Author: Danilo Andrade de Jesus, Wrocław University of Technology
Optical Coherence Tomography (OCT) has become a popular instrument to analyze the anterior segment of the eye. It is particularly attractive due its capability to provide, in real time, cross sectional images of tissue structure in situ. Interferometry, the measurement technique on which OCT is based, gives rise to speckle, which has been considered a form of noise that degrades the quality of the OCT image. In fact, speckle can also be signal-carrying and be used to infer about the properties of the tissue, as it has been done in ultrasound.
Therefore, we have been trying to assess the corneal biomechanical properties modelling the corneal speckle from Optical Coherence Tomography. In order to achieve such goal, multiple mathematical statistical models have been used to fit the corneal backscattering data and the parameters of competing models were calculated using maximum likelihood estimation. The influence of choosing different regions of interest has also been into account. The applicability of the best model was tested analyzing corneal speckle statistics of subjects with different ages. In addition, variation of the corneal backscattering on subjects with induced corneal edema was tracked.
Generalized Gamma Distribution has proven so far, to be the best model to fit the OCT corneal speckle. Its scaling and two shape parameters have shown to be sensitive to the variation of corneal backscattering properties. Differences among people with different ages was observed, showing the possibility to access corneal age-related changes using OCT corneal envelope statistics. Similar results were obtained for subjects with induced corneal edema showing that corneal backscattering statistics can also be used to track corneal biomechanical properties.
So far, we have seen that Generalized Gamma distribution can be used to fit the corneal speckle and may have a great potential to be a helpful complement to evaluate the structure and elastic properties of the cornea in-vivo. The results of this study will be presented on the Annual meeting of the Association for Research in Vision and Ophthalmology in Seattle, 1-5 May, 2016.
Author: Cari Pérez Vives, PhD, Medical Affairs, Alcon Management (Switzerland)
The Industry-week for the Ageye consortium in Alcon Spain took place the second week of February 2016 in Barcelona. The purpose of this meeting was to introduce the fellows to the industry, since it might be an interesting option for them when they will finish their PhD studies.
The first day we met in the Alcon/Novartis offices where the Surgical Business Head, Medical & Regulatory Head from Alcon
Iberia and Medical Franchise Lead from Alcon EMEA explain us the organization and structure of Alcon, global leader in
eye care multinational company with more than 24.000 associates in 75 countries and product distribution to 180 countries. They also showed the portfolio covering a broad range of eye conditions and diseases for the full life cycle of eye care needs.
The second day, Alcon employees from Regulatory Affairs, Medical Affairs, Clinical operations, Safety, HR, Marketing, Medinfo, Market Access and CAS (Clinical Application Specialist) explained us their role in Alcon as well as their background. HHRR team explained how to look for Alcon job offers in their website, they showed some examples of these job descriptions and gave some advises to the fellows on how to apply for the different positions. The ER Marie Curie fellow (Cari Perez) also showed which are her activities as a post-doctoral fellow in Alcon and explained the interest of this fellowship in the private sector and her future opportunities.
The third day we visited the manufacturing plan, the library, the medieval pharmacy, the museum and the wetlab in El Masnou. In the wetlab an Equipment Manager explained us several surgical equipment from Alcon and we had the chance to practice with them.
The last day we went to IMO (Instituto de Microcirugia Ocular) where we saw how an eye hospital is working. We did a tour around outside the operation rooms (OR) watch eye surgery live on screens and they explained us the OR organization. IMO also has a wetlab and some fellows had the opportunity to perform cataract surgeries and vitrectomies in pig eyes. We finished the day visiting the IMO facilities and the laboratory of genetics.
According to a survey completed by the fellows, this industry-week was a fruitful event, since the meeting met the expectations of all of them; they found it educative and substantially increased their knowledge about the private sector. The favorite days were Alcon employees’ roles and IMO’s visit. The following quotes were reported:
After this week I clarify/encourage/raise (my) interest of industry as an option for my near future
I have a wider vision of the different roles in a company and also how important is the flexibility for a personal development.
We have to take risk and go out the comfort zone to be successful and feel rewarding with our job.
A company success comes not only from the product but from the people behind.
Author: Eleni Papadatou, MSc, University of Valencia, Spain
Bifocal and trifocal diffractive IOLs are designed to concentrate the light in two or three foci. However, not all the energy can be accurate focalized and therefore the presence of visual artifacts due to diffractive effects is possible to occur. In vitro evaluation of IOLs is essential to assure that they meet a minimum quality standard.
