23/10/2016

Author: Danilo Andrade de Jesús, Wroclaw University of Technology

Cornea is a dynamic tissue which is affected by short and long-term changes such as hypoxia and ageing, respectively. Understanding the dynamics of the corneal biomechanics is of high interest in many fields such as refractive surgery, keratoconus disease, contact lens fitting and glaucoma management. Since there is no standard methodology recognized by all scientific community to infer about corneal biomechanics in-vivo, further studies are necessary. Therefore, in Wroclaw University of Science and Technology in collaboration with University of Manchester, we have explored the potential of corneal speckle by Optical Coherence Tomography (OCT) to help us better understanding the corneal biomechanical behaviour. So far we have been studying the effects of ageing, corneal swelling and intraocular pressure on corneal speckle.

Corneal ageing has shown to be significantly correlated with the speckle resulted from OCT imaging. This may be explained by the change of the corneal micro-structure in terms of collagen fibres organization and keratocytes density with ageing. Such changes are reflected on the interaction of the light with corneal tissue and consequently result on different profiles of the intensity histograms which are fitted with probabilistic models. Moreover, our results have shown that corneal biomechanics is influenced by ageing, with younger subjects recovering faster than older subjects from induced corneal swelling. This last work entitled as “A new perspective about the corneal structure based on Optical Coherence Tomography speckle” was presented last august at the 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society in Orlando, USA (fig. 1). At the present time, we are exploring the corneal OCT speckle as a new method to correct the intraocular pressure measurements by applanation tonometry.

Figure 1: Poster presentation at the 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society in Orlando, USA

05/09/2016

Author: Irene Sisó-Fuertes, University of Manchester, United Kingdom

Networking is about making connections and building enduring, mutually beneficial relationships. Having a Marie Curie fellowship within an initial training network gives you the chance to attend several international meetings and therefore is an excellent opportunity to develop channels and maintain co-operative networks and working relationships. This facilitates to get to know people with the same interests and professional aims and expands the employability

Top: ESR from EDEN Marie Curie ITN visits the lab at the University of Manchester. Bottom: ESR2 attends ARVO 2016 in Seattle. Right: ESR2 visits the facilities at the University of California Eye Centre.

03-10-2016

ITN Meeting at the Institute of Biomedical Engineering and Instrumentation at the Wroclaw University of Technology in Wroclaw (Poland).

Principal Investigator Prof. Robert D. Iskander organized the meeting where the fellows of the different Academic and Industry partners showed their current projects outocmes and interact.

 20/07/2016

Author: Cari Pérez Vives, PhD, Medical Affairs, Alcon Management (Switzerland)

The Ultraviolet (UV) radiation belongs to the short wavelength range (100-400 nm), which is not visible for the human eye. Short-wave radiation (UV-C) is almost completely filtered out by the atmosphere and the ozone layer, reaching the earth just in small amounts. It is well known that the UV radiation is harmful for the human eye, which is exposed to high levels of radiation from light. The intensity of the sunlight which the eye is exposed depends on the wavelength of the light, latitude, altitude, season, time of the day and weather conditions.

Due to the filter properties of the cornea, aqueous humor, lens, and vitreous body, the retina in an adult eye with a natural lens appears to be protected against phototoxic UV light in the range 200-400 nm. The natural lens absorbs wavelength from 300 nm to 400 nm; this absorption of high energy radiation leads to the photo-oxidative processes in the lens, which leads to the formation of yellow-brown pigments, changing the transmission characteristics of the natural lens with aging. Nevertheless, after cataract surgery, the natural lens and therefore the protection of the retina against UV-B and above all UV-A light is removed, leaving the eye more sensitive to phototoxic damage.

