muscles relax →canaliculi and sac expand(negative
pressure)+capillarity= tears into sac.

59. REFERENCES
• Wolff'sAnatomy of the Eye and Orbit.
• Adler'sPhysiology of the Eye .
• The Lacrimal System Diagnosis, Management, and Surgery by Adam J. Cohen, Michael
Mercandetti & Brian G. Brazzo.
• The dry eye , a practical approach by SudiPatel & Kenny J Blades.
• Jack J Kanski’sclinical ophthalmology
• Clinical Anatomy of the Eye by Richard S. Snell & Michael A. Lemp.