<prompt> Most common cause of proptosis in adults isOrbital cellulitisThyroid ophthalmopathyCarotico-cavernous fistulaTrauma  <response>: Refer: AK Khurana Comprehensive Ophthalmology, 6th edition, pg no. 403 - 407The most common cause of unilateral proptosis in children is orbital cellulitisThe most common cause of unilateral proptosis in adults is thyroid ophthalmopathy 