Suchergebnisse

16 pags., 7 figs. -- OCIS codes: (110.4500) Optical coherence tomography; (110.6880) Three-dimensional image acquisition; (330.7322) Visual optics, accommodation; (100.2960) Image analysis; (330.7327) Visual optics, ophthalmic instrumentation ; The full shape of the accommodating crystalline lens was estimated using custom three-dimensional (3-D) spectral OCT and image processing algorithms. Automatic segmentation and distortion correction were used to construct 3-D models of the lens region visible through the pupil. The lens peripheral region was estimated with a trained and validated parametric model. Nineteen young eyes were measured at 0-6 D accommodative demands in 1.5 D steps. Lens volume, surface area, diameter, and equatorial plane position were automatically quantified. Lens diameter & surface area correlated negatively and equatorial plane position positively with accommodation response. Lens volume remained constant and surface area decreased with accommodation, indicating that the lens material is incompressible and the capsular bag elastic. ; European Research Council under the European Union's Seventh Framework Program (FP/2007-2013) / ERC Grant Agreement (ERC-2011-AdG- 294099); Spanish Government (FIS2011-25637); Spanish Government (FIS2014-56643-R). ; Peer Reviewed

12 pags., 14 figs., 1 tab. ; Purpose. To characterize the geometrical properties of keratoconic corneas upon intracorneal ring segments (ICRS) implantation, using custom-developed optical coherence tomography (OCT). Methods. Ten keratoconic corneas were measured pre- and post-ICRS surgery (7, 30, and 90 days). Corneal topographic and pachymetric maps were obtained from three-dimensional (3D) images acquired with OCT, provided with custom algorithms for image analysis, distortion correction, and quantification. The 3D positioning of the ICRS was also estimated longitudinally, relative to the pupil center and iris plane. Results. Preoperatively, the average corneal radii of curvature were 7.02 ± 0.54 mm (anterior) and 5.40 ± 0.77 mm (posterior), and the minimum corneal thickness was 384 ± 60 μm. At 90 days, the average corneal radii of curvature were 7.26 ± 0.53 mm (anterior) and 5.44 ± 0.71 mm (posterior), and the minimum corneal thickness was 396 ± 46 μm. ICRS implantation produced a significant decrease of corneal power (by 1.71 ± 1.83 diopters [D] at 90 days). Corneal irregularities (defined by high order Zernike terms of the corneal elevation maps) and the corneal thickness distribution decreased in some patients and increased in others. The 3D ICRS depth matched the planned ICRS depth well (within 23.93 ± 23.49 μm). On average, ICRS showed an overall tilt of -6.8 ± 2.6° (temporal) and -2.1 ± 0.8° (superior) at 7 days. Conclusions. Spectral OCT (sOCT) provided with distortion correction and analysis tools, is an excellent instrument for evaluating the changes produced by ICRS in keratoconic corneas, and for analyzing the 3D ICRS position during the follow up. ICRS produced flattening on the anterior corneal surface, although the benefit for corneal surface regularization varied across patients. © 2013 The Association for Research in Vision and Ophthalmology, Inc. ; Supported by funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007- 2013)/European Research Council Grant Agreement Number 294099. This study has been also supported by Ministerio de Educacion y Ciencia, Spain (Grants FIS2011-25637, CEN-2091021), ´ and European Union Grant EURHORCs-ESF (SM). Authors also acknowledge Unidad Asociada IO-CSIC/FJD.

