Spherical aberration in relation to visual performance in contact lens wear

Pettersson, Anna; Mårtensson, L.; Salkic, Jasna; Unsbo, Peter; Brautaset, Rune

doi:10.1016/j.clae.2010.08.008

Cited by 18 publications

(10 citation statements)

References 24 publications

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“…Aberration measurements were done in a dark room and the subjects were covered with a dark cloth to get maximum pupil size without the use of dilation. For detailed description of the aberration method, see Lindskoog Pettersson et al [34,35]. Aberration measurements were taken to evaluate the change in spherical aberration (SA) induced by the lens.…”

Section: Aberration Measurementsmentioning

confidence: 99%

Accommodation in young adults wearing aspheric multifocal soft contact lenses

Pettersson

Ramsay

Lundström

et al. 2011

Journal of Modern Optics

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The aim of the present project was to investigate accommodative behavior in young adults and adolescents fitted with an aspheric multifocal (center distance) contact lens with focus on evaluating whether these lenses can be an alternative treatment for subjects in which a reduced level of blur and thereby accommodation in near vision is aimed at. Twenty normal subjects aged between 21 and 35 years participated in the study. Aberrometry was perfomed using a Zywave TM aberrometer, first on the uncorrected eyes of all subjects, and again while the subjects wore a multifocal contact lens with a þ1.00 add. A Shin-Nippon N Vision-K 5001 Autoref-Keratometer was used to measure accommodative response with two different refractive corrections: (1) habitual spectacle correction only, and (2) habitual correction and a aspheric multifocal (center distance) contact lens. Four hours of adaptation to the lens was allowed. The lag when wearing only the habitual spectacles was compared with the lag while wearing both the habitual spectacles and the aspheric multifocal contact lens. The mean lag of accommodation for the subject group was 0.85 D (AE0.57 SD) and 0.75 D (AE0.52 SD) without and with the multifocal lens, respectively. Statistical analyses showed no difference in lag (t ¼ 0.8479, p ¼ 0.407) with and without the lens. In conclusion, young normal subjects do not relax accommodation when fitted with aspheric multifocal center distance lenses when the addition is þ1.00. It is therefore unlikely that subjects with accommodative ability, in whom the treatment purpose is to reduce blur and thereby accommodation, can be effectively treated with such lenses.

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Section: Aberration Measurementsmentioning

confidence: 99%

Accommodation in young adults wearing aspheric multifocal soft contact lenses

Pettersson

Ramsay

Lundström

et al. 2011

Journal of Modern Optics

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“…[7][8][9][10][11][12] However, at scotopic light levels a myopic shift accompanied increasing pupil radius. 7 With the now routine control of SA levels of both intraocular lenses and contact lenses, sometimes adding negative SA, [13][14][15][16][17] sometimes removing SA, 13,15,18,19 and sometimes introducing large amounts of SA to achieve multifocality, 20,21 it is timely to examine the impact of SA manipulation on spherical refractions.…”

Section: Introductionmentioning

confidence: 99%

Influence of spherical aberration, stimulus spatial frequency, and pupil apodisation on subjective refractions

