Perceived Transverse Chromatic Aberration study, published in Biomedical Optics Express


We implemented a new channel in a polychromatic Adaptive Optics system to measure Transverse Chromatic Aberration (TCA). Perceived TCA (measured with a large pupil) differs from optical TCA (measured with a small pupil). Besides, correcting monochromatic aberrations changed TCA orientation and increased its magnitude. We found that estimations of perceived TCA considering measured optical TCA, Stiles-Crawford Effect, Monochromatic Aberrations and Longitudinal Chromatic Aberration accurately predicted the measured perceived TCA. The study allows therefore understanding the relative contributions of different factors to polychromatic chromatic image quality.

Full reference: Sara Aissati, Maria Vinas, Clara Benedi-Garcia, Carlos Dorronsoro, and Susana Marcos, “Testing the effect of ocular aberrations in the perceived transverse chromatic aberration,” Biomed. Opt. Express 11, 4052-4068 (2020).

Full article here

Gradient index distribution in guinea pig crystalline lenses


We used Optical Coherence Tomography and an inverse optimization technique to estimate the crystalline lens gradient index distribution in guinea pig, a popular animal model for myopia. Measurements were obtained in eyes of different refractions and ages. GRIN followed a parabolic profile, and the nucleus and surface refractive index values were consistent with those of other mammals. We found that the presence of GRIN reduced the magnitude of lens spherical aberration, and this tended to increase with age.

The study is the result of collaborative work between CSIC (Viobio Lab, Institute of Optics) and the University of Newcastle, Australia.

Full reference: Alberto de Castro, Eduardo Martinez‐Enriquez, Pablo Perez‐Merino, Miriam Velasco‐Ocaña, Luis Revuelta, Sally McFadden, Susana Marcos “Crystalline lens gradient refractive index distribution in the guinea pig” Ophthalmic & Physiological Optics 40, 308–315 (2020) doi:

Full article here

Changes of full crystalline lens shape with age, published in IOVS

Paper Edu IIThree-dimensional quantitative OCT was used to study the age-dependency of geometric parameters of the full isolated human crystalline lens, including surface radii of curvature and asphericities, lens volume, surface area, equatorial diameter and equatorial plane position. We found that most of the lens geometric parameters showed a biphasic behavior, changing rapidly before age 20 years and with a slower linear growth thereafter.

The study is the result of collaborative work between the Ophtalmic BIophysics Groups at Bascom Palmer Eye Research Institute (University of Miami),  LVPrasad Eye Institute and the Visual Optics and Biophotonics Lab (Institute of Optics, CSIC).

Full reference: Eduardo Martinez-Enriquez, Alberto de Castro, Ashik Mohamed, N. Geetha Sravani, Marco Ruggeri, Fabrice Manns, Susana Marcos. Age-Related Changes to the Three-Dimensional Full Shape of the Isolated Human Crystalline Lens. Invest. Ophthalmol. Vis. Sci. 61(4):11 (2020) doi:

Full article here

Interactions of chromatic & polychromatic aberrations published in JRS


The study measured chromatic longitudinal aberration and monochromatic aberrations at various wavelengths in patients implanted with a new monofocal intraocular lens (Clareon). We found that the effect of LCA is highest in the least aberrated eyes.

These results have interest in understanding optimal quality of the pseudophakic eyes and implications on the effect of modulating chromatic aberrations with future IOL designs. The study is a collaborative effort between VioBio Lab (IO-CSIC) and Fundación Jiménez Díaz.

Full reference: Susana Marcos, Mercedes Romero, Clara Benedí-García, Ana González-Ramos, Maria Vinas, Nicolás Alejandre, Ignacio Jiménez-Alfaro, Interaction of Monochromatic and Chromatic Aberrations in Pseudophakic Patients. Journal of Refractive Surgery. 36(4):230-238 (2020) doi:10.3928/1081597X-20200303-01

Full article here

Collagen organization after in vivo Rose Bengal/Green & Riboflavin/UVA Cross-Linking in Rabbits, published in IOVS


One option for treating keratoconus, a degenerative disease that results in a weakened cornea and vision loss, is cross-linking. Cross-linking strengthens the overall structure of the cornea by promoting the creation of covalent bonds between neighboring collagen fibrils or between fibrils and the surrounding extracellular matrix. To measure how cross-linking affects the cornea at different depths inside the stroma, three different corneal treatments were performed on rabbit animal models: no treatment, Riboflavin instillation/Ultraviolet irradiation, and Rose Bengal instillation/Green light irradiation. Rabbits were sacrificed one and two months after treatment. Images of corneal lamellae were taken with a second harmonic generation laser scanning microscopic developed at VioBio Lab and were analyzed with a MATLAB script to measure the different directions of the collagen fibers. The collagen fibers in the cross-linked corneas had more uniform fiber orientations than in untreated corneas through a depth of 300 microns. The amount of second harmonic generation is also greater in cross-linked corneas than in control corneas. Both the organization and second harmonic generation signal increased between one month and two months after treatment. This research was a collaboration between CSIC, the University of Valladolid, and the Wellman Center for Photomedicine.

