Comparison of the efficiency, MTF and chromatic properties of four diffractive bifocal intraocular lens designs

Castignoles, Fannie; Flury, Manuel; Lépine, Thierry

doi:10.1364/oe.18.005245

Cited by 35 publications

(40 citation statements)

References 7 publications

(14 reference statements)

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“…The expected light distribution between the three foci as provided by the manufacturer is shown in Figure 2. It is worth emphasizing that this distribution of energy is indeed the theoretical diffraction efficiency [15,23] of the far, intermediate and near foci of the IOL. Since the amount of the energy transmitted by the trifocal IOL and sent to each of the foci is proportional to this diffraction efficiency, it is generally assumed that the theoretical light distribution showed in Figure 2 will correspond to the energy correctly focused onto the respective image planes.…”

Section: Iol Characteristicsmentioning

confidence: 73%

“…Finally, additional (although presumably small) contributions to the background may also come from higher diffraction orders. [23] The performance of the intermediate focus deserves further explanation. We have found that for IOL-pupils up to 3.0 mm approximately, the experimental energy efficiency of this focus is, somehow surprising, larger than the provided values of diffraction efficiency (Figure 8), the smaller the pupil the larger the difference.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, it has been pointed out the importance of the shape factor and aspheric design [24,25] of the base lens of the IOL to properly tackle with the converging and aberrated wavefront [26,27] that impinges upon the IOL in order to obtain a high quality retinal image. Additional issues such as the presence of higher diffraction orders (i.e., others than the ones that create the three foci), [23] scattering in the diffractive steps [28,29] or the dependence of the depth of focus on the pupil size, also make that a significant fraction of the diffracted energy, which otherwise would be sent to a particular focus, gets out of focus at the image plane. This extra out of focus energy increases the background noise of the image and may reduce the efficiency of the foci [18] below the values that are predicted just taking into consideration their theoretical diffraction efficiency.…”

Section: Iol Characteristicsmentioning

confidence: 99%

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Energy efficiency of a new trifocal intraocular lens

Vega

Alba-Bueno

Millán

2014

J. Eur. Opt. Soc.-Rapid Publ.

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The light distribution among the far, intermediate and near foci of a new trifocal intraocular lens (IOL) is experimentally determined, as a function of the pupil size, from image analysis. The concept of focus energy efficiency is introduced because, in addition to the theoretical diffraction efficiency of the focus, it accounts for other factors that are naturally presented in the human eye such as the level of spherical aberration (SA) upon the IOL, light scattering at the diffractive steps or the depth of focus. The trifocal IOL is tested in-vitro in two eye models: the aberration-free ISO model, and a so called modified-ISO one that uses an artificial cornea with positive spherical SA in instead. The SA upon the IOL is measured with a Hartmann-Shack sensor and compared to the values of theoretical eye models. The results show, for large pupils, a notorious reduction of the energy efficiency of the far and near foci of the trifocal IOL due to two facts: the level of SA upon the IOL is larger than the value the lens is able to compensate for and there is significant light scattering at the diffractive steps. On the other hand, the energy efficiency of the intermediate focus for small pupils is enhanced by the contribution of the extended depth of focus of the near and far foci. Thus, while IOLs manufacturers tend to provide just the theoretical diffraction efficiency of the foci to show which would be the performance of the lens in terms of light distribution among the foci, our results put into evidence that this is better described by using the energy efficiency of the foci.

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Section: Iol Characteristicsmentioning

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Iol Characteristicsmentioning

confidence: 99%

See 1 more Smart Citation

Energy efficiency of a new trifocal intraocular lens

Vega

Alba-Bueno

Millán

2014

J. Eur. Opt. Soc.-Rapid Publ.

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“…Finally it is worth to mention that the experimental analysis of chromatic properties of MIOLs [18,19] is readily possible with our proposal simply by changing the light source. …”

Section: Discussionmentioning

confidence: 99%

Through-focus response of multifocal intraocular lenses evaluated with a spatial light modulator

et al. 2012

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“…There is a great interest to determine either in a test bench [43], [44] or in clinical studies [45], [46] the conditions and the degree to which the aspheric design in apodized diffractive multifocal IOLs might be advantageous versus a conventional spherical design, particularly when some studies have shown little or no benefit of aspheric IOLs with small pupils [47, [48]. For the assessment of the optical performance of multifocal IOLs, the common metrics (point spread function, modulation transfer function, and visual acuity) have to be measured [38], [49][50][51][52] and also its behaviour in terms of the energy balance between the distance an near images and its variation with the pupil diameter. Very recent studies carried out in an optical bench show a discrepancy between the theoretical prediction of the design and the experimentally measured energy distribution between the two foci in apodized diffractive multifocal IOLs [53].…”

Section: Model Eyes For Iol Testingmentioning

confidence: 99%

New trends in intraocular lens imaging

2011

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As a result of modern technological advances, cataract surgery can be seen as not only a rehabilitative operation, but a customized procedure to compensate for important sources of image degradation in the visual system of a patient, such as defocus and some aberrations. With the development of new materials, instruments and surgical techniques in ophthalmology, great progress has been achieved in the imaging capability of a pseudophakic eye implanted with an intraocular lens (IOL). From the very beginning, optical design has played an essential role in this progress. New IOL designs need, on the one hand, theoretical eye models able to predict optical imaging performance and on the other hand, testing methods, verification through in vitro and in vivo measurements, and clinical validation. The implant of an IOL requires a precise biometry of the eye, a prior calculation from physiological data, and an accurate position inside the eye. Otherwise, the effects of IOL calculation errors or misplacements degrade the image very quickly. The incorporation of wavefront aberrometry into clinical ophthalmology practice has motivated new designs of IOLs to compensate for high order aberrations in some extent. Thus, for instance, IOLs with an aspheric design have the potential to improve optical performance and contrast sensitivity by reducing the positive spherical aberration of human cornea. Monofocal IOLs cause a complete loss of accommodation that requires further correction for either distance or near vision. Multifocal IOLs address this limitation using the principle of simultaneous vision. Some multifocal IOLs include a diffractive zone that covers the aperture in part or totally. Reduced image contrast and undesired visual phenomena, such as halos and glare, have been associated to the performance of multifocal IOLs. Based on a different principle, accommodating IOLs rely on the effort of the ciliary body to increase the effective power of the optical system of the eye in near vision. Finally, we present a theoretical approach that considers the modification of less conventional ocular parameters to compensate for possible refractive errors after the IOL implant.

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Comparison of the efficiency, MTF and chromatic properties of four diffractive bifocal intraocular lens designs

Cited by 35 publications

References 7 publications

Energy efficiency of a new trifocal intraocular lens

Energy efficiency of a new trifocal intraocular lens

Through-focus response of multifocal intraocular lenses evaluated with a spatial light modulator

New trends in intraocular lens imaging

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