Until the mid-80’s IOLs had no UV filter, which meant that the retina was exposed to UV-Light to an extent like never before in lifetime, following cataract surgery and IOL implantation. More UV light than ever before surgery was able to reach the retina. There are in-vitro, animal data and clinical studies reporting cell damage and death, and higher incidence of macular edema in those eyes implanted without UV-blocker IOLs. Nowadays, all IOLs in the market have UV filter, but not all of them filter the UV in the same way. It has been reported that IOLs should provide a complete UV protection; several studies recommend a maximum transmission of 10% at close at 400 nm, in order to ensure adequate UV protection following cataract surgery.

In this study the spectral transmission curves of 5 commercialized IOLs were measured in vitro, mainly focus on the UVA and UVB interval (290-380 nm). The transmission curves of the IOLs were obtained by using a Perkin-Elmer Lambda 800 UV/ VIS spectrometer. This apparatus can measure the spectrum from 200 nm onwards, which means that spectral transmission in UVA, UVB and part of UVC are accurately determined (precision is up to 1 nm). The air was taken as a reference to measure transmittance. Figure 1 shows the transmission curves of 5 different IOLs in the market. IOL 1 and 4 showed the better transmission outcomes, almost reaching 10% of transmission at 400 nm (396 and 398 nm, respectively). In contrast, IOL 3 showed the worst results having 10% of transmission at 360 nm. Due to study design challenges, clinical evidence for the effectiveness of IOL UV filter in reducing the incidence of retinal disorders has not been established yet. But, as UV light can damage retinal structures, a UV-blocker IOL with maximum transmission of 10% close to 400 nm should be implanted after cataract surgery in order to guarantee UV protection of the retina after the cataract operation.

Figure 1: Transmission curves of 5 different IOLs in the market.

29/06/2016

Author: Grzegorz Łabuz, Rotterdam Ophthalmic Institute, University of Murcia

 Straylight is light scattered due to imperfections of the optics of the eye causing a veil of light over the retina. Although crystalline lens extraction is effective in lowering straylight, some patients experience straylight increase after surgery. As the reason of the observed increase is still unknown, to address this problem, we studied several explanted intraocular lenses that were removed from the eye due to others than straylight reason. We found that some of the routinely explanted lenses showed increased straylight up to a level known to be of functional significance (Fig 1).

Fig 1. Straylight values of explanted intraocular lenses. Three of the explanted lenses showed straylight levels well below the level of a young crystalline lens (green dashed line). Two of the studied lenses showed straylight close to that of the crystalline lens at age 70 (red dashed line).

The results of this study were presented and discussed with the scientific community at the Association for Research in Vision and Ophthalmology (ARVO) meeting in Seattle, USA. 

27/06/2016

Author: Eleni Papadatou, University of Valencia, Spain

 The annual meeting of ARVO took place this year in Seattle, USA (1-5 May) and its theme was "Research: A Vision for Hope". This meeting is the largest gathering of vision researchers worldwide and more than 10.000 attendees from all over the world participate each year.  The meeting encourages connections among scientists and vision experts to explore cutting-edge basic and clinical eye science.

This year, I had the opportunity to participate in the meeting and present a poster with results from my work. My poster was focused on the results of the research I have conducted for a series of multifocal intraocular lenses regarding their in-vitro optical quality (MTF measurements, straylight measurements).

The poster session was a very positive experience which gave me the opportunity to interact and discuss with fellows about my work and to make connections with researchers working on the same field. The feedback I got from those connections was very useful for my research and it will help me to improve and take under consideration new parameters.

Eleni Papadatou at her poster presentation in ARVO 2016, Seattle, USA.

25/06/2016

Author: Zoulinakis Georgios, University of Valencia

ESR10 studied the optical and visual quality of combinations of corrective elements (intraocular and contact lenses) in his secondment in Wroclaw University of Technology in Poland. In this study, topographic data from real subjects were used retrospectively in order to simulate real corneas in theoretical eye models. Then, in these models were designed intraocular and contact lenses, either customized or optimized ones and the visual and optical quality of the system was accessed.

