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  • 1.
    Lewis, Peter
    et al.
    Linnaeus Univ, Dept Med & Optometry, Kalmar, Sweden..
    Venkataraman, Abinaya Priya
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Contrast Sensitivity in Eyes with Central Scotoma: Effect of Stimulus Drift2018In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 95, no 4, p. 354-361Article in journal (Refereed)
    Abstract [en]

    SIGNIFICANCE: In the field of visual rehabilitation of patients with central visual field loss (CFL), knowledge on how peripheral visual function can be improved is essential. This study presents measurements of peripheral dynamic contrast sensitivity (with optical correction) for off-axis viewing angles in subjects with CFL. PURPOSE: Subjects with CFL rely on a peripheral preferred retinal locus (PRL) for many visual tasks. It is therefore important to ascertain that contrast sensitivity (CS) is maximized in the PRL. This study evaluates the effect of stimulus motion, in combination with optical correction, on CS in subjects with CFL. METHODS: The off-axis refractive errors in the PRL of five young CFL subjects were measured with a COAS open-view Hartmann-Shack aberrometer. Low-contrast (25% and 10%) and high-contrast resolution acuity for stationary gratings was assessed with and without optical correction. High-contrast resolution was also measured for gratings drifting at 7.5 Hz (within a fixed Gaussian window). Furthermore, resolution CS was evaluated for both stationary and moving gratings with optical correction for a total of two to three spatial frequencies per subject. RESULTS: High-contrast resolution acuity was relatively insensitive to stimulus drift motion of 7.5 Hz, whereas CS for gratings of 0.5 cycles per degree improved with drift for all subjects. Furthermore, both high- and low-contrast static resolution improved with optical correction. CONCLUSIONS: Just as for healthy eyes, stimulus motion of 7.5 Hz enhances CS for gratings of low spatial frequency also in the PRL of eyes with CFL. Concurrently, high-contrast resolution is unaffected by the 7.5-Hz drift but improves with off-axis optical correction. This highlights the importance of providing optimal refractive correction for subjects with CFL and that stimulus motion can be used to further enhance CS at low spatial frequencies.

  • 2. Lewis, Peter
    et al.
    Venkataraman, Abinaya Priya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Optical correction and stimulus motion improve peripheral vision in eyes with central scotomaManuscript (preprint) (Other academic)
  • 3.
    Lundström, Linda
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Venkataraman, Abinaya Priya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lewis, Peter R.
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Spatiotemporal contrast sensitivity in the 10 degrees visual field2016In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 57, no 12Article in journal (Refereed)
  • 4.
    Rosén, Robert
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Venkataraman, Abinaya Priya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Winter, Simon
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Quick contrast sensitivity measurements in the periphery2014In: Journal of Vision, ISSN 1534-7362, E-ISSN 1534-7362, Vol. 14, no 8Article in journal (Refereed)
    Abstract [en]

    Measuring the contrast sensitivity function (CSF) in the periphery of the eye is complicated. The lengthy measurement time precludes all but the most determined subjects. The aim of this study was to implement and evaluate a faster routine based on the quick CSF method (qCSF) but adapted to work in the periphery. Additionally, normative data is presented on neurally limited peripheral CSFs. A peripheral qCSF measurement using 100 trials can be performed in 3 min. The precision and accuracy were tested for three subjects under different conditions (number of trials, peripheral angles, and optical corrections). The precision for estimates of contrast sensitivity at individual spatial frequencies was 0.07 log units when three qCSF measurements of 100 trials each were averaged. Accuracy was estimated by comparing the qCSF results with a more traditional measure of CSF. Average accuracy was 0.08 log units with no systematic error. In the second part of the study, we collected three CSFs of 100 trials for six persons in the 20 degrees nasal, temporal, inferior, and superior visual fields. The measurements were performed in an adaptive optics system running in a continuous closed loop. The Tukey HSD test showed significant differences (p < 0.05) between all fields except between the nasal and the temporal fields. Contrast sensitivity was higher in the horizontal fields, and the inferior field was better than the superior. This modified qCSF method decreases the measurement time significantly and allows otherwise unfeasible studies of the peripheral CSF.

