Ординатура / Офтальмология / Английские материалы / Comprehensive Ophthalmology_Khurana_2007

B. Causes of bilateral proptosis include:

1.Developmental anomalies of the skull: craniofacial dysostosis e.g., oxycephaly (tower skull).

2.Osteopathies: Osteitis deformans, rickets and acromegaly.

3.Inflammatory conditions: Mikulicz’s syndrome and late stage of cavernous sinus thrombosis.

4.Endocrinal exophthalmos: It may be thyrotoxic or thyrotropic.

5.Tumours: These include symmetrical lymphoma or lymphosarcoma, secondaries from neuroblastoma, nephroblastoma, Ewing’s sarcoma and leukaemic infiltration.

6.Systemic diseases: Histiocytosis, systemic amyloidosis, xanthomatosis and Wegener’s granulomatosis.

C.Causes of acute proptosis. It develops with extreme rapidity (sudden onset). Its common causes are: orbital emphysema fracture of the medial orbital wall, orbital haemorrhage and rupture of ethmoidal mucocele.

D.Cause of intermittent proptosis. This type of proptosis appears and disappears of its own. Its common causes are: orbital varix, periodic orbital oedema, recurrent orbital haemorrhage and highly vascular tumours.

E.Causes of pulsating proptosis. It is caused by pulsating vascular lesions such as caroticocavernous fistula and saccular aneurysm of ophthalmic artery. Pulsating proptosis also occurs due to transmitted cerebral pulsations in conditions associated with deficient orbital roof. These include congenital meningocele or meningoencephalocele, neurofibromatosis and traumatic or operative hiatus.

Investigation of a case of proptosis

I. Clinical evaluation

(A)History. It should include: age of onset, nature of onset, duration, progression, chronology of orbital signs and symptoms and associated symptoms.

(B)Local examination. It should be carried out as follows:

1. Inspection. (i) To differentiate proptosis from pseudoproptosis which is seen in patients with buphthalmos, axial high myopia, retraction of upper lid and enophthalmos of the opposite eye;

(ii) to ascertain whether the proptosis is unilateral or bilateral; (iii) to note the shape of the skull; and (iv) to observe whether proptosis is axial or eccentric.

2.Palpation. It should be carried out for retrodisplacement of globe to know compressibility of the tumour, for orbital thrill, for any swelling around the eyeball, regional lymph nodes and orbital rim.

3.Auscultation. It is primarily of value in searching for abnormal vascular communications that generate a bruit, such as caroticocavernous fistula.

4.Transillumination. It is helpful in evaluating anterior orbital lesions.

5.Visual acuity. Orbital lesions may reduce visual acuity by three mechanisms: refractive changes due to pressure on back of the eyeball, optic nerve compression and exposure keratopathy.

6.Pupil reactions. The presence of Marcus Gunn pupil is suggestive of optic nerve compression.

7.Fundoscopy. It may reveal venous engorgement, haemorrhage, papilloedema and optic atrophy. Choroidal folds and opticociliary shunts may be seen in patients with meningiomas.

8.Ocular motility. It is restricted in thyroid ophthalmopathy, extensive tumour growths and neurological deficit.

9.Exophthalmometry. It measures protrusion of the apex of cornea from the outer orbital margin (with the eyes looking straight ahead). Normal values vary between 10 and 21 mm and are symmetrical in both eyes. A difference of more than 2 mm between the two eyes is considered significant. The simplest instrument to measure proptosis is

Luedde’s exophthalmometer (Fig. 16.4). However, the Hertel’s exophthalmometer (Fig. 16.5) is the most commonly used instrument. Its advantage is that it measures the two eyes simultaneously.

(C) Systemic examination. A thorough examination should be conducted to rule out systemic causes of proptosis such as thyrotoxicosis, histiocytosis, and primary tumours elsewhere in the body (secondaries in orbits). Otorhinolaryngological examination is necessary when the paranasal sinus or a nasopharyngeal mass apears to be a possible etiological factor.

Fig. 16.4. Luedde’s exophthalmometer.

Fig. 16.5. Hertel’s exophthalmometer.