This work was presented in ARVO 2016 congress, in Seattle, USA (figure 1).

Figure 1. ESR10 Zoulinakis Georgios, representing his poster in ARVO 2016, Seattle, USA.

The same project is now being studied with diffractive multifocal intraocular lenses.

(For access to the poster, follow the link or contact at This email address is being protected from spambots. You need JavaScript enabled to view it.)

Link to poster: https://drive.google.com/open?id=0B847t8B9bkP9eG1mZU5oZC04Qmc

07/06/2016

Author: Irene Sisó Fuertes, University of Manchester

As part of their training and aiming to promote the cooperation between the academic and the private sectors, some of the AGEYE fellows completed a placement at Optegra Manchester. Optegra is a global private hospital group that offers ophthalmic services in the United Kingdom, China, Germany, Czech Republic and Poland. They are pioneers in eye health care and leaders at the forefront of the ophthalmic field with an important R&D department.

During their placement, the fellows have been able to understand the day-to-day business at a private hospital such as Optegra, visit all the hospital’s facilities, to attend to some of the surgeries that are usually performed as well as accompany some of the eye care professionals during their daily basis duties. Moreover, in collaboration with the R&D department, some of the fellows are analysing data provided by the hospital in order to write scientific articles to be published in peer-reviewed journals.

AGEYE fellows Katerina Moulakaki, Juan Zapata-Diaz, Alejandra Consejo and Irene Siso-Fuertes (right to left) with Optegra Oculo Plastic, Orbital and Adnexal surgeon Mr Dan Nolan.

20/04/2016

Author: Zoulinakis Georgios, University of Valencia

The 24^th international congress of optometry, contact lenses and ophthalmic optics – OPTOM 2016, was held between 8 and 10 of April 2016 in Madrid, Spain. More than 1000 opticians, optometrists and scientists working in the field were brought together to present their works and discuss on future horizons.

Ageye project and GIO group was represented there by members of both teams. Two posters were supported by Ageye ESR10 Zoulinakis Georgios, entitled as:

“UN MÉTODO ALTERNATIVO PARA EL DISEÑO ÓPTICO DE LENTES INTRAOCULARES -

ALTERNATIVE METHOD FOR OPTICAL DESIGN OF INTROCULAR LENSES”

“DISTRIBUCIÓN DE POTENCIA ÓPTICA EN LENTES INTRAOCULARES MONOFOCALES ESFÉRICAS -

OPTICAL POWER DISTRIBUTION ON SPHERICAL MONOFOCAL INTRAOCULAR LENSES”

Both posters describe parts of the general project entitled “Optical Impact of Correcting Elements” which will be defended by the ESR 10 in 2017.

 05/04/2016

Author: Eleni Papadatou, University of Valencia

Background: Life’s expectancy increment will lead a great part of the population in spending almost half of their lives being presbyopes. Spectacle correction is the most common solution for presbyopia compensation but current lifestyle and aesthetics drive new presbyopes to other correcting techniques. Simultaneous vision multifocal contact lenses seem an appealing solution although the fitting rates are still relatively low.¹ The concept of these designs is the projection of both in-focus and out-of-focus images at the same time and their success relies on the visual system’s ability to suppress the blurred out-of-focus images (regarding the viewing distance).² Under in-vitro experimental conditions, power profiles^3,4 of these lenses can give important information about the power distribution across their optical zone.

Study: In this study, we studied different types of simultaneous vision multifocal contact lenses (center near and center distance designs, different addition powers). By using a power mapping device (NIMO TR1504, LAMBDA-X, Belgium) the power profiles of the lenses were obtained for a 6 mm pupil size. Based on their power profiles we calculated the proportions of power distribution for different pupil sizes, i.e. 3 mm, 4.5 mm and 6 mm (Figure 1).

Figure 1: power distribution (%) of a center near multifocal contact lens at three different pupil sizes. The nominal power of the lens was -3.00 D.

