Ординатура / Офтальмология / Английские материалы / Comprehensive Ophthalmology_Khurana_2007

probing will relieve the obstruction. In case of failure, it may be repeated after an interval of 3-

4 weeks.

4.Intubations with silicone tube may be performed if repeated probings are failure. The silicone tube should be kept in the NLD for about six months.

5.Dacryocystorhinostomy (DCR) operations: When the child is brought very late or repeated probing is a failure, then conservative treatment by massaging, topical antibiotics and intermittent lacrimal syringing should be continued till the age of 4 years. After this, DCR operation should be performed.

ADULT DACRYOCYSTITIS

Adult dacryocystitis may occur in an acute or a chronic form.

CHRONIC DACRYOCYSTITIS

Chronic dacryocystitis is more common than the acute dacryocystitis.

Etiology

The etiology of chronic dacryocystitis is multifactorial. The well-established fact is a vicious cycle of stasis and mild infection of long duration.The etiological factors can be grouped as under:

A. Predisposing factors

1.Age. It is more common between 40 and 60 years of age.

2.Sex. The disease is predominantly seen in females (80%) probably due to comparatively narrow lumen of the bony canal.

3.Race. It is rarer among Negroes than in Whites; as in the former NLD is shorter, wider and less sinuous.

4.Heredity. It plays an indirect role. It affects the facial configuration and so also the length and width of the bony canal.

5.Socio-economic status. It is more common in low socio-economic group.

6.Poor personal hygiene. It is also an important predisposing factor.

B.Factors responsible for stasis of tears in lacrimal sac

1.Anatomical factors, which retard drainage of tears include: comparatively narrow bony canal, partial canalization of membranous NLD and excessive membranous folds in NLD.

2.Foreign bodies in the sac may block opening of NLD.

3.Excessive lacrimation, primary or reflex, causes stagnation of tears in the sac.

4.Mild grade inflammation of lacrimal sac due to associated recurrent conjunctivitis may block the NLD by epithelial debris and mucus plugs.

5.Obstruction of lower end of the NLD by nasal diseases such as polyps, hypertrophied inferior concha, marked degree of deviated nasal septum, tumours and atrophic rhinitis causing stenosis may also cause stagnation of tears in the lacrimal sac.

C.Source of infection. Lacrimal sac may get infected from the conjunctiva, nasal cavity (retrograde spread), or paranasal sinuses.

D.Causative organisms. These include: staphylococci, pneumococci, streptococci and Pseudomonas pyocyanea. Rarely chronic granulomatous infections like tuberculosis, syphilis, leprosy and occasionally rhinosporiodosis may also cause dacryocystitis.

Clinical picture

Clinical picture of chronic dacryocystitis may be divided into four stages:

1.Stage of chronic catarrhal dacryocystitis. It is characterised by mild inflammation of the lacrimal sac associated with blockage of NLD. In this stage the only symptom is watering eye and sometimes mild redness in the inner canthus. On syringing the lacrimal sac, either clear fluid or few fibrinous mucoid flakes regurgitate. Dacryocystography reveals block in NLD, a normal-sized lacrimal sac with healthy mucosa.

2.Stage of lacrimal mucocoele. It follows chronic stagnation causing distension of lacrimal sac. It is characterised by constant epiphora associated with a swelling just below the inner canthus (Fig. 15.8). Milky or gelatinous mucoid fluid regurgitates from the lower punctum on pressing the swelling. Dacryocystography at this stage reveals a distended sac with blockage somewhere in the NLD.

Sometimes due to continued chronic infection, opening of both the canaliculi into the sac are blocked and a large fluctuant swelling is seen at the inner canthus with a negative regurgitation test. This is called encysted mucocele.

Fig. 15.8. Lacrimal mucocele.

3.Stage of chronic suppurative dacryocystitis. Due to pyogenic infections, the mucoid discharge becomes purulent, converting the mucocele into ‘pyocoele’. The condition is characterised by epiphora, associated recurrent conjunctivitis and swelling at the inner canthus with mild erythema of the overlying skin. On regurgitation a frank purulent discharge flows from the lower punctum. If openings of canaliculi are blocked at this stage the so called encysted pyocoele results.

4.Stage of chronic fibrotic sac. Low grade repeated infections for a prolonged period ultimately result in a small fibrotic sac due to thickening of mucosa, which is often associated with persistent epiphora and discharge. Dacryocystography at this stage reveals a very small sac with irregular folds in the mucosa.