II. Laboratory investigations

These should include:

Thyroid function tests,

Haematological studies (TLC, DLC, ESR, VDRL test),

Casoni’s test (to rule out hydatid cyst),

Stool examination for cysts and ova, and

Urine analysis for Bence Jones proteins for multiple myeloma.

III. Imaging Technique

(A) Non-invasive techniques

1.Plain X-rays. It is still the most frequently used initial radiological examination. Commonly required exposures are in the Caldwell view, the Water’s view, a lateral view and the Rhese view (for optic foramina). X-ray signs of orbital diseases include enlargement of orbital cavity, enlargement of optic foramina, calcification and hyperostosis.

2.Computed tomography scanning. It is very useful for determining the location and size of an orbital

mass. A combination of axial (CAT) and coronal (CCT) cuts enables a three-dimensional visualisation. CT scan is capable of visualising various structures like globe, extraocular muscles and optic nerves. Further, this technique is also useful in examining areas adjacent to the orbits such as orbital walls, cranial cavity, paranasal sinuses and nasal cavity. Its main disadvantage is the inability to distinguish between pathologically soft tissue masses which are radiologically isodense.

3.Ultrasonography. It is a non-radiational noninvasive, completely safe and extremely valuable initial scanning procedure for orbital lesions. In the diagnosis of orbital lesions, it is superior to CT scanning in actual tissue diagnosis and can usually differentiate between solid, cystic, infiltrative and spongy masses.

4.Magnetic resonance imaging (MRI). It is a major advance in the imaging techniques. It is very sensitive for detecting differences between normal and abnormal tissues and has excellent image resolution. The technique produces tomographic images which are superficially very similar to CT scan but rely on entirely different physical principles for their production.

(B) Invasive procedures

1.Orbital venography. It is required in patients who are clinically suspected of having orbital varix. It confirms the diagnosis and also outlines the size and extent of the anomaly which facilitates proper surgical planning.

2.Carotid angiography. It is now performed only in cases of pulsating exophthalmos and in those associated with a bruit or thrill. The principal role of carotid angiography in orbital diagnosis is to identify the location and extent of ophthalmic artery aneurysms, and the pathologic circulation associated with various arteriovenous communications along the ophthalmic artery– cavernous sinus complex. It is also useful to identify the feeding vessels prior to undertaking surgery in patients with vascular orbital tumours.

3.Radioisotope studies. These are, nowadays, sparingly employed. Radioisotope arteriography has been found useful in proptosis of vascular lesions. In this technique, sodium pertechnetate Tc 99 m is injected intravenously and its flow is visualised by a gamma scintillation camera.

IV. Histopathological studies

The exact diagnosis of many orbital lesions cannot be made without the help of histopathological studies which can be accomplished by following techniques:

1.Fine-needle aspiration biopsy (FNAB). It is a reliable, accurate (95%), quick and easy technique for cytodiagnosis in orbital tumours. The biopsy aspirate is obtained under direct vision in an obvious mass and under CT scan or ultrasonographic guidance in retrobulbar mass using a 23-gauge needle.

2.Incisional biopsy. Undoubtedly, for accurate tissue diagnosis a proper biopsy specimen at least 5 to 10 mm in length is required. However, the scope of incisional biopsy in the diagnosis of orbital tumours is not clearly defined. It may be undertaken along with frozen tissue study in infiltrative lesions which remain undiagnosed.

3.Excisional biopsy. It should always be preferred over incisional biopsy in orbital masses which are well encapsulated or circumscribed. It is performed by anterior orbitotomy for a mass in the anterior part of orbit and by lateral orbitotomy for a retrobulbar mass.

ENOPHTHALMOS

It is the inward displacement of the eyeball. About 50 percent cases of mild enophthalmos are misdiagnosed as having ipsilateral ptosis or contralateral proptosis.

Common causes are:

1.Congenital. Microphthalmos and maxillary hypoplasia.

2.Traumatic. Blow out fractures of floor of the orbit.

3.Post-inflammatory. Cicatrization of extraocular muscles as in the pseudotumour syndromes.