Additionally, we divided the power profiles into different distance zones (far, intermediate and near with respect to the nominal power of the lenses) and we calculated the proportion of the area of lens’ surface dedicated to each zone as function of pupil size (Figure 2).

Figure 2: example of calculation of the area of the lens dedicated for near zone (right figure) as a function of pupil size. In this case the lens is of center near design. In left graph, which illustrates the power profile of the lens, the dashed lines indicate the thresholds between far, intermediate and near vision zones (in respect with the nominal power of the lens which was -3.00 D). 

Summarizing, the two basic findings of the study were that the resulting refractive power at a given pupil size relies on the design of the lens and its addition power and that all the 3 lenses types we studied, regardless their design, enhanced intermediate vision at moderate pupil sizes. This study has been submitted as an original paper work and is currently evaluated by a peer reviewed scientific journal.

References

1. Morgan PB, Efron N, Woods, CA. An international survey of contact lens prescribing for presbyopia. Clin Exp Optom 2011; 94: 87-92.
2. Charman WN. Developments in the correction of presbyopia I: Spectacle and contact lenses. Ophthalmic Physiol Opt 2014; 34: 8-29.
3. Madrid-Costa D, Ruiz-Alcocer J, García-Lázaro S, Ferrer-Blasco T,  Montés-Micó R. Optical power distribution of refractive and aspheric multifocal contact lenses: Effect of pupil size. Cont Lens Anterior Eye 2015; 38:317-21.
4. Plainis S, Atchison DA, Charman WN. Power profiles of multifocal contact lenses and their interpretation. Optom Vis Sci 2013; 90: 1066-1077. 

14/03/2016

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.

25/02/2016

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.

18/01/2016

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).

References:

1. 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.
2. 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.
3. 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.

15/01/2016

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.

11/01/2016

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.

25/11/2015

Author: Cari Pérez Vives, PhD, Medical Affairs, Alcon Management (Switzerland)

Dr. Barry presented at the ESCRS congress, Barcelona 2015, the latest findings from the ESCRS EUREQUO study on FLACS (Femto Laser Assisted Cataract Surgery). This observational retrospective study was performed in 16 centres of 10 countries. The study compared femtosecond technology in 2814 cases versus manual phacoemulsification in 4918 cases. They found superior astigmatism correction in femto-second group compared to manual group, but femto-second group showed more postoperative complications than manual group, such as higher PCO rates, corneal edema and uveitis.

In the presence of these negative results for the femto-second laser technology, the role of Medical Affairs in Alcon is to understand the study and create a document to help addressing potential questions. This scientific document basically explains the limitations, their potential influence on the results of the EUREQUO study and, based on the previous scientific literature, reports contradictory results, and different views. This “barrier-handler” document is distribute internally in the company and also was presented by the training team to the product managers to enable them to discuss with the doctors in case of questions.  

 16/11/2015

Author: Alejandra Consejo, Wrocław University of Technology

The aim of this work, which hopefully will be presented in the IEEE International Symposium on Biomedical Imaging (2016, Prague), was to develop a curvature based estimator for the location of limbus, defined as the junction between cornea and sclera. Data collected from a simulated example, an artificial bi-sphere test surface and a real eye is used to validate the method. Since curvature calculation requires double differentiation of the surface under analysis and differentiation calculation greatly amplify any noise present in the data, applying regularization techniques is needed in order to control the noise effect. Different regularization techniques are tested, resulting in Deriche filtering operators that found to be the most applicable. Determining the change in the curvature of the surface of the anterior part of the eye is possible using Deriche filtering operators. This regularization technique provides accurate results for limbal demarcation. The proposed method is applied successfully on the bisphere test surface as the figure shows. The radius obtained has 0.98 % relative error. The study suggest that the shape of the limbus in the human eye is not symmetric – an important consideration in contact lens design.

