Chandler classification of orbital infections

Chandler classification is the most commonly used system for dividing the different types of orbital cellulitis. The system describes five stages :

• stage I: preseptal orbital cellulitis with inflammation and edema anterior to the orbital septum.
• stage II: orbital cellulitis with extension of the inflammation and edema beyond the orbital septum. 
• stage III: subperiosteal abscess beneath the periosteum of lamina papyracea.
• stage IV: orbital abscess and purulent collection within orbit. 
• stage V: cavernous sinus thrombosis after posterior extension of the infection through the superior ophthalmic veins.