4-Lacrimal system

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LACRIMAL SYSTEM AFFECTIONS

I-ATRESIA OF THE LACRIMAL PUNCTA OR IMPERFORATE PUNCTA: -

Definition:

It is a congenital anomaly in which the upper and/or the lower puncta is absent. The condition may be unilateral or bilateral. As the absence of the upper punctum usually present without any clinical signs, absence of the lower punctum is most commonly observed.

Symptom:

Epiphora (abnormal flow of tears over the face) and excessive moisture of the medial canthal skin. In most cases the obstruction consists of a thin layer of conjunctiva over the lumen.

Differential diagnosis from:

1-Simple obstruction of the punctum by inflammatory products

2-Absence of punctum and canaliculus

3-Displacement of the punctum

4-Dacryocystitis.

Treatment:

Surgical opening of the affected punctum. A lacrimal cannula is inserted into the patent punctum or at the nasal punctum and flushing is performed under pressure. The thin membrane is balloons under pressure and can be identified and excised by a scissors leaving an oval or round defect. Also a cruciate incision may be performed in this area. Insertion of a nasolacrimal catheter is recommended for 2-3 weeks until healing takes place. Topical antibiotic-corticosteroid solutions are instilled 6-8 times daily for 10 days to maintain patency.

II-DISPLACEMENT OF THE LOWER PUNCTUM: -

Definition:

The lower punctum is displaced few millimeters ventral to its normal position.

Causes:

1-Primary as a congenital anomaly

2-Secondary to entropion, trauma, or scaring. Senile ectropion usually results in displacement of the lower punctum outwards.

Symptoms:

1-Continuous epiphora (with closure of the punctum by exudates) and the hair at the medial canthal skin is usually moist.

2-The ventral conjunctival cul-de-sac may be hyperaemic.

Diagnosis:

1-Signs

2-Fluorescein passage from the eye is delayed or absent.

3-The nasolacrimal flush usually indicates patency.

4-Examination by surgical microscope confirm ventral displacement of the lower punctum.

Treatment:

It is only indicated in severe cases. The displaced lower punctum may be relocated to their normal position or a new exit for tear drainage is constructed (conjunctivorhinostomy or conjunctivoralos-

tomy).

III-OBSTRUCTION OF THE CANALICULI: -

Obstruction of the canaliculi is observed at the lower canaliculus as the obstruction of the upper one not associated by epiphora, thereby escaping detection.

Causes:

1-Congenital absence of the canaliculus is related to the absence of the punctum.

2-Obstruction of the lower punctum is associated with inflammatory debris and foreign materials (sand or planet owns).

Diagnosis:

Nasolacrimal flushing reveals no passage in cases of congenital absence of the canaliculus and punctum.

Treatment:

1-In cases of foreign body obstruction, the inflammatory debris or foreign body will be expelled during flushing.

2-Conjunctivoralostomy or conjunctivorhinostomy is the operations of choice in cases of absence of the lower canaliculus.

IV-CANALICULUS LACERATIONS: -

Most lacerations involve the lateral aspect of the palpebral fissure but sometimes affect the medial part of the lower eyelid.

Symptoms:

1-The eyelid is usually edematous

2-Debris and hemorrhage may obscure the extent of injury so the area of laceration must be examined carefully with a magnification

Treatment:

1-The punctum is cannulated during the process of suturing of the wound

2-Topical antibiotic-corticosteruid is applied

V-DACRYOCYSTITIS: -

Definition:

It is inflammation of the nasolacrimal sac. Dacryocystitis usually is a concurrent with or sequelae to conjunctivitis. The accumulation of cellular debris and other foreign bodies within the lacrimal sac provides a good medium for bacterial proliferation. The resultant inflammation of the mucous membrane constricts the lumen or even close it.

Symptoms:

1-The condition may be acute or chronic

2-Thick mucoid or mucopurulent discharge is present at the medial canthus.

3-Mucopurulent conjunctivitis is usually present.

4-Small swelling at the. medial canthus is evident and painful to palpation. Digital pressure over this swelling may extrude mucopurulent exudates.