12 pags., 14 figs., 1 tab. ; Purpose. To characterize the geometrical properties of keratoconic corneas upon intracorneal ring segments (ICRS) implantation, using custom-developed optical coherence tomography (OCT). Methods. Ten keratoconic corneas were measured pre- and post-ICRS surgery (7, 30, and 90 days). Corneal topographic and pachymetric maps were obtained from three-dimensional (3D) images acquired with OCT, provided with custom algorithms for image analysis, distortion correction, and quantification. The 3D positioning of the ICRS was also estimated longitudinally, relative to the pupil center and iris plane. Results. Preoperatively, the average corneal radii of curvature were 7.02 ± 0.54 mm (anterior) and 5.40 ± 0.77 mm (posterior), and the minimum corneal thickness was 384 ± 60 μm. At 90 days, the average corneal radii of curvature were 7.26 ± 0.53 mm (anterior) and 5.44 ± 0.71 mm (posterior), and the minimum corneal thickness was 396 ± 46 μm. ICRS implantation produced a significant decrease of corneal power (by 1.71 ± 1.83 diopters [D] at 90 days). Corneal irregularities (defined by high order Zernike terms of the corneal elevation maps) and the corneal thickness distribution decreased in some patients and increased in others. The 3D ICRS depth matched the planned ICRS depth well (within 23.93 ± 23.49 μm). On average, ICRS showed an overall tilt of -6.8 ± 2.6° (temporal) and -2.1 ± 0.8° (superior) at 7 days. Conclusions. Spectral OCT (sOCT) provided with distortion correction and analysis tools, is an excellent instrument for evaluating the changes produced by ICRS in keratoconic corneas, and for analyzing the 3D ICRS position during the follow up. ICRS produced flattening on the anterior corneal surface, although the benefit for corneal surface regularization varied across patients. © 2013 The Association for Research in Vision and Ophthalmology, Inc. ; Supported by funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007- 2013)/European Research Council Grant Agreement Number 294099. This study has been also supported by Ministerio de Educacion y Ciencia, Spain (Grants FIS2011-25637, CEN-2091021), ´ and European Union Grant EURHORCs-ESF (SM). Authors also acknowledge Unidad Asociada IO-CSIC/FJD.

Custom high-resolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT) provided with automatic quantification and distortion correction algorithms was used to characterize three-dimensionally (3-D) the human crystalline lens in vivo in four subjects, for accommodative demands between 0 to 6 D in 1 D steps. Anterior and posterior lens radii of curvature decreased with accommodative demand at rates of 0.73 and 0.20 mm/D, resulting in an increase of the estimated optical power of the eye of 0.62 D per diopter of accommodative demand. Dynamic fluctuations in crystalline lens radii of curvature, anterior chamber depth and lens thickness were also estimated from dynamic 2-D OCT images (14 Hz), acquired during 5-s of steady fixation, for different accommodative demands. Estimates of the eye power from dynamical geometrical measurements revealed an increase of the fluctuations of the accommodative response from 0.07 D to 0.47 D between 0 and 6 D (0.044 D per D of accommodative demand). A sensitivity analysis showed that the fluctuations of accommodation were driven by dynamic changes in the lens surfaces, particularly in the posterior lens surface. © 2013 Optical Society of America. ; The authors acknowledge funding from Predoctoral fellowship CSIC-I3P2006 to EG; FNP Ventures Program co-financed by the EU Funds to MG; EURYI-01/2008-PL (EURHORCs) to MW; MICINN FIS2011-02065 to SM. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013) / ERC Grant Agreement n. [294099] to SM. The authors acknowledge technical hardware and software support of Ireneusz Grulkowski and Maciej Szkulmowski from NCU Toruń. ; Peer Reviewed

