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Evaluating the peripheral optical effect of multifocal contact lenses
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
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2012 (English)In: Ophthalmic & physiological optics, ISSN 0275-5408, E-ISSN 1475-1313, Vol. 32, no 6, 527-534 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: Multifocal soft contact lenses have been used to decrease the progression of myopia, presumably by inducing relative peripheral myopia at the same time as the central image is focused on the fovea. The aim of this study was to investigate how the peripheral optical effect of commercially available multifocal soft contact lenses can be evaluated from objective wavefront measurements. Methods: Two multifocal lenses with high and low add and one monofocal design were measured over the ±40° horizontal field, using a scanning Hartmann-Shack wavefront sensor on four subjects. The effect on the refractive shift, the peripheral image quality, and the depth of field of the lenses was evaluated using the area under the modulation transfer function as the image quality metric. Results: The multifocal lenses with a centre distance design and 2 dioptres of add induced about 0.50 dioptre of relative peripheral myopia at 30° in the nasal visual field. For larger off-axis angles the border of the optical zone of the lenses severely degraded image quality. Moreover, these multifocal lenses also significantly reduced the image quality and increased the depth of field for angles as small as 10°-15° Conclusions: The proposed methodology showed that the tested multifocal soft contact lenses gave a very small peripheral myopic shift in these four subjects and that they would need a larger optical zone and a more controlled depth of field to explain a possible treatment effect on myopia progression.

Place, publisher, year, edition, pages
2012. Vol. 32, no 6, 527-534 p.
Keyword [en]
Defocus, Depth of field, Multifocal/bifocal/dual-focus contact lenses, Myopia, Peripheral wavefront aberrations
National Category
URN: urn:nbn:se:kth:diva-104947DOI: 10.1111/j.1475-1313.2012.00937.xISI: 000309747600012ScopusID: 2-s2.0-84867434065OAI: diva2:567908
Vinnova, VINNMER 2008-00992

QC 20121114

Available from: 2012-11-14 Created: 2012-11-14 Last updated: 2013-03-27Bibliographically approved
In thesis
1. Peripheral Vision: Adaptive Optics and Psychophysics
Open this publication in new window or tab >>Peripheral Vision: Adaptive Optics and Psychophysics
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is about our peripheral vision. Peripheral vision is poor compared to central vision, due to both neural and optical factors. The optical factors include astigmatism, defocus and higher order aberrations consisting mainly of coma. Neurally, the density of ganglion cells decreases towards the periphery, which limits the sampling density. The questions that this thesis attempts to answer are how much and under which circumstances correction of optical errors can improve peripheral vision. For this, an adaptive optics system has been constructed with a wavefront sensor and a deformable mirror working in closed loop to perform real-time correction of optical errors. To investigate vision, psychophysical routines utilizing Bayesian methods have been evaluated and modified for peripheral vision to handle the presence of aliasing, fixation instability and rapid fatigue.

We found that correcting both refractive errors and higher order aberrations improved peripheral low-contrast resolution acuity. \\

We looked at two specific topics in peripheral vision research in particular: Central visual field loss and myopia development. Persons with central visual field loss have to rely on their remaining peripheral vision, and it is of great interest to understand whether optical correction can offer them any benefits. In a case study on a single subject, we found meaningful improvements in vision with both optimized refractive correction as well as additional benefits with aberration correction. These improvements were larger than for comparable healthy subjects with a similar magnitude of aberrations. When it comes to myopia development, an interesting hypothesis is that peripheral optics affect and guide the emmetropization process. We have found an asymmetric depth of field in the periphery for myopic subjects, caused by their higher order aberrations, and presented a model on how this asymmetry may influence the emmetropization process.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. xiii, 72 p.
Trita-FYS, ISSN 0280-316X ; 2013:08
National Category
Other Physics Topics
urn:nbn:se:kth:diva-120077 (URN)978-91-7501-698-6 (ISBN)
Public defence
2013-04-19, Sal FD5, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)

QC 20130327

Available from: 2013-03-27 Created: 2013-03-27 Last updated: 2013-04-12Bibliographically approved

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Rosén, RobertUnsbo, PeterLundström, Linda
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