This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
All the following signs could result from infection within 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 

Source → Infection from nose, sinuses, orbits, ear or pharynx
Onset → Abrupt with high fever and chills and with signs of toxemia.
Cranial N involvement → III to VII
Ocular features


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)
Ophthalmegia (due to palsy of 3rd , 4th and 6th cranial N)
Dilated pupil (due to 3rd N involvement)
Retinal veins shows congestion
Papilloedema
Fundus may be normal