Variability of Resolution Perimetry in Normals and Patients with Idiopathic Intracranial Hypertension

A problem with conventional automated perimetry (CAP) is the magnitude oftest-retest variability of disturbed visual fields. Large degrees of intertest variability have been reported by Heijl and colleagues in glaucoma patients especially in areas of low sensitivity. In fact, test points with loss of 8 to 18 db had a 95% prediction interval that included the full measurement spectrum ofthe perimeter.1 This is especially undesirable as the most important test loci for determining change (the areas of damage induced low sensitivity) are the ones with the highest variability. This has led Flammer to suggest with CAP, the first sign of a visual field defect may be an increase in variability.