Cumulative defect (Bebie) curves for frequency-doubling technology perimetry

Purpose: Cumulative defect curves have been employed in conventional automated perimetry to permit the subjective classification of diffuse and localized visual field loss. The purpose of this investigation was to determine whether a similar procedure Could be developed for frequency-doubling technology (FDT) perimetry. Methods: FDT results from 407 normal subjects between the ages of 18 and 85 years were used to construct cumulative defect (Bebie) curves. After adjusting for the effects of normal aging (normalizing to an 'average' 45-year-old), total deviation values (deviation from the average normal sensitivity) were determined for the 19 stimulus locations of the N-30 full threshold program. The total deviation values were then rank-ordered from the best (most plus, least minus) to worst (least plus, most minus) values and the fifth and 95th percentiles were determined. Results: FDT cumulative defect (Bebie) curves for FDT are remarkably similar in form to those derived for conventional automated perimetry. Clinical examples are presented to illustrate how these curves can be employed to characterize normal, diffuse. localized and mixed visual field properties for FDT. Discussion: Cumulative defect (Bebie) curves for FDT are a useful means of distinguishing diffuse from localized visual field loss.