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M. J. Leys, J. O. Mali, J. V. Odom; Masking Effects of Laminar Flow on Heading Perception in Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3641.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate differences in the precision of masking of heading judgments by laminar flow stimuli in four groups of patients: normals aged 21-59 years, normals aged 60 years or more, Advanced AMD patients with 20/40 or better binocular best corrected visual acuity (BBCVA), and advanced AMD patients with 20/60 or worse BBCVA. In each group of AMD patients 13/15 had received antiVEGF in at least one eye.
Observers were seated 50 cm from a display that subtended 44.6 arc deg in the horizontal dimension. Pressing a mouse button began a 833 ms trial during an optic flow pattern of 100 white dots on a black background appeared. Seventy-five dots appeared at random locations and moved away from a focus of expansion (FOE). 25 dots moved across the screen. The observers’ pressed either the left or right mouse button to indicate if the FOE was to the right or left of a red line. An interleaved double staircase was employed to determine a threshold for the FOEs to the right and to the left of the center. Precision was ½ the difference of the thresholds. Bias was the average of the two thresholds. Observers repeated the judgments twice, once as the laminar flow moved from left to right and once when it moved from left to right.
Precision varied across groups (p < 0.0005), but not based on the direction of laminar flow (p > 0.10). Bias did not differ across groups (p > 0.10), but did differ depending on direction of laminar flow (p < 0.001). The mean precision was 3.56 for young normals, 4.53 for older normals, 5.94 for AMD patients with good BBCVA and 7.27 for AMD patients with poor BBCVA. AMD with poor BBCVA had elevated thresholds compared to both of the normal groups. Precision thresholds of the AMD group with good BBCVA were elevated compared to younger normals.
While laminar flow significantly impairs heading judgments of AMD patients with poor BBCVA, it does not impair the function of AMD patients with good BBCVA significantly more than the effects observed in older normal subjects.
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