Anatomy of the Orbit and Infections

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Questions and Answers

What is the primary function of the orbital septum in relation to orbital infections?

The orbital septum serves as a fibrous membrane that separates the orbital compartment from the preseptal compartment, helping to contain infections.

Identify two direct routes of infection spread to the orbits.

Infection can spread directly from the ethmoid sinus through the lamina papyracea or from the frontal and maxillary sinuses.

Explain the difference between preseptal cellulitis and orbital cellulitis.

Preseptal cellulitis occurs anterior to the orbital septum and is limited to the eyelids and periorbital structures, while orbital cellulitis occurs posterior to the septum and involves the soft tissue within the bony orbit.

What anatomical feature allows for the indirect spread of infection from cranial to midface structures?

The valveless venous drainage system with multiple anastomoses allows for indirect spread of infection. Signup and view all the answers

List one common etiology for cellulitis related to orbital infections.

One common etiology is the spread of infection from adjacent structures, such as the skin or sinuses. Signup and view all the answers

What is the primary cause of a chalazion and how does it differ from an external hordeolum?

A chalazion is caused by a blocked meibomian gland, whereas an external hordeolum is a localized abscess in an eyelash follicle. Signup and view all the answers

Describe the management strategies for a chalazion.

Management includes warm compresses, massage, excision, or steroid injection. Signup and view all the answers

What bacterium is primarily responsible for erysipelas and what are its characteristic features?

Erysipelas is usually caused by Group A Streptococcus and is characterized by intensely erythematous skin with sharply demarcated borders. Signup and view all the answers

Explain the self-propagating process related to blepharitis and its impact on eyelid swelling.

Blepharitis leads to impeded venous flow and lymphatic drainage, causing eyelid swelling and worsening the condition. Signup and view all the answers

How can lid margin cleansing and low-dose oral doxycycline contribute to the prevention of chalazia?

Lid margin cleansing removes debris that can block glands, while low-dose oral doxycycline may reduce inflammation. Signup and view all the answers

What is the most common etiology of a hordeolum?

Staphylococcus. Signup and view all the answers

What are the two types of hordeolum?

Internal and external. Signup and view all the answers

List two common symptoms of dacryocystitis.

Pain and swelling. Signup and view all the answers

What is the first-line treatment for herpes zoster dermatoblepharitis if identified within 72 hours?

Acyclovir. Signup and view all the answers

What imaging study is recommended for orbital celluitis when neurological signs are present?

Orbital CT. Signup and view all the answers

What are the systemic signs associated with orbital cellulitis?

Fever and leukocytosis. Signup and view all the answers

Which antibiotic regimen is often recommended for children with orbital cellulitis?

IV antibiotics. Signup and view all the answers

Name a non-infectious cause of orbital inflammatory disease.

Thyroid ophthalmopathy. Signup and view all the answers

What does the presence of proptosis indicate in a case of cellulitis?

Orbital involvement. Signup and view all the answers

Which patient population is particularly at risk for necrotizing infections such as those causing orbital cellulitis?

Diabetics and immunocompromised patients. Signup and view all the answers

What is a common feature distinguishing preseptal from orbital cellulitis?

Presence of proptosis. Signup and view all the answers

How should an abscess associated with preseptal cellulitis be managed?

Incised and drained. Signup and view all the answers

What is the primary treatment for preseptal cellulitis in adults?

Oral antibiotics. Signup and view all the answers

In children, what is the most common cause of preseptal cellulitis?

Underlying sinusitis. Signup and view all the answers

What is preseptal cellulitis and how does it differ from orbital cellulitis?

Preseptal cellulitis is an infection or inflammatory process of the eyelids and periorbital structures occurring anterior to the orbital septum, while orbital cellulitis occurs posterior to the orbital septum and involves the soft tissue within the bony orbit. Signup and view all the answers

What is the role of the orbital septum in relation to orbital infections?

The orbital septum is a fibrous membrane that separates the orbital compartment from the preseptal compartment, helping to contain infections within the preseptal area. Signup and view all the answers

Describe one route of direct spread of infection to the orbit.

One route of direct infection spread to the orbit occurs via the ethmoid sinus through the lamina papyracea. Signup and view all the answers

List one common cause of cellulitis related to orbital infections aside from spread from adjacent structures.

Direct inoculation following trauma is a common cause of cellulitis related to orbital infections. Signup and view all the answers

What anatomical boundary helps to define the area of preseptal cellulitis?

The orbital septum defines the anterior boundary of preseptal cellulitis, containing the infection within the eyelids and periorbital structures. Signup and view all the answers

What is a chalazion and how does it form?