  • 5.
    Rosén, Robert
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Venkataraman, Abinaya Priya
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Winter, Simon
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Quick measurements of contrast sensitivity in the peripheral visual field2014In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 55, no 13Article in journal (Other academic)
  • 6.
    Venkataraman, Abinaya Priya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vision Beyond the Fovea: Evaluation and Stimuli Properties2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This research is about evaluating vision in the periphery. Peripheral vision is of fundamental importance in the performance of our everyday activities. The aim of this thesis is to develop methods suitable for the evaluation of peripheral vision and to assess how different visual functions vary across the visual field. The results have application both within the field of visual rehabilitation of people with central visual field loss (CFL)and as well as in myopia research.

    All methods for assessing peripheral vision were implemented with adaptive psychophysical algorithms based on Bayesian statistics. A routine for time-efficient evaluation of peripheral contrast sensitivity was implemented and verified for measurements out to 30° in the visual field. Peripheral vision was evaluated for different properties of the stimuli: sharpness, motion, orientation, and extent. Optical quality was controlled using adaptive optics and/or corrective spectacles specially adapted for the peripheral viewing angle. We found that many peripheral visual functions improved with optical correction, especially in people with CFL. We also found improvements in peripheral contrast sensitivity for low spatial frequencies when stimuli drifted at 5 to 10 Hz; this applies both for people with normal vision and those with CFL. In the periphery, it is easier to see lines that are oriented parallel with respect to the visual field meridian. We have shown that this directional bias is present for both resolution and detection tasks in the periphery, even when the asymmetric optical errors are minimized. For accurate evaluation of peripheral vision, we therefore recommend using gratings that are oriented oblique to the visual  field meridian. The directional bias may have implications in how peripheral image quality affects myopia progression. Another proof that peripheral vision can influence central visual function is the fact that, when the stimulus extent was increased beyond the fovea, the blur in the stimulus was less noticeable.

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  • 7.
    Venkataraman, Abinaya Priya
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Lewis, Peter R.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Optical Correction and Stimulus Motion to Improve Vision in Eccentric Preferred Retinal Locus2016In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 57, no 12Article in journal (Refereed)
  • 8.
    Venkataraman, Abinaya Priya
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lewis, Peter
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Peripheral contrast sensitivity for drifting stimuliManuscript (preprint) (Other academic)
  • 9.
    Venkataraman, Abinaya Priya
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Winter, Simon
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. Royal Inst Technol, KTH, Biomed & Xray Phys, Stockholm, Sweden..
    Small and Large Field Blur Adaptation: Foveal and Peripheral Contrast Sensitivity Changes2014In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 55, no 13Article in journal (Other academic)
  • 10.
    Venkataraman, Abinaya Priya
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Papadogiannis, Petros
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Romashchenko, Dmitry
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Winter, Simon
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Peripheral resolution and contrast sensitivity: effects of monochromatic and chromatic aberrations2019In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 36, no 4, p. B52-B57Article in journal (Refereed)
    Abstract [en]

    Correction and manipulation of peripheral refractive errors are indispensable for people with central vision loss and in optical interventions for myopia control. This study investigates further enhancements of peripheral vision by compensating for monochromatic higher-order aberrations (with an adaptive optics system) and chromatic aberrations (with a narrowband green filter, 550 nm) in the 20 degrees nasal visual field. Both high-contrast detection cutoff and contrast sensitivity improved with optical correction. This improvement was most evident for gratings oriented perpendicular to the meridian due to asymmetric optical errors. When the natural monochromatic higher-order aberrations are large, resolution of 10% contrast oblique gratings can also be improved with correction of these errors. Though peripheral vision is mainly limited by refractive errors and neural factors, higher-order aberration correction beyond conventional refractive errors can still improve peripheral vision under certain circumstances.

  • 11.
    Venkataraman, Abinaya Priya
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Radhakrishnan, A.
    Dorronsoro, C.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Marcos, S.
    Role of parafovea in blur perception2017In: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 138, p. 59-65Article in journal (Refereed)
    Abstract [en]

    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.

  • 12.
    Venkataraman, Abinaya Priya
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Radhakrishnan, Aiswaryah
    Dorronsoro, Carlos
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Marcos, Susana
    Effect of parafovea on blur perceptionManuscript (preprint) (Other academic)
  • 13.
    Venkataraman, Abinaya Priya
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Winter, Simon
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Rosén, Robert
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Choice of grating orientation for evaluation of peripheral vision2016In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 93, no 6, p. 567-574Article in journal (Refereed)
    Abstract [en]

    Purpose: Peripheral resolution acuity depends on the orientation of the stimuli. However, it is uncertain if such a meridional effect also exists for peripheral detection tasks because they are affected by optical errors. Knowledge of the quantitative differences in acuity for different grating orientations is crucial for choosing the appropriate stimuli for evaluations of peripheral resolution and detection tasks. We assessed resolution and detection thresholds for different grating orientations in the peripheral visual field.

