María S Millán

• Doctor of Philosophy
• Research Director at Polytechnic University of Catalonia

This study investigates whether a diffractive presbyopia-correcting multifocal intraocular lens disrupts the favorable interaction between chromatic and monochromatic aberrations in the eye. This is analyzed not only for distant objects but also for closer viewing distances, where the lens utilizes different diffraction orders depending on its desi...

PURPOSE To assess the power profile and optical performance of two extended range of vision (ERV) intraocular lenses (IOLs), TECNIS® Eyhance (ICB00) and LuxSmart TM , and compare them with their monofocal counterpart lenses with similar platforms and materials: TECNIS® 1-piece (ZCB00) and LuxGood TM , respectively. SETTING Optics and Optometry Fac...

Diffractive optics is a valuable technique for designing presbyopia-correcting lenses, but its effectiveness is wavelength-dependent. This study investigates the spatio-chromatic alterations in visual resolution associated with diffractive multifocal lenses by using non-invasive, removable diffractive bifocal contact lenses. The study combines theo...

To evaluate the impact of residual astigmatism on the optical and visual performance of an enhanced-monofocal isofocal intraocular lens (EM Isopure, BVI medical, Belgium) compared to a monofocal one (Micropure, BVI medical, Belgium). Laboratory investigation and prospective, comparative and randomized clinical study. Optical quality was assessed on...

Background: This study aims to detect alterations in the spatio-chromatic pseudophakic vision produced by multifocal diffractive intraocular lenses (IOLs) and provides a physical interpretation. Methods: In vitro characterization of the imaging performance of two diffractive IOLs: AT LISA Tri (Zeiss) and FineVision (PhysIOL) in on-bench model ey...

The strong wavelength dependency of diffractive elements casts reasonable doubts on the reliability of near-infrared- (NIR)-based clinical instruments, such as aberrometers and double-pass systems, for assessing, post-surgery, the visual quality of eyes implanted with diffractive multifocal intraocular lenses (DMIOLs). The results obtained for such...

Some ocular and cardiovascular diseases can be detected through the increased tortuosity of retinal blood vessels. Objective tortuosity measures can be obtained from digital image analysis of a retinography. This study tested a set of local tortuosity indices under a change in the frame center (macula, optic disc) of the eye fundus image. We illust...

A novel nonlinear encryption–decryption system based on a joint transform correlator (JTC) and the Gyrator transform (GT) for the simultaneous encryption and decryption of multiple images in grayscale is proposed. This security system features a high level of security for the single real-valued encrypted image and a high image quality for the multi...

In this work, we present a new nonlinear joint transform correlator (JTC) architecture in the Fourier domain (FD) for the encryption and decryption of two simultaneous images. The main features of the proposed system are its increased level of security, the obtention of a single real-valued encrypted signal that contains the ciphered information of...

Purpose To assess the optical quality and halo formation of a beam-shaping extended depth-of-focus (EDOF) intraocular lens (IOL) (AcrySof IQ Vivity; Alcon Laboratories, Inc) with corneas of long-range spherical aberration (SA) such as those resulting from myopic laser ablations. Methods The optical quality of the EDOF IOL and a reference monofocal...

Specular microscopy assessment of the human corneal endothelium (CE) in Fuchs’ dystrophy is challenging due to the presence of dark image regions called guttae. This paper proposes a UNet-based segmentation approach that requires minimal post-processing and achieves reliable CE morphometric assessment and guttae identification across all degrees of...

Purpose: To assess the optical performance of four extended range of vision (ERV) intraocular lenses (IOLs) and predict the visual quality of the average pseudophakic patient. Methods: Four ERV IOLs (LuxSmart, Bausch & Lomb; Vivity, Alcon Laboratories, Inc; Tecnis Eyhance, Johnson & Johnson Vision; and Isopure, PhysIOL) were inserted in an on-be...

