the lacrimal system

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the lacrimal system anatomy and clinical


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The lacrimal system Done by: Mohammed A Qazzaz

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the lacrimal glands normally produce 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: tear composition. the drainage of tears.

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ABNORMALITIES IN COMPOSITION If 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.

Aqueous insufficiency—dry eye:

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 a dry 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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SYMPTOMS Patients have non-specific symptoms of grittiness, burning, photophobia, heaviness of the lids and ocular fatigue. These symptoms are worse in the evening because the eyes dry during the day. In more severe cases visual acuity may be reduced by corneal damage.


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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TREATMENT 1- 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.

Inadequate mucus production :

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)

Stevens–Johnson’s syndrome).:

Stevens–Johnson’s syndrome). there is an acute episode of inflammation causing macular ‘target’ lesions on the skin and discharging lesions on the eye, mouth and vulva. In the eye this causes conjunctival shrinkage 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 conjunctiva caused 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.

Vitamin A deficiency (xerophthalmia):

Vitamin A deficiency ( xerophthalmia ) is a condition causing childhood blindness on a worldwide scale. It is associated with generalized malnutrition in countries such as India and Pakistan. Goblet cells are lost from the conjunctiva and the ocular surface becomes keratinized ( xerosis ). An aqueous deficiency may also occur. The characteristic corneal melting and perforation which occurs in this condition ( keratomalacia ) may be prevented 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

Malposition of the eyelid margins:

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 the problem. If the defect is temporary, artificial tears and lubricants can be applied. If lid closure is inadequate a temporary ptosis can be induced with a local injection of botulinum toxin into the levator muscle. A more permanent result can be obtained by suturing together part of the apposed margins of the upper and lower lids (e.g. lateral tarsorrhaphy ;


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 is termed epiphora ).

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Obstruction of tear drainage (infant) The naso-lacrimal system develops as a solid cord which subsequently canalizes and is patent just before term. Congenital obstruction of the duct is common. The distal end of the naso-lacrimal duct may remain imperforate, causing a watering eye. If the canaliculi also become partly obstructed the non-draining pool of tears in the sac may become infected and accumulate as a mucocoele or cause dacrocystitis .

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Diagnostically the discharge may be expressed from the puncta by pressure over the lacrimal sac. The conjunctiva, however, is not inflamed. Most obstructions resolve spontaneously in the first year of life. If epiphora persists beyond this time, patency can be achieved by passing a probe via the punctum through the naso-lacrimal duct to perforate the occluding membrane ( probing ). A general anaesthetic is required.

Obstruction of tear drainage (adult) :

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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SIGNS A stenosed punctum may be apparent on slit lamp examination. Epiphora is unusual if one punctum continues to drain.

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Acquired obstruction beyond the punctum is diagnosed by syringing the naso-lacrimal system with 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 regurgitate from the non- canulated punctum . The exact location of the obstruction can be confirmed by injecting a radio-opaque dye into the naso-lacrimal system ( dacrocystogram ); X-rays are then used to follow the passage of the dye 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.


INFECTIONS OF THE NASO-LACRIMAL SYSTEM Closed obstruction of the drainage system predisposes to infection of the sac ( dacryocystitis ; Fig. 6.4). The organism involved is usually Staphylococcus . Patients present with a painful swelling on the medial side of the orbit, which is the enlarged, infected sac.Treatment is with systemic antibiotics. A mucocoele results from a collection of mucus in an obstructed sac, it is not infected. In either case a DCR may be necessary to prevent recurrence.

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