Eye Movements During Perimetry and the Effect that Fixational Instability Has on Perimetric Outcomes.
S Demirel, AJ Vingrys
J Glaucoma | Published : 1994
SUMMARY: Fixation of subjects is assumed to be stable during perimetry, although few studies have addressed the nature of fixation over prolonged test periods. In this study, the horizontal eye movements of 12 normal subjects were measured using an infrared eye monitor while they performed automated thresholds. Our results indicate that no observer can maintain steady fixation within +/-3 of the fixation marker for the entire period of a threshold test. Fixational instability in the order of +/-5 is found in all observers, whereas some show substantially greater fixation losses on occasion (up to 10-15). We also consider the effect that fixational losses have on perimetric outcomes by perfor..View full abstract