Normal aging effects for frequency doubling technology perimetry

Purpose. To determine the influence of normal aging on contrast sensitivity for frequency doubling technology (FDT) perimetry. Methods. Contrast sensitivity measures were obtained for frequency-doubled stimuli (0.25 cycles per degree sinusoidal gratings undergoing 25 Hz counterphase flicker) at 17 target locations (4 per quadrant plus the central 5 degrees) using a prototype of the Welch Allyn (Skaneateles, NY)/Humphrey Systems FDT perimeter (Humphrey Systems, Dublin, CA). A total of 407 normal subjects (761 eyes) between the ages of 15 and 85 years were tested. Results. Between the ages of 15 and 60 years there was an approximately linear decrease in contrast sensitivity of 0.6 dB per decade. After the age of 70, there was a slightly greater sensitivity loss with age. There were no meaningful differences in sensitivity loss as a function of age for different visual field locations. A small but consistent reduction in contrast sensitivity (approximately 0.7 dB) was found at all visual field locations for the second eye tested that may be due to a central adaptation process. Conclusions. Normal aging effects for FDT perimetry are similar to those obtained for conventional automated perimetry, except that the FDT perimetry aging effects do not appear to be eccentricity dependent. These normative data provide a basis for establishing a statistical analysis procedure and probability plots for FDT perimetry.