11 pags., 5 figs., 4 tabs. -- Open Access funded by Creative Commons Atribution Licence 4.0 ; In a cataract surgery, the opacified crystalline lens is replaced by an artificial intraocular lens (IOL). To optimize the visual quality after surgery, the intraocular lens to be implanted must be selected preoperatively for every individual patient. Different generations of formulas have been proposed for selecting the intraocular lens dioptric power as a function of its estimated postoperative position. However, very few formulas include crystalline lens information, in most cases only one-dimensional. The present study proposes a new formula to preoperatively estimate the postoperative IOL position (ELP) based on information of the 3-dimensional full shape of the crystalline lens, obtained from quantitative eye anterior segment optical coherence tomography imaging. Real patients were measured before and after cataract surgery (IOL implantation). The IOL position and the postoperative refraction estimation errors were calculated by subtracting the preoperative estimations from the actual values measured after surgery. The proposed ELP formula produced lower estimation errors for both parameters-ELP and refraction-than the predictions obtained with standard state-of-the-art methods, and opens new avenues to the development of new generation IOL power calculation formulas that improve refractive and visual outcomes. ; The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement ERC-2011-AdG- 294099. This study has been also supported by Spanish government grants FIS2011-25637 and FIS2014-56643-R to S. Marcos. The funding organizations had no role in the design or conduct of this research. ; Peer Reviewed

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017 ; Support European Research Council ERC-2011-AdG-294099; ERC-PoC-713422 (SimVisSim); Spanish Government FIS2014 ; Peer reviewed

9 pags.; 6 figs.; 2 tabs.; . Published by SPIE under a Creative Commons Attribution 3.0 Unported License. ; Measurement of intraocular lens (IOL) alignment implanted in patients in cataract surgery is important to understand their optical performance. We present a method to estimate tilt and decentration of IOLs based on optical coherence tomography (OCT) images. En face OCT images show Purkinje-like images that correspond to the specular reflections from the corneal and IOL surfaces. Unlike in standard Purkinjeimaging, the tomographic nature of OCT allows unequivocal association of the reflection with the corresponding surface. The locations of the Purkinje-like images are linear combinations of IOL tilt, IOL decentration, and eye rotation. The weighting coefficients depend on the individual anterior segment geometry, obtained from the same OCT datasets. The methodology was demonstrated on an artificial model eye with set amounts of lens tilt and decentration and five pseudophakic eyes. Measured tilt and decentration in the artificial eye differed by 3.7% and 0.9%, respectively, from nominal values. In patients, average IOL tilt and decentration from Purkinje were 3.30 ± 4.68 deg and 0.16 ± 0.16 mm, respectively, and differed on average by 0.5 deg and 0.09 mm, respectively, from direct measurements on distortion-corrected OCT images. Purkinje-based methodology from anterior segment en face OCT imaging provided, therefore, reliable measurements of IOL tilt and decentration. © The Authors. ; This study has been funded by Spanish Government Grant No. FIS2011-25637 and European Research Council ERC-2011 AdG-294099 "Bio-inspired optical correction of presbyopia" to S. Marcos, and Marie Curie Actions-Networks of Initial Training (ITN) FP7-PEOPLE-2010-ITN 264605 (OpAL-Optical and adaptational limits of vision). ; Peer Reviewed

12 pags., 6 figs., 3 tabs. -- OCIS codes: (110.4500) Optical coherence tomography, (110.6880) Three-dimensional image acquisition, (100.2960) Image analysis, (330.7327) Visual optics, ophthalmic instrumentation, (330.7324) Visual optics, comparative animal models, (330.5370) Physiological optics ; Custom Spectral Optical Coherence Tomography (SOCT) provided with automatic quantification and distortion correction algorithms was used to measure the 3-D morphology in guinea pig eyes (n = 8, 30 days; n = 5, 40 days). Animals were measured awake in vivo under cyclopegia. Measurements showed low intraocular variability (<4% in corneal and anterior lens radii and <8% in the posterior lens radii, <1% interocular distances). The repeatability of the surface elevation was less than 2 µm. Surface astigmatism was the individual dominant term in all surfaces. Higher-order RMS surface elevation was largest in the posterior lens. Individual surface elevation Zernike terms correlated significantly across corneal and anterior lens surfaces. Higher-order-aberrations (except spherical aberration) were comparable with those predicted by OCT-based eye models. ; European Research Council under the European Union´s Seventh Framework Program (FP/2007-2013;) / ERC Grant Agreement [ERC-2011-AdC-294099], and Spanish Government grant FIS2011-25637; and FIS2014-56643-R to SM. ; Peer Reviewed

