Disorder of lacrimal system
Anatomy of the lacrimal system
1.Secretory system
2.Drainage system
The lacrimal secretory system
The lacrimal secretory system is formed of
The main lacrimal gland.
The accessory lacrimal glands.
Conjunctival goblet cells.
The main lacrimal gland
: Almond in shape and is formed of 2 parts:
Orbital portion: It is the main part of the gland, situated in a shallow bony fossa in
the anterolateral part of the roof of the orbit.
Palpebral portion (1/4 of the whole gland): It is continuous with the orbital portion
posteriorly, traversed by the levator muscle and interiorly it rests on the superior
fornix. It can be seen on lid eversion.
The lacrimal ducts: 10-12 ducts arise from the orbital portion of the gland to pass
through the palpebral portion and then open in the lateral part of superior fornix.
Accessory lacrimal glands:
They are microscopic in size and open into conjunctival sac by fine ductules:
The glands of Krause: In the conjunctival fornices (40 in the upper fornix and 10 in
the lower fornix)
The glands of wolfring: Located in the palpebral conjunctiva opposite the mid-
tarsus.
Goblet cells of the conjunctiva: They are unicellular mucionous glands.
Precorneal tear film:
It is formed of 3 layers.
1.Outer lipid layer: secreted by the meibomian glands.
Function:
a. Prevent rapid evaporation of tears.
b. Lubricates the eyelids over the globe
2.Middle aqueous layer: Secreted by the lacrimal gland.
Function:
a.Supplies oxygen to the corneal epithelium.
b.Antibacterial as it contains lysozymes.
3.Inner mucinous layer: Secreted by the goblet cells.
Function:
Makes the corneal epithelium hydrophilic.
The Lacrimal Drainage system
The lacrimal drainage system is formed of 2 canaliculi, the lacrimal sac, and the
nasolacrimal duct ending in the inferior meatus of the nose.
1.Two puncti:
Located at the posterior edge of the lid margin, not seen except when the lid is
everted. Each punctum lies 6 mm. from medial canthus on a slightly elevated portion
called the papilla.
2.Two canaliculi:
Are fine tubes which carry tears from the puncti to the lacrimal sac. Each
canaliculus is made of 2 portions:
Vertical part: 2mm
Horizontal part: 8mm
Before entering the lacrimal sac, they unite into a common canal, 1-2 mm long that
opens at the junction between the upper 1/3 and the lower 2/3 of the sac.
Lacrimal Sac:
Site: the lacrimal sac lies in the lacrimal fossa in the medial wall of the orbit.
Size: 8x12mm (when distended).
The lacrimal sac is formed of:
Body: which forms the main part.
Fundus: Blind upper portion, it lies above the medial palpebral ligament.
Neck: The neck is narrow and continuous with the nasolacrimal duct.
Nasolacrimal duct:
The nasolacrimal duct is 12-24 mm long. It passes from the end of the sac to open in
the inferior meatus of the nose. The direction of the duct is: downwards, slightly
backwards and laterally.
Nose: the opening of nasolacrimal duct into the meatus of the nose is guarded
Hasner's valve.
Tear Drainage
1.Evaporation: 25% of tears.
2.Excretion
Passive: Gravity and capillarity.
Active: lacrimal pump through the action of the lacrimal portion of orbicularis
muscle ( Horner's muscle ).
DRY EYE
Etiology:
1.Old age due to decreased amount of tears.
2.Congenital absence of the lacrimal gland.
3.Inflammation of lacrimal gland e.g sarcoidsis.
4.Tumors of lacrimal gland: e.g mixed lacrimal gland tumor.
Keratoconjunctivits sicca:
Autoimmune disease leading to atrophy and fibrosis
of the lacrimal gland, it occurs usually in females and may be associated with arthritis
and dry mouth ( sjogren's syndrome)
Conjunctival scarring : Due to Tachoma, chemical burns, stevens- Johnson
syndrome and ocular cicatrial pemphigoid.
Drugs as antiglucoma therapy.
Vitamin A difficiency.
Clinical picture:
Symptoms: irritation and foreign body sensation.
Signs:
Deficient precorneal tear film and loss of corneal luster.
Punctuate epithelial erosion of the cornea.
Investigations:
Tear film break – up time (BUT) is diminished (normally it is 15 second).
Schirmer's test: A normal person wets 10-30 mm. of a whatman number 41 filter
paper strip (5mm. wide x 30 mm. long) in 5 minutes. Values less than 5mm. indicate
hyposecretion.
