<prompt> Most common cause of proptosis in adults is ?Orbital cellulitisThyroid OphthalmopathyCarotico - cavernous fistulaTrauma  <response>: Ans. is b i.e., Thyroid Ophthalmopathy The most common cause of unilateral proptosis in children is orbital cellulitis. The most common cause of unilateral proptosis in adults is thyroid ophthalmopathy. 