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
A woman complains of coloured halos around lights in the evening, with nausea and vomiting, IOP is normal; Diagnosis is: 
Select and explain. 
A. Incipient stage glaucoma open angle, B. Prodromal stage, closed angle glaucoma, C. Migraine, D. Raised ICT
B: Prodromal stage, closed angle glaucoma
Answer: B: Prodromal stage, closed angle glaucoma 
Explanation: The patient in question presents with symptoms suggestive of glaucoma, but a normal IOP on examination. This is therefore most likely a case of Prodromal stage of Glaucoma. Ref: Concise Textbook Of Ophthalmology By Sharma, Page119 ; Clinical Ophthalmology By Kanski, 3rd Edition, Page 255 and 4th Edition, Page 213 ; Comprehensive Ophthalmology A K Khurana 4th Edition, Page 225