Design and validity of a miniaturized open-field aberrometer

Bhatt, Uday; Sheppard, Amy L.; Shah, Sunil; Dua, Harmindar; Mihashi, Toshifumi; Yamaguchi, Tatsuo; Wolffsohn, James S.

doi:10.1016/j.jcrs.2012.08.052

Cited by 11 publications

(14 citation statements)

References 18 publications

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“…Only Magnetic Resonance Imaging avoids the distortions of the intervening media due to its physical properties (which are therefore difficult to accurately correct for) (Khan et al, 2018;Richdale et al, 2016; but this is of lower spatial and temporal resolution although higher tesla devices are becoming available (Stahnke et al, 2016). Direct accommodation assessment requires measurement of changes of the optics of the eye which can be achieved objectively through autorefractors (Win-Hall et al, 2010;Wolffsohn et al, 2011a) or aberrometers (Bhatt et al, 2013;Glasser et al, 2017;Perez-Merino et al, 2014).…”

Section: 5mentioning

confidence: 99%

Presbyopia: Effectiveness of correction strategies

Wolffsohn

Davies

2019

Progress in Retinal and Eye Research

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Presbyopia is a global problem affecting over a billion people worldwide. The prevalence of unmanaged presbyopia is as high as 50% of those over 50 years of age in developing world populations, due to a lack of awareness and accessibility to affordable treatment, and is even as high as 34% in developed countries. Definitions of presbyopia are inconsistent and varied, so we propose a redefinition that states "presbyopia occurs when the physiologically normal age-related reduction in the eye's focusing range reaches a point, when optimally corrected for distance vision, that the clarity of vision at near is insufficient to satisfy an individual's requirements". Strategies for correcting presbyopia include separate optical devices located in front of the visual system (reading glasses) or a change in the direction of gaze to view through optical zones of different optical powers (bifocal, trifocal or progressive addition spectacle lenses), monovision (with contact lenses, intraocular lenses, laser refractive surgery and corneal collagen shrinkage), simultaneous images (with contact lenses, intraocular lenses and corneal inlays), pinhole depth of focus expansion (with intraocular lenses, corneal inlays and pharmaceuticals), crystalline lens softening (with lasers or pharmaceuticals) or restored dynamics (with 'accommodating' intraocular lenses, scleral expansion techniques and ciliary muscle electrostimulation); these strategies may be applied differently to the two eyes to optimise the range of clear focus for an individual's task requirements and minimise adverse visual effects. However, none fully overcome presbyopia in all patients. While the restoration of natural accommodation or an equivalent remains elusive, guidance is given on presbyopic correction evaluation techniques.

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Section: 5mentioning

confidence: 99%

Presbyopia: Effectiveness of correction strategies

Wolffsohn

Davies

2019

Progress in Retinal and Eye Research

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217

178

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“…All subjective acuities were corrected for magnification effects associated with the lens power and back vertex distance [50]. Objective measurements of ocular aberrations (up to the 8th radial order of Zernike polynomials) and also pupil size at each level of defocus were acquired using the Aston open field Shack-Hartmann aberrometer [54], with participants viewing and reading the smallest visible letters from the 4 m distance logMAR chart (TestChart 2000Pro, Thomson Software Solutions, Hatfield, UK) through the instruments beam splitter (Figure 1). The letters were randomized between each presentation in order to reduce learning effect [49,50], with each correctly read letter scored as 0.02 logMAR; participants were encouraged to guess if unsure.…”

Section: Methodsmentioning

confidence: 99%

“…The letters were randomized between each presentation in order to reduce learning effect [49,50], with each correctly read letter scored as 0.02 logMAR; participants were encouraged to guess if unsure. A validation study comparing the Aston aberrometer with a conventional aberrometer found a mean difference of 0.02 D ± 0.49 D [95% confidence interval] in mean spherical equivalent (MSE) and excellent intrasession repeatability (MSE = 1.000, p < 0.001) [54]. Simultaneously with subjective vision assessment, the aberrometer captured aberrations centered on the pupil, and over the whole of the pupil area as well as pupil diameter at each level of set defocus.…”

Section: Methodsmentioning

confidence: 99%

Factors Influencing Pseudo-Accommodation—The Difference between Subjectively Reported Range of Clear Focus and Objectively Measured Accommodation Range

