lacrimal system anatomy and clinical

32
The lacrimal system Done by: Mohammed A Qazzaz

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lacrimal system anatomy and clinical

Transcript of lacrimal system anatomy and clinical

Page 1: lacrimal system anatomy and clinical

The lacrimal system

Done by:

Mohammed A Qazzaz

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the lacrimal glands normallyproduce about 1.2 μl of tears per minute. Some

are lost via evaporation.The remainder are drained via the naso-lacrimal system.The tear film is reformed

with every blink.

INTRODUCTION

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Abnormalities are found in:1. tear composition.2. the drainage of tears.

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ABNORMALITIES IN COMPOSITIONIf certain components of the tear film are

deficient or there is a disorder of eyelid apposition then there can be a disorder of ocular

wetting.

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Aqueous insufficiency—dry eye

A deficiency of lacrimal secretion occurs with age and results in keratoconjunctivitis sicca (KCS) or dry eyes..

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When this deficiency is associated with adry mouth and dryness of other mucous membranes the condition is

called primary Sjögren’s syndrome When KCS is associated with an auto-immune

connective tissue disorder the condition is called secondary Sjögren’s syndrome.

Rheumatoid arthritis is the commonest of these associated disorders

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SYMPTOMSPatients have non-specific symptoms of

grittiness, burning, photophobia,heaviness of the lids and ocular fatigue. These

symptoms are worse in theevening because the eyes dry during the day. In more severe cases visual acuity may be

reduced by corneal damage.

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SIGNS

In mild cases there are few obvious signs. Staining of the eye with fluorescein will show small dots of fluorescence (punctate staining) over the exposed corneal and conjunctival surface.

In severe cases tags of abnormal mucus may attach to the corneal surface (filamentary keratitis) causing pain due to tugging on these filaments during blinking

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TREATMENT1- Supplementation of the tears with tear

substitutes helps to reduce symptoms. 2-In severe cases it may be necessary to

occlude the punta with plugs, or more permanently with surgery, to conserve the

tears.

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Inadequate mucus production

Destruction of the goblet cells occurs in most forms of dry eye,

but particularly in cicatricial conjunctival disorders such as erythema multiforme

(Stevens–Johnson’s syndrome)

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Stevens–Johnson’s syndrome).

there is an acute episode ofinflammation causing macular ‘target’ lesions

on the skin and discharginglesions on the eye, mouth and vulva. In the eye

this causes conjunctivalshrinkage with adhesions forming between the

globe and the conjunctiva (symblepharon).

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There may be both an aqueous and mucin deficiency and

problems due to lid deformity and trichiasis.

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1-Chemical burns of the eye,particularly by alkalis 2- trachoma (chronic inflammation of the

conjunctivacaused by a type of chlamydial infection;

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The symptoms are similar to those seen with an aqueous deficiency.

Examination may reveal scarred, abnormal conjunctiva and areas of fluorescein staining.

Treatment requires the application of artificial lubricants.

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Vitamin A deficiency (xerophthalmia)

is a condition causing childhoodblindness on a worldwide scale. It is associated with

generalized malnutritionin countries such as India and Pakistan. Goblet cells are lost

fromthe conjunctiva and the ocular surface becomes keratinized

(xerosis). Anaqueous deficiency may also occur. The characteristic corneal melting and perforation which

occurs in this condition (keratomalacia) may beprevented by early treatment with vitamin A.

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Abnormal or inadequate production of meibomian oil

Absence of the oil layer causes tear film instability, associated with

blepharitis

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Malposition of the eyelid margins

If the lid is not apposed to the eye (ectropion), or there is insufficient closure of the eyes (e.g. in

a seventh nerve palsy or if the eye protrudes (proptosis) as in dysthyroid eye disease) the preocular tear film will not

form adequately

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Correction of the lid deformity is the best answer to theproblem. If the defect is temporary, artificial tears and

lubricants can beapplied. If lid closure is inadequate a temporary ptosis can be

induced witha local injection of botulinum toxin into the levator muscle. A

more permanentresult can be obtained by suturing together part of the apposedmargins of the upper and lower lids (e.g. lateral tarsorrhaphy;

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DISORDERS OF TEAR DRAINAGE

When tear production exceeds the capacity of the drainage system,

excess tears overflow onto the cheeks. It may be caused by:

•00irritation of the ocular surface, e.g. by a corneal foreign body, infection

or blepharitis;•00occlusion of any part of the drainage system (when

the tearing istermed epiphora).

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Obstruction of tear drainage (infant)The naso-lacrimal system develops as a solid cord which

subsequentlycanalizes and is patent just before term. Congenital obstruction

of theduct is common. The distal end of the naso-lacrimal duct may

remainimperforate, causing a watering eye. If the canaliculi also

become partlyobstructed the non-draining pool of tears in the sac may

become infectedand accumulate as a mucocoele or cause dacrocystitis.

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Diagnostically thedischarge may be expressed from the puncta by pressure over

thelacrimal sac. The conjunctiva, however, is not inflamed. Most

obstructionsresolve spontaneously in the first year of life. If epiphora

persists beyondthis time, patency can be achieved by passing a probe via the

punctumthrough the naso-lacrimal duct to perforate the occluding

membrane(probing). A general anaesthetic is required.

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Obstruction of tear drainage (adult)

The tear drainage system may become blocked at any point, although the

most common site is the naso-lacrimal duct. Causes include infection or

direct trauma to the naso-lacrimal system.

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HISTORY

The patient complains of a watering eye sometimes associated with

stickiness. The eye is white. Symptoms may be worse in the wind or in

cold weather.There may be a history of previous trauma or infection.

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SIGNSA stenosed punctum may be apparent on slit

lamp examination. Epiphorais unusual if one punctum continues to drain.

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Acquired obstructionbeyond the punctum is diagnosed by syringing the naso-lacrimal systemwith saline using a fine cannula inserted into a canaliculus.

A patent system is indicated when the patient tastes the saline as it reaches the pharynx. If

there is an obstruction of the naso-lacrimal duct then fluid will regurgitatefrom the non-canulated punctum. The exact location of the obstructioncan be confirmed by injecting a radio-opaque dye into the naso-lacrimalsystem (dacrocystogram); X-rays are then used to follow the passage of thedye through the system.

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TREATMENT

It is important to exclude other ocular disease that may contribute to watering such as blepharitis. Repair of the occluded naso-lacrimal duct requires surgery to connect the mucosal surface of the lacrimal sac to the nasal mucosa by removing the intervening bone (dacryocystorrhinostomy or

The operation can be performed through an incision on the side of the nose but it may also be performed endoscopically through the nasal passages thus avoiding a scar on the face.

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INFECTIONS OF THE NASO-LACRIMAL SYSTEM

Closed obstruction of the drainage system predisposes to infectionof the sac (dacryocystitis; Fig. 6.4). The organism involved is usuallyStaphylococcus. Patients present with a painful swelling on the medial sideof the orbit, which is the enlarged, infected sac.Treatment is with systemicantibiotics.A mucocoele results from a collection of mucus in anobstructed sac, it is not infected. In either case a DCR may be necessaryto prevent recurrence.

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