Increasing negative spherical aberration with soft contact lenses improves high and low contrast visual acuity in young adults

Rae, Sheila; Allen, Peter M.; Radhakrishnan, Hema; Theagarayan, Baskar; Price, Holly; Sailaganathan, Ananth; Calver, Richard; O’Leary, Daniel J.

doi:10.1111/j.1475-1313.2009.00678.x

Cited by 18 publications

(11 citation statements)

References 56 publications

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“…It has been shown that power distribution across a soft contact lens' optical zone can affect visual performance, peripheral refraction and growth of the eye [4,5,21,[29][30][31][32][33]. Studies found bi-or multifocal contact lens wear to be effective treatments for progressing myopic children [8,34] with some contrary findings [13,14,35].…”

Section: Discussionmentioning

confidence: 96%

“…Many of these manufacturer's designs were based on a premise that negative spherical aberration in the optical zone would counteract the eye's natural spherical aberration and improve vision [29]. Regardless of the validity or otherwise of this hypothesis it is clear from the evidence that excessive peripheral optical negative power stimulated myopia in the growing eye and that manufacturers should rather design lenses that meet the Smith hypothesis by using decreased negative power in the peripheral part of the optical zone.…”

Section: Discussionmentioning

confidence: 98%

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Power profiles of single vision and multifocal soft contact lenses

Wagner¹,

Conrad²,

Bakaraju³

et al. 2015

Contact Lens and Anterior Eye

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 98%

Power profiles of single vision and multifocal soft contact lenses

Wagner¹,

Conrad²,

Bakaraju³

et al. 2015

Contact Lens and Anterior Eye

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“…Although the contribution of higher order aberrations on visual performance is generally small, negative spherical aberration has shown to improve high-and low-contrast visual acuity [6]. To our knowledge no studies have yet assessed whether single vision contact lens wearers can perceive visual differences when comparing commercially available contact lens designs.…”

Section: Introductionmentioning

confidence: 98%

Visual performance of single vision and multifocal contact lenses in non-presbyopic myopic eyes

Fedtke

Bakaraju

Ehrmann

et al. 2016

Contact Lens and Anterior Eye

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“…[13][14][15][16] Also, the level of SA varies approximately linearly with sphere power in spherically surfaced SCLs 2, 11 as predicted by geometrical optics. 17 In this study we employ two types of ShackHartmann wavefront aberrometers to measure the sphere power and SA of several common SCLs on the eye and in a wet cell.…”

mentioning

confidence: 94%

Comparing the Optical Properties of Soft Contact Lenses On and Off the Eye

Kollbaum¹,

Bradley²,

Thibos³

2013

Optometry and Vision Science

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Purpose-The purpose of the current study was to examine the on-and off-eye optical performance of two types of soft contact lenses (hydrogel and silicone hydrogel).Methods-The monochromatic aberrations (lambda = 850 nm) of contact lenses were measured on-eye using a clinical Shack-Hartmann ocular aberrometer. Additionally, we used an off-eye single-pass contact lens aberrometer (lambda = 540 nm) in which the soft contact lens was placed within a wet cell. Comparison of the lower and higher order aberrations measured with these two methods required compensation for different wavelengths and knowledge of the refractive index of the contact lens materials.Results-The measured on-eye sphere and spherical aberration values were generally similar to those measured off-eye and those specified by the lens manufacturers for both types of soft contact lenses. However, there were notable differences, especially for high plus-powered lenses, which typically exhibited lower sphere power on the eye than expected from the lens specifications and from the off-eye measured powers, both of which were almost identical. Longitudinal spherical aberration varied with lens power in the hydrogel lenses, as expected from geometrical optics theory. Longitudinal spherical aberration measurements on-and off-eye, however, deviated significantly from that expected of a thin lens with spherical surfaces due to surface asphericities. The difference between on-and off-eye optics can be modeled as a tear lens, or as relative lens thickness changes caused by lens flexure. Conclusions-The results of the current study reveal that the major difference between the oneye lens optics and the manufacturers' specifications are not due to lens errors, but due to eye-lens interactions, which could be either lens flexure or a tear lens forming behind the soft contact lens.Keywords contact lens; spherical aberration; aspheric; flexure; supplemental powerThe paraxial power of a thin lens is proportional to the difference in curvature of its front and back surfaces with a constant of proportionality equal to the difference in refractive index between the lens and surrounding material: P=(Δn)/(1/r 1 − 1/r 2 ). Likewise, a thin conforming soft contact lens (SCL) will change the refracting power of an eye by changing the curvature of the air/eye interface by the difference in curvature of its front and back surfaces. Because of this, the power of a thin SCL in air will approximate its refractive effect on the eye. 1, 2 These two values may not be identical, however, for a combination of several reasons. First, a SCL may fail to conform to the cornea creating an effective "tear Corresponding author: Pete Kollbaum, Indiana University, School of Optometry, 800 East Atwater Ave, Bloomington, IN 47405, kollbaum@indiana.edu. The authors have no financial interest in any of the products or instruments used in this study. lens" between the lens and cornea, as occurs with gas permeable lens fittings. 1,3,4 Second, the lens may change shape and relative thickness w...

show abstract

Increasing negative spherical aberration with soft contact lenses improves high and low contrast visual acuity in young adults

Abstract: Manipulation of spherical aberration, taking account of the participants' baseline level of aberration, can cause statistically significant improvements in high and low contrast distance visual acuity although these improvements are too small in magnitude to be of clinical significance.

Cited by 18 publications

References 56 publications

Power profiles of single vision and multifocal soft contact lenses

Power profiles of single vision and multifocal soft contact lenses

Visual performance of single vision and multifocal contact lenses in non-presbyopic myopic eyes

Comparing the Optical Properties of Soft Contact Lenses On and Off the Eye

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