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
[{'content': 'A woman complains of coloured haloes around lights in the evening, with nausea and vomiting, IOP is normal Diagnosis is – \nSelect and explain. \nA. Incipent stage glaucoma open angle, B. Prodromal stage, closed angle glaucoma, C. Migraine, D. Cluster Headache', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Features of latent PACG (Prodromal stage) are :-\n\n\nShallow anterior chamber\nOccasionally complain of halos around light\nSometimes slight-haziness or blurring of vision\nNormal IOP\n\n\nIt is the only phase of glaucoma, where IOP pressure is normal at all the time. Whereas in incipient stage, there is recurrent elevation of IOP by predisposing factors like dim light.', 'role': 'assistant'}]