A woman complains of coloured haloes around lights in the evening, with nausea and vomiting, IOP is normal Diagnosis is –
Features of latent PACG (Prodromal stage) are :-


Shallow anterior chamber
Occasionally complain of halos around light
Sometimes slight-haziness or blurring of vision
Normal IOP


It 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.
Incipent stage glaucoma open angle
Prodromal stage, closed angle glaucoma
Migraine
Cluster Headache