HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Anderson, A. J. Articles by McKendrick, A. M. Search for Related Content PubMed PubMed Citation Articles by Anderson, A. J. Articles by McKendrick, A. M.

Quantifying Adaptation and Fatigue Effects in Frequency Doubling Perimetry

From the Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia.

PURPOSE. The second eye tested in frequency doubling perimetry has higher thresholds (reduced sensitivity) than the first. The authors investigated how this "second-eye effect" evolves over time and studied systematic changes in threshold in the first eye.

METHODS. Thresholds were measured in four subjects for 5°-square, 0.5-cyc/deg sine wave gratings counterphase-flickered at 18 Hz, using a "method of a thousand staircases" to track changes in thresholds at 10-second intervals. Stimuli appeared in 1 of 5 interleaved horizontal locations. Subjects adapted binocularly (background, 45 cd/m²) for 5 minutes before performing a 5-minute test with one eye (the "first eye") followed immediately by the other (the "second eye"). These results were compared with baseline monocular thresholds measured over 3.5 minutes according to a conventional staircase procedure. In addition, two subjects repeated the main experiment with a translucent, rather than opaque, patch.

RESULTS. On average, second-eye thresholds were raised by 6 dB (0.3 log) at the beginning of the test and were reduced to 4 dB toward the end. Little change was observed in the magnitude of the second-eye effect as a function of eccentricity. A significant "first-eye effect" was also observed in which thresholds increased by approximately 2 dB as the first-eye test progressed. Translucent patching largely abolished first- and second-eye effects, indicating neither was the result of fatigue.

CONCLUSIONS. Steady adaptation in both eyes is important for obtaining stable perimetric thresholds. Unless appropriate tests are performed, the effects of adaptation could easily be mistaken for those of fatigue.

This article has been cited by other articles:

				R. E. Hogg and A. J. Anderson Appearance of the Frequency-Doubling Stimulus at Threshold Invest. Ophthalmol. Vis. Sci., March 1, 2009; 50(3): 1477 - 1482. [Abstract] [Full Text] [PDF]