Complications

Chronic intractable conjunctivitis, acute on chronic dacryocystitis.

Ectropion of lower lid, maceration and eczema of lower lid skin due to prolonged watering.

Simple corneal abrasions may become infected leading to hypopyon ulcer.

If an intraocular surgery is performed in the presence of dacryocystitis, there is high risk of developing endophthalmitis. Because of this, syringing of lacrimal sac is always done before attempting any intraocular surgery.

Treatment

1. Conservative treatment by repeated lacrimal syringing. It may be useful in recent cases only. Longstanding cases are almost always associated with

blockage of NLD which usually does not open up with repeated lacrimal syringing or even probing.

2.Dacryocystorhinostomy (DCR). It should be the operation of choice as it re-establishes the lacrimal drainage. However, before performing surgery, the infection especially in pyocoele should be controlled by topical antibiotics and repeated lacrimal syringings.

3.Dacryocystectomy (DCT). It should be performed only when DCR is contraindicated. Indications of DCT include: (i) Too young (less than 4 years) or too old (more than 60 years) patient. (ii) Markedly shrunken and fibrosed sac. (iii) Tuberculosis, syphilis, leprosy or mycotic infections of sac. (iv) Tumours of sac. (v) Gross nasal diseases like atrophic rhinitis (vi) An unskilled surgeon, because it is said that, a good ‘DCT’ is always better than a badly done ‘DCR’.

4.Conjunctivodacryocystorhinostomy (CDCR). It is performed in the presence of blocked canaliculi.

ACUTE DACRYOCYSTITIS

Acute dacryocystitis is an acute suppurative inflammation of the lacrimal sac, characterised by presence of a painful swelling in the region of sac.

Etiology

It may develop in two ways:

1.As an acute exacerbation of chronic dacryocystitits.

2.As an acute peridacryocystitis due to direct involvement from the neighbouring infected structures such as: paranasal sinuses, surrounding

bones and dental abscess or caries teeth in the upper jaw.

Causative organisms. Commonly involved are Streptococcus haemolyticus, Pneumococcus and Staphylococcus.

Clinical picture

Clinical picture of acute dacryocystitis can be divided into 3 stages:

1. Stage of cellulitis. It is characterised by a painful swelling in the region of lacrimal sac associated with epiphora and constitutional symptoms such as fever and malaise. The swelling is red, hot, firm and tender. Redness and oedema also spread to the lids and cheek. When treated resolution may occur at this stage. However, if untreated, self-resolution is rare.

2.Stage of lacrimal abscess. Continued inflammation causes occlusion of the canaliculi due to oedema. The sac is filled with pus, distends and its anterior wall ruptures forming a pericystic swelling. In this way, a large fluctuant swelling the lacrimal abscess is formed. It usually points below and to the outer side of the sac, owing to gravitation of pus and presence of medial palpebral ligament in the upper part (Fig. 15.9).

3.Stage of fistula formation. When the lacrimal abscess is left unattended, it discharges spontaneously, leaving an external fistula below the medial palpebral ligament (Fig. 15.10). Rarely, the abscess may open up into the nasal cavity forming an internal fistula.

Complications

These include:

Acute conjunctivitis,

Corneal abraision which may be converted to corneal ulceration,

Lid abscess,

Osteomyelitis of lacrimal bone,

Orbital cellulitis,

Facial cellulitis and acute ethmoiditis.

Rarely cavernous sinus thrombosis and very rarely generalized septicaemia may also develop.

Treatment

1.During cellulitis stage. It consists of systemic and topical antibiotics to control infection; and systemic anti-inflammatory analgesic drugs and hot fomentation to relieve pain and swelling.

2.During stage of lacrimal abscess. In addition to the above treatment when pus starts pointing on the skin, it should be drained with a small incision. The pus should be gently squeezed out, the dressing done with betadine soaked roll gauze.

Later on depending upon condition of the lacrimal sac either DCT or DCR operation should be carried out, otherwise recurrence will occur.

3.Treatment of external lacrimal fistula. After controlling the acute infection with systemic antibiotics, fistulectomy along with DCT or DCR operation should be performed.

Fig. 15.9. Acute dacryocystitis: Stage of lacrimal abscess.

Fig. 15.10. Acute dacryocystitis: Stage of external lacrimal fistula.