A chalazion is a blocked meibomian gland resulting in an inflammatory nodule or cyst. Signup and view all the answers

What are the management strategies for a chalazion?

Management includes warm compresses, massage, excision, or steroid injection. Signup and view all the answers

Describe the appearance and characteristics of erysipelas.

Erysipelas presents as intensely erythematous skin with sharply demarcated borders, usually caused by Group A Streptococcus. Signup and view all the answers

What is the difference between an external hordeolum and an internal hordeolum?

An external hordeolum is a localized abscess of the eyelash follicle, while an internal hordeolum is an acute bacterial infection of the meibomian glands. Signup and view all the answers

How does blepharitis lead to eyelid swelling?

Blepharitis impedes venous flow and lymphatic drainage, resulting in a self-propagating process of eyelid swelling. Signup and view all the answers

What symptoms typically characterize a hordeolum?

A hordeolum is typically characterized by pain and swelling in the eyelid. Signup and view all the answers

What is the most common bacteria associated with dacryocystitis?

Gram-positive bacteria, especially Staphylococcus aureus and Streptococcus pneumoniae, are most common. Signup and view all the answers

What is the primary treatment for herpes zoster dermatoblepharitis?

The primary treatment is antivirals, such as acyclovir, if identified within 72 hours. Signup and view all the answers

How can preseptal cellulitis be differentiated from orbital cellulitis?

Preseptal cellulitis lacks proptosis and typically has normal vision, while orbital cellulitis presents with proptosis and vision impairment. Signup and view all the answers

What immediate management is recommended for preseptal cellulitis in children under one year old?

Children under one year old should be hospitalized and treated with intravenous antibiotics. Signup and view all the answers

What are the typical ocular signs associated with orbital cellulitis?

Typical signs include proptosis, motility disturbance, and chemosis. Signup and view all the answers

Why is it important to culture in cases of preseptal cellulitis?

Culturing is important to identify the causative organism, especially after traumatic insults. Signup and view all the answers

What role do warm compresses play in the management of dacryocystitis?

Warm compresses help alleviate pain and promote drainage. Signup and view all the answers

What might indicate a need for imaging in preseptal cellulitis?

Imaging is needed if the source of infection is not determined or if the patient is not responding quickly to treatment. Signup and view all the answers

What is the most typical cause of preseptal cellulitis in children?

The most common cause is underlying sinusitis. Signup and view all the answers

What is the characteristic skin manifestation of herpes zoster dermatoblepharitis?

It typically presents as a vesicular rash in the V1 distribution. Signup and view all the answers

What are the systemic signs that may indicate orbital cellulitis?

Systemic signs often include severe symptoms like fever and leukocytosis. Signup and view all the answers

What is often the main reason for the high incidence of orbital cellulitis in children?

Orbital cellulitis in children is often related to extensions of sinus disease. Signup and view all the answers

What are common non-infectious causes of orbital inflammatory disease?

Common non-infectious causes include thyroid ophthalmopathy and orbital pseudotumor. Signup and view all the answers

Study Notes

Anatomy of the Orbit

The orbital septum is a fibrous membrane that separates the orbital from the preseptal compartment.
The upper eyelid extends from the periosteum of the orbital rim to the levator aponeurosis.
The lower eyelid extends from the periosteum of the orbital rim to the inferior border of the tarsal plate.

Routes of Infection Extension to Lids and Orbit

Indirect Spread: Venous drainage system shared by cranial and midface structures, with multiple anastomoses and a valveless system.
Direct Spread:
- Ethmoid sinus through lamina papyracea - Can be contained as a subperiosteal abscess or progress to orbital involvement.
- Frontal and maxillary sinus
- Orbital floor
- Odontogenic: Maxillary sinus --> Orbit

Preseptal Cellulitis

An infection or inflammatory process of the eyelids and periorbital structures.
Occurs anterior to and is contained by the orbital septum.

Orbital Cellulitis

Occurs posterior to the orbital septum
Involves the soft tissue within the bony orbit.

Cellulitis - Common Etiologies

Spread from adjacent structures: skin and sinuses.
Direct inoculation following trauma.
Bacterial spread from the upper respiratory tract or middle ear.

Preseptal Cellulitis - Associated Factors

Hordeola and chalazia
Impetigo/erysipelas
Blepharitis
Conjunctivitis
Canaliculitis
Dacryocystitis
Viral dermatitis – Herpes simplex & Herpes zoster

Chalazion

The most common inflammatory lesion of the eyelid.
Blocked Meibomian gland
Inflammatory nodule/cyst (Lipogranulomatous)
Not infectious
Typically not painful

Chalazion - Management

Warm compresses and massage
Excision/steroid injection

Chalazion - Prevention

Routine use of warm compresses
Lid margin cleansing
Low dose oral doxycycline

Erysipelas

Superficial cellulitis.
Usually caused by group A strep.
Intensely erythematous (red) with a sharply demarcated border.