5-In acute dacryocystitis, abscess may be formed and opens subcutaneous at the medial canthus and a fistula may develop connecting the sac with external skin.

Treatment:

1-Medical treatment is directed towards combating infection and re-establishing the patency of the duct. Irrigation is applied first by antiseptic solution then a broad-spectrum antibiotic and corticosteroid are added to the ophthalmic lotion.

2-Surgical treatment consists of catheterization and placement retention tubing at the lower canaliculus. The tube is left in place for 2-3 weeks. Flush the lower punctum daily until discharge stops. Medicate the eye 3-4 times daily by ophthalmic ointment until the tube is removed. The catheter or polyethylene tube can be sutured in place at the face.

N.B.:

Dacryocystitis occurs in donkeys due to infection by Histoplasma species. The disease is very common in some localities in Egypt and is usually observed unilaterally but the other eye get the infection after sometime from the first one. The medial part of the lower eyelid at the medial canthus of the eyeball becomes swollen and the conjunctiva gets inflamed. The lower punctum is dilated and transformed into rounded aperture. The lower eyelid is turned out at the medial canthus. A granulomatous tissues start to protrude through the puncta lacrimalis. In later stages a huge granulomatous tissue mass protrudes completely through the lower punctum and extends toward the cornea. These tissues are fleshy, rosy red in color, friable and easily detachable with moderate bleeding. Severe epiphora and blepharospasm are detected. Mucopurulent discharge may be observed in some cases. Long standing dacryocystitis may be complicated by maxillary sinusitis and purulent discharge is extruded from the nostril of the affected side.

The treatment is mainly surgical. The lacrimal sac is squeezed by digital pressure in early cases and retrograde flushing is performed. In advanced cases the granulomatous tissues are excised with a blunt scissors. The lacrimal sac is opened through the medial canthus, the content is evacuated and the lumen is curetted. Flushing is performed several times daily for 10 successive days with antibiotics and fungicidal solutions. Recovery is usually obtained but recurrences have been recorded in many cases.

VI-OBSTRUCTION OF THE NASOLACRIMAL DUCT: -

Congenital atresia of the nasolacrimal duct has been reported. Acquired obstruction is simply related to inflammatory debris or foreign materials in the lumen of the duct. It may be due to inflammation of the wall of the duct resulted in stenosis or complete obstruction. Also pressure of a tumour or abscess from outside may obliterate the lumen of the duct.

Signs of obstruction:

1-Epiphora, moisture and tear staining of the medial canthus

2-Serous or seromucoid conjunctivitis                        

Treatment:

1-In congenital atresia of a segment of the duct, conjunctivoralostomy or conjunctivorhinostomy is the treatment of choice

2-In cases of acquired obstruction flushing of the duct is performed 2-3 times daily for several days with ophthalmic solutions containing antibiotics and corticosteroid.

VII-ATRESIA OF NASAL PUNCTUM: -

It means absence of the nasal punctum at the nostrils. The lumen of the duct is distended with saline via the lacrimal puncta and the mucosa at the nostrils is dissected until the lumen is entered. Lacrimal cannula is inserted for several days until the opening have been established.

VIII-EPIPHORA: -

Definition:

It means abnormal flow of tears outside the eye. This condition is common in miniature breeds of dogs as Toy, Poodle and small Terriers.

Causes:

1-Medial lower entropion                                         2-Hair from the caruncle acting as a wick

3-Prominence of the globe (exophthalmos) with shallow lacrimal lake

4-Obstruction of the lower punctum                         5-Nasolacrimal duct obstruction

6-Congenital absence of the lower punctum or canaliculus

7-Localized inflammation along the course of the duct

8-Excessive tear production secondary to irritation caused by entropion, ectropion, distichiasis, trichiasis, and ectopic cilia.

Symptoms:

Flow of tears outside the eye with tear staining of the medial canthus skin and hair

Treatment:

Try to correct the primary cause after thorough examination of the eyeball and its adnexa.