SURGICAL TECHNIQUE OF DACRYOCYSTORHINOSTOMY

Dacryocystorhinostomy (DCR) operation can be performed by two techniques:

Conventional external approach DCR, and

Endonasal DCR

Conventional external approach DCR (Fig. 15.11)

1.Anaesthesia. General anaesthesia is preferred, however, it may be performed with local infiltration anaesthesia in adults.

2.Skin incision. Either a curved incision along the anterior lacrimal crest or a straight incision 8 mm medial to the medial canthus is made.

3.Exposure of medial palpebral ligament (MPL) and Anterior lacrimal crest. MPL is exposed by blunt dissection and cut with scissors to expose the anterior lacrimal crest.

4.Dissection of lacrimal sac. Periosteum is separated from the anterior lacrimal crest and along with the lacrimal sac is reflected laterally with blunt dissection exposing the lacrimal fossa.

5.Exposure of nasal mucosa. A 15 mm × 10 mm bony osteum is made by removing the anterior lacrimal crest and the bones forming lacrimal fossa, exposing the thick pinkish white nasal mucosa.

6.Preparation of flaps of sac. A probe is introduced into the sac through lower canaliculus and the sac is incised vertically. To prepare anterior and posterior flaps, this incision is converted into H shape.

7.Fashioning of nasal mucosal flaps. is also done by vertical incision converted into H shape.

8.Suturing of flaps. Posterior flap of the nasal mucosa is sutured with posterior flap of the sac using 6-0 vicryl or chromic cat gut sutures. It is followed by suturing of the anterior flaps.

9.Closure. MPL is sutured to periosteum, orbicularis muscle is sutured with 6-0 vicryl and skin is closed with 6-0 silk sutures.

Endonasal DCR

Presently many eye surgeons, alone or in collaboration with the ENT surgeons, are pereferring endonasal DCR over conventional external approach DCR because of its advantages (described below). surgical steps of endonasal DCR are (Fig. 15.12):

1. Preparation and anaesthesia. Nasal mucosa is prepared for 15-30 minutes before operation with nasal

decongestant drops and local anaesthetic agent. Conjunctival sac is anaesthetised with topically instilled 2% lignocaine. Then 3 ml of lignocaine 2% with 1 in 2 lac adrenaline is injected into the medial parts of upper and lower eyelids and via subcaruncular injection to the lacrimal fossa region.

2. Identification of sac area. A 20-gauge light pipe is inserted via the upper canaliculi into the sac. With the

help of endoscope, the sac area which is transilluminated by the light pipe is identified (Fig. 15.12A) and a further injection of lignocaine with adrenaline is made below the nasal mucosa in this area.

3. Creation of opening in the nasal mucosa, bones forming the lacrimal fossa and posteromedial wall of sac can be accomplished by two techniques:

i By cutting the tissues with appropriate instruments or

iiBy ablating with Holmium YAG laser (endoscopic laser assited DCR).

Note: The size of opening is about 12 mm × 10 mm (Fig. 15.12B).

4.Stenting of rhinostomy opening. The outflow system is then stented using fine silicone tubes passed via the superior and inferior canaliculi into the rhinostomy and secured with a process of knotting (Fig. 15.12C). Nasal packing and dressing is done.

5.Postoperative care and removal of sialistic lacrimal stents. After 24 hours of operation nasal packs are removed and patient is advised to use decongestent, antibiotic and steroid nasal drops for 3-4 weeks. The sialistic lacrimal stents are removed 8-

12weeks after surgery and the nasal drops are continued further for 2-3 weeks.

Advantages and disadvantages of endoscopic DCR vis-a-vis external DCR

Advantages and disadvantages of endoscopic DCR vis-a-vis external DCR are summerized in Table 15.1.

SURGICAL TECHNIQUE OF

DACRYOCYSTECTOMY (DCT)

1 to 4 steps are same as for external DCR operation.

5.Removal of lacrimal sac. After exposing the sac, it is separated from the surrounding structures by blunt dissection followed by cutting its connections with the lacrimal canaliculi. It is then held with artery forceps and twisted 3-4 times to tear it away from the nasolacrimal duct (NLD).

6.Curettage of bony NLD. It is done with the help of a lacrimal curette to remove the infected parts of membranous NLD.

7.Closure. It is done as for external DCR (Step 9).

SWELLINGS OF THE

LACRIMAL GLAND

DACRYOADENITIS

Dacryoadenitis may be acute or chronic.