4.Paralytic enophthalmos. It is seen in Horner’s syndrome (due to paralysis of cervical sympathetics).

5.Atrophy of orbital contents. Senile atrophy of orbital fat, atrophy due to irradiation of malignant tumour, following cicatrizing metastatic carcinoma and due to scleroderma.

DEVELOPMENTAL ANOMALIES

OF THE ORBIT

Developmental anomalies of the orbit are commonly associated with abnormalities of skull and facial bones. They are frequently hereditary (autosomal dominant) in origin.

Ocular features of developmental orbital anomalies may be one or more of the following:

Proptosis,

Strabismus,

Papilloedema, and

Optic atrophy.

Details of such anomalies are beyond the scope of

the book. However, a few salient features of some anomalies are mentioned below:

Craniosynostosis

Craniosynostosis results from premature closure of one or more cranial sutures. Depending upon the suture involved craniosynostosis may be of following types:

Ocular features include:

1.Bilateral proptosis due to shallow orbits.

2.Strabismus—either esotropia or exotropia.

3.Papilloedema and/or optic atrophy.

Craniofacial dysostosis

Craniofacial dysostosis (Crouzon’s syndrome) refers to premature closure of all sutures (brachycephaly) associated with maxillary hyperplasia.

Ocular features include (1) Proptosis due to shallow orbits, (2) Divergent squint, (3) Hypertelorism i.e., widely separated eyeballs (increased interpupillary distance), and (4) optic atrophy.

Systemic features are: (1) mental retardation, (2) higharched palate, (3) irregular dentition, and (4) hooked (parrot beak) nose.

Mandibulofacial dysostosis

Mandibulofacial dysostosis (Treacher-Collin syndrome) refers to a condition resulting from hypoplasia of zygoma and mandible.

Ocular features include: (1) indistinct inferior orbital margin, (2) coloboma of the lower eyelid, and (3) antimongoloid slant.

Systemic features are: (1) macrostomia with higharched palate, (2) external ear deformity, and (3) birdlike face.

Median facial cleft syndrome

The main ocular features of this developmental anomaly are: (1) hypertelorism, (2) telecanthus and

(3) divergent squint; and main systemic features include: (1) cleft-nose, lip and palate, and (2) V-shaped frontal hair line (widow’s peak).

Oxycephaly-syndactyle (Apert’s syndrome)

Systemic features include: (1) tower skull with flat occiput, (2) mental retardation, (3) ventricular septal defect, (3) high arched palate, and (4) syndactyly of the fingers and toes.

Ocular features are: (1) hypertelorism—increased IPD,

(2) bilateral proptosis due to shallow orbits, (3) congenital ptosis, (4) antimongoloid slant, and (5) divergent squint.

Hypertelorism

It is a condition of widely separated eyeballs resulting from widely separated orbits and broad nasal bridge. Hypertelorism may occur de novo or as a part of various syndromes such as Apert’s syndrome, Crouzon’s syndrome and median facial cleft syndrome.

Ocular features of hypertelorism are: (1) increased interpupillary distance (IPD)—may be 85 mm (normally, average IPD in an adult is 60 mm),

(2) telecanthus, (3) divergent squint, (4) antimongoloid slant, and (5) optic atrophy may be associated in some cases due to narrow optic canal.

ORBITAL INFLAMMATIONS

CLASSIFICATION

(A) Acute orbital and related inflammations

1.Pre-septal cellulitis

2.Orbital cellulitis and intraorbital abscess

3.Orbital osteoperiostitis

4.Orbital thrombophlebitis

5.Tenonitis

6.Cavernous sinus thrombosis

(B) Chronic orbital inflammations

I.Specific inflammations

1.Tuberculosis

2.Syphilis

3.Actinomycosis

4.Mycotic infections e.g., mucormycosis

5.Parasitic infestations

II.Chronic non-specific inflammations

1.Idiopathic orbital inflammatory disease (Inflammatory pseudotumours)

2.Tolosa-Hunt syndrome

3.Chronic orbital periostitis

Salient features of some orbital inflammations of interest are described here.