IX-KERATOCONJUNCTIVITIS SICCA, KCS, DRY EYE, OR XEROPHTHALRNIA: -

Definition:

KCS is a disease involving the cornea and conjunctiva results from deficiency of the aqueous portion of the tear film. It is a common condition in dogs and uncommon in cat and rare in other domestic animals.

Causes:

1-Congenital absence of the lacrimal glands

2-Spontaneous senile atrophy of the glands

3-Lack of normal innervation of the glands; may be due to traumatic causes, infection or spontaneously from unknown cause. This results in lack of lacrimal gland activity.

4-Trauma to the orbital and supraorbital area damaging the lacrimal gland

5-Surgical removal of the nictitans gland of the third eyelid

6-Systemic diseases, as canine distemper, the cause is a virus affecting the lacrimal and nictitans glands and may result in gland dysfunction.

7-Drug reaction as long term using of sulphadiazine

8- Idiopathic causes; the majority of cases are of unknown cause

Symptoms:

The clinical signs of KCS vary according to the degree of hyposecretion and the duration of the disease, also depending on whether the condition is bilateral or unilateral, acute or chronic and temporary or permanent.

1-Blepharospasm (increased blinking) as a result of intense ocular pain and discomfort

2-Mucoid and mucopurulent discharge. The eye and eyelids are covered with mucoid discharge. Absence of the tears leads to accumulation of the discharge over the eye.

3-Changes of the mucoid thread. As the tear production decreases, mucous production is increased as a protective mechanism for the eye resulting in increase in the size of mucous thread, change in its color into yellow green and becomes adherent to the conjunctiva.

4-Corneal changes. Include, loss of luster, opacity, vascularization, pigmentation and keratinization.

5-Conjunctival changes. Conjunctiva becomes thick, dry and inflamed.

6- Nostrils may be normal or dry.

Diagnosis:

1-History

2-Clinical signs

3-Schirmer tear test: The average normal tear wetting per minute is 20 mm, suspicious levels are 5-10 mm wetting per minute and most KCS patients exhibit wetting values less than 5 mm per minute.

4-Rose-bengal staining: 0.5% solution is instilled in the eye and the excess is flushed away with normal saline. Rose-bengal stains the degenerated and devitalized corneo-conjunctival epithelium.

Treatment:

1-Medical treatment:

a-Replacement of precorneal tear film by artificial tears as Methyl-cellulose 1%. Frequent instillation is essential.

b-Stimulation of lacrimal secretion; by pilocarpine 1% solution, 1-4 drops added to the food.

c-Remove the excess of mucous by gentle and frequent washing and cleaning of the eyeball and eyelids with 5% acetylcysteine (Mucomyst).

d-Control of infection by using broad spectrum antibiotics as chloramphenicol or gentamycin 4-6 times daily.

e-Anti-inflammatory agent as corticosteroids. It reduces conjunctival inflammation, conjunctival exudates, corneal vascularization and pigmentation.

2-Surgical treatment:

a-Surgical or cautery ablation of the lower punctum. This method is used to conserve the small amount of tears, if present. This technique has not been successful as KCS is usually absolute condition without any tear production.

b-Surgical reduction of the size of palpebral fissure through lateral tarsorrhaphy. Success of the procedure is dependent on some lacrimal activity.

c-Hydrophilic soft lenses applied to the cornea after application of medication to retains enough moisture and protect the cornea for several hours.

d-Parotid duct transportation: This operation is indicated when the medical treatment have been failed. A minimum of 3 months of medical treatment is desirable before starting surgical therapy as some dogs regain tear production during this time. Before surgical intervention, the function of the parotid salivary gland must be evaluated. This is performed by application of a few drops of 1% atropine ophthalmic solution to the patient's tongue or oral mucosa and observing the papilla of, the parotid duct for profuse salivation, associated with bitter taste of atropine. The papilla is presented adjacent to the caudal aspect of the cranial tooth. The saliva has nearly the same structure of tears and is non-irritant to the eye.