I. Acute dacryoadenitis

Etiology. It may develop as a primary inflammation of the gland or secondary to some local or systemic

infection. Dacryoadenitis secondary to local infections occurs in trauma, erysipelas of the face, conjunctivitis (especially gonococcal and staphylococcal) and orbital cellulitis. Dacryoadenitis secondary to systemic infections is associated with mumps, influenza, infectious mononucleosis and measles.

Clinical picture. Acute inflammation of the palpebral part is characterised by a painful swelling in the lateral part of the upper lid. The lid becomes red and swollen with a typical S-shaped curve of its margin (Fig. 15.13). Acute orbital dacryoadenitis produces some painful proptosis in which the eyeball moves down and in.A fistula in the upper and lateral quadrant of the upper lid may develop as a complication of suppurative dacryoadenitis.

Table 15.1: Advantages and disadvantages of endonasal DCR vis-a-vis external DCR

Fig. 15.13. A patient with bilateral dacryoadenitis: note, s-shaped curve of upper eyelid.

Treatment. It consists of a course of appropriate systemic antibiotic, analgesic and anti-inflammatory drugs along with hot fomentation. When pus is formed, incision and drainage should be carried out.

II. Chronic dacryoadenitis

It is characterised by engorgement and simple hypertrophy of the gland.

Etiology. Chronic dacryoadenitis may occur: (i) as sequelae to acute inflammation; (ii) in association with chronic inflammations of conjunctiva and; (iii) due to systemic diseases such as tuberculosis, syphilis and sarcoidosis.

Clinical features. These include (i) a painless swelling in upper and outer part of lid associated with ptosis; (ii) eyeball may be displaced down and in; and (iii) diplopia may occur in up and out gaze.

On palpation, a firm lobulated mobile mass may be felt under the upper and outer rim of the orbit.

Differential diagnosis from other causes of lacrimal gland swellings is best made after fine needle aspiration biopsy or incisional biopsy.

Treatment consists of treating the cause.

MIKULICZ’S SYNDROME

It is characterised by bilaterally symmetrical enlargement of the lacrimal and salivary glands associated with a variety of systemic diseases. These include: leukaemias, lymphosarcomas, benign lymphoid hyperplasia, Hodgkin’s disease, sarcoidosis and tuberculosis.

DACRYOPES

TUMOURS OF THE LACRIMAL GLAND

These are not so common and in a simplified way can be classified as below:

1.Lymphoid tumours and inflammatory pseudotumours. These constitute approximately 50 percent of cases.

2.Benign epithelial tumours. These include ‘benign mixed tumours’ which account for 25 percent cases.

3.Malignant epithelial tumours. These also constitute 25 percent of cases and include: malignant mixed tumour, adenoid cystic carcinoma, mucoepidermoid carcinoma and adenocarcinoma.

Benign mixed tumour

It is also known as pleomorphic adenoma and occurs predominantly in young adult males.

Clinically it presents as a slowly progressive painless swelling in the upper-outer quadrant of the orbit displacing the eyeball downwards and outwards (Fig. 15.14). It is locally invasive and may infiltrate its own pseudocapsule to involve the adjacent periosteum. Histologically, it is characterised by presence of pleomorphic myxomatous tissue, just like benign mixed tumour of salivary gland.

Treatment consists of complete surgical removal with the capsule. Recurrences are very common following incomplete removal.

Malignant mixed tumour

It occurs in the older age group as compared to the benign mixed tumour. It presents as a painful swelling of short duration. Histologically, areas resembling benign mixed tumour are seen along with the adenocarcinomatous areas.

It is a cystic swelling, which occurs due to retention of lacrimal secretions following blockage of the lacrimal ducts.

Fig. 15.14. Down and out displacement of right eyeball in a patient with benign mixed tumour.

APPLIED ANATOMY

BONY ORBIT

The bony orbits are quadrangular truncated pyramids situated between the anterior cranial fossa above and the maxillary sinuses below (Fig. 16.1). Each orbit is about 40 mm in height, width and depth and is formed by portions of seven bones : (1) frontal, (2) maxilla,

(3) zygomatic, (4) sphenoid, (5) palatine, (6) ethmoid and (7) lacrimal. It has four walls (medial, lateral, superior and inferior), base and an apex.

The medial walls of two orbits are parallel to each other and, being thinnest, are frequently fractured during injuries as well as during orbitotomy operations and, it also accounts for ethmoiditis being the commonest cause of orbital cellulitis.

