This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of orbit, Lids and lacrimal apparatus, Subject name: Ophthalmology
All the following signs could result from infection with in the right cavernous sinus except- 
Select and explain. 
A. Constricted pupil in response to light, B. Engorgement of the retinal veins upon ophthalmoscopic examination, C. Ptosis of the right eyelid, D. Right ophthalmoplegia
A: Constricted pupil in response to light
Answer: A: Constricted pupil in response to light 
Explanation: Cavernous sinus thrombosis *Patient develops severe pain in the eye and forehead of the involved side. *Conjunctiva is swollen and congested. *Proptosis *Ptosis (due to 3rd N.Palsy) *Dilated pupil (due to 3rd N involvement ) *Retinal veins shows congestion. *Papilloedema *Fundus may be normal Ref: Khurana 7th/e p.428