Specular microscopy assessment of the human corneal endothelium (CE) in Fuchs' dystrophy is challenging due to the presence of dark image regions called guttae. This paper proposes a UNet-based segmentation approach that requires minimal post-processing and achieves reliable CE morphometric assessment and guttae identification across all degrees of...

Purpose: To evaluate the optical and clinical performance of an enhanced monofocal intraocular lens (IOL) (TECNIS Eyhance ICB00; Johnson & Johnson Vision) in patients with high hyperopia and a short axial length. Methods: Power mapping, wavefront analysis, and the through-focus modulation transfer function area (TF-MTFa) were measured in vitro f...

The need for fast, inexpensive, and robust medical technology is now more crucial than ever [...]

Purpose: To assess the in vitro optical quality and halo formation of the AcrySof IQ Vivity intraocular lens (IOL) (Alcon Laboratories, Inc) and to evaluate the clinical outcomes in patients who had bilateral implantation of this IOL. Methods: The optical quality was evaluated with the PMTF optical bench (Lambda-X). Through-focus modulation tran...

We explore the possibility of extending the depth of focus of an imaging lens with an asymmetric quartic phase-mask, while keeping the aberration within a relatively low level. This can be intended, for instance, for ophthalmic applications, where no further digital processing can take place, relying instead on the patient’s neural adaptation to th...

The defocus curve (DC) has become the gold standard method for assessing the visual performance at different distances, and hence, to evaluate the depth of focus that is provided by modern presbyopia-compensating intraocular lenses that are used in cataract surgery. A former study, carried out by other authors, reported that the DC method, based on...

This work aims to evaluate the size and intensity of the halos generated in distance vision by bifocal and extended depth of focus (EDOF) intraocular lenses (IOLs) as a function of pupil size, lens base power and lens addition. To this end, an EDOF-IOL (Tecnis® Symfony ZXR00) and three bifocal IOLs (Tecnis® +4.00 diopter (D) ZMB00, +3.25D ZLB00 and...

Clinical relevance It is important to distinguish between visual acuity, optical quality and quality of vision when outcomes obtained with intraocular lenses are evaluated. These parameters, that includeobjective and subjective tests, should be assessed to obtain results that are not biased. Background To assess the difference in visual and optica...

La catarata o pérdida de transparencia del cristalino es un trastorno de la visión muy invalidante que ha sufrido la humanidad a lo largo de la historia. En las últimas décadas se trata con éxito mediante la sustitución de la lente natural por una lente artificial intraocular. Este estudio se centra en los aspectos ópticos, desde el diseño del impl...

Purpose compare subjective (Rx) and objective (ObjRx) refractions outcomes with two autorefractors models and an aberrometer in eyes implanted with a hydrophobic trifocal IOL (FineVision POD F GF, Physiol, Liége, Belgium) and a hydrophilic one (FineVision POD F, Physiol, Liége, Belgium). Methods prospective comparative cohort study, with 100 subje...

Two theoretical sinusoidal diffractive profile models to build up a trifocal intraocular lens (IOL) are analysed. Topographic features of the diffractive zones such as their shape, step height and radii, as well as the energy efficiency (EE) of the foci, depends on the particular model, and are compared to the ones experimentally measured in a trif...

Purpose To evaluate the changes in pupil diameter in women and men after cataract surgery. The correlation of pupillary changes with the variables age and anterior chamber depth will be analyzed. Methods The values of 109 randomized eyes who underwent cataract surgery were obtained and divided into two groups, 71 women and 38 men. Pupil diameter w...

The 3rd central IDL Event in Spain probably gathered the largest number of activities for the 16th May commemoration in 2021. Conferences, debates, workshops, exhibitions, light shows, and photo contests, adapted to severe constraints due to the pandemic, achieved the participation of a wide and diverse audience.

