Noise robust phase unwrapping with a virtual pyramid


Now, it is possible to effectively unwrap phase with noisy and low-signal interferometric measurements with the new method of phase unwrapping called the virtual pyramid wavefront sensor. This was demonstrated while reconstructing wavefronts from interferograms obtained in a digital (SLM-based) phase-shifting point diffraction interferometer. In comparison with existing methods, this new phase unwrapping method was found to be robust to random noise. We believe that this method can be applied to several metrology applications in ophthalmology, magnetic elastography and astronomy.

Full Citation: Vyas Akondi, Brian Vohnsen, and Susana Marcos, “Virtual pyramid wavefront sensor for phase unwrapping,” Applied Optics 55(29), 8363-8367 (2016).

Full Article:


Reconstructing full crystalline lens shape in vivo using OCT imaging, published in IOVS


We developed a methodology to reconstruct the entire crystalline lens shape, beyond the area visible through the pupil. The method uses data from ex vivo crystalline lenses to develop, test and validate the model. The accuracy in the estimation of lens volume, lens diameter or the equatorial lens position exceeds that achieved by state-of-the art methods. The method was applied in vivo in accommodating and cataract eyes. The paper is published in IOVS (Special issue commemorating 25 years of OCT)

Full reference: Martinez-Enriquez E, Sun M, Velasco-Ocana M, Birkenfeld J, P´erez-Merino P, Marcos S. Optical coherence tomography based estimates of crystalline
lens volume, equatorial diameter,and plane position. InvestOphthalmol Vis Sci. 2016;57:OCT600–OCT610.


New in the lab: Xoana Barcala


We welcome Xoana Barcala who will be joining VioBio to work on her Master Thesis work. Xoana is a Masters Student of the Vision Science Interuniversity Program led by the University of Valladolid, who has led BSc. studies in optometry and vision science at the Universidad Complutense de Madrid and Univesity of Latvia. Her interests reside in adaptive optics and temporal multiplexing approaches to simultaneous vision simulation.


New in the lab: Neeraj Kumar Singh


We welcome Neeraj Kumar, joining VioBio Lab today as a Early Career Research Fellow in MyFun Marie Curie ITN.  Neeraj comes to us from the Schepens Eye Research Institute-MEEI, Harvard University, where he has trained with Prof. Eli Peli, following Vision Science and Optometry Studies at the Elite Schol of Optometry in Chenai, India.
He joins other 13 young scientists in an international,  at the interface of physics and biology, to study unresolved questions about the visual control of eye growth as part of the MyFun ITN Network.
More information on MyFun ITN network can be found in:

New in the lab: Geethika Muralidharan


We welcome Geethika Muralidharan, joining VioBio Lab today as a Early Career Research Fellow in MyFun Marie Curie Sklowdoska  ITN.  Geethika, a MSc in Physics, comes to us from Cochin University of Science and Technology, in India, with a specialty in Photonics.
She joins other 13 young scientists in an international,  at the interface of physics and biology, to study unresolved questions about the visual control of eye growth as part of the MyFun ITN Network.
More information on MyFun ITN network can be found in:


Visual perception with different bifocal designs simulated with a 2-channel SimVis, published in Biomedical Optics Express


A 2-channel Simultaneous Vision Simulator provided with a spatial light modulator was used to generate 14 bifocal patterns (concentric, angularly segmented and hybrid). Patients performed perceived visual scoring, pattern preference and visual acuity tests at near, intermediate and far with the simulated lenses. Angularly segmented designs tended to outperfom the rest of designs on average. However, the high intersubject difference in preference and performance suggests patient specific interactions of the eye’s optics and the lens, and perceptual factors, which should be considered for bifocal design selection. Simultaneous Vision Simulators are excellent tools to identify the optimal correction for a patient, taking into account these factors.  The study has been published yesterday in Biomedical Optics Express.
Carlos Dorronsoro, Aiswaryah Radhakrishnan, Pablo de Gracia, Lucie Sawides, and Susana Marcos, “Perceived image quality with simulated segmented bifocal corrections,” Biomed. Opt. Express 7, 4388-4399 (2016).



Effect of orientation of a rotationally asymmetric bifocal lens design on visual quality using SimVis, published in JCRS


We used a two-channel Simultaneous Vision Simulator provided with a spatial light simulator to simulate the impact of the orientation of an angularly segmented bifocal lens design on vision. The lens represents a commercially-available design (Oculentis Mplus), but texperiments can be performed on the same eye (i.e. not involving IOL implant, and making it possible to compare across 8 different rotation positions).  We found that the bias towards particular orientations in some individuals could be explained by the interactions of the optics of the eye with the lens design. The paper appears in the current issue of the Journal of Cataract and Refractive Surgery

Full reference: Radhakrishnan, Dorronsoro and Marcos. Differences in visual quality with orientation of a rotationally asymmetric bifocal intraocular lens design Journal of Cataract & Refractive Surgery 42 (9) 1276–1287 (2016)

IBE.TV interview to Susana Marcos in “El Arbol de la Ciencia”



El Arbol de la Ciencia, a program of, a plaform for education, culture, science and cooperation in iberoamerica, interviews Susana Marcos, in a series of program dedicated to Women Scientists.  Susana Marcos talks about aspects about her life and career.

You can watch the interview in this link:énero-particularmente-en-f%C3%ADsica.htm


Linking science and art: Susana Marcos discussing presbyopia around a painting at the Prado Museum


Susana Marcos discusses art and science at the Museo del Prado, around the painting of Saint Jeronimus reading a letter, by French artist Georges de la Tour. The program is an inniative of the Fundacion Para la Ciencia y la Tecnología, and Museo del Prado, and was featured in La Aventura del Saber, of RTVE
You can now watch the video (in Spanish):

Susana Marcos, selected member of the “Seleccion Española de Ciencia” by QUO


The Spanish science magazine QUO has selected the third Seleccion Española de Ciencia, formed by the most prestigious researchers in Spain. This year’s selection includes Prof. Susana Marcos Director of the Visual Optics and Biophotonics Lab at the Instituto de Optica, CSIC.

Full link to article (in Spanish):

Link to interview to Susana Marcos (in Spanish):


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