The inferior orbital wall (floor) is triangular in shape and being quite thin is commonly involved in blowout fractures and is easily invaded by tumours of the maxillary antrum.

The lateral wall of the orbit is triangular in shape. It covers only posterior half of the eyeball. Therefore, palpation of the retrobulbar tumours is easier from this side. Because of its advantageous anatomical position, a surgical approach to the orbit by lateral orbitotomy is popular.

The roof is triangular in shape and is formed mainly by the orbital plate of frontal bone.

Base of the orbit is the anterior open end of the orbit. It is bounded by thick orbital margins.

The orbital apex (Fig. 16.2). It is the posterior end of orbit. Here the four orbital walls converge. It has two orifices, the optic canal which transmits optic nerve and ophthalmic artery and the superior orbital fissure which transmits a number of nerves, arteries and veins (Fig. 13.2).

ORBITAL FASCIA

It is a thin connective tissue membrane lining various intraorbital structures. Though, it is one continuous tissue, but for the descriptive convenience it has been

divided into fascia bulbi, muscular sheaths, intermuscular septa, membranous expansions of the extraocular muscles and ligament of Lockwood. Fascia bulbi (Tenon’s capsule) envelops the globe from the margins of cornea to the optic nerve. Its lower part is thickened to form a sling or hammock on which the globe rests; this is called ‘suspensory ligament of Lockwood’.

CONTENTS OF THE ORBIT

The volume of each orbit is about 30 cc. Approximately one-fifth of it is occupied by the eyeball. Other contents of the orbit include: part of optic nerve, extraocular muscles, lacrimal gland, lacrimal sac, ophthalmic artery and its branches, third, fourth and sixth cranial nerves and ophthalmic and maxillary divisions of the fifth cranial nerve, sympathetic nerve, orbital fat and fascia.

SURGICAL SPACES IN THE ORBIT

These are of importance as most orbital pathologies tend to remain in the space in which they are formed. Therefore, their knowledge helps the surgeon in choosing the most direct surgical approach. Each orbit is divisible into four surgical spaces (Fig. 16.3).

1.The subperiosteal space. This is a potential space between the bone and the periorbita (periosteum).

2.The peripheral space. It is bounded peripherally by the periorbita and internally by the four recti with thin intermuscular septa. Tumours present here produce eccentric proptosis and can usually be palpated. For peribulbar anaesthesia, injection is made in this space.

3.The central space. It is also called muscular cone or retrobulbar space. It is bounded anteriorly by the Tenon’s capsule lining back of the eyeball and peripherally by the four recti muscles and their intermuscular septa in the anterior part. In the posterior part, it becomes continuous with the peripheral space. Tumours lying here usually produce axial proptosis. Retrobulbar injections are made in this space.

4.Tenon’s space. It is a potential space around the eyeball between the sclera and Tenon’s capsule.

PROPTOSIS

It is defined as forward displacement of the eyeball beyond the orbital margins. Though the word exophthalmos (out eye) is synonymous with it; but somehow it has become customary to use the term exophthalmos for the displacement associated with thyroid disease.

CLASSIFICATION

Proptosis can be divided into following clinical groups:

Unilateral proptosis

Bilateral proptosis

Acute proptosis

Intermittent proptosis

Pulsating proptosis

ETIOLOGY

Important causes of proptosis in each clinical group are listed here:

A. Causes of unilateral proptosis include:

1.Congenital conditions. These include: dermoid cyst, congenital cystic eyeball, and orbital teratoma.

2.Traumatic lesions. These are: orbital haemorrhage, retained intraorbital foreign body, traumatic aneurysm and emphysema of the orbit.

3.Inflammatory lesions. Acute inflammations are orbital cellulitis, abscess, thrombophlebitis, panophthalmitis, and cavernous sinus thrombosis (proptosis is initially unilateral but ultimately becomes bilateral). Chronic inflammatory lesions include: pseudotumours, tuberculoma, gumma and sarcoidosis.

4.Circulatory disturbances and vascular lesions.

These are: angioneurotic oedema, orbital varix and aneurysms.

5.Cysts of orbit. These include: haematic cyst, implantation cyst and parasitic cyst (hydatid cyst and cysticercus cellulosae).

6.Tumours of the orbit. These can be primary, secondary or metastatic.

7.Mucoceles of paranasal sinuses, especially frontal (most common), ethmoidal and maxillary sinus are common causes of unilateral proptosis.