Definition of orbital cellulitis : 

Definition : Orbital cellulitis is purulent inflammation of the soft tissues of the orbit.

Age : Occur at any age but is more common in children.

Symptoms of orbital cellulitis :

1. Sudden onset of unilateral severe pain & swelling of the lids.
2. Diplopia.
3. Lacrimation
4. Photophobia.
5. Impairment of vision lately
6. Frequently associated with fever.
7. Severe malaise.
8. Unilateral, tender, warm and red periorbital oedema.
9. Proptosis.
10. Lid swelling
11. Painful ophthalmoplegia.
12. Optic nerve dysfunction
13. Impaired pupillary light reaction.

Causes of orbital cellulitis :

1. Sinusitis : Most commonly ethmoidal. This is the commonest cause.
2. Extension of pre-septal cellulitis through the orbital septum.
3. Thrombophlebitis: From a focus in the adjacent skin.
4. Local spread : From adjacent dacryocystitis, and mild facial or dental infection.
5. Haematogenous spread.
6. Post-traumatic : Penetrating orbital injury.
7. Post-operative : May complicate retinal, lacrimal or orbital surgery.
8. Causative organisms :

• Streptococcus pneumoniae.
• Staphylococcus aureus.
• Streptococcus pyogens.
• Haemophilus influenzae in children under 5 years of age.

Investigations of cellulitis :

1. White cell count.
2. Blood culture.
3. Nasal & conjunctival swab culture.
4. X-ray PNS.
5. CT scan of orbit, sinuses and brain to see intracranial spread & it shows pre-septal and orbital opacification.
6. Lumbar puncture and CSF study.

Treatment of cellulitis :

.Immediate hospital admission.

.Antimicrobial therapy:

• Inj. Ceftazidime 1gm 8 hourly and oral metronidazole 500 mg 8 hourly.
• Alternative treatment is intravenous vancomycin.
• Therapy should be continued until the patient is apyrexial for 4 days.

.Monitoring of optic nerve function : Every 4 hours by testing pupillary reactions,  visual acuity, color vision and light brightness appreciation.

.Hot compress & analgesics to relieve pain.

.Surgical intervention : Should be considered in the following circumstances-

• Unresponsiveness to antibiotics.
• Decreasing vision.
• Orbital or subperiosteal abscess.
• Atypical picture, which may merit a biopsy.

Surgery :

1. Drainage of the orbital abscess.
2. Incision & drainage of the lid abscess.
3. In most cases, it is necessary to drain the infected sinuses as well.

Complications of orbital cellulitis :

1) Subsides completely with prompt treatment.

2) Subperiosteal abscess.

3) Orbital abscess.

4) Ocular complications :

• Exposure keratopathy.
• Raised intraocular pressure.
• Occlusion of the central retinal artery or vein.
• Endophthalmitis.
• Optic neuropathy.
• Blindness.

5) Intracranial complications :

• Meningitis
• Brain abscess.
• Cavernous sinus thrombosis.

Treat pre-septal cellulitis : 

Clinical presentation :

1. Acute periorbital swelling & redness.
2. Increased warmth & tenderness of the eyelids.
3. Conjunctival chemosis.
4. Sometimes, fever with leucocytosis.
5. A fluctuating mass signifies abscess formation.

Treatment :

• Hot compress
• Oral antibiotics
• Analgesics.
• Topical antibiotics.

Orbital tumours : 

Congenital : 

• Dermoid cyst.
• Teratoma.

Vascular :

• Capillary haemangioma.
• Cavernous haemangioma.
• Lymphangioma.

Neural : 

• Optic nerve Meningioma.
• Plexiform neurofibroma.
• Optic nerve Meningioma.
• Schwannoma.
• Neurofibroma.

Mesenchymal :

• Rhabdomyosarcoma.
• Fibrous histiocytoma.
• Osteoma.

Haemopoietic :

• Acute myeloid leukaemia
• Lymphoma.

Metastatic : 

• Neuroblastoma.
• Ewing sarcoma.
• Wilm’s tumour.
• Breast cancer.
• Prostate cancer.
• Lung cancer.