Dhallu

Sheppard

Drew

et al. 2019

Vision

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The key determinants of the range of clear focus in pre-presbyopes and their relative contributions to the difference between subjective range of focus and objective accommodation assessments have not been previously quantified. Fifty participants (aged 33.0 ± 6.4 years) underwent simultaneous monocular subjective (visual acuity measured with an electronic test-chart) and objective (dynamic accommodation measured with an Aston open-field aberrometer) defocus curve testing for lenses between +2.00 to −10.00 DS in +0.50 DS steps in a randomized order. Pupil diameter and ocular aberrations (converted to visual metrics normalized for pupil size) at each level of blur were measured. The difference between objective range over which the power of the crystalline lens changes and the subjective range of clear focus was quantified and the results modelled using pupil size, refractive error, tolerance to blur, and ocular aberrations. The subjective range of clear focus was principally accounted for by age (46.4%) and pupil size (19.3%). The objectively assessed accommodative range was also principally accounted for by age (27.6%) and pupil size (15.4%). Over one-quarter (26.0%) of the difference between objective accommodation and subjective range of clear focus was accounted for by age (14.0%) and spherical aberration at maximum accommodation (12.0%). There was no significant change in the objective accommodative response (F = 1.426, p = 0.229) or pupil size (F = 0.799, p = 0.554) of participants for levels of defocus above their amplitude of accommodation. Pre-presbyopes benefit from an increased subjective range of clear vision beyond their objective accommodation due in part to neural factors, resulting in a measured depth-of-focus of, on average, 1.0 D.

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“…The responses were measured with a custom-made, compact SHWA (Topcon Corporation and Aston University) which allowed us to determine the dynamic changes of accommodation, wavefront aberrations, pupillary size and shape simultaneously [25].…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Wavefront Aberrations and Pupillary Shapes Induced by Electrical Stimulation of Ciliary Nerve in Cats Measured with Compact Wavefront Aberrometer

et al. 2014

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To investigate the changes in the wavefront aberrations and pupillary shape in response to electrical stimulation of the branches of the ciliary nerves in cats. Seven eyes of seven cats were studied under general anesthesia. Trains of monophasic pulses (current, 0.1 to 1.0 mA; duration, 0.5 ms/phase; frequency, 5 to 40 Hz) were applied to the lateral or medial branch of the short ciliary nerve near the posterior pole of the eye. A pair of electrodes was hooked onto one or both branch of the short ciliary nerve. The electrodes were placed about 5 mm from the scleral surface. The wavefront aberrations were recorded continuously for 2 seconds before, 8 seconds during, and for 20 seconds after the electrical stimulation. The pupillary images were simultaneously recorded during the stimulation period. Both the wavefront aberrations and the pupillary images were obtained 10 times/sec with a custom-built wavefront aberrometer. The maximum accommodative amplitude was 1.19 diopters (D) produced by electrical stimulation of the short ciliary nerves. The latency of the accommodative changes was very short, and the accommodative level gradually increased up to 4 seconds and reached a plateau. When only one branch of the ciliary nerve was stimulated, the pupil dilated asymmetrically, and the oblique astigmatism and one of the asymmetrical wavefront terms was also altered. Our results showed that the wavefront aberrations and pupillary dilations can be measured simultaneously and serially with a compact wavefront aberrometer. The asymmetric pupil dilation and asymmetric changes of the wavefront aberrations suggest that each branch of the ciliary nerve innervates specific segments of the ciliary muscle and dilator muscle of the pupil.

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Design and validity of a miniaturized open-field aberrometer

Abstract: The new aberrometer gave valid, repeatable measurements of refractive error and HOAs over a large range. It can measure continuously, thus providing direct feedback on the optical status of the visual system to surgeons during intraocular lens implantation and corneal surgery.

Cited by 11 publications

References 18 publications

Presbyopia: Effectiveness of correction strategies

Presbyopia: Effectiveness of correction strategies

Factors Influencing Pseudo-Accommodation—The Difference between Subjectively Reported Range of Clear Focus and Objectively Measured Accommodation Range

Asymmetric Wavefront Aberrations and Pupillary Shapes Induced by Electrical Stimulation of Ciliary Nerve in Cats Measured with Compact Wavefront Aberrometer

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