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Received 6 October 2014; revised 5 November 2014; accepted 5 November 2014; posted 6 November 2014 (Doc. ID 224120); published 4 December 2014, In a previous contribution [Appl. Opt. 51, 8599 (2012)], a coauthor of this work presented a method for reconstructing the wavefront aberration from tangential refractive power data measured using dynamic skiascopy. Here we propose a new regularized least squares method where the wavefront is reconstructed not only using tangential but also sagittal curvature data. We prove that our new method provides improved quality reconstruction for typical and also for highly aberrated wavefronts, under a wide range of experimental error levels. Our method may be applied to any type of wavefront sensor (not only dynamic skiascopy) able to measure either just tangential or tangential plus sagittal curvature data., Ministerio de Economía y Competitividad (MINECO), Sección Deptal. de Óptica (Óptica), Fac. de Óptica y Optometría, TRUE, pub

En abierto en la web del editor. Received 7 Oct 2015; revised 4 Feb 2016; accepted 9 Feb 2016; published 9 Mar 2016 © 2016 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited., A new method for fitting a series of Zernike polynomials to point clouds defined over connected domains of arbitrary shape defined within the unit circle is presented in this work. The method is based on the application of machine learning fitting techniques by constructing an extended training set in order to ensure the smooth variation of local curvature over the whole domain. Therefore this technique is best suited for fitting points corresponding to ophthalmic lenses surfaces, particularly progressive power ones, in non-regular domains. We have tested our method by fitting numerical and real surfaces reaching an accuracy of 1 micron in elevation and 0.1 D in local curvature in agreement with the customary tolerances in the ophthalmic manufacturing industry., Ministerio de Economía y Competitividad (MINECO), Depto. de Óptica, Sección Deptal. de Óptica (Óptica), Fac. de Ciencias Físicas, Fac. de Óptica y Optometría, TRUE, pub

We present a psychophysical method and a simple setup for the clinical assessment of the longitudinal chromatic aberration (LCA) in phakic and pseudophakic eyes. A proof of concept built from inexpensive and non-sophisticated optomechanical components were used to obtain the preliminary clinical results presented in this work, Peer Reviewed, Postprint (published version)

Current methods to measure intraocular scattering provide information on the total scattered light, which consists of the combined contributions originating from different ocular structures. In this work, we propose a technique for the objective and independent assessment of scattering caused by the cornea and the lens based on the analysis of the contrast of the third and fourth Purkinje images. The technique is preliminarily validated first by using artificial eyes with different levels of corneal and lens scattering; second, it is validated in eyes wearing customized contact lenses to simulate corneal scattering and eyes with nuclear cataracts. Finally, it is tested on a larger population of eyes with cataracts and corneal disorders to prove its clinical usefulness., Postprint (published version)

A method for tear film break up measurements based on the degradation of corneal reflex images caused by dry spots is presented. The experimental setup, which is based on recording the corneal reflex image or the first Purkinje image, is described, as well as the method used to determine tear film stability by means of the associated break up time using the corneal reflex image degradation. Images obtained through simulations of the experimental setup are also shown., Postprint (published version)

A numerical 3D ray tracing model was used to evaluate the long-term visual effects of two regimens of corneal crosslinking (CXL) treatment of 48 patients with the corneal degeneration keratoconus. The 3D ray tracing analyses were based on corneal elevation data measured by Scheimpflug photography. Twenty-two patients were treated with standard CXL applied uniformly across the corneal surface, whereas 26 patients underwent a customized, refined treatment only at local zones on the cornea (photorefractive intrastromal CXL; PiXL). Spot diagrams, spot root-mean-square (RMS) values, and Strehl ratios were evaluated for the patients prior to and 1, 3, 6, and 12 months after treatment. It was found that the group of patients treated with PiXL, on average, tended to attain a long-term improvement of the corneal optical performance, whereas only minor changes of the optical parameters were found for group treated with standard CXL. Our results confirmed that standard CXL treatment stabilizes the corneal optical quality over time, and thus halts the progression of the corneal degeneration. In addition to stabilization, the results showed that a significantly higher proportion of subjects treated with PiXL improved in RMS, 3, 6, and 12 months after treatment, compared to with CXL (p<0.05). This finding indicates that the PiXL treatment might improve optical quality over time.