Hordeolum

Bacterial infection of the Meibomian gland or ciliary glands (Zeiss or Moll)
Internal or external
Usually painful
Can lead to preseptal cellulitis

Hordeolum - Etiology

Staphylococcal infection (most common)

Hordeolum - Management

Systemic antibiotics
Lance/drain

Dacryocystitis

Pain, redness, and swelling below the medial canthal tendon.
Typically associated with blockage of the nasolacrimal system.
Tear stasis and retention --> Secondary bacterial infection.

Dacryocystitis - Management

Systemic antibiotics
Warm compresses
Drainage

Dacryocystitis - Bacterial Etiology

Gram Positive bacteria (most common)
Consider Gram negative in diabetics and immunocompromised patients.
IV antibiotics often necessary in severe cases or when associated with orbital cellulitis.

Herpes Zoster Dermatoblpehartitis

Recurrence or reactivation of Varicella Zoster virus.
Burning, stabbing pain of the forehead/scalp.
Vesicular rash in the V1 trigeminal nerve distribution.

Herpes Zoster Dermatoblpehartitis - Management

Antivirals (acyclovir or famciclovir) if identified within 72 hours of skin lesion onset.

Preseptal Cellulitis - Other Causes of Eyelid Swelling

Contact dermatitis (Thickened, erythematous, scaly skin)
Insect bites
Thyroid eye disease (Periorbital edema)
Dacryoadenitis (Inflammation of the lacrimal gland, superior temporal pain, swelling, erythema, 's' shape lid deformity)

Preseptal Cellulitis - Management

Typically treated outpatient with oral antibiotics.
All children under one year of age should be hospitalized with IV antibiotics.
Culture when able (more likely after traumatic insult)
Most common bacteria in adults: Staphylococcus aureus and Streptococcus pyogenes.
Most common bacteria in children: Haemophilus influenza type B and Streptococcus pneumonia.
If an abscess develops, it should be incised and drained.

Preseptal Cellulitis - Management in Teenagers and Adults

Usually arises from a superficial source (trauma, chalazion)
Treated with oral antibiotics
Commonly penicillinase-resistant penicillin or Bactrim
Imaging should be considered if:
- Source of infection is not determined.
- No quick response to treatment
- Orbital process is suspected.

Preseptal Cellulitis - Management in Children

Most common cause is underlying sinusitis
CT scan should be ordered quickly if no easily identifiable source of direct inoculation.
Hospitalization and IV antibiotics.

Orbital Cellulitis - Ophthalmic Signs

Proptosis (eye bulging)
Motility disturbance (limited eye movement)
Pronounced edema (swelling) and erythema (redness)
Impaired vision with afferent pupillary defect (APD)
Conjunctival chemosis (swelling) and hyperemia (redness)
Reduced corneal sensation

Orbital Cellulitis - Sources of Infection

Similar to Preseptal cellulitis
- Extension of sinus disease
- Penetrating trauma
- Infections in adjacent structures
Other less common sources:
- Scleral buckles, aqueous drainage devices, endophthalmitis

Orbital Cellulitis - Etiology

90% of all cases related to underlying sinus disease
Children: Usually single organism from sinus (S aureus or S pneumoniae)
Adolescents and Adults: More complex bacteriology, often 2-5 organisms.
Trauma: Gram-negative rods
Dental: Mixed, aggressive aerobes and anaerobes
Immunocompromised / Diabetics: Fungi

Orbital Cellulitis - Laboratory Studies

CBC (Complete Blood Count)
Blood cultures
Nasal swab (if purulent material is present)
Lumbar puncture if meningeal signs are present

Orbital Cellulitis - Imaging Studies

Orbital CT (Thin, axial, and coronal without contrast)
Include orbits, paranasal sinuses, frontal lobes
If neurologic involvement is present, include the head.