PRESEPTAL CELLULITIS

Preseptal (or periorbital) cellulitis refers to infection of the subcutaneous tissues anterior to the orbital septum. Strictly speaking it is not an orbital disease but is included here under because the facial veins are valveless and preseptal cellulitis may spread posteriorly to produce orbital cellulitis.

Causes

Causative organisms are usually staphylococcus aureus or sreptococcus pyogenes.

Modes of intection. The organisms may invade the preseptal tissue by any of the following modes.

1.Exogenous infection may result following skin laceration or insect bites.

2.Extension from local infections such as from an acute hordeolum or acute dacryocystitis.

3.Endogenous infection may occur by haematogenous spread from remote infection of the middle ear or upper respiratory tract.

Clinical features

Preseptal cellulitis presents as inflammatory oedema of the eyelids and periorbital skin with no involvement of the orbit.Thus, Characteristic features are painful acute periorbital swelling, erythema and hyperaemia of the lids (Fig. 16.6). There may be associated fever and leukocytosis.

Fig. 16.6. Preseptal cellulitis.

Treatment

Consists of oral antibiotics and anti inflammatory drug, with close follow up care.

ORBITAL CELLULITIS AND INTRAORBITAL ABSCESS

Orbital cellulitis refers to an acute infection of the soft tissues of the orbit behind the orbital septum. Orbital cellulitis may or may not progress to a subperiosteal abscess or orbital abscess.

Etiology

Orbits may be infected by following modes:

1.Exogenous infection. It may result from penetrating injury especially when associated with retention of intraorbital foreign body, and following operations like evisceration, enucleation, dacryocystectomy and orbitotomy.

2.Extension of infection from neighbouring structures. These include paranasal sinuses, teeth, face, lids, intracranial cavity and intraorbital structures. It is the commonest mode of orbital infections.

3.Endogenous infection. It may rarely develop as metastatic infection from breast abscess, puerperal sepsis, thrombophlebitis of legs and septicaemia. Causative organisms. Those commonly involved are: Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus pyogenes and Haemophilus influenzae.

Pathology

system the protective agents are limited to local phagocytic elements provided by the orbital reticular tissue; (ii) due to tight compartments, the intraorbital pressure is raised which augments the virulence of infection causing early and extensive necrotic sloughing of the tissues; and (iii) as in most cases the infection spreads as thrombophlebitis from the surrounding structures, a rapid spread with extensive necrosis is the rule.

Clinical features

Symptoms include swelling and severe pain which is increased by movements of eye or pressure. Other associated symptoms may be fever, nausea, vomiting, prostrations and sometimes loss of vision.

Signs of orbital cellulitis (Fig. 16.7) are:

A marked swelling of lids characterised by woody hardness and redness.

A marked chemosis of conjunctiva, which may protrude and become desiccated or necrotic.

The eyeball is proptosed axially.

Frequently, there is mild to severe restriction of the ocular movements.

Fundus examination may show congestion of retinal veins and signs of papillitis or papilloedema.

Complications

These are quite common if not treated promptly.

1. Ocular complications are usually blinding and include exposure keratopathy, optic neuritis and central retinal artery occlusion.

2. Orbital complications are progression of orbital cellulitis into subperiosteal abscess and/or orbital abscess:

i.Subperiosteal abscess is collection of purulent material between the orbital bony wall and periosteum, most frequently located along the medial orbital wall. Clinically, subperiosteal abscess is suspected when clinical features of orbital cellulitis are associated with eccentric proptosis; but the diagnosis is confirmed by CT scan.

ii.Orbital abscess is collection of pus within the orbital soft tissue. Clinically it is suspected by signs of severe proptosis, marked chemosis,

complete ophthalmoplegia, and pus points below the conjunctiva, but is confirmed by CT scan.

3.Temporal or parotid abcsesses may occur due to spread of infection around the orbit.

4.Intracranial complications include cavernous sinus thrombosis, meningitis and brain abscesses.

5.General septicemia or pyaemia may occur eventually in few cases.

Investigations

1.Bacterial cultures should be performed from nasal and conjunctival swabs and blood samples.