In a new study, the optical quality of fresh commercially available IOLs (aspeheric monofocal and diffractive multifocal IOLs) was evaluated by means of the modulation transfer function (MTF) and straylight. The MTF was obtained with the PMTF instrument (Lambda-X) for different pupil sizes and the straylight was recorded using the C-Quant device (Oculus) with a modification that allows for in vitro IOLs straylight assessment.
The results demonstrated thatalthough monofocal IOLs yielded a better optical quality in terms of MTF, multifocal IOLs were less affected by pupil size (Figure 1). In terms of straylight, all the IOLs values were too low when comparing to the normal eye (Figure 2). Moreover, multifocal IOLs had values similar to the monofocal IOLs, thus diffractive effects per se of these IOLs are not expected to elevate postoperative straylight of the eye.
Figure 1: Through Focus MTF at 50 cy/mm
Figure 2: Straylight values of IOLs (expressed in straylight parameter)
Preliminary data of this study have been submitted in an abstract form for ARVO 2016 congress (Seattle, USA).
- Montés-Micó, R., Madrid-Costa, D., Ruiz-Alcocer, J., Ferrer-Blasco, T., & Pons, Á. M. (2013). In vitro optical quality differences between multifocal apodized diffractive intraocular lenses. Journal of Cataract & Refractive Surgery, 39(6), 928-936.
- Łabuz, G., Reus, N. J., & Van Den Berg, T. J. (2015). Ocular straylight in the normal pseudophakic eye. Journal of Cataract & Refractive Surgery, 41(7), 1406-1415.
- Łabuz, G., Vargas-Martín, F., van den Berg, T. J., & López-Gil, N. (2015). Method for in vitro assessment of straylight from intraocular lenses. Biomedical optics express, 6(11), 4457-4464.
Author: Matt Jaskulski, University of Murcia
The modern MPlus intra-ocular lenses (IOL's) (Oculentis®, http://www.oculentis.com/lentis-mplus-x.html) offer to the wearers an expanded depth of focus thanks to their multi focal design. However some (about 6% according to the manufacturer) users wearing them express discontent regarding their vision quality. Within the AGEYE network we developed a novel computational method based on simulations of retinal images that aims to answer the question "why".
Our custom simulator program allows the computation of polychromatic smulated retinal images from experimental aberrometric data. The software uses a novel implementation of Fourier and geometrical optics and the Indiana Eye Model to calculate polychromatic PSF's (pointspread functions) and simulated retinal images. It can perform through-focus simulations and image quality estimation. It has been used to perform analyses of 5 presbyopic eyes with implanted IOL's (3.0D of addition). The optical design of this family of lenses, where the power varies continuously along the surface, allows us to perform aberrometric measurements using commonly available aberrometers.
Our analysis confirmed that most of the subjects have two zones of distances with better image quality. The dioptric range between the two points of maximum IQ was 2.2 ± 0.3D. In the "content" group of eyes that meant that a decent visual acuity (VA) of at least 0.4 - 0.5 logMAR was achieved within this range of distances. The IQ in the "discontent" was 2 to 3 times lower and the simulated images either exhibited double "ghost" images or no bifocality at all. And so the two possible causes of discontent: lack of bi-focality or double "ghost" images. We believe that in the future it will be possible to find the required change of optical aberrations that will optimize the IQ for each particular eye without the need to extract the lens from the eye.
Author: Zoulinakis Georgios, University of Valencia
In a new study simulations of intraocular lenses (IOLs) and contact lenses (CLs) were designed in eye models with customized corneal topographies. Topographic data were collected with Medmont E300 Corneal Topographer from 10 normal corneas and 12 astigmatic. The data were fitted with a series of Zernike polynomials and input in an optical design software in order to design the customized corneas for the eye models.
A series of optimized and non-optimized IOLs and CLs were designed in order to test which would be a better way to correct presbyopic visual problems. For this we collected data such as wavefront root mean square (RMS) error on retinal field and visual Strehl ratio based on the optical transfer function (VSOTF).
Our results show that a combination of two lenses (IOL and CL), even if they are non-optimized, offers a better visual quality, instead of using one optimized lens. A combination of two non-optimized lenses offers decreased visual quality from a combination of fully optimized lenses but that decrease amounts on average to less than 0.1 logMAR.
This study has been submitted in ARVO 2016, Seattle, USA.
Figure: VSOTF and wavefront RMS results. IOL stands for intraocular lens, IOL&CL stands for intraocular and contact lens, opt stands for optimized and non opt stands for non-optimized lenses.