Orbital Cellulitis - Medical Management

Hospital admission for IV antibiotics
Cephalosporin I - ampicillin or pipercillin
Vancomycin for MRSA (Methicillin-Resistant Staphylococcus aureus)
Clindamycin for anaerobic coverage.
Nasal decongestants
Transition to oral antibiotics outpatient treatment for 1-3 weeks

Orbital Cellulitis - Surgical Management

If an orbital abscess is present
Early drainage of the involved sinus
If orbital signs are progressing

Orbital Cellulitis - Morbidity

Significant morbidity if not treated appropriately:
- Orbital apex syndrome
- Blindness
- Cavernous sinus thrombosis
- Cranial nerve palsies
- Meningitis
- Intracranial abscess

Differentiating Features of Cellulitis

Feature	Preseptal Cellulitis	Orbital Cellulitis
Proptosis	Absent	Present
Motility	Normal - Pain	Decreased + pain and double vision
Vision	Normal	Reduced
Pupillary Reaction	Normal	+/- APD
Chemosis	Rare	Common
Corneal Sensation	Normal	May be reduced
Systemic Signs	Absent/Mild	Commonly severe (Fever/Leukocytosis)

Orbital Cellulitis - Noninfectious Causes of Orbital Inflammatory Disease

Inflammatory and Autoimmune:
- Thyroid ophthalmopathy
- Orbital pseudotumor
- Lymphoma
- Dermatomyositis-Polymyositis
Vascular:
- Orbital venous malformation
- Cavernous sinus thrombosis
- Arteriovenous fistula
Neoplasms of orbit and lacrimal gland:
- Pediatric: Rhabdomyosarcoma, Leukemia, Metastatic Neuroblastoma, Retinoblastoma
- Adult: Lymphoma

Orbital Anatomy

The orbital septum is a fibrous membrane separating the orbital compartment from the preseptal compartment.
The upper eyelid extends from the periosteum of the orbital rim to the levator aponeurosis.
The lower eyelid extends from the periosteum of the orbital rim to the inferior border of the tarsal plate.

Routes of Infection to Lids and Orbit

Infections can spread indirectly through the venous drainage system which is shared between cranial and midface structures.
The venous system has multiple anastomoses and lacks valves.
Infections can spread directly through the ethmoid sinus via the lamina papyracea, frontal and maxillary sinus, orbital floor, and odontogenically through the maxillary sinus to the orbit.

Preseptal Cellulitis

Preseptal cellulitis is an infection or inflammatory process in the eyelids and periorbital structures.
Inflammation occurs anterior to and is contained by the orbital septum.

Orbital Cellulitis

Orbital cellulitis occurs posterior to the orbital septum.
Occurs within the bony orbit.

Cellulitis Etiologies

Infections commonly spread from adjacent structures (skin and sinuses).
Infections can result from direct inoculation following trauma.
Infections can occur via bacterial spread from the upper respiratory tract or middle ear.

Preseptal Cellulitis Associated Factors

Common preseptal cellulitis-associated factors include hordeola, chalazia, impetigo, erysipelas, blepharitis, conjunctivitis, canaliculitis, dacryocystitis, and viral dermatitis (herpes simplex and herpes zoster).

Chalazion

Chalazion is the most common inflammatory lesion of the eyelid.
It is caused by a blocked meibomian gland and results in an inflammatory nodule or cyst.
The lesion is lipogranulomatous.
Usually not infectious and typically not painful.

Chalazion Management

Chalazia are managed with warm compresses and massage.
Surgical excision or steroid injection may be used to treat a chalazion.

Chalazion Prevention

Routine use of warm compresses, lid margin cleansing, and low-dose oral doxycycline can help prevent chalazia.

Erysipelas

Erysipelas is a superficial cellulitis typically caused by group A streptococcus.
It is characterized by intense erythema with a sharply demarcated border.

Hordeolum

A hordeolum is a bacterial infection of the meibomian gland or ciliary glands (Zeiss or Moll).
Internal or external hordeola occur and are typically painful.
A hordeolum can progress to preseptal cellulitis.

Hordeolum Management

Staphylococcus is the most common causative organism.
Treatment includes systemic antibiotics.
Incision and drainage may be required.

Dacryocystitis

Dacryocystitis presents with pain, redness, and swelling below the medial canthal tendon.
It is typically associated with a blockage of the nasolacrimal system, tear stasis, and retention that results in secondary bacterial infection.

Dacryocystitis Management

Management includes systemic antibiotics, warm compresses, and drainage.
Oral antibiotics are used for treatment.
Gram-positive bacteria are the most common causative organisms.
Consider gram-negative organisms in diabetic or immunocompromised patients.
Patients with severe dacryocystitis or associated orbital cellulitis may require IV antibiotics.
Drainage of abscesses may be needed.

Herpes Zoster Dermatoblapharitis

This is caused by a reactivation of varicella zoster virus.
Presentation includes burning and stabbing pain in the forehead and scalp.
A vesicular rash occurs in the V1 distribution.

Herpes Zoster Dermatoblapharitis Management

Treatment with antivirals, such as acyclovir or cyclovir, is recommended if identified within 72 hours of skin lesion onset.