Bradley

Thibos

et al. 2014

Ophthalmic Physiologic Optic

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Purpose To test competing hypotheses (Stiles Crawford pupil apodising or superior imaging of high spatial frequencies by the central pupil) for the pupil size independence of subjective refractions in the presence of primary spherical aberration. Methods Subjective refractions were obtained with a variety of test stimuli (high contrast letters, urban cityscape, high and low spatial frequency gratings) while modulating pupil diameter, levels of primary spherical aberration and pupil apodisation. Subjective refractions were also obtained with low-pass and high-pass stimuli and using “darker” and “sharper” subjective criteria. Results Subjective refractions for stimuli containing high spatial frequencies focus a near paraxial region of the pupil and are affected only slightly by level of Seidel spherical aberration, degree of pupil apodisation and pupil diameter, and generally focused a radius of about 1 to 1.5 mm from the pupil centre. Low spatial frequency refractions focus a marginal region of the pupil, and are significantly affected by level of spherical aberration, amount of pupil apodisation, and pupil size. Clinical refractions that employ the “darker” or “sharper” subjective criteria bias the patient to use lower or higher spatial frequencies respectively. Conclusions In the presence of significant levels of spherical aberration, the pupil size independence of subjective refractions occurs with or without Stiles Crawford apodisation for refractions that optimise high spatial frequency content in the image. If low spatial frequencies are optimised by a subjective refraction, spherical refractive error varies with spherical aberration, pupil size, and level of apodisation. As light levels drop from photopic to scotopic, therefore, we expect a shift from pupil size independent to pupil size dependent subjective refractions. Emphasising a “sharper” criterion during subjective refractions will improve image quality for high spatial frequencies and generate pupil size independent refractions.

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“…1,32,45,46 There are also changes in 3rd-order aberrations 44 and SA and coma change as an eye accommodates. 8 Wavefront aberrations vary from an unaccommodated to an accommodated eye, and from subject to subject. Ocular accommodation plays a significant role in regulating WA within the eyes, thereby affecting the optical image quality.…”

Section: Ocular Accommodationmentioning

confidence: 99%

“…In most young populations, provided samples are large enough, HOA average out to almost zero (instances of positive SA in a sense neutralises those for negative SA), with minor mean amounts of positive SA (0.14 ± 0.1 µm) for a 6 mm pupil. 6,7,8,9 The positive spin-off to this small amount of SA is an increase in depth of field. In addition, in young, healthy eyes, corneal aberrations are almost totally compensated for by the internal aberrations of the eye.…”

Section: Introductionmentioning

confidence: 99%

A review of higher order aberrations of the human eye

Suliman

Rubin

2019

African Vision and Eye Health

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Background: This literature review is part of a research study for aberration-correcting soft contact lenses, where wavefront aberrometry was utilised.Aim: This study was conducted as part of a postgraduate research degree by the first author with particular relevance to spherical aberrations in relation to myopia and soft contact lenses, both aberration control and non-control types.Setting: This study reports on a literature review of higher order aberrations.Methods: A comprehensive review of various databases was performed, including PubMed and Google Scholar in terms of aberration control contact lenses and particular customised contact lenses for compensation of spherical aberration in myopia, was performed.Results: Wavefront sensing and Zernike polynomials are increasingly used in optometry and ophthalmology to quantify the wavefronts for an optical system such as the eye, using either lower order (LOA) or higher order aberrations (HOA). Although other mathematical methods are available, zero, 1st and 2nd orders of the Zernike polynomial expansion are LOA. Defocus ( 2 0 Z ) and astigmatism ( − and 2 2 2 2 Z Z ) are 2nd-order modes that usually can be corrected by clinicians using ordinary sphero-cylindrical compensations such as spectacle lenses. Until recently, only LOA were easily correctable by clinicians in optometry and ophthalmology. Higher order aberrations are those modes in the third radial order, n = 3 and higher, which in the past were not correctable. However, HOA contribute to only about 7% of retinal image quality and often go unnoticed by individuals, although in some instances, for example, with keratoconus or after refractive surgery, such aberrations can become more problematic. Today, new treatments are available via specially designed or customised (to an individual) rigid or soft contact lenses that are claimed to reduce or eliminate HOA such as spherical aberration ( 4 0 Z ). Conclusion:Although such specially designed or customised contact lenses have some effect on HOA, there are conflicting reports and so further investigation of this intriguing aspect remains necessary.

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Spherical aberration in relation to visual performance in contact lens wear

Cited by 18 publications

References 24 publications

Accommodation in young adults wearing aspheric multifocal soft contact lenses

Accommodation in young adults wearing aspheric multifocal soft contact lenses

Influence of spherical aberration, stimulus spatial frequency, and pupil apodisation on subjective refractions

A review of higher order aberrations of the human eye

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