Transcript LAC.SYSTEM I-ANATOMY, PHYSIOLOGY, CONGENITAL
O , my sustainer! Open my Heart and make my task easy for me and loosen the knot from my tongue so that, they might understand my speech
Surah Taha (16:25-290)____Al Quran
DR. FAIZUR RAHMAN Professor of Ophthalmology PESHAWAR MEDICAL COLLEGE
LEARNING OBJECTIVES
BY THE END OF THE SESSION THE STUDENTS WOULD BE ABLE TO:
Correlate the structure of the lacrimal system with its function and clinical presentation in common clinical disorders.
Outline the clinical examination protocol for the assessment of lacrimal system in patient presenting with epiphora.
Lacrimal System
Consist of two parts: Tear production Tear drainage
Tear production: *Main Lacrimal gland *Accessory lacrimal glands Glands of Krause Glands of Wolfring
LACRIMAL GLANDS
Serous glands
Situated at the upper and outer angle of the orbit, just within the orbital margin, in a depression on the orbital plate of the frontal bone (Fossa for the lacrimal gland)
Embryology
Lacrimal gland forms as a series of ectodermal buds that grow supero-laterally from the sup. fornix of the conjunctiva into the underlying mesenchyme. These buds then canalize forming the secretary units and multiple ducts of the gland.
Lacrimal sac and NLD develop as a solid cord of ectodermal cells between lat. nasal process & maxillary process of the developing face.
LACRIMAL GLANDS-Anatomy.
Anteriorly divided by aponeurosis of levator palpabrae superioris into: Upper orbital part Lower palpabral part
Ducts are 12 in number, pass through the palpabral part of the gland and open into the conjunctival sac, 4.5 mm above the upper border of the superior tarsus
Location
LACRIMAL GLAND
LOCATION
LACRIMAL GLAND
LACRIMAL GLAND
12 ducts of the lacrimal gland pass from the orbital part through the palpebral part into the superior conjunctival fornix. In addition to Lacrimal gland, small accessory glands are also present in the conjunctiva.
In case of non functioning of lacrimal gland, these glands keep cornea wet .
MICROSCOPIC STRUCTURE
Lacrimal gland is lobulated tubulo acinar structure. On cross section, the acini are seen as round or tube shaped masses of columnar cells.
Acini cells 80% are surrounded by Myoepithelial cells for squeezing out the secreted fluid.
RELATIONS
Palpebral part of Lacrimal gland lies below the Aponeurosis of Levator palpebrae superioris.
It extends into the upper eye lid. Superiorly=Aponeurosis of Levator Palpabrae Superioris. Inferiorly= Superior fornix- conjunctiva
.
BLOOD SUPPLY Is from Lacrimal artery ( a branch of Ophthalmic artery) , and from Infra orbital artery ( a branch of Maxillary artery) VENOUS DRAINAGE Venous drainage is through Sup. Ophthalmic vein into cavernous sinus.
LYMPHATIC DRAINAGE Lymphatic drainage occurs into the superficial Parotid lymph nodes.
NERVE SUPPLY
Two types of nerve supply that is Autonomic and sensory nerve supply.
Autonomic nerve supply consist of Parasympathetic and sympathetic components.
In parasympathatic system, the Nervous intermedius from the secretomotor nucleus of Facial nerve join a branch of Great petrosal nerve to form nerve of Pterygoid canal which goes to Pterygo palatine ganglion. From here nerve fibers pass through Maxillary , Zygomatic N; Zygomatico temporal and finally Lacrimal nerve.
In sympathatic system, superior cervical sympathatic ganglion,Plexus of nerves around ICA, deep petrosal nerve, nerve of Pterygoid canal, Maxillary nerve, Zygomatic N .Zygomatico temporal nerve & Lacrimal nerve
Sensory nerve supply;
Lacrimal nerve.
SECRETORY INNERVATION
LACRIMAL GLAND
SECRETORY INNERVATION
POSTGANGLIONIC SYMPATHATIC FIBRERS
Accessory lacrimal glands
Same structure as main lacrimal gland
Very small in size
Glands of Krause: 20 in number, in the upper lid and 8 in the lower lid, deeply situated in the conjunctiva near the fornix on lateral side
Glands of Wolfring: are few in number, situated near the upper border of the tarsal plate
Physiology
Secretes tear, a slightly alkaline serous fluid.
Consist of water and minute quantities of sodium chloride, sugar , urea and protein.
Contains lysozyme which is bactericidal
Starts 3-4 weeks after birth.
Tear drainage system
Consist of puncta, ampula, canaculi, lacrimal sac and nasolacrimal duct *Punctum: Situated near the medial end of each eyelid.
Face slightly posterior in normal condition.
slightly evert the medial end of the eyelid and the punctum will become visible. *Ampula: (Vertical canaliculus) The most proximal portion of the canaculus, measuring 2 mm.
Tear drainage…cont.
*
Horizontal canaliculus: -8 mm long, in 90% the upper and lower unite to open in the lateral wall of the sac.
-In 10% both open separately.
-A flap of mucosa (valve of Rozenmuller) prevents regurg from the sac.
Tear drainage…cont.
*
Lacrimal sac: - It is 10 mm long and lies in the lacrimal fossa.
- Lacrimal bone and frontal process of Maxilla separate it from middle meatus of nose.
*Nasolacrimal duct: -Passes down medially & posteriorly to open in the inferior meatus.
-Opening is gauded by a valve. (valve of Hasner)
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.
Physiology
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.
Physiology
-
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.
Physiology
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.
Congenital disorders.
Canalicular abnormalities: Very rare and often undiagnosed.
Absence of punctum: very rarely one or both the puncta may be absent congenitally, usually the site may be visible (congenital stenosis)
Congenital disorders.
Congenital NLD blockage: More common condition leading to epiphora in small children (non-canalization of the NLD cord) Managed by massages and simple antibiotics till the age of 6 months in the hope of spontaneous canalisation If no improvement in 6 months the probing is tried three times till the age of 2 years.
Congenital disorders
After the age of 2 years the success of probing decreases and the child may require a DCR when he/she reaches the age of 6 years.
EVALUATION
History *watering, discharge, swelling and pain *usually prolonged, usually unilateral
Examination *Inspection ectropion, swelling, fistula *Palpation cystic swelling, any stones, regurg test
EVALUATION…Cont.
*
Slitlamp exam *Punctal exam for malposition, stenosis *Press canaliculus for infection *Examine marginal tear strip *Froceful closure of lids—puncta may evert—lids may overlap *Fouroscein disappearance test—2 minutes
EVALUATION…Cont.
Clinical tests Probing *Hard stop *Soft stop Irrigation *Canacular block *Partial block *NLD block
Patency of Canaliculus
Jones tests
Jones I (Primary)
Hypersecretion or Obstruction
Jones II (Secondary) Upper passages obstruction or Pump failure
Dacrocystography Types:
Plain DCG
Distention DCG
Macro DCG
Cinematography
Dacroscintigraphy
Contrast DCG
Digital substraction DCG
Dacrocystography
Radiopaque dyes: Lipoidal in water or lipoidal with olive oil Iodized oil Neohydroil angioraphin Dionosil aqueous Conray Diagonal viscous
Dacrocystography
Conventional (Lipiodal ultra fluid is used) Dacrocystography Macrodacrocystography
Computerized: Subtsaction
Dacrocystography
Dacrocystography
Scintiligraphy
Dynamic
Radioactive technetium is used
Site of obstruction can be documented