Learning effects among perimetric novices in frequency doubling technology perimetry

To investigate learning effects, including improvements in reliability indices, in frequency doubling technology (FDT) perimetry in subjects without glaucoma who have not undergone previous automated perimetry.

Prospective consecutive case series.

Eighty-one normal subjects.

Normal subjects were recruited from the University of Washington Eye Clinic who had no history of automated visual field testing. All eyes underwent complete ophthalmic examination. The C-20-5 screening mode of FDT perimetry (Zeiss-Humphrey, San Leandro, CA) was performed after appropriate instruction, including a demonstration of the frequency doubling phenomenon. If any abnormal areas were identified or there were greater than 33% fixation losses or false-positive results, then the test was readministered up to three times or until a normal result was returned.

Normal FDT test.

The mean age was 54.8 years (range, 19-94). Sixty-nine subjects (85.2%) returned a normal test after a single test administration. Nine subjects (11.1%) required two administrations, and two subjects (2.5%) required three or more administrations to return a normal test. One subject still tested unreliably after four tests. The number or severity of abnormal locations did not predict the number of trials necessary to overcome learning effects. Fixation loss was the most common reliability problem. Subjects who demonstrated learning effects did not differ significantly in age, visual acuity, refraction, or test time from those who did not.

Some perimetric novices demonstrate learning effects in C-20-5 screening-mode FDT perimetry. Learning effects in FDT perimetry must be considered during screening for glaucoma or other ocular disease.