12 pags., 5+3 figs. -- Open Access funded by Creative Commons Atribution Licence 4.0 ; PURPOSE: Standard evaluation of aberrations from wavefront slope measurements in patients implanted with a rotationally asymmetric multifocal intraocular lens (IOL), the Lentis Mplus (Oculentis GmbH, Berlin, Germany), results in large magnitude primary vertical coma, which is attributed to the intrinsic IOL design. The new proposed method analyzes aberrometry data, allowing disentangling the IOL power pupillary distribution from the true higher order aberrations of the eye. METHODS: The new method of wavefront reconstruction uses retinal spots obtained at both the near and far foci. The method was tested using ray tracing optical simulations in a computer eye model virtually implanted with the Lentis Mplus IOL, with a generic cornea or with anterior segment geometry obtained from custom quantitative spectral-domain optical coherence tomography in a real patient. The method was applied to laser ray tracing aberrometry data at near and far fixation obtained in a patient implanted with the Lentis Mplus IOL. RESULTS: Higher order aberrations evaluated from simulated and real retinal spot diagrams following the new reconstruction approach matched the nominal aberrations (approximately 98%). Previously reported primary vertical coma in patients implanted with this IOL lost significance with the application of the proposed reconstruction. CONCLUSIONS: Custom analysis of ray tracing-based retinal spot diagrams allowed decoupling of the true higher order aberrations of the patient's eye from the power pupillary distribution of a rotationally asymmetric multifocal IOL, therefore providing the appropriate phase map to accurately evaluate through-focus optical quality. ; Supported by Consejería de Educación, Juventud y Deporte of Comunidad de Madrid and the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement no. 291820 to VA; ERC Grant Agreement [ERC-2011-AdG 294099] and Spanish Government Grants FIS2011-25637 and FIS2014-56643-R to SM. ; Peer Reviewed

8 pags., 6 figs. ; Purpose: The crystalline lens undergoes morphological and functional changes with age and may also play a role in eye emmetropisation. Both the geometry and the gradient index of refraction (GRIN) distribution contribute to the lens optical properties. We studied the lens GRIN in the guinea pig, a common animal model to study myopia. Methods: Lenses were extracted from guinea pigs (Cavia porcellus) at 18 days of age (n = 4, three monolaterally treated with negative lenses and one untreated) and 39 days of age (n = 4, all untreated). Treated eyes were myopic (−2.07 D on average) and untreated eyes hyperopic (+3.3 D), as revealed using streak retinoscopy in the live and cyclopeged animals. A custom 3D spectral domain optical coherence tomography (OCT) system (λ = 840 nm, Δλ = 50 nm) was used to image the enucleated crystalline lens at two orientations. Custom algorithms were used to estimate the lens shape and GRIN was modelled with four variables that were reconstructed using the OCT data and a minimisation algorithm. Ray tracing was used to calculate the optical power and spherical aberration assuming a homogeneous refractive index or the estimated GRIN. Results: Guinea pig lenses exhibited nearly parabolic GRIN profiles. When comparing the two age groups (18- and 39 day-old) there was a significant increase in the central thickness (from 3.61 to 3.74 mm), and in the refractive index of the surface (from 1.362 to 1.366) and the nucleus (from 1.443 to 1.454). The presence of GRIN shifted the spherical aberration (−4.1 µm on average) of the lens towards negative values. Conclusions: The guinea pig lens exhibits a GRIN profile with surface and nucleus refractive indices that increase slightly during the first days of life. GRIN plays a major role in the lens optical properties and should be incorporated into computational guinea pig eye models to study emmetropisation, myopia development and ageing. ; This work was supported by European Research Council (ERC) Grant Agreement ERC-2011-AdC- 294099; ERC under the European Union's Horizon 2020 research and innovation programme (H2020-MSCA COFUND-2015 FP-713694, MULTIPLY) and under grant agreement No 779960, IMCUSTOMEYE and No 675137 (MyFUun MSCA ITN); Spanish Government Grant FIS2017-84753-R; Hunter Medical Research Institute G1400967 and the University of Newcastle (FVG 1031537 and SSP).