We describe a first-and-second-diffractive-order intraocular lens ((1st,2nd)DIOL) within the class of hybrid refractive-diffractive designs for intraocular lenses (IOLs) and analyse its properties of focus extension and compensation of longitudinal chromatic aberration (LCA), particularly for lenses with low addition. Power, energy efficiency and their wavelength dependence are extended from monofocal IOL and conventional bifocal zeroth-and-first-diffractive-order IOL ((0th,1st)DIOL) to (1st,2nd)DIOL of low addition. Compensation of LCA is experimentally assessed in optical bench through the through-focus energy efficiency of three Tecnis IOLs with red, green and blue illuminations: ZA9003 (monofocal), ZKB00 (bifocal (0th,1st)DIOL with + 2.75 D add) and Symfony ZXR00. We prove Tecnis Symfony ZXR00 IOL can be considered an example of (1st,2nd)DIOL design of low addition, with LCA compensation in both the distance and intermediate foci, whereas the bifocal (0th,1st)DIOL does not compensate in the distance focus. However, the energy efficiency of (1st,2nd)DIOL for wavelengths other than the design wavelength is markedly more asymmetric., Postprint (published version)

En abierto en la web del editor. Received 7 Oct 2015; revised 4 Feb 2016; accepted 9 Feb 2016; published 9 Mar 2016 © 2016 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited., A new method for fitting a series of Zernike polynomials to point clouds defined over connected domains of arbitrary shape defined within the unit circle is presented in this work. The method is based on the application of machine learning fitting techniques by constructing an extended training set in order to ensure the smooth variation of local curvature over the whole domain. Therefore this technique is best suited for fitting points corresponding to ophthalmic lenses surfaces, particularly progressive power ones, in non-regular domains. We have tested our method by fitting numerical and real surfaces reaching an accuracy of 1 micron in elevation and 0.1 D in local curvature in agreement with the customary tolerances in the ophthalmic manufacturing industry., Ministerio de Economía y Competitividad (MINECO), Depto. de Óptica, Sección Deptal. de Óptica (Óptica), Fac. de Ciencias Físicas, Fac. de Óptica y Optometría, TRUE, pub

Based on numerical 3D ray tracing, we propose a new procedure to optimize personalized intra-ocular lenses (IOLs). The 3D ray tracing was based on measured corneal elevation data from patients who suffered from advanced keratoconus. A mathematical shape description of the posterior IOL surface, by means of a tensor product cubic Hermite spline, was implemented. The optimized lenses provide significantly reduced aberrations. Our results include a trade-off study that suggests that it is possible to considerably reduce the aberrations with only minor perturbations of an ideal spherical lens. The proposed procedure can be applied for correction of aberrations of any optical system by modifying a single surface.

Adaptive optics (AO) retinal imaging has been widely used for high resolution in vivo imaging studies in the human eye over the last two decades. More recently, this technology has been applied to image the retina of small animals such as rodents. Small animal eyes offer many advantages for the scientific study of retinal diseases, and theoretically have potential for superior image quality compared to human eyes. Unfortunately, to date AO image quality in practice is inferior to state-of-the-art image quality obtained from the human eye, and the cause of these limitations has not been fully understood. This work aimed to investigate and address the limitations to AO image quality in rodent eyes, and explore novel techniques in adaptive optics correction and image processing to overcome these limitations. The first experiment used optical modelling to test several commonly made assumptions in human AO imaging. These assumptions were found to be inappropriate for extrapolation to rodent eyes, due to their very high power and dioptric thickness of the retina. Specifically, results showed that AO image quality for the human eye is robust against positioning errors of the AO corrector and to differences in imaging depth and wavelength compared to the wavefront beacon. On the other hand, image quality for the rat eye declined sharply with each of these manipulations. The second experiment used a purpose-built flood-illumination AO ophthalmoscope designed for rat eyes to validate the modelling results from the first experiment, using physical model eyes of varying optical power. It was found that in general, AO image quality from the lower powered (60 D) model eye was much less susceptible to manipulations similar to those described in the first experiment, compared to the higher powered (220 D) model eye, thus confirming the optical modelling results. The same optical system was then used to account for these limitations as much as possible, while imaging adult pigmented

Received 6 October 2014; revised 5 November 2014; accepted 5 November 2014; posted 6 November 2014 (Doc. ID 224120); published 4 December 2014, In a previous contribution [Appl. Opt. 51, 8599 (2012)], a coauthor of this work presented a method for reconstructing the wavefront aberration from tangential refractive power data measured using dynamic skiascopy. Here we propose a new regularized least squares method where the wavefront is reconstructed not only using tangential but also sagittal curvature data. We prove that our new method provides improved quality reconstruction for typical and also for highly aberrated wavefronts, under a wide range of experimental error levels. Our method may be applied to any type of wavefront sensor (not only dynamic skiascopy) able to measure either just tangential or tangential plus sagittal curvature data., Ministerio de Economía y Competitividad (MINECO), Sección Deptal. de Óptica (Óptica), Fac. de Óptica y Optometría, TRUE, pub

Lens average and equivalent refractive indices are required for purposes such as lens thickness estimation and optical modeling. We modeled the refractive index gradient as a power function of the normalized distance from lens center. Average index along the lens axis was estimated by integration. Equivalent index was estimated by raytracing through a model eye to establish ocular refraction, and then backward raytracing to determine the constant refractive index yielding the same refraction. Assuming center and edge indices remained constant with age, at 1.415 and 1.37 respectively, average axial refractive index increased (1.408 to 1.411) and equivalent index decreased (1.425 to 1.420) with age increase from 20 to 70 years. These values agree well with experimental estimates based on different techniques, although the latter show considerable scatter. The simple model of index gradient gives reasonable estimates of average and equivalent lens indices, although refinements in modeling and measurements are required.

