<prompt> A woman complains of coloured haloes around lights in the evening, with nausea and vomiting, IOP is normal Diagnosis isIncipent stage glaucoma open angleProdromal stage, closed angle glaucomaMigraineCluster Headache  <response>: Features of latent PACG Prodromal stage are :-Shallow anterior chamberOccasionally complain of halos around lightSometimes slight-haziness or blurring of visionNormal IOPIt 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. 