2.Complete haemogram may reveal leukocytosis.

3.X-ray PNS to identify associated sinusitis.

4.Orbital ultrasonography to detect intra-orbital abscess.

5.CT scan and MRI are useful:

in differentiating between preseptal and postseptal cellulitis;

in detecting subperiosteal abscesses and orbital abscesses.

in detecting intracranial extension;

in deciding when and from where to drain an orbital abscess.

Treatment

1.Intensive antibiotic therapy to overcome the infection. After obtaining nasal, conjunctival and blood culture samples, intravenous antibiotics should be administered. For staphylococcal infections high doses of penicillinase-resistant antibiotic (e.g., oxacillin) combined with ampicillin should be given. To cover H. influenzae especially in children, chloramphenicol or clavulanic acid should also be added. Cefotaxime, ciprofloxacin or vancomycin may be used alternative to oxacillin and penicillin combination.

2.Analgesic and anti-inflammatory drugs are helpful in controlling pain and fever.

3.Surgical intervention. Its indications include unresponsiveness to antibiotics, decreasing vision and presence of an orbital or subperiosteal abscess.

Techniques

i.A free incision should be made into the abscess when it points under the skin or conjunctiva.

ii.Subperiosteal abscess is drained by a 2-3 cm curved incision in the upper medial aspect.

iii.In most cases it is necessary to drain both the orbit as well as the infected paranasal sinuses.

ORBITAL MUCORMYCOSIS

Etiology. It is a severe fungal infection of the orbit. The most common fungal genera causing phacomycosis are Mucor (mucormycosis) and Rhizopus. Infection usually begins in the sinuses and erodes into the orbital cavity. The organisms have a tendency to invade vessels and cause ischemic necrosis. A necrotizing reaction destroys muscles, bone and soft tissue, frequently without causing signs of orbital cellulitis.

Clinical features. The patients prone to such infections are diabetics and immuno-compromised such as those with renal failure, malignant tumours and those on antimetabolite or steroid therapy; so most of the patients are serously ill and present with

Pain and proptosis, and

Necrotic areas with black eschar formation may be seen on the mucosa of palate, turbinates and nasal septum and skin of eyelids (Fig. 16.8).

Complications. If not treated energetically, patient develops meningitis, brain abscess and dies within days to weeks.

Diagnosis is made clinically and confirmed by biopsy of the involved area and finding of nonseptate broad branching hyphae.

Treatment is often difficult and inadequate. Therefore, recurrences are common. Treatment includes:

correction of underlying disease, if possible;

surgical excision of the involved tissue; and

intravenous amphotericin B or other appropriate antifungal drug.

Fig. 16.8. Areas of black ischar and necrosis on the eyelids in a patient with rhino-orbital mucormycosis.

Exentration may be required in severe unresponsive cases.

ORBITAL PERIOSTITIS

Orbital periostitis, i.e., inflammation of the periorbita is not very common. It may rarely involve the surrounding bones producing orbital osteoperiostitis.

Etiology. It may result from injuries or as an extension of infection from the surrounding structures (similar to orbital cellulitis). Tubercular periostitis is known in children and syphilitic in adults.

Clinical picture. It may present in two forms:

1.Anterior orbital periostitis. It involves the orbital margin and is characterised by severe pain, tenderness and swelling of the inflamed area. Subperiosteal abscess, when formed, frequently bursts on the skin surface. Tubercular anterior orbital periostitis usually manifests as non-healing fistula.

2.Posterior (deep) periostitis. It is characterised by deep-seated orbital pain, mild to moderate proptosis and slight limitation of ocular movements. When the orbital apex is implicated in addition, the typical picture of ‘orbital apex syndrome’ is also produced. It is characterised by a triad of: (i) ophthalmoplegia due to paresis of third, fourth and sixth cranial nerves; (ii) anaesthesia in the region of supply of ophthalmic division of fifth nerve; and (iii) amaurosis due to involvement of optic nerve.

Treatment. It is on the lines of orbital cellulitis.

