THRESHOLD VARIATION IN AUTOMATED PERIMETRY

A physiologic fluctuation in threshold levels exists in automated peri metry, which is greater in glaucoma and ocular hypertensive patients t han in normal subjects. Fluctuation increases with greater eccentricit y from fixation and in areas of reduced retinal sensitivity. Other fac tors related to automated perimetry testing potentially may influence threshold fluctuation including: a learning effect, reliability, pupil size, age, and the mode of stimulus presentation. Statistical softwar e may aid in analyzing both the single field and the changes between s uccessive fields. However, statistical programs cannot replace physici an judgment, and all factors that may influence threshold levels shoul d be considered when interpreting automated visual fields.