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M Weiss, A Seiderman, F Schaeffe; Accommodation to artificial ON-/OFF stimulation? . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1493.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To learn more about the visual cues for both accommodation and, perhaps, emmetropization, three artificially generated patterns were used to stimulate accommodation in humans. Methods: (1) A rectangular pattern was programmed (BorlandC 3.0 under DOS) with about 200 filled circles of random diameter (see figure). The temporal brightness profile of each of the circles had a saw-tooth-like shape to stimulate preferentially on- or off-channels. The phases between the luminance changes of each of the circles were random, the frequency was 0.5 Hz. (2) In addition, pattern (1) was low-pass filtered (defocused) and refocused at 0.5 Hz. (3) The size of pattern (1) changed size over time (looming). All three variables could be independently changed. Seven young subjects viewed the patterns monocularly on a computer monitor through a 0.5 mm pinhole pupil to eliminate accommodation feedback. Accommodation was continuously recorded in the fellow eye (covered with an IR filter), using the PowerRefractor. Results: Pattern (1) had to be presented after low pass filtering to produce a consistent and strong impression of motion in depth in all subjects (OFF-stimulus: approaching, ON-stimulus: departing) but it elucidated no significant accommodation response. (2) Addition of apparent defocus (increasing when the target appeared to approach) did not elucidate accommodation either. (3) Addition of looming induced prominent accommodation changes, but only in 2 of the 7 subjects. Conclusion: The accommodation response is very selective for true defocus and does not respond to depth changes that appear to take place during selective stimulation of ON- or OFF-channels. Only looming could produce accommodation in a few subjects, as previously reported by Kruger (ARVO 1997, #4555). View OriginalDownload SlideView OriginalDownload Slide
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