Rose Bengal staining of devitalized epithelial cells.
Treatment:
Protective glasses and contact lenses.
Artificial tears eye drops.
Occlusion of the puncti to reduce tear drainage.
Systemic steroids.
WATERY EYE
Lacrimation
Lacrimation is over secretion of tears
Etiology:
Emotional conditions
Reflex lacrimation from foreign body or inflammation.
The reflex:
Afferent: trigeminal nerve
Efferent : facial nerve
Epiphora:
Epiphora is overflow of tears onto the cheek due to inadequate drainage, which
may be due to lacrimal pump failure or obstruction of the lacrimal passages.
ACUTE DACRYOCYSTITIS
Definition: Acute suppurative inflammation of the lacrimal sac.
Etiology:
Predisposing factor: nasolacrimal duct obstruction.
Causative agent: pneumococci, staphylococci and streptococci.
Clinical picture:
Symptoms:
Severe pain.
Fever
Signs:
Marked edema and redness of skin over the sac.
Regurgitation test: excessive reflex of pus.
Tender swelling of lacrimal sac.
Abscess formation with fluctuation.
Treatment:
During the acute phase.
Antibiotics: systemic and topical.
Hot fomentations.
Lotions: to clean the pus.
Incision and drainage if an abscess forms.
After the acute attack subsides: dacryocystorhinostomy with fistulectomy if needed
CHRONIC DACRYOCYSTITIS
Definition:
A chronic inflammation of lacrimal sac secondary to obstruction of the naso-lacrimal
duct. It is the commonest lacrimal sac disorder.
Etiology:
Predisposing factor: Nasolacrimal duct obstruction.
Causative agent:
Pneumococci in 80%
Staphylococci, streptococcus, trachoma, and fungi
TB and syphilis: rare
Clinical picture:
Symptoms:
Watery eye.
Discharge.
Signs:
The inner canthus is red and hyperemic.
Swelling of lacrimal sac below the medial palpebral ligament.
Regurgitation test +ve : pressure on the swelling causes regurge of mucous or pus.
Congenital Nasolacrimal Duct Obstruction
Nasolacrimal duct obstruction is a blockage of the lacrimal drainage system. In
children the majority of nasolacrimal duct obstruction is congenital.
Congenital nasolacrimal duct obstruction occurs in approximately 5% of normal
newborn infants. The blockage occurs most commonly at the valve of Hasner at the
distal end of the duct. There is no sex predilection and no genetic predisposition. The
blockage can be unilateral or bilateral. The rate of spontaneous resolution is
estimated to be 90% within the first year of life
.
Etiology
The etiology of congenital nasolacrimal duct obstruction is most commonly a
membranous obstruction at the valve of Hasner at the distal end of the nasolacrimal
duct. General stenosis of the duct is the second most common cause of duct
obstruction. Congenital proximal lacrimal outflow dysgenesis involves
maldevelopment of the punctum and canaliculus
Signs
The signs of nasolacrimal duct obstruction consist of an increased tear lake, mucous
or mucopurulent discharge, and epiphora
Treatment of congenital dacryocystitis:
Antibiotics: systemic and topical (drops and ointment)
Hydrostatic massage: the mother is instructed to press on the lacrimal sac in a
downward direction. This may help to remove any remnants of epithelium or to open
hasner's valve. This is tried for a long period up to 1 year.
Probing: is successful if done carefully as the lacrimal passages are still elastic and
can be stretched on the probe.
Irrigation: repeated syringing with saline may cure the condition.
Dacryocystorhinostomy
Treatment of acquired dacryocystitis:
Treatment of the cause of obstruction: e.g relieve congestion, removal of a nasal
polyp.
Dacryocystorhinostomy: operation of choice.
Dacryocystectomy: in neglected cases.
DACRYOCYSTORHINOSTOMY ( DCR )
Principle: is to create a surgical opening between the lacrimal sac and the nasal
mucosa of the middle meatus, allowing drainage of tears directly into the nose
bypassing the obstructed naso – lacrimal duct.
Indications:
Chronic dacryocystits.
Mucocele of lacrimal sac.
Lacrimal fistula (DCR and fistulectomy)
Contraindications:
Bad lacrimal sac: extensive adhesions and neglected cases.
Bad nasal mucousa: atrophic rhinitis and polypi.
DACROCYSTECTOMY
Removal of the lacrimal sac.
Indications: indicated in cases where DCR cannot be done, and the lacrimal sac is
fibrosed.