<prompt> 19 year old young girl with previous history of repeated pain over medial canthus and chronic use of nasal decongestants, presented with abrupt onset of fever with chills rigor, diplopia on lateral gaze,moderate proptosis chemosis. On examination optic disc is congested. Most likely diagnosis isCavernous sinus thrombosisOrbital cellulitisAcute Ethmoidal sinusitisOrbital apex syndrome  <response>: It Stas initially as a unilateral condition which soon becomes bilateral due to intercavernous connection. It should be differentiated from orbital cellulitis and panophthalmitis. Ref: ak khurana 6th edition pg no412 