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- Venkataraman, Abinaya Priya, et al.
(författare)
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Peripheral resolution and contrast sensitivity : Effects of stimulus drift
- 2017
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Ingår i: Vision Research. - : Pergamon Press. - 0042-6989 .- 1878-5646. ; 133, s. 145-149
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Tidskriftsartikel (refereegranskat)abstract
- Optimal temporal modulation of the stimulus can improve foveal contrast sensitivity. This studyevaluates the characteristics oftheperipheral spatiotemporal contrast sensitivity function in normal-sighted subjects.The purpose is to identify a temporal modulation that can potentially improve the remaining peripheral visual function in subjects with central visual field loss. High contrast resolution cut-off for grating stimuli with four temporal frequencies (0, 5, 10 and 15 Hz drift) was first evaluated in the 10° nasal visual field.Resolution contrast sensitivity for all temporal frequencies was then measured at four spatial frequencies between 0.5 cycles per degree (cpd) and the measured stationary cut-off. All measurements were performed with eccentric optical correction. Similar to foveal vision, peripheral contrast sensitivity is highest for a combination of low spatial frequency and 5 to 10 Hz drift. At higher spatial frequencies, there was a decrease in contrast sensitivity with 15 Hz drift.Despitethis decrease, the resolution cut-off did not vary largely between the different temporal frequencies tested. Additional measurements of contrast sensitivity at 0.5 cpd and resolution cut-off for stationary (0 Hz) and 7.5 Hz stimuli performed at 10, 15, 20 and 25° in the nasal visual field also showed the same characteristics across eccentricities.
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| 2. |
- Venkataraman, Abinaya Priya, et al.
(författare)
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Role of parafovea in blur perception
- 2017
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Ingår i: Vision Research. - : Elsevier. - 0042-6989 .- 1878-5646. ; 138, s. 59-65
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Tidskriftsartikel (refereegranskat)abstract
- The blur experienced by our visual system is not uniform across the visual field. Additionally, lens designs with variable power profile such as contact lenses used in presbyopia correction and to control myopia progression create variable blur from the fovea to the periphery. The perceptual changes associated with varying blur profile across the visual field are unclear. We therefore measured the perceived neutral focus with images of different angular subtense (from 4° to 20°) and found that the amount of blur, for which focus is perceived as neutral, increases when the stimulus was extended to cover the parafovea. We also studied the changes in central perceived neutral focus after adaptation to images with similar magnitude of optical blur across the image or varying blur from center to the periphery. Altering the blur in the periphery had little or no effect on the shift of perceived neutral focus following adaptation to normal/blurred central images. These perceptual outcomes should be considered while designing bifocal optical solutions for myopia or presbyopia.
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