Preseptal Cellulitis Management

Preseptal cellulitis is typically treated outpatient with oral antibiotics.
All children younger than 1 year old should be hospitalized and treated with IV antibiotics.
Perform cultures when possible.
Most common bacteria involved for adults are Staphylococcus aureus and Streptococcus pyogenes.
Most common bacteria for children are Haemophilus influenzae type B and Streptococcus pneumoniae.
Incise and drain any abscesses that develop.

Preseptal Cellulitis Management in Teenagers and Adults

The most common cause of preseptal cellulitis in this age group is a superficial source, such as trauma or a chalazion.
Treatment with oral antibiotics, such as penicillinase-resistance penicillin or Bactrim is common.
Imaging is recommended if:
- The source of infection cannot be determined.
- The patient is not responding well to treatment.
- Orbital cellulitis is suspected.

Preseptal Cellulitis Management in Children

The most common cause of preseptal cellulitis in children is underlying sinusitis.
CT scans are recommended to identify the source of infection if no direct source is evident.
Hospitalization and IV antibiotics are required.

Orbital Cellulitis

Common ophthalmic signs include:
- Proptosis
- Motility disturbance
- Pronounced edema and erythema
- Impaired vision with an afferent pupil defect
- Conjunctival chemosis and hyperemia
- Reduced corneal sensation

Orbital Cellulitis Etiologies

Similar to preseptal cellulitis, causes can be:
- Extension of sinus disease
- Penetrating trauma
- Infection of adjacent structures
Additional, less common sources include:
- Scleral buckles
- Aqueous drainage devices
- Endophthalmitis

Orbital Cellulitis in Children

Greater than 90% of cases are related to underlying sinus disease.
Most children have a single organism from the sinus (usually Staphylococcus aureus or Streptococcus pneumoniae).

Orbital Cellulitis in Adolescents and Adults

Adolescents and adults have more complex infections, often with two to five causative organisms.
Gram-negative rods are more common with trauma.
Mixed, aggressive aerobes and anaerobes are commonly identified with dental sources .
Fungal infections are more likely in immunocompromised and diabetic patients.

Orbital Cellulitis Laboratory Studies

Run CBC and blood cultures.
Take nasal swabs for culture if purulent material is present.
Perform a lumbar puncture if meningeal signs exist.

Orbital Cellulitis Imaging Studies

Conduct an orbital CT scan.
Perform thin, axial, and coronal images without contrast.
Include the orbits, paranasal sinuses, and frontal lobes in the scan.
Include the head in the scan if neurologic involvement is suspected.

Orbital Cellulitis Medical Management

Admit patients for IV antibiotics.
Consider cephalosporin (I- generation), ampicillin, pipercillin, or vancomycin for MRSA coverage, and clindamycin for anaerobic coverage.
Prescribe nasal decongestants.
Transition to outpatient oral antibiotics for one to three weeks.

Orbital Cellulitis Surgical Management

Perform drainage of the infected sinus if an orbital abscess is present.
Consider surgical drainage if the orbital signs worsen.

Orbital Cellulitis Morbidity

If not treated appropriately, orbital cellulitis is associated with significant morbidity.
Potential complications include:
- Orbital apex syndrome
- Blindness
- Cavernous sinus thrombosis
- Cranial nerve palsies
- Meningitis
- Intracranial abscess

Differentiating Cellulitis Features

Feature	Preseptal Cellulitis	Orbital Cellulitis
Proptosis	Absent	Present
Motility	Normal (pain)	Decreased with pain and double vision
Vision	Normal	Reduced (check vision and color vision)
Pupillary Reaction	Normal	+/- APD (check swinging flashlight test)
Chemosis	Rare	Common
Corneal Sensation	Normal	May be reduced
Systemic Signs	Absent or mild	Commonly severe (fever/leukocytosis)

Non-Infectious Causes of Orbital Inflammatory Disease

Inflammatory and Autoimmune

Thyroid ophthalmopathy
Orbital pseudotumor
Lymphoma
Dermatomyositis-polymyositis

Vascular

Orbital venous malformation
Cavernous sinus thrombosis
Arteriovenous fistula

Neoplasms of Orbit and Lacrimal Gland

Pediatric: Rhabdomyosarcoma, leukemia, metastatic neuroblastoma, retinoblastoma
Adult: Lymphoma

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Description

This quiz covers the anatomy of the orbit, including the orbital septum, eyelid structures, and routes of infection that can affect the eyelids and orbit. Key topics include preseptal cellulitis and orbital cellulitis, highlighting the differences and implications of each condition.