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B. Wang, K.J. Ciuffreda, D. Wong; Depth–of–Focus to Naturalistic Stimulation Across the Near Retinal Periphery . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2929.
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Purpose: Although the depth–of–focus (DOF) has been investigated separately in the foveal region and in the near retinal periphery, knowledge about their relative contribution to overall blur perception for more naturalistic stimuli remains unknown. In the present study, the DOF was assessed at the fovea and across the near retinal periphery as a function of pictorial target size. Methods: The total DOF was measured using a moderate contrast (∼40%), variably–sized pictorial target (garden scene) of 0.5, 1, 2, 3, 4, 5, 6, 7, and 8 degrees in radius centered about the fovea. Subjects were comprised of 10 visually–normal young adults. The psychophysical ascending method of limits was employed. The target was presented monocularly in a Badal optometer, with accommodation paralyzed and with full refractive correction in place. Results: The group mean total DOF progressively and significantly increased linearly from 1.46 D for the 0.5 degree target to 2.30 D for the 8 degree target, at a rate of 0.11 D/degree (y=0.11x+1.46). Based on the individual subject slope values, the subjects were divided into two subgroups: a predominantly foveally–driven (F only; y=0.05x+1.22) subgroup (slope<0.10) and a foveally + peripherally–driven (F+P; y=0.20x+1.83) subgroup (slope≥0.10). The subgroup slopes were significantly different from each other, as well as from zero. Conclusions: The DOF increased with the addition of blur stimulation across the near retinal periphery. The results implicated partial cone pooling of blur information, as well as influence from perceptual, attentional, and optical aspects. However, the subgroup response profiles suggested individual differences in the weighting of the near peripheral blur information at the retinal level and perhaps at higher–level areas of the visual system. The present findings should be incorporated into current models of accommodation having fixed DOF values, as target size will affect the DOF in many individuals. In addition, blur perception may be affected in patients with visual field scotomas in the fovea or near retinal periphery.
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