Monthly Archives: September 2013

Crystalline lens shape, GRIN and spherical aberration changes with accommodation, published in IOVS


We present OCT-based measurements of crystalline lens shape and Gradient Index distribution with in vitro simulated accommodation, and their contribution to the changes in spherical aberration. GRIN plays a significant role in shifting spherical aberration towards more negative values, at all accommodative stages, although the average and equivalent index of refraction do not change significantly with accommodation.

The study is a collaborative effort between the Visual Optics and Biophotonics Lab (Instituto de Optica, CSIC) and Bascom Palmer Eye Institute (University of Miami), partly funded by CSIC i-LINK

Full reference:  Alberto de Castro, Judith Birkenfeld, Bianca Maceo, Fabrice Manns, Esdras Arrieta, Jean-Marie Parel and Susana Marcos. Influence of Shape and Gradient Refractive Index in the Accommodative Changes of Spherical Aberration in Nonhuman Primate Crystalline Lenses, Invest. Ophthalmol. Vis. Sci. , 2013 vol. 54 no. 9 6197-6207

Quantitative OCT-Based Longitudinal Evaluation of Intracorneal Ring Segment Implantation in Keratoconus, published in IOVS


Quantification tools in OCT were used to fully characterize anterior and posterior corneal topography as well as intracorneal ring segments pre- and post-operatively (7, 30 and 90 days) in keratoconic patients. ICRS produced flattening on the anterior corneal surface, although the benefit for corneal surface regularization varied across patients. The ICRS rotated by around 7 deg post-implantation. The study demonstrates that high speed OCT provided with quantitative tools is an excellent technique to evaluate ICRS surgery in keratoconus.

Full reference: Perez-Merino P, Ortiz S, Alejandre N, Jimenez-Alfaro I, Marcos S. Quantitative OCT-based longitudinal evaluation of intracorneal ring segmentation implantation in karatoconus. Invest Ophthalmol Vis Sci. 2013;54:6040–6051

The study is part of collaborative work between the Visual Optics and Biophotonics Lab (IO, CSIC) and Instituto de Investigacion Sanitaria Fundacion Jimenez Diaz, though an Associated Unit

Multizonal mulifocal phase patterns, published in Optics Letters



This computational study explores radially and angularly segmented multifocal patterns. The analysis reveals that angularly segmented (3-4 segments) are optimal patterns, providing more extended depth of focus and higher optical performance than patterns with larger amount of segments, radially concentric patterns, or spherical aberration inducing patterns. The study has been published today in Optics Letters.

Full reference:    Pablo de Gracia, Carlos Dorronsoro, Susana Marcos, “Multiple zone multifocal phase designs”, Optics Letters, Vol. 38, Issue 18, pp. 3526-3529 (2013).

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