ARVO Annual Meeting Abstract (2019) ; Support European Research Council ERC-2011-AdG 294099; Spanish Government FIS2014-56643-R, FIS2017-84753-R; H-2020-MSCA-COFUND-2015 713694 ; Peer reviewed

9 pags., 6 figs., 2 tabs. -- Open Access funded by Creative Commons Atribution Licence 4.0 ; PURPOSE. To compare corneal biomechanical properties after in vivo and ex vivo cross-linking (CXL) using rose bengal–green light (RGX) or riboflavin-UVA (UVX). METHODS. Corneas of 30 rabbits were treated in vivo by the two CXL modalities monolaterally (Group 1) or bilaterally (Group 2). Rabbits in Group 1 were euthanized 1 month after treatments and in Group 2 two months after treatment. Ex vivo CXL was also performed. Eyes were measured by Scheimpflug air puff corneal deformation imaging (Corvis ST) under constant IOP. Corneal deformation parameters were assessed. Inherent corneal biomechanical properties were estimated using inverse finite element modeling. RESULTS. Peak to peak distance decreased 16% 2 months after RGX, and 4% and 20% 1 and 2 months after UVX, respectively. The equivalent Young's modulus (Eeq) increased relative to the control during the post treatment period for both RGX and UVX. The Eeq increased by factors of 3.4 (RGX) and 1.7 (UVX) 1 month and by factors of 10.7 (RGX) and 7.3 (UVX) 2 months after treatment. However, the Eeq values for ex vivo CXL were much greater than produced in vivo. The ex vivo Eeq was greater than the 1-month in vivo values by factors of 8.1 (RGX) and 9.1 (UVX) and compared with 2 month by factors of 2.5 (RGX) and 2.1 (UVX). CONCLUSIONS. These results indicate that corneal stiffness increases after CXL, and further increases as a function of time after both RGX and UVX. Also, while biomechanical properties determined after ex vivo CXL are indicative of corneal stiffening, they may not provide entirely accurate information about the responses to CXL in vivo. ; Supported by the European Research Council under the European Union's Seventh Framework Program ERC Advanced Grant agreement no. 294099; Comunidad de Madrid and EU Marie Curie COFUND program (FP7/2007-2013/REA 291820); and the Spanish Government Grant FIS2014-56643-R. ; Peer Reviewed

In vivo three-dimensional (3-D) anterior segment biometry before and after cataract surgery was analyzed by using custom highresolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT). The system was provided with custom algorithms for denoising, segmentation, full distortion correction (fan and optical) and merging of the anterior segment volumes (cornea, iris, and crystalline lens or IOL), to provide fully quantitative data of the anterior segment of the eye. The method was tested on an in vitro artificial eye with known surfaces geometry at different orientations and demonstrated on an aging cataract patient in vivo. Biometric parameters CCT, ACD/ILP, CLT/ILT Tilt and decentration are retrieved with a very high degree of accuracy. IOL was placed 400 οm behind the natural crystalline lens, The IOL was aligned with a similar orientation of the natural lens (2.47 deg superiorly), but slightly lower amounts (0.77 deg superiorly). The IOL was decentered superiorly (0.39 mm) and nasally (0.26 mm). © 2013 Optical Society of America. ; This study has been funded by Spanish Government Grant FIS2011-25637 and European Research Council Grant ERC-2011-AdG-294099 to S. Marcos. ; Peer Reviewed