Purpose: To compare the chromatic performance of the Bausch & Lomb Versario 3F trifocal intraocular lens (IOL) with the PhysIOL FineVision MicroF trifocal IOL and the Johnson & Johnson Vision TECNIS Symfony ZXR00 extended range of vision (ERV) IOL. Methods: The through-focus energy efficiency (TF-EE) was measured in vitro with red (R), green (G)...

Purpose: To test the performance of a new monofocal intraocular lens, intended to extend depth of focus (Tecnis Eyhance, ICB00; Johnson & Johnson Vision, Inc) (ICB-IOL), in comparison to a standard monofocal IOL (Tecnis 1-piece, ZCB00; Johnson & Johnson Vision, Inc) (ZCB-IOL) of the same platform and material. Methods: Assessment of the optical...

Automated cell counting in in-vivo specular microscopy images is challenging, especially in situations where single-cell segmentation methods fail due to pathological conditions. This work aims to obtain reliable cell segmentation from specular microscopy images of both healthy and pathological corneas. We cast the problem of cell segmentation as a...

Accurate endothelial cell density with specular microscopy is essential for correct clinical assessment of the cornea. Commercial specular microscopes incorporate automated cell segmentation methods to estimate cell density. However, these methods are prone to false cell detections in pathological corneas. This project aims to obtain a reliable aut...

We present a new experimental system for optical encryption using a nonlinear joint transform correlator (JTC) to implement the optical security technique of the double random phase encoding (DRPE). The DRPE, which is usually performed in a 4f-processor, encodes an image into a noisy distribution (encrypted image) by using two random phase masks (R...

This article studies the relationship between two metrics, the area under the modulation transfer function (MTFa) and the energy efficiency (EE), and their ability to predict the visual quality of patients implanted with multifocal intraocular lenses (IOLs). The optical quality of IOLs is assessed in vitro using two metrics, the MTFa and EE. We mea...

The optical quality of three multifocal intraocular lenses (MIOLs) was measured in vitro using the area under the modulation transfer function (MTFa) and energy efficiency (EE). We evaluated those metrics through-focus (TF) by axially scanning the image space with three wavelengths (R, G, B). High linear correlation between MTFa and EE was found fo...

We propose a new encryption system based on a nonlinear joint transform correlator (JTC) using the information of two biometrics (one digital fingerprint for each user) as security keys of the encryption system. In order to perform the decryption and authentication in a proper way, it is necessary to have the two digital fingerprints from the respe...

We describe a psychophysical method and a simple setup – an autorefractor with a Scheiner disc, sequentially illuminated with red and blue lights – for the clinical assessment of the longitudinal chromatic aberration (LCA) in phakic and pseudophakic patients. This method applies to the unaccommodated eye, even in the presence of positive or negativ...

A liquid crystal on silicon spatial light modulator (LCoS SLM) with large phase modulation has been thoroughly characterized to operate optimally with several linear phase modulation ranges (π, 2π, 3π, 4π, 6π, and 8π) for an intermediate wavelength of the visible spectrum (λG = 530 nm). For each range, the device response was also measured for two...

In this work, the occlusion and noise test on the encrypted image produced by a joint transform correlator-based encryption system in the Fresnel domain (FrD) are computed and presented, in order to check the performance of this security system with respect to the image quality resulting in the decryption process for the retrieved image. The encryp...

Ecos del discurso de ingreso en la Real Academia Española. Bajando por mi rama en el árbol de la genealogía académica, llegué un día hasta Blas Cabrera Felipe. Quise bajar más y saber quién le había dirigido la tesis. No encontré una respuesta concluyente, pero descubrí, eso sí, la influencia de Ramón y Cajal en su formación científica. Y seguí ind...

Objective To compare visual quality in patients implanted with Tecnis® monofocal (ZCB00) and multifocal (ZMB00) intraocular lenses taking into account their optical quality measured in vitro with an eye model. Methods In total, 122 patients participated in this study: 44 implanted with monofocal and 78 with multifocal intraocular lenses. Measureme...

