Dr Sabin Sahu

MS Ophthalmology

SCEH. Lahan

Lacrimal Apparatus The lacrimal apparatus include structures concerned

with:

a) Formation of tears - Lacrimal gland

b) Drainage of tears - Lacrimal passage

The lacrimal passage include: puncta, canaliculi, lacrimal sac and nasolacrimal duct (NLD)

Diagram of lacrimal apparatus

Lacrimal gland Main Lacrimal gland

Location - in the superior lateral quadrant of the orbit within the fossa for lacrimal gland

Parts – superior orbital part and inferior palpebral part

Ducts – 10 to 12 ducts of lacrimal gland open into the superior fornix

Blood supply – lacrimal artery, a branch of ophthalmic artery

Nerve supply – lacrimal nerve, a branch of ophthalmic division of fifth cranial nerve

Accessory lacrimal glands

These include - Glands of Krause, Glands of Wolfring

Lacrimal passages1) Lacrimal puncta

Two small round or oval openings one each on the upper and lower eyelid

It is located at the posterior edge of the lid margin

Normally they face slightly posteriorly and can be inspected by everting the medial aspect of the lids.

2) Lacrimal canaliculi

Parts : Vertical part – 2 mm (ampullae) and

horizontal part - 8 mm

The superior and inferior canaliculi usually (>90%) unite to form the common canaliculus, which opens into the lacrimal sac.

A small flap of mucosa (Rosenmüller valve) at the junction of the common canaliculus and the lacrimal sac prevents reflux of tears into the canaliculi.

3) The lacrimal sac

It is 10–12 mm long and lies in the lacrimal fossa

The lacrimal bone and the frontal process of the maxilla separate the lacrimal sac from the middle meatus of the nasal cavity.

Parts: fundus (portion above the opening of canaliculi), body (middle part) and

neck (lower part opening into nasolacrimal duct)

In a dacryocystorhinostomy (DCR) an anastomosis is created between the sac and the nasal mucosa to bypass an obstruction in the nasolacrimal duct.

4) The naso-lacrimal duct

It is 12–18 mm long and is the inferior continuation of the lacrimal sac.

It is directed downwards, outwards and backwards.

Parts: intraosseous part and intrameatal part

It opens into the nasal cavity in the inferior nasal meatus

The opening of the duct is partially covered by a mucosal fold (valve of Hasner).

Physiology About 10% of tear elimination occurs by evaporation in

young and about 20% in elderly person

Most of the tear is actively pumped from tear lake by lacrimal pump mechanism

Lacrimal pump mechanism

Brought about by preseptal fibres of orbicularis oculimuscle (Horner’s muscle)

On eyelid closing

Contraction of preseptal fibres of orbicularis (Horner’s muscle) pulls the lacrimal fascia and wall of lacrimal sac Opens the lacrimal sac create negative pressure draws tears from canaliculi into lacrimal sac

When the eyelid opens

Relaxation of preseptal fibres of orbicularis (Horner’s muscle) Allows the lacrimal sac to collapse create positive pressure expels fluid downwards into nasolacrimal duct

Lacrimal pump mechanism

Syringing Procedure:

1. Topical anaesthesia - 4 per cent Xylocaine drops

2. Lower punctum is dilated with a punctum dilator

3. Normal saline is pushed into the lacrimal sac through the lower punctum with the help of a syringe and lacrimalcannula

Results are interpreted as follows:

a) A free passage of saline through lacrimal passages into the nose no obstruction or partial obstruction.

b) Regurgitation of purulent fluid from upper punctum, sac fills up obstruction in nasolacrimal duct

c) Regurgitation of clear fluid from upper punctum, sac doesn’t fill up, no fluid pass into nose common canaliculi block

d) Immediate reflux of the saline through the lower punctum, no fluid pass into nose lower canalicularobstruction Under these circumstances the procedure should be repeated

through the upper punctum.

A free passage of saline into the nose will confirm the blockage in the lower canaliculus while regurgitation back through the same punctum will indicate block in both canaliculus.