10 pags., 10 figs. ; PURPOSE. To study corneal wound healing after two cross-linking techniques using either rose bengal and green light (RGX) or the conventional treatment using riboflavin and UVA radiation (UVX). METHODS. Corneas of New Zealand rabbits were monolaterally treated with UVX (21 eyes) or RGX (25 eyes). Treatments involved corneal de-epithelialization (8-mm diameter), soaking with photosensitizer (0.1% riboflavin in 20% dextran for 30 minutes for UVX; 0.1% rose bengal for 2 minutes for RGX), and light irradiation (370 nm, 3 mW/cm, 30 minutes for UVX; 532 nm, 0.25 W/cm, 7 minutes for RGX). Contralateral eyes were used as controls. Clinical follow-up included fluorescein staining, haze measurement, and pachymetry. Healing events analyzed after euthanasia at 2, 30, and 60 days included cell death (TUNEL assay), cell proliferation (BrdU [bromodeoxyuridine] immunofluorescence), and differentiation to myofibroblasts (α-SMA [alpha smooth muscle actin] immunohistochemistry). RESULTS. Re-epithelialization and pachymetries were similar after RGX and UVX. The haze from day 1 to 15 was greater after UVX. Cell death was deeper after UVX, being localized in the anterior and middle stroma, and was superficial (anterior third) after RGX. Cell proliferation appeared after 2 days and was localized in the middle and posterior stroma in the UVX group but was superficial in the RGX group. After 60 days the number of stromal cells had not returned to the control number in either group. CONCLUSIONS. The deeper and longer-lasting cell damage caused by UVX compared to RGX may underlie the slower cell repopulation after UVX and other differences in healing. Shallower damage and a shorter treatment time suggest that RGX may be appropriate for stiffening thin corneas. ; Supported by European Research Council ERC-2011-AdC-294099 (SM), Spanish Government Grants FIS2011-25637-R (SM), FIS2014- 56643-R, and FIS2017-84753-R (SM)

Acanthamoeba keratitis is a serious pathogenic corneal disease, with challenging diagnosis. Standard diagnostic methods include corneal biopsy (involving cell culture) and in vivo reflection corneal microscopy (in which the visualization of the pathogen is challenged by the presence of multiple reflectance corneal structures). We present a new imaging method based on fluorescence sectioned microscopy for visualization of Acanthamoeba. A fluorescent marker (MT-11-BDP), composed by a fluorescent group (BODIPY) inserted in miltefosine (a therapeutic agent against Acanthamoeba), was developed. A custom-developed fluorescent structured illumination sectioned corneal microscope (excitation wavelength: 488 nm; axial/lateral resolution: 2.6 μm/0.4-0.6 μm) was used to image intact enucleated rabbit eyes, injected with a solution of stained Acanthamoeba in the stroma. Fluorescent sectioned microscopic images of intact enucleated rabbit eyes revealed stained Acanthamoeba trophozoites within the stroma, easily identified by the contrasted fluorescent emission, size and shape. Control experiments show that the fluorescent maker is not internalized by corneal cells, making the developed marker specific to the pathogen. Fluorescent sectioned microscopy shows potential for specific diagnosis of Acanthamoeba keratitis. Corneal confocal microscopy, provided with a fluorescent channel, could be largely improved in specificity and sensitivity in combination with specific fluorescent marking. © 2012 Optical Society of America. ; The authors acknowledge funding from a CSIC Proyecto Intramural Frontera PIF80F0171/2/3; Ministerio de Ciencia e Innovación, Spain, FIS2008-02065 (S. M.), FIS2011-25637 (S. M.), RYC2006-2920 (J. R. I.), FIS2009-07966 (J. R. I.), CTQ2010-16457 (A. U. A.), PROFIT CIT-300100-2007-50 (J. M. L.); Instituto de Salud Carlos III ISCIII- (RICET)-FEDER RD 06/0021/0006 (L. R.), and FIS 2009-01928 (L. R.); European Union FP7 HEALTH-2007-223414 (L. R.); EURHORCS-ESF Grant EURYI-05-102-ES (S. M.). ; Peer Reviewed