We consider the changes produced in the quality of eye fundus images of patients before and after cataract surgery with intraocular lens implantation and propose a measure to quantitatively assess those changes. Several factors concerning the optical system of the eye, the ocular media, and the specific characteristics of the implanted intraocular...

The optical quality of a set of IOLs (modeling set: one monofocal and two bifocals) was assessed through focus by the area under the modulation transfer function (MTFa) metric and related to the visual acuity (VA) defocus curves of pseudophakic patients implanted with said IOLs. A non-linear relationship between the MTFa and clinical VA was obtaine...

A new unsupervised method for segmentation of objects of diverse nature with the common feature of connectivity (e.g. branching trees or net-shaped objects) is proposed. A preferred application to the vasculature segmentation of retinal images has been illustrated using images from DRIVE database. In the pre-processing stage, the method overcomes t...

Retinal fundus cameras suffer from dust particles attaching to the sensor and lens, which manifest as small artifacts on the images. We propose a new strategy for the detection and removal of dust particle artifacts in retinal images. We consider as input two or more color fundus images acquired within the same session, in which we assume the artif...

Purpose: To examine and assess the halos generated in distance vision by multifocal intraocular lenses (IOLs) using both in vitro objective and in vivo subjective methods. Setting: The objective method was carried out in the optics laboratory of the Applied Optics and Image Processing Group (Universitat Politècnica de Catalunya -Barcelona). The psy...

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 t...

Purpose To compare objective image quality at distant, intermediate, and near foci with the corresponding visual acuity (VA) in patients symmetrically implanted with 5 different diffractive multifocal intraocular lenses (IOLs) (ReSTOR SV25T0, Tecnis ZKB00, Tecnis ZLB00, AT LISA 809, and AT LISA Tri 839MP) and a monofocal lens (Tecnis ZA9003) 3 mont...

Medical digital imaging has become a key element of modern health care procedures. It provides visual documentation and a permanent record for the patients, and most important the ability to extract quantitative information about many diseases. Modern ophthalmology relies on the advances in digital imaging and computing power. In this paper we pres...

This paper presents results of the research related with the development of the doctoral thesis of Lenny Alexandra Romero Pérez. This work covers the design, the characterization and the analysis of several programmable diffractive optical elements (PDOEs) such as: Fresnel lenses, multifocal lenses, integrated combinations of phase-masks with lense...

The optical characterization of an intraocular lens (IOL) provides objective and quantitative information that is essential to fully understand its performance as an implant that replaces the crystalline lens in the human visual system. Additionally, it can be used to predict the performance of the new IOL designs. This characterization has to be c...

An increasing demand of spectacle independence after cataract surgery or clear lens extraction has greatly stimulated the development of multifocal intraocular lenses (MIOLs). Optical design has played an essential role in this progress. Based on the principle of simultaneous vision, MIOLs overcome the loss of accommodation by providing at least tw...

Retinal eye fundus images are used for diagnostic purposes, but despite controlled conditions in acquisition they often suffer from uneven illumination and blur. In this work, we propose the use of multi-channel blind deconvolution for the restoration of blurred retinal images. The estimation of an adequate point-spread function (PSF) is highly dep...

Information security and authentication are important challenges facing society. Recent attacks by hackers on the databases of large commercial and financial companies have demonstrated that more research and development of advanced approaches are necessary to deny unauthorized access to critical data. Free space optical technology has been investi...

Purpose: The study evaluated-theoretically and experimentally-the longitudinal chromatic aberration (LCA) and through-focus energy efficiency (TF-EE) of diffractive-refractive bifocal intraocular lenses (2f-IOLs). Methods: Four aspheric 2f-IOLs (Tecnis +4.00 diopter [D] ZMA00, +2.75 D ZKB00, and AcrySof +4.0 D SN6AD3, +2.5 D SV25T0) of same base...

