Predicting the performance of accommodating intraocular lenses using ray tracing

Ho, Arthur; Manns, Fabrice; Pham, Therese; Parel, Jean Marie

doi:10.1016/j.jcrs.2005.07.047

Cited by 21 publications

(29 citation statements)

References 32 publications

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“…In practice, both elements of the AIOL would translate during accommodation due to the various forces exerted by the ciliary body, zonules and capsule, as well as the hydraulic and mechanical resistance from the vitreous and iris (Crawford et al , 1990; Heatley et al , 2004). For simplicity, we adopted the same simplified conditions as employed in an earlier study (Ho et al , 2006). Hence, in this study: Configuration 1 comprised an AIOL with a mobile front element in which the back element is maintained in a fixed position; and Configuration 2 comprised an AIOL with a mobile back element where the front element remained fixed.…”

Section: Methodsmentioning

confidence: 99%

“…As employed in an earlier study (Ho et al , 2006), the introduction of the fixed-position reference planes to this model simplifies derivation of the paraxial formulae as it provides a fixed point of reference from which the position of either the front or back element of 2E-AIOL can be defined as a function of lens element translation.…”

Section: Methodsmentioning

confidence: 99%

“…To evaluate the performance of AIOLs, we employed an indicator derived previously (Ho et al , 2006) and defined accommodative performance (P k ) as the rate of change in vergence of the rays with translation of the mobile lens element. A large value represents greater amount of accommodation induced by a given amount of translation.…”

Section: Methodsmentioning

confidence: 99%

“…Studies which only consider existing or available designs would be limited in their scope of evaluation and may not identify the ultimate optimum design configuration. Similarly, studies which employ finite ray-tracing techniques (Nawa et al , 2003; Ho et al , 2006) would in practice, be limited to evaluate only selected design examples. Extrapolation of the findings from such studies risks losing validity.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the performance of accommodating IOLs using a paraxial optics analysis

Ale

Manns

2010

Ophthalmic and Physiological Optics

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Purpose We employed an analytical approach to evaluate the key parameters for the potential design optimisation of accommodating intra-ocular lenses (AIOL) and to use these parameters to predict their accommodative performance. Methods Paraxial thin-lens equations to predict the accommodative performances of single-element (1E) and two-element (2E) AIOLs were developed. 2E-AIOLs with either mobile front or back lens elements were analysed as well as 1E-AIOL for their accommodative performance. A paraxial model including key ocular components (corneal surfaces, pupil and retina) as well as AIOL was used to evaluate the key control parameters and optimal design configurations. A range of variants of the model, representing varying powers of front and back optical elements and with either front or back optical element mobile was tested. Results Optimal accommodative performance of 2E-AIOL is governed by the power combinations of its optical elements; design variants with higher positive front element power produced greater accommodative efficacy, while mobility of the front element contributed more to the accommodative performance than the back element. The performance of 1E-AIOL is primarily governed by the power of the AIOL; the higher the AIOL power, the better the accommodative performance. Conclusions From an accommodative performance standpoint, the optimal design of 2E-AIOL should comprise a high plus power front element. Considering the maximum potential amounts of element translation available clinically, 2E-AIOLs are predicted to offer higher accommodative performance compared to 1E-AIOL.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of the performance of accommodating IOLs using a paraxial optics analysis

Ale

Manns

2010

Ophthalmic and Physiological Optics

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“…30 Ho et al investigated accommodating IOLs using RRT. 31 There is also some literature regarding the actual calculation-beyond a simple analysis-of optical components, such as IOLs, employing RRT. [32][33][34][35][36][37][38][39][40] There are other published studies that are not directly IOL-or refractive-surgery-related; for instance, some studies used RRT for the analysis of schematic eyes.…”

Section: Introductionmentioning

confidence: 99%

The Individual Virtual Eye: a Computer Model for Advanced Intraocular Lens Calculation

Einighammer

Oltrup

Bende

et al. 2009

Journal of Optometry

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PURPOSE:To describe the individual virtual eye, a computer model of a human eye with respect to its optical properties. It is based on measurements of an individual person and one of its major application is calculating intraocular lenses (IOLs) for cataract surgery. METHODS: The model is constructed from an eye's geometry, including axial length and topographic measurements of the anterior corneal surface. All optical components of a pseudophakic eye are modeled with computer scientific methods. A spline-based interpolation method efficiently includes data from corneal topographic measurements. The geometrical optical properties, such as the wavefront aberration, are simulated with real ray-tracing using Snell's law. Optical components can be calculated using computer scientific optimization procedures. The geometry of customized aspheric IOLs was calculated for 32 eyes and the resulting wavefront aberration was investigated. RESULTS: The more complex the calculated IOL is, the lower the residual wavefront error is. Spherical IOLs are only able to correct for the defocus, while toric IOLs also eliminate astigmatism. Spherical aberration is additionally reduced by aspheric and toric aspheric IOLs. The efficient implementation of time-critical numerical ray-tracing and optimization procedures allows for short calculation times, which may lead to a practicable method integrated in some device. CONCLUSIONS: The individual virtual eye allows for simulations and calculations regarding geometrical optics for individual persons. This leads to clinical applications like IOL calculation, with the potential to overcome the limitations of those current calculation methods that are based on paraxial optics, exemplary shown by calculating customized aspheric IOLs. (J Optom 2009;2:70-82 ©2009 Spanish Council of Optometry) KEY WORDS: real ray-tracing; Snell's law; corneal topography; wavefront aberration; intraocular lens calculation. RESUMEN OBJETIVO:Describir el ojo virtual individualizado, que es un modelo computacional de ojo humano con respecto a sus propiedades ópticas. Está basado en las medidas realizadas en cada persona, de manera individual. Una de sus principales aplicaciones es el cálculo de lentes intraoculares (LIO) para cirugía de cataratas. MÉTODOS:El modelo está construido a partir de datos de geometría ocular; en particular, la longitud axial y las medidas topográficas de la cara anterior de la córnea. Todos los componentes ópticos de un ojo pseudofáquico se modelan por medio de métodos computacionales científicos. El método de interpolación por splines permite incluir de manera eficiente los datos obtenidos en las medidas de topografía corneal. Las propiedades relacionadas con la óptica geométrica, como el patrón de aberración del frente de onda, se obtienen a partir de la simulación de un trazado de rayos reales, el cual emplea la ley de Snell. Los componentes ópticos se pueden calcular empleando procedimientos computacionales de optimización. Para 32 ojos distintos, se calculó la geometría de la c...

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Aberrometry in Patients Implanted With Accommodative Intraocular Lenses

Pérez-Merino

Birkenfeld

Dorronsoro

et al. 2014

American Journal of Ophthalmology

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Predicting the performance of accommodating intraocular lenses using ray tracing

Cited by 21 publications

References 32 publications

Evaluation of the performance of accommodating IOLs using a paraxial optics analysis

Evaluation of the performance of accommodating IOLs using a paraxial optics analysis

The Individual Virtual Eye: a Computer Model for Advanced Intraocular Lens Calculation

Aberrometry in Patients Implanted With Accommodative Intraocular Lenses

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