Thesis (Ph. D.)--University of Rochester. Institute of Optics, 2012. Chapter 2 co-authored with Kenneth P. Greenberg and others; chapters 3-4 co-authored with Lee Anne Schery and others., The rodent has become an increasingly valuable model for human diseases and development due to its availability for genetic manipulations. Non-invasive microscopic imaging of the rodent retina would allow tracking of retinal development, disease progression, and the efficacy of therapy in single animals. Correction of the eye’s aberrations using adaptive optics (AO) could improve the resolution of in vivo rodent retinal images, but previous attempts have been limited by the small size of its eye and the difficulty in measuring its aberrations due to poor Shack-Hartmann wavefront sensor (SHWS) spot quality. The work in this thesis describes methods developed to measure the rodent eye optics and to optimize its retinal image quality in vivo. Our first attempt was modifying a confocal fluorescence adaptive optics scanning laser ophthalmoscope (AOSLO) originally built for imaging the primate and human eye to accommodate the rat eye. Despite achieving in vivo resolution sufficient to resolve sub-cellular structures in fluorescent ganglion cells, problems were identified with aberration measurements and AO image quality. We then constructed a SHWS customized for the small mouse eye, and found a solution to the aberration measurement problem. The custom designed SHWS can favor light from a specific retinal layer and provide good wavefront spot quality. This wavefront sensor was incorporated into a confocal AOSLO custom designed for the mouse eye. High quality images were obtained in the mouse retina revealing multiple cell layers, including the photoreceptor mosaic, nerve fiber bundles, fine capillaries/blood flow, and ganglion cell bodies and fine processes. The in vivo resolution of the system was directly characterized to be sub-[micrometer] laterally, and ~10 [micrometers] axially. This fine resolution has allowed classification of ganglion cells in vivo. The value of the instrument was also demonstrated in two functional imaging scientific studies.

A new and complete methodology of monofocal intraocular lens (IOL) design is presented aiming at isoplanatism, i.e. IOLs that provide the eye with optimized optical quality over a wide field of view (typically in a range of ten degrees). The methodology uses a merit function considering dimensional and biomechanical constraints, and a geometrical optical quality metric that is evaluated simultaneously at different field angles. As an example, we present new isoplanatic designs based on different commercial IOL platforms. Aspheric isoplanatic designs improve peripheral quality over current aspheric IOLs. Also, isoplanatic designs provide more stable optical quality across the field and across pupil diameter.

We present a prototype of an adaptive intraocular lens based on a modal liquid-crystal spatial phase modulator with wireless control. The modal corrector consists of a nematic liquid-crystal layer sandwiched between two glass substrates with transparent low- and high-ohmic electrodes, respectively. Adaptive correction of ocular aberrations is achieved by changing the amplitude and the frequency of the applied control voltage. The convex-shaped glass substrates provide the required initial focusing power of the lens. A loop antenna mounded on the rim of the lens delivers an amplitude-modulated radio-frequency control signal to the integrated rectifier circuit that drives the liquid-crystal modal corrector. In vitro measurements of a 5-mm clear aperture prototype with an initial focusing power of +12.5 diopter, remotely driven by a radio-frequency control unit at ~6 MHz, were carried out using a Shack-Hartmann wavefront sensor. The lens based on a 40-?m thick liquid-crystal layer allows for an adjustable defocus of 4 waves, i. e. an accommodation of ~2.51 dioptres at a wavelength of 534 nm, and correction of spherical aberration coefficient ranging from –0.8 to 0.67 waves. Frequency-switching technique was employed to increase the response speed and eliminate transient overshoots in aberration coefficients. The full-scale settling time of the adaptive modal corrector was measured to be ~4 s., Micro Electronics, Electrical Engineering, Mathematics and Computer Science

We propose and demonstrate a novel liquid deformable mirror, based on electrocapillary actuation, for highorder wavefront correction. The device consists of a two-dimensional array of vertically oriented microchannels filled with two immiscible liquids, an aqueous electrolyte, and a viscous dielectric liquid, where the dielectric liquid overfills the top end of the channel and forms a thin layer on top. To remedy the poor reflectivity of pure liquids, a free-floating reflective membrane or a dye-coated liquid can be used. The proposed device offers several advantages for adaptive optics applications. These advantages include a high number of actuators, high stroke dynamic range, low power dissipation, fast response time, an initially flat surface, and low cost. However, the device is mainly suitable for dynamic wavefront correction and is limited by its orientation., Imaging Science and Technology, Applied Sciences