Full reference: James A. Germann, Eduardo Martínez-Enríquez, M. Carmen Martínez-García, Irene E. Kochevar, Susana Marcos; Corneal Collagen Ordering After In Vivo Rose Bengal and Riboflavin Cross-Linking. Invest. Ophthalmol. Vis. Sci. 61(3):28 (2020). 

Full article here

LightLens awarded the second prize of the 2019 Healthstart Madri+d Program


LightLens project has been awarded the second prize of the 4th edition of the Healthstart Madri+d program. The LightLens project is a tech transfer venture of an accommodating intraocular lens, which mimics the natural functioning of the young crystalline lens, enabled by photobonding, a VioBio Lab developed technology. The concept, prototype and demonstration of an intraocular lens capable of dynamically reshape is the result of the ERC Advanced Grant PRESBYOPIA. 

Healthstart Madri+d is aimed at entrepreneurs and professionals in the healthcare sector with technological projects developed at hospitals, universities and research centers within the Madrid Region, who want to make their project a reality. The program seeks to enhance highly added value research results, throughout all the commercialization process.

  • More information about Healthstart Madri+d Awards here
  • LightLens project video here



Invited Article on Adaptive Optics in The Ida Mann 2020 Special Issue (Ophthalmic and Physiological Optics)


VioBio Lab has contributed with a review paper on Adaptive Optics Visual Simulation in The Ida Mann 2020 Special Issue celebrating some of the leading female vision scientists worldwide. This issue is a tribute to the distinguished Professor and Opthalmologist Dame Ida Caroline Mann, the first woman to receive a professorship at Oxford, in 1945.

The paper reviews past and current work of the Visual Optics and Biophotonics Lab (development of two AO systems, and applications ranging from the understanding of the effect of optical aberrations on vision, neural adaptation to optical blur, and vision with simulated contact and intraocular lenses), has been co-authored by all women vision scientists at VIOBIO.

Full reference: Susana Marcos, Clara Benedí‐García, Sara Aissati, Ana M Gonzalez‐Ramos, Carmen Lago, Aishwaryah Radhkrishnan, Merces Romero, Shrilekha Vedhakrishnan, Lucie Sawides & Maria Vinas. VioBio lab adaptive optics: technology and applications by women vision scientists. Ophthalmic Physiol Opt 2020; 40: 75– 87.

Full article here

Susana Marcos, recognized in hometown Salamanca, in the International Day of Women


Susana Marcos received the recognition of the city of Salamanca last March 9,  for her achievements in science and technology transfer, in a fully packed city theater, along with Lourdes Losa (Airforce Captain) and Beatriz Dominguez (Director of the National Center of Organ Transplants). In her speech, Prof. Marcos stressed that “days like today provide the motivation and inspiration in science and all fields to promote diversity and bet on talent, wherever that is”.

More information about the event: 

New in the lab: Mar Fernández

Mar Fernandez

Mar Fernández, BSc in Pharmacy and PhD in Pharmacology by University of Salamanca, has recently joined VioBio Lab within the framework of the H2020 ERC Advanced Grant SILK-EYE. Mar developed her professional career at the Institute of Polymer Science and Technology (CSIC), group of Biomaterials, where she specialized in the development of polymer systems applied to healthcare. She has extensive experience in the design, preparation and characterization, both physicochemical and biological, of systems for covering cardiovascular devices. 

New in the lab: Pilar Urizar

Pilar Urizar

We welcome Pilar Urizar (BSc in Physics, Universidad de Zaragoza) who is joining VioBio Lab (CSIC) and spin-off company 2EyesVision under an Industrial Doctorate Program funded by Madrid Regional Government. Pilar holds a MSc in Photonics by Universidad Politécnica de Cataluña and she has extended experience in the assembly of optical systems and the development of activities related to optical design. She will be working on the OCT team focused on the development of a new biometer.

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