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Vision Beyond the Fovea: Evaluation and Stimuli Properties
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0002-2155-7030
2016 (English)Doctoral 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.

Abstract [sv]

Denna forskning handlar om att utvärdera synen i periferin. Vår perifera syn är ovärderlig i det dagliga livet. Målsättningen med denna avhandling är dels att utveckla metoder speciellt lämpade för perifer synutvärdering och dels att mäta hur olika synfunktioner varierar över synfältet. Resultaten har tillämpning både inom synrehabilitering för personer med centraltsynfältsbortfall och inom närsynthetsforskning.

Adaptiv psykofysisk metodologi baserad på Bayesiansk statistik användes vid all utvärdering av det perifera seendet. Vi implementerade en rutin för tidseffektiv mätning av perifer kontrastkänslighet och verifierade den ut till 30° i synfältet. Den perifera synen utvärderades för olika egenskaper hos objektet: skärpa, rörelse, riktning och utbredning. Skärpan kontrollerades med hjälp av adaptiv optik och/eller glasögonkorrektion speciellt anpassad för den perifera synvinkeln. Vi fann att många periferasynfunktioner förbättras av optisk korrektion, särskilt för personer med centralt synfältsbortfall. Vi hittade även förbättringar i periferkontrastkänslighet för låga ortsfrekvenser när objektet modulerades med hastigheter mellan 5 och 10 Hz, vilket gäller både normalseende och personer med centralt synfältsbortfall. I periferin är det lättare att se linjer som är orienterade parallellt med synfältsmeridianen. Vi har visat att denna riktningsbias gäller både för upplösning och detektion i periferin, även när de asymmetriska optiska felen minimeras. För bästa mätnoggrannhet rekommenderar vi därför att använda randmönster som ligger snett relativt synfältsmeridianen. Denna riktningsbias skulle även kunna påverka hur den perifera bildkvalitén inverkar på utvecklingen av närsynthet. Ytterligare ett bevis för att perifer syn kan påverka den centrala synfunktionen är att, när objektets utbredning ökades, uppfattade personen det som mindre suddigt.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. , 64 p.
Series
TRITA-FYS, ISSN 0280-316X ; 2016:57
Keyword [en]
Peripheral vision, Visual optics, Optical correction, Orientation, Stimulus extent, Moving stimulus, Contrast sensitivity, Visual acuity, Central vision loss, Myopia
National Category
Physical Sciences
Research subject
Biological Physics
Identifiers
URN: urn:nbn:se:kth:diva-191212ISBN: 978-91-7729-071-1OAI: oai:DiVA.org:kth-191212DiVA: diva2:955507
Public defence
2016-09-23, FB 42, Albanova University Center, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

QC 20160826

Available from: 2016-08-26 Created: 2016-08-25 Last updated: 2016-08-29Bibliographically approved
List of papers
1. Choice of grating orientation for evaluation of peripheral vision
Open this publication in new window or tab >>Choice of grating orientation for evaluation of peripheral vision
2016 (English)In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 93, no 6, 567-574 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Lippincott Williams & Wilkins, 2016
Keyword
grating orientation, peripheral vision, resolution, detection, meridional effect, psychophysics, forced-choice procedure
National Category
Ophthalmology
Identifiers
urn:nbn:se:kth:diva-186323 (URN)10.1097/OPX.0000000000000832 (DOI)000377852500003 ()26889822 (PubMedID)
Funder
Swedish Research Council, 621-2011-4094
Note

QC 20160511

Available from: 2016-05-10 Created: 2016-05-10 Last updated: 2016-08-25Bibliographically approved
2. Peripheral contrast sensitivity for drifting stimuli
Open this publication in new window or tab >>Peripheral contrast sensitivity for drifting stimuli
(English)Manuscript (preprint) (Other academic)
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-191197 (URN)
External cooperation:
Note

QC 20160826

Available from: 2016-08-25 Created: 2016-08-25 Last updated: 2016-08-26Bibliographically approved
3. Optical correction and stimulus motion improve peripheral vision in eyes with central scotoma
Open this publication in new window or tab >>Optical correction and stimulus motion improve peripheral vision in eyes with central scotoma
(English)Manuscript (preprint) (Other academic)
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-191201 (URN)
External cooperation:
Note

QC 20160826

Available from: 2016-08-25 Created: 2016-08-25 Last updated: 2016-08-26Bibliographically approved
4. Quick contrast sensitivity measurements in the periphery
Open this publication in new window or tab >>Quick contrast sensitivity measurements in the periphery
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2014 (English)In: Journal of Vision, ISSN 1534-7362, E-ISSN 1534-7362, Vol. 14, no 8Article in journal (Refereed) Published
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.

Keyword
peripheral vision, contrast sensitivity, adaptive optics, qCSF
National Category
Ophthalmology
Identifiers
urn:nbn:se:kth:diva-156464 (URN)10.1167/14.8.3 (DOI)000343878600003 ()2-s2.0-84904265976 (ScopusID)
Note

QC 20141128

Available from: 2014-11-28 Created: 2014-11-28 Last updated: 2016-08-25Bibliographically approved
5. Blur adaptation: Contrast sensitivity changes and stimulus extent
Open this publication in new window or tab >>Blur adaptation: Contrast sensitivity changes and stimulus extent
2015 (English)In: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 110, no PA, 100-106 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Adaptation, Contrast sensitivity, Optical defocus, Article, human, human experiment, normal human, optical blur, optics, priority journal, retina fovea, spatial frequency discrimination, visual acuity, visual adaptation, visual field, visual stimulation
National Category
Neurology
Identifiers
urn:nbn:se:kth:diva-167737 (URN)10.1016/j.visres.2015.03.009 (DOI)000354149100012 ()2-s2.0-84926320831 (ScopusID)
Funder
Swedish Research Council
Note

QC 20150601

Available from: 2015-06-01 Created: 2015-05-22 Last updated: 2016-08-25Bibliographically approved
6. Effect of parafovea on blur perception
Open this publication in new window or tab >>Effect of parafovea on blur perception
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-191202 (URN)
External cooperation:
Note

QC 20160826

Available from: 2016-08-25 Created: 2016-08-25 Last updated: 2016-08-26Bibliographically approved

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