Anatomical consideration:

Surgical exposure of the parotid duct is performed at the cheek area. The skin is thick and facial muscles are thin. The parotid duct is formed by several small ductules emerging from the ventral part of the gland and extends directly across the masseter muscle. The duct opens into the buccal cavity by a small papilla, lateral to the posterior aspect of carnassial tooth. The dorsal and ventral buccal nerves are located in the facia external to the parotid duct above and below it. A connecting branches usually crosses external to the parotid duct. The facial vein also crosses external to the parotid duct.

Surgical procedure:

The operation is performed under effect of general anesthesia and the check is prepared for aseptic operation. The papilla of the parotid duct is identified near the base of the carnassial tooth. Care should be taken not to confuse it with the papillae of the zygomatic salivary gland, which open near the gingival border above the last molar tooth.  A 0 to 2-0 monfilment nylon suture material with a blunt tip (the tip is flamed to be blunt) is passed through the parotid duct papilla. The mucosa anterior to the papilla is grasped rostrally to straighten the duct and facilitate catheterization. The nylon thread can be seen moving beneath the skin and can be felt as it passes in the parotid duct to the gland. After the suture has nearly reached the gland, it is cut 1-2 cm from the papilla. Place a piece of cotton soaked in antiseptic solution over the papilla and return the lip to normal position. As the nylon suture can be 'palpated through the cheek, a skin incision is made along the duct through the skin and facial muscles exposing the duct. Careful dissection of the duct from the masseter muscle is performed and a piece of umbilical tape is used for retraction and elevation of this duct during dissection to prevent its trauma. The duct is dissected free posteriorly to the angle of the mandible or where the duct begins to divide into smaller ductules. Carefully start dissection forward, avoiid facial vein and the anastomotic branches between the two buccal nerves. Near the buccal mucosa the duct continues for 1 cm submucosally before terminating in the papilla. A rounded or oval incision of the mucosa around the papilla is performed and the papilla with the mucosa are pulled back into the external facial incision. The oral mucosa is apposed with fine catgut with simple interrupted suture and set aside all instruments used in the mouth. The surgeon should reglove. A canthotomy incision is performed if the palpebral fissure is narrow and eyelid opening is small. With a mosquito artery forceps, a subcutaneous tunnel is made along the surface of the masseter muscle from the angle of the mandible to the lateral canthus. Force the forceps through the conjunctiva and grasp the point with another artery forceps and then withdraw the first one until the tip of the second one appears at the facial wound. Grasp the edge of the mucosa, containing the papilla, with the forceps and draw the duct through the tunnel to the eye. 4 simple interrupted 6-0 chromic catgut sutures are placed apposing the mucosa around the papilla to the conjunctiva. The skin and canthotomy incisions are closed as usual. A closed technique eliminates the need for facial incision has been practised with a great chance for kinking, twisting and damaging the duct. In this procedure the oral mucosa plug is performed and dissection is continued around the duct to the angle of the mandible. Next, tunnel is formed from the conjunctiva! fornix to the angle of the mandible and the mucosa with the papilla is transpositioned to the conjunctival sac.

The papilla is fixed to the conjunctiva as mentioned before and the oral wound is closed. Such technique is difficult and blind dissection usually results in many complications.

Postoperative care:

1-Topical antibiotic-corticosteroid, 4-6 times daily.

2-Systemic antibiotic, 7-10 days.

3-Diuretics are recommended in cases of facial edema.

4-Skin stitches are removed in 7-10 days.

5-A drop of atropine is applied to the tongue postoperative! y to check for duct patency.

6-Epiphora during eating is the common complaint.

Postoperative complications:

1-Twisting or tortion of the duct during operation may be exhibited by intermittent reduced or absent secretion.   

2-Stenosis of the duct due to fibrosis in certain areas along its course. Removal of fibrotic tissues at the seat of stenosis can be performed.

3-Atrophy of the parotid gland is rare.

4-Corneal and periocular crystalization occurs in rare cases. In such cases a mineral-like deposit is formed over the cornea and eyelids. It is usually non-irritating.