A novel nonlinear image encryption scheme based on a fully phase nonzero-order joint transform correlator architecture (JTC) in the Gyrator domain (GD) is proposed. In this encryption scheme, the two non-overlapping data distributions of the input plane of the JTC are fully encoded in phase and this input plane is transformed using the Gyrator tran...

Retinal images are used for diagnostic purposes by ophthalmologists. However, despite controlled conditions in acquisition retinal images often suffer from non-uniform illumination which hinder their clinical use. In this work we propose the compensation of the illumination by modeling the intensity as a sum of non-stationary signals using bidimens...

Purpose: The purpose of this study was to compare the optical performance of diffractive multifocal intraocular lenses (DMIOLs) with visible (VIS) illumination with that of near infrared (NIR) illumination, the latter being used to test pseudophakic eyes in clinical aberrometers and double-pass systems. Methods: Two DMIOLs of different design (T...

15 mins presentation for the International OSA(Optical society of America) network of students in intraocular lenses symposium

Published ISBN 978-84-608-4609-3 (Abstract Contributions)

Poster presented in the 11th volume for the scientific national meeting for optics

In this work, we present the integration of the photon counting technique (PhCT) with an encryption system in the Gyrator domain (GD) for secure image authentication. The encryption system uses two random phase masks (RPMs), one RPM is defined at the spatial domain and the other RPM is defined at the GD, in order to encode the image to encrypt (ori...

To compare, as a function of pupil size, the through-focus performance and halo features of four diffractive intraocular lenses (IOLs). Three diffractive bifocal IOLs (ReSTOR +2.5 D SV25T0, Tecnis +2.75 D ZKB00, and AT LISA +3.75 D 809M) and a diffractive trifocal IOL (AT LISA tri +3.33 D, +1.66 D 839MP) were tested in vitro in a modified Internati...

The multifactor optical ID tag reinforces high security verification purposes for credit cards, passports, and productidentification marks. In this applications, the optical ID tag should be robust to external distortions. In this work, weinvestigate the robustness to external distortions of multifactor optical identification (ID) tag based on mult...

The multifactor optical encryption authentication method [Opt. Lett., 31 721-3 (2006)] reinforces optical security by allowing the simultaneous authentication of up to four factors. In this work, the photon-counting imaging technique is applied to the multifactor encrypted function so that a sparse phase-only distribution is generated for the encry...

Retinal images often suffer from blurring which hinders disease diagnosis and progression assessment. The restoration of the images is carried out by means of blind deconvolution, but the success of the restoration depends on the correct estimation of the point-spread-function (PSF) that blurred the image. The restoration can be space-invariant or...

The depth of focus (DOF) defines the axial range of high lateral resolution in the image space for object position. Optical devices with a traditional lens system typically have a limited DOF. However, there are applications such as in ophthalmology, which require a large DOF in comparison to a traditional optical system, this is commonly known as...

Retinal photography is important for the assessment of eye diseases. The task of fine focusing the image is demanding and lack of focus is often the cause of suboptimal photographs. The advent of digital cameras has provided the opportunity to automate the focusing process. In this work, we propose an auto-focus system for non-mydriatic retinal ima...

We propose a generalization of the encryption system based on double random phase encoding (DRPE) and a joint transform correlator (JTC), from the Fourier domain to the fractional Fourier domain (FrFD) by using the fractional Fourier operators, such as the fractional Fourier transform (FrFT), fractional traslation, fractional convolution and fracti...

Objective: To present the theoretical and experimental characterization of the halo in multifocal intraocular lenses (MIOL). Method: The origin of the halo in a MIOL is the overlaying of 2 or more images. Using geometrical optics, it can be demonstrated that the diameter of each halo depends on the addition of the lens (ΔP), the base power (P(d)...

Ophthalmology can profit greatly from the analysis of digital images because they can aid in establishing an early diagnosis even before the first symptoms appear. This dissertation [1] contributes to the digital analysis of such images and the problems that arise along the imaging pipeline of fundus photography, a field that is commonly referred t...