Biomechanical eye model and measurement setup for investigating accommodating intraocular lenses

Eppig, Timo; Gillner, M; Zoric, Katja; Jager, J.T. de; Löffler, André; Langenbucher, Achim

doi:10.1016/j.zemedi.2013.02.003

Cited by 8 publications

(6 citation statements)

References 46 publications

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“…Passive accommodative lenses today are mostly designed as translation lenses with one or more optics and may lack sufficient accommodation [4, 13, 14] in case of lens epithelial cell proliferation (e.g., with secondary cataract); multifocal lenses show strong deteriorations in contrast transmission due to superposition of images in focus and out of focus and straylight and customized excimer laser ablations are often subject to regression effects and irregular astigmatism in the transient zone between near and far distance focus.…”

Section: Introductionmentioning

confidence: 99%

Vignetting and Field of View with the KAMRA Corneal Inlay

Langenbucher

Goebels

Szentmáry

et al. 2013

BioMed Research International

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Purpose. To evaluate the effect of the KAMRA corneal inlay on the retinal image brightness in the peripheral visual field. Methods. A KAMRA inlay was “implanted” into a theoretical eye model in a corneal depth of 200 microns. Corneal radius was varied to a steep, normal, and flat (7.37, 7.77, and 8.17 mm) version keeping the proportion of anterior to posterior radius constant. Pupil size was varied from 2.0 to 5.0 mm. Image brightness was determined for field angles from −70° to 70° with and without KAMRA and proportion of light attenuation was recorded. Results. In our parameter space, the attenuation in brightness ranges in between 0 and 60%. The attenuation in brightness is not affected by corneal shape. For large field angles where the incident ray bundle is passing through the peripheral cornea, brightness is not affected. For combinations of small pupil sizes (2.0 and 2.5 mm) and field angles of 20–40°, up to 60% of light may be blocked with the KAMRA. Conclusion. For combinations of pupil sizes and field angles, the attenuation of image brightness reaches levels up to 60%. Our theoretical findings have to be clinically validated with detailed investigation of this vignetting effect.

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Section: Introductionmentioning

confidence: 99%

Vignetting and Field of View with the KAMRA Corneal Inlay

Langenbucher

Goebels

Szentmáry

et al. 2013

BioMed Research International

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“…Similar lens stretching protocols are currently being implemented to study accommodation and presbyopia 4,6,7,9,12 . However, these protocols are generally complex and expensive, requiring intricate machinery and software programming.…”

Section: Discussionmentioning

confidence: 99%

“…To study lens accommodation, a number of devices have been developed to simulate the phenomenon ex vivo 4,6,7,8,9 . Spinning disks were first introduced to monitor the stretching of the lens via centrifugal forces 8 .…”

Section: Introductionmentioning

confidence: 99%

“…To more faithfully replicate the phenomenon, lens stretching devices were gradually introduced and innovated. Using a lens stretcher, Manns et al characterized the force required to accommodate the lens while correlating such to lens power and equatorial diameter 9 . Current understanding is that the lens stiffens with age, resulting in a reduced change in lens shape in response to an equal force from the ciliary body 3,10,11,12 .…”

Section: Introductionmentioning

confidence: 99%

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Simulating the Mechanics of Lens Accommodation via a Manual Lens Stretcher

Webb

Dong

Bernal³

et al. 2018

JoVE

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The goal of this protocol is to mimic the biomechanics of physiological accommodation in a cost-efficient, practical manner. Accommodation is achieved through the contraction of the ciliary body and relaxation of zonule fibers, which results in the thickening of the lens necessary for near vision. Here, we present a novel, simple method in which accommodation is replicated by tensing the zonules connected to the lens capsule via a manual lens stretcher (MLS). This method monitors the radial stretching achieved by a lens when subjected to a consistent force and allows for a comparison of accommodating lenses, which can be stretched, to non-accommodating lenses, which cannot be stretched. Importantly, the stretcher couples to the zonules directly, and not to the sclera of the eye, thus only requiring the lens, zonules, and ciliary body rather than the entire globe sample. This difference can significantly decrease the cost of acquiring donor cadaver lenses by about 62% compared to acquiring an entire globe.

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“…The CURV (Lambda-X) is based on Placido rings and measures ROCs between 6 and 25 mm with an accuracy of 10 μm [17]. Other optical techniques for laboratory tests are based on wave-front sensing, OCT, and interferometric or imaging-based techniques [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Inspection of freeform intraocular lens topography by phase measuring deflectometric methods

et al. 2013

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Manufacturing spherical, aspheric, and freeform surfaces requires testing throughout the development and production process. State-of-the-art topography measurement is limited in applicability for intraocular lenses (IOLs), and there is no dedicated commercial surface measurement system available for freeform IOLs. The purpose of this work was to validate a deflectometric setup for surface measurement, detection of defects, and shape fidelity analysis for the development and production of IOLs. The setup is based on a phase measuring deflectometer with a field-of-view of 80 mm×80 mm and a mean repetition accuracy of 1.6·10(-3) D. The technique is suitable for detection of global and local surface errors, extracted from geometry and topography analysis. For validation according to DIN ISO 5725:2002, spherical IOLs with radii of curvature of 10 and 20 mm, a commercial aspheric IOL, and single-sided freeform IOL samples were used.

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Biomechanical eye model and measurement setup for investigating accommodating intraocular lenses

Cited by 8 publications

References 46 publications

Vignetting and Field of View with the KAMRA Corneal Inlay

Vignetting and Field of View with the KAMRA Corneal Inlay

Simulating the Mechanics of Lens Accommodation via a Manual Lens Stretcher

Inspection of freeform intraocular lens topography by phase measuring deflectometric methods

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