Lens internal curvature effects on age-related eye model and lens paradox

Giovanzana, Stefano; Evans, Tanya; Pierscionek, Barbara K.

doi:10.1364/boe.8.004827

Cited by 9 publications

(5 citation statements)

References 29 publications

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“…Although the refractive index of the crystalline lens centre does not change significantly with age (Augusteyn, 2010), the nucleus increases in size with age, causing the gradient between high and low refractive indices to become steeper (Jones et al, 2005;Kasthurirangan et al, 2008), however, the exact shape and location of the gradient remains equivocal (Pierscionek and Regini, 2012). More recently, the gradient index (GRIN) model has been proposed as the most accurate way to represent the crystalline lens with a lamellar, shell-like structure (Giovanzana et al, 2017).…”

Section: Anatomical Structure Of the Accommodative System With Ageingmentioning

confidence: 99%

Presbyopia: Effectiveness of correction strategies

Wolffsohn

Davies

2019

Progress in Retinal and Eye Research

232

178

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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: Anatomical Structure Of the Accommodative System With Ageingmentioning

confidence: 99%

Presbyopia: Effectiveness of correction strategies

Wolffsohn

Davies

2019

Progress in Retinal and Eye Research

232

178

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“…Thus later authors4, 5 developed new, simplified, eye models to make calculations easier to perform. In contrast, with the availability of computers to speed calculation, other more recent models have often included additional characteristics in order to achieve a better approximation to real eyes, such as: aspheric surfaces6, 7, 8, 9, 10, 11, 12; chromatic dispersion6, 9, 12; intraocular scattering 13 ; changes with accommodation3, 4, 6, 9, 11, 12, 14; and age 7, 11, 15, 16. In the last few years, information produced by new devices capable of taking numerous “ in vivo” clinical measurements of the optical parameters of real eyes has been used by some authors to develop further eye models based on statistical data for the ocular parameters 11, 12, 17, 18, 19…”

mentioning

confidence: 99%

Accommodation and age-dependent eye model based on in vivo measurements

Zapata-Díaz

Radhakrishnan

Charman

et al. 2019

Journal of Optometry

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“…In the human eye, the GRIN crystalline lens is a combination of radial and linear GRIN systems. The lens is a decreasing GRIN lens, and the refractive index is a function of the transverse ( y ) and longitudinal ( z ) positions, describing a transverse parabolic distribution 8 117. The transference of a GRIN lens will depend on the maximum and minimum refractive indices, age, lens thickness, radii of curvature of the lens and nucleus front- and back-surfaces, number of shells and the power chosen to represent the distribution of the GRIN across a normalised distance 8 117…”

Section: Discussion: Applicationsmentioning

confidence: 99%

“…The transference is easily obtained for schematic eyes, including the reduced eye, 12 Le Grand’s eye, 13 14 an astigmatic schematic eye 65 105 and an eye with a GRIN lens. 117 One important advantage of linear optics is modelling optical properties to aid understanding of clinical phenomena. For example, linear optics was used to illustrate chromatic aberrations in an astigmatic eye.…”

Section: Discussionmentioning

confidence: 99%

Linear optics of the eye and optical systems: a review of methods and applications

Evans

Rubin

2022

BMJ Open Ophth

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The purpose of this paper is to review the basic principles of linear optics. A paraxial optical system is represented by a symplectic matrix called the transference, with entries that represent the fundamental properties of a paraxial optical system. Such an optical system may have elements that are astigmatic and decentred or tilted. Nearly all the familiar optical properties of an optical system can be derived from the transference. The transference is readily obtainable, as shown, for Gaussian and astigmatic optical systems, including systems with elements that are decentred or tilted. Four special systems are described and used to obtain the commonly used optical properties including power, refractive compensation, vertex powers, neutralising powers, the generalised Prentice equation and change in vergence across an optical system. The use of linear optics in quantitative analysis and the consequences of symplecticity are discussed.A systematic review produced 84 relevant papers for inclusion in this review on optical properties of linear systems. Topics reviewed include various magnifications (transverse, angular, spectacle, instrument, aniseikonia, retinal blur), cardinal points and axes of the eye, chromatic aberrations, positioning and design of intraocular lenses, flipped, reversed and catadioptric systems and gradient indices. The optical properties are discussed briefly, with emphasis placed on results and their implications. Many of these optical properties have applications for vision science and eye surgery and some examples of using linear optics for quantitative analyses are mentioned.

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Lens internal curvature effects on age-related eye model and lens paradox

Cited by 9 publications

References 29 publications

Presbyopia: Effectiveness of correction strategies

Presbyopia: Effectiveness of correction strategies

Accommodation and age-dependent eye model based on in vivo measurements

Linear optics of the eye and optical systems: a review of methods and applications

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