Magnetresonanzmikroskopie des Akkommodationsapparats

Stahnke, Thomas; Hadlich, Stefan; Wree, Andreas; Guthoff, Rudolf; Stachs, Oliver; Langner, Sönke

doi:10.1055/s-0042-118599

Cited by 4 publications

(4 citation statements)

References 11 publications

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“…Ultrasound sound waves can partially pass through the pupil, but the technique has a lower resolution and is more invasive than optical coherence tomography. 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

216

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: 5mentioning

confidence: 99%

Presbyopia: Effectiveness of correction strategies

Wolffsohn

Davies

2019

Progress in Retinal and Eye Research

216

178

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“…MRM enabled differentiation of the choroid, retina and sclera of the human eye ex vivo (Figure 6) 113 and supported ex vivo studies of the accommodation apparatus 114 . Ex vivo examinations of the human eye at 9.4 T permitted an in-plane spatial resolution of 32-50 µm 34,112 .…”

Section: Mreye Microscopymentioning

confidence: 73%

Ophthalmic Magnetic Resonance Imaging: Where Are We (Heading To)?

Niendorf

Beenakker²,

Langner

et al. 2021

Current Eye Research

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Magnetic resonance imaging of the eye and orbit (MReye) is a cross-domain research field, combining (bio)physics, (bio)engineering, physiology, data sciences and ophthalmology. A growing number of reports document technical innovations of MReye and promote their application in preclinical research and clinical science. Realizing the progress and promises, this review outlines current trends in MReye. Examples of MReye strategies and their clinical relevance are demonstrated. Frontier applications in ocular oncology, refractive surgery, ocular muscle disorders and orbital inflammation are presented and their implications for explorations into ophthalmic diseases are provided. Substantial progress in anatomically detailed, high-spatial resolution MReye of the eye, orbit and optic nerve is demonstrated. Recent developments in MReye of ocular tumors are explored, and its value for personalized eye models derived from machine learning in the treatment planning of uveal melanoma and evaluation of retinoblastoma is highlighted. The potential of MReye for monitoring drug distribution and for improving treatment management and the assessment of individual responses is discussed. To open a window into the eye and into (patho)physiological processes that in the past have been largely inaccessible, advances in MReye at ultrahigh magnetic field strengths are discussed. A concluding section ventures a glance beyond the horizon and explores future directions of MReye across multiple scales, including in vivo electrolyte mapping of sodium and other nuclei. This review underscores the need for the (bio)medical imaging and ophthalmic communities to expand efforts to find solutions to the remaining unsolved problems and technical obstacles of MReye, with the objective to transfer methodological advancements driven by MR physics into genuine clinical value.

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“…Different layers of the lens, like the epithelium, lens capsule, cortex, or within the nucleus, are identifiable with micro-CT ( Figures 2B,3,4,6A ) ( 15 ). Micro-CT scans of moist lenses allow for more detailed imaging than MRI ( 11 , 33 ), while the risk of artificial damages is reduced compared to histological methods ( 11 ). Within the lens nucleus, IPI contrasting enabled further differentiation ( Figure 3 ) which resembles the results of Scheimpflug photography ( 34 ).…”

Section: Discussionmentioning

confidence: 99%

“…In comparison, section-based histology provides morphological ex vivo insights of higher magnification and resolution. The generation of spacious 3D visualizations based on histology, however, is time-consuming and vulnerable to artifacts resulting from sectioning (e.g., tissue compression; tissue damage, loss of alloplastic implant materials) which particularly concerns ocular samples ( 11 ).…”

Section: Introductionmentioning

confidence: 99%

Micro-CT in ophthalmology: ex vivo preparation and contrasting methods for detailed 3D-visualization of eye anatomy with special emphasis on critical point drying

Runge¹,

Stahnke²,

Guthoff³

et al. 2022

Quant Imaging Med Surg

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Background: Micro-computed tomography (micro-CT) provides detailed 3-dimensional (3D) visualization of anatomical structures and encourages morphological reinvestigation of organs with delicate features. The low radiodensity of soft tissues necessitates preceding sample preparation to conduct X-ray imaging with decent contrast between different tissues. In this study, we demonstrate the preparation with three radiopaque agents in combination with elimination of liquids by critical point drying (CPD) introduced for ocular samples.Methods: Enucleated porcine eyes were prepared with ethanolic iodine (EI), aqueous iodine-potassium iodide, or ethanolic phosphotungstic acid (EPTA). Micro-CT scans of the samples were conducted in a moist environment with an isotropic resolution of 9.2-12.5 µm voxel size. Subsequently, samples were chemically dehydrated and critical point (CP) dried to conduct a second scan in a dry environment with a resolution up to 4.7-5.4 µm in voxel size. The visualization effects were qualitatively and semi-quantitatively evaluated with regard to the generated contrast between different ocular tissues.Results: All three contrast agents accumulated well in most of the investigated ocular tissues and lead to an increased X-ray attenuation which allowed for differentiated visualization of ocular structures. Problematic agent penetration into the lens was obvious for iodine-potassium iodide and EPTA. Artificial damages of the lens and thickness reduction for the cornea and sclera due to CPD were noticed. The effects of the different contrasting treatments are described and compared with regard to the effects of CPD. Exclusively CP dried samples that were not treated with contrast agents could also be visualized excellently with a good distinction of different ocular structures from each other.Conclusions: All ocular structures can be visualized by micro-CT. To contrast moist samples, the best results were achieved with iodine potassium iodide (IPI). CPD improved the scan quality in all cases. Even without pretreatment with contrasting agents, the CP dried samples showed a contrast similar to the IPI treated samples.

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Magnetresonanzmikroskopie des Akkommodationsapparats

Cited by 4 publications

References 11 publications

Presbyopia: Effectiveness of correction strategies

Presbyopia: Effectiveness of correction strategies

Ophthalmic Magnetic Resonance Imaging: Where Are We (Heading To)?

Micro-CT in ophthalmology: ex vivo preparation and contrasting methods for detailed 3D-visualization of eye anatomy with special emphasis on critical point drying

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