    Methods: Resolution and detection thresholds were evaluated for gratings of four different orientations in eight different visual field meridians in the 20-deg visual field in white light. Detection measurements in monochromatic light (543 nm; bandwidth, 10 nm) were also performed to evaluate the effects of chromatic aberration on the meridional effect. A combination of trial lenses and adaptive optics system was used to correct the monochromatic lower- and higher-order aberrations.

    Results: For both resolution and detection tasks, gratings parallel to the visual field meridian had better threshold compared with the perpendicular gratings, whereas the two oblique gratings had similar thresholds. The parallel and perpendicular grating acuity differences for resolution and detection tasks were 0.16 logMAR and 0.11 logMAD, respectively. Elimination of chromatic errors did not affect the meridional preference in detection acuity.

    Conclusions: Similar to peripheral resolution, detection also shows a meridional effect that appears to have a neural origin. The threshold difference seen for parallel and perpendicular gratings suggests the use of two oblique gratings as stimuli in alternative forced-choice procedures for peripheral vision evaluation to reduce measurement variation.

  • 14.
    Venkataraman, Abinaya Priya
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Winter, Simon
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Blur adaptation: Contrast sensitivity changes and stimulus extent2015In: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 110, no PA, p. 100-106Article in journal (Refereed)
    Abstract [en]

    A prolonged exposure to foveal defocus is well known to affect the visual functions in the fovea. However, the effects of peripheral blur adaptation on foveal vision, or vice versa, are still unclear. In this study, we therefore examined the changes in contrast sensitivity function from baseline, following blur adaptation to small as well as laterally extended stimuli in four subjects. The small field stimulus (7.5° visual field) was a 30. min video of forest scenery projected on a screen and the large field stimulus consisted of 7-tiles of the 7.5° stimulus stacked horizontally. Both stimuli were used for adaptation with optical blur (+2.00. D trial lens) as well as for clear control conditions. After small field blur adaptation foveal contrast sensitivity improved in the mid spatial frequency region. However, these changes neither spread to the periphery nor occurred for the large field blur adaptation. To conclude, visual performance after adaptation is dependent on the lateral extent of the adaptation stimulus.

  • 15.
    Winter, Simon
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Fathi, Mohammad Taghi
    Venkataraman, Abinaya Priya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Rosén, Robert
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Seidemann, Anne
    Esser, Gregor
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Effect of induced transverse chromatic aberration on peripheral vision2015In: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 32, no 10, p. 1764-1771Article in journal (Refereed)
    Abstract [en]

    Transverse chromatic aberration (TCA) is one of the largest optical errors affecting the peripheral image quality in the human eye. However, the effect of chromatic aberrations on our peripheral vision is largely unknown. This study investigates the effect of prism-induced horizontal TCA on vision, in the central as well as in the 20 degrees nasal visual field, for four subjects. Additionally, the magnitude of induced TCA (in minutes of arc) was measured subjectively in the fovea with a Vernier alignment method. During all measurements, the monochromatic optical errors of the eye were compensated for by adaptive optics. The average reduction in foveal grating resolution was about 0.032 +/- 0.005 logMAR/arcmin of TCA (mean +/- std). For peripheral grating detection, the reduction was 0.057 +/- 0.012 logMAR/arcmin. This means that the prismatic effect of highly dispersive spectacles may reduce the ability to detect objects in the peripheral visual field.

  • 16.
    Winter, Simon
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. Royal Inst Technol, Biomed & Xray Phys, Stockholm, Sweden..
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Fathi, Mohammad Taghi
    Rodenstock GmbH, Corp Res & Dev, Munich, Germany..
    Venkataraman, Abinaya Priya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Seidemann, Anne
    Rodenstock GmbH, Corp Res & Dev, Munich, Germany..
    Unsbo, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Horizontally induced transverse chromatic aberration reduces peripheral acuity2014In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 55, no 13Article in journal (Other academic)
1 - 16 of 16
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