Wolff's Anatomy of
the Eye and Orbit.
Adler's Physiology 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 Sudi Patel
& Kenny J Blades.
Jack J Kanski’s clinical ophthalmology
Clinical Anatomy of the Eye by Richard S. Snell
& Michael A. Lemp.
It is concerned with
the tear formation &
Lacrimal passage includes :
The following components of
apparatus are discussed :
and nasolacrimal duct : ectoderm
of the naso-optic furrow or nasolacrimal furrow
The ectoderm of
the furrow buries and forms a
solid cord .
begins at 4 months and may
continue after birth.
The lacrimal sac
fossa is a depression in the
inferomedial orbital rim,
the anterior lacrimal crest
(maxillary bone) & posterior lacrimal crest
The fossa is approximately 16-mm high, 4- to 9mm wide, and 2-mm deep.
The medial orbital wall :
Frontal process of
maxilla, lacrimal , ethmoid , lesser wing of
The frontoethmoidal suture is important in
It marks the roof of the ethmoid sinus.
dissection superior to this suture may expose
the dura of the cranial cavity.
The nasolacrimal canal
originates at base of
the maxillary bone laterally and the
lacrimal and inferior turbinate bones medially.
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.
It includes lacrimal
Lacrimal gland is
above & anterolateral to globe.
Secretes tears into
Tears moisten &
gland, accessory glands
lubricates the : cornea
It contributes 43D
of 50D of refractive power of
It consists of
Large Orbital Part
Smaller Palpebral Part
of levator separates the parts
Paired almond-shaped glands.
present in a fossa on the anterolateral area
It has 2 surfaces, 2 borders, 2 extremities
Levator palpebrae superioris & lateral rectus
Contact with orbital fat , level with posterior
Rest on lateral rectus
size of orbital part
, seen on lid eversion.
situated upon the course of ducts
levator superiorly, inferiorly to
Posteriorly it continues with
Are small, compound, branched, tubular glands
in the middle of lid (Wolfring glands)
or superior & inferior fornices (Krause glands).
Ectopic portions of lacrimal gland tissue.
with connective tissue coat and excretory
The excretory duct splits &
ducts, connected to secretory glandular
Secretory epithelia have
short, branched tubules
are pyramidal secretory cells with apex
towards a central lumen .
Myoepithelial cells., contractile &
secretory cells are joined by
microvilli extend into the lumen
and rough endoplasmic reticulum are
basal in the cells.
Abundant secretory granules, at
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)
Artery supply :
Lacrimal artery , branch of
: Ophthalmic Vein.
: Joins that of conjunctiva &
drain into the preauricular lymph nodes.
supply : lacrimal nerve
, branch of ophthalmic division of Vth nerve
supply : carotid plexus
: superior salivary
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
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
Lacrimal fossa, formed by
lacrimal bone and
frontal process of maxilla .
closed above and open below, is
continuous with the nasolacrimal duct.
is enclosed by a periorbita, splits &form
the lacrimal fascia .
Medial : periorbita and bone, arc of ethmoid
Lateral : skin, orbicularis oculi, and lacrimal
Anterior: medial palpebral ligament and
Posterior : lacrimal fascia and muscle
The nasolacrimal duct,
continuation of lacrimal
sac to the inferior meatus.
It lies in
a canal formed by the maxilla, lacrimal
bone and lacrimal process of inferior concha.
It descends posterolaterally, a
a line from medial canthus to first upper molar.
They are folds of mucous
membrane with no
The most constant is
'valve' of Hasner at the
It prevents sudden blast of
air (when blowing the
nose) from entenng the
The superficial layer composed of
cells, the deeper cells being flatter.
The membranous wall
of the sac is of
fibroelastic tissue, the elastic element being
continued around the canaliculi.
Around the nasolacrimal duct is
vessels, forming erectile tissue like that on the
these vessel obstruct the duct.
The course of the lacrimal sac
and duct can be
demonstrated by dacryocystography
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
Infratrochlear and anterior superior alveolar nerves.
The tear film overlays corneal and conjunctival
Tears produced by the ocular surface epithelia
Thickness of up to 40 µm,
Volume of tears covering the ocular surface
range from 2.74 ± 2.0µL to 7 µL
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
regulated by neural reflexes ,causing
vasodilation and vasoconstriction of blood sinus.
Evaporation depends blink
temperature, humidity, and wind speed.
To protect the cornea from drying;
the refractive power of the cornea;
To defend against
To allow gas
to move between the air and the
To support corneal dehydration (assisted by
tear film hyperosmolality).
The glycocalyx is a network of polysaccharides that project
from cellular surfaces.
Mucins are classified into secreted and membrane-spanning
Secreted mucins are either gel-forming or small soluble
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
The mucous layer backbone is the gel-forming
mucin , synthesized and secreted by conjunctival
To resistance of the eye to infection by providing
protection against microorganisms.
Mucins serve as wetting agents that keep the apical
Lacrimal gland produce aqueous layer.
Other ocular surface epithelia also contribute to the
aqueous layer, eg. conjunctiva, accessory lacrimal
Without the lubrication , the shearing forces
produced on blinking will cause accumulative
ocular surface damage.
Composed of water, with
many solutes, including
dissolved mucins, electrolyte sand proteins.
The osmotic pressure :
sodium, potassium and chloride ions.
film’s osmotic pressure is important in
the control of cornea–tear film water flux.
carbonate : pH
buffering, maintaining the pH at 7.3–7.6 when the
eyes open & 6.8 eyes closed.
Aqueous layer function
Aqueous deficiency dry eye.
Protection from bacterial infection
Reflex secretion washes away noxious
Protects against changes in pH.
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
Hydrophobic barrier to prevent tear overflow.
The meibom forms a
water-tight seal of the
apposed lid margins during sleep.
Reduce tear evaporation .
Lipids enhance the stability of
film and provide a smooth optical.
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
mucocutaneous junction of the lid,
lost from the conjunctiva sac by
absorption, evaporation, and nasolacrimal
related to the size of the palpebral
aperture, the blink rate, ambient temperature
the upper and lower marginal strips → upper and
lower canaliculi (capillarity+suction)
Pretarsal orbicularis oculi compresses the
ampullae+ shortens and compresses
Lacrimal part of the orbicularis oculi, contracts →
compresses the sac,(positive pressure) tears →
nasolacrimal duct → nose.
Muscles relax → canaliculi and sac expand(negative
pressure)+capillarity= tears into sac.
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