CAVERNOUS SINUS THROMBOSIS

Septic thrombosis of the cavernous sinus is a disastrous sequela, resulting from spread of sepsis travelling along its tributaries.

Communications of cavernous sinus and sources of infection (Fig. 16.9 A & B)

1.Anteriorly, the superior and inferior ophthalmic veins drain in the sinus. These veins receive blood from face, nose, paranasal sinuses and orbits, Therefore, infection to cavernous sinus may spread from infected facial wounds, eryseplas, squeezing of stye, furuncles, orbital cellulitis and sinusitis.

2.Posteriorly, the superior and inferior petrosal sinuses leave it to join the lateral sinus. Labyrinthine veins opening into the inferior petrosal sinuses bring infections from the middle ear. Mastoid emissary veins may spread infection from the mastoid air cells.

3.Superiorly, the cavernous sinus communicates with veins of the cerebrum and may be infected from meningitis and cerebral abscesses.

4.Inferiorly, the sinus communicates with pterygoid venous plexus.

5.Medially, the two cavernous sinuses are connected with each other by transverse sinuses which account for transfer of infection from one side to the other.

Clinical picture

Cavernous sinus thrombosis starts initially as a unilateral condition, which soon becomes bilateral in more than 50 percent of cases due to intercavernous communication. The condition is characterised by general and ocular features.

General features. Patient is seriously ill having high grade fever with rigors, vomiting and headache.

Ocular features. Patient develops:

Severe pain in the eye and forehead on the affected side.

Conjunctiva is swollen and congested.

Proptosis develops rapidly.

Palsy of third, fourth and sixth cranial nerves occurs frequently.

Oedema in mastoid region is a pathognomonic sign. It is due to back pressure in the mastoid emissary vein.

Fundus may be normal with unimpaired vision in early cases. In advanced cases, retinal veins show congestion and there may appear papilloedema.

Complications

At any stage, the hyperpyrexia and signs of meningitis or pulmonary infarction may precede death.

Differential diagnosis

The rapidly developing, acute inflammatory type of proptosis seen in cavernous sinus thrombosis needs

to be differentiated from orbital cellulitis and panophthalmitis as summarised in Table 16.1.

Treatment

1.Antibiotics are the sheet anchor of treatment. Massive doses of modern potent broad spectrum antibiotics should be injected intravenously.

2.Analgesics and anti-inflammatory drugs control pain and fever.

3.Anticoagulants’ role is controversial.

SPECIFIC CHRONIC ORBITAL INFLAMMATIONS

These include: foreign body granuloma, orbital sarcoidosis, orbital vasculitis, Wegener’s granulomatosis, specific granulomatous inflammation caused by tuberculosis, syphilis, fungi, viruses, parasites, leaking dermoid cyst, polyarteritis nodosa and so on. At one time or another all these conditions were diagnosed as pseudotumours.

IDIOPATHIC ORBITAL INFLAMMATORY DISEASE (PSEUDOTUMOURS)

The term ‘pseudotumour’ was coined for those conditions of the orbit which clinically presented as tumours but histopathologically proved to be chronic inflammations. However, recently, the use of this term has been restricted for an idiopathic localized inflammatory disease consisting principally of a lymphocytic infiltration associated with a polymorphonuclear cellular response and a fibrovascular tissue reaction that has a variable but self-limiting course. Presently, idiopathic orbital inflammatory disease (IOID) is a term being preferred to denote this condition.

Clinical features (Fig. 16.10): Pseudotumour can occur throughout the orbit from the region of lacrimal gland to the orbital apex and thus produce varied clinical presentations. The most commonly noted features are:

Fig. 16.10. Pseudotumour involving the right orbit.

Swelling or puffiness of the eyelids, proptosis, orbital pain, restricted ocular movements, diplopia, chemosis and redness.

Most cases are unilateral, although both sides may be involved occasionally.

The condition typically affects individuals between 40 and 50 years; however, age is no bar.

Spontaneous remissions after a few weeks are known in pseudotumour.

Recurrences are also common. In some patients severe prolonged inflammation may cause progressive fibrosis of the orbital tissues leading to a frozen orbit with visual impairment.