Figure. Change in the curvature detection for the artificial bi-sphere. Overlapping blue asterisks indicate the registered curvature change in each meridian and yellow line indicates the fit of a circle of the points.

 03/11/2015

Author: Eleni Papadatou, University of Valencia

 During September of 2015, the ESR9 participated in two scientific congresses that both took place in Spain. The first one was the XIII Congress of the European Society of Cataract and Refractive Surgeons (ESCRS), 05/09 -09/09 in Barcelona and the second one was the International OSA Network of Students (IONS), 24/09-26/09 in Valencia.

In both events, the ESR 9 presented in front of audience different parts of her work related with optical quality of multifocal intraocular lenses (MIOLs) assessment. Moreover, ESR9 had the opportunity to interact and discuss several aspects of her work with other participants who showed interest on it.

Picture 1: ESR9 at her presentation for the International OSA Network of Students congress in Valencia.

26/10/2015

Author: Zoulinakis Georgios, University of Valencia

The International OSA Network of Students (IONS) successfully completed its last meeting in Valencia, Spain, the weekend 24-26 September 2015. The OSA is the Optical Society interested in every field that includes optics. Between these fields is applications in Vision and Optometry.

The Optometry Research Group (GiO) from the University of Valencia was there to present different studies in the field of optometry and vision. Between these studies, Georgios Zoulinakis, from the Ageing Eye (AGEYE) program presented his poster entitled “Simulation of diffractive multifocal intraocular lenses (IOLs) with a new designing method”.

In this study a Matlab code was created in order to design diffractive mutifocal intraocular lenses. This code uses a number of points in order to design the profile of the lens and provides control of the number of the escheletes, the step height, the diffractive region radius and the function between the steps. The code provides a text file which can be introduced in optical design programs and create a simulation of this IOL in any theoretical eye model.

15/10/2015

Author: Juan F. Zapata-Díaz, The University of Manchester.

The XIII Congress of the European Society of Cataract and Refractive Surgeons (ESCRS), one of the biggest and most important meetings in ophthalmology and vision research, took place in Barcelona from the 5^th to the 9^th of September of 2015.

With an attendance of more than 8000 eye care professionals and researchers, and the presentation of a massive number of studies, the meeting was a great opportunity to communicate the state-of-the-art of the vision research.

The AGEYE consortium was present at the ESCRS 2015 with a great contribution that included more than 15 communications between talks and posters, which show the advances of the project, and more than 30 collaborations in external studies.

Some of the AGEYE consortium partners present at the meeting were: The University of Valencia, The Rotterdam Ophthalmic Institute, The University of Manchester, The University of Murcia, Wroclaw University of Technology, Optegra, Alcon and Staar Surgical.

Some of the studies presented were:

- “New experimental design of phakic intraocular lens for presbyopia correction”. C. Pérez-Vives, T. Ferrer-Blasco, A. Cerviño, D. Madrid-Costa, R. Montés-Micó.

- “Myopic implatable collamer lens of -20.00 D after 5-year follow-up”. C. Pérez-Vives, C. Lisa, B. Baamonde, R. Montés-Micó, J. Alfonso.

- “Effect of daily disponsable soft contact lenses on tear film quality, assessing the higher-order aberrations after blinking”. A. Moulakaki, A. Rechioni, J. Esteve-Taboada, A. Del Águila-Carrasco, R. Montés-Micó.

- “Norm for ocular straylight of the pseudophakic eye”. G. Labuz, N. Reus, T. van den Berg.

- “A new metric for quantifying the optical quality of multifocal intraocular lenses by means of axial modulation transfer function”. E. Papadatou, A. Del Águila-Carrasco, J. Esteve-Taboada, D. Madrid-Costa, R. Montés-Micó.

- “Cataract and visual function: a prospective observational study of surgical selection”. S. Gholami, P. Aspinall, B. Dhillon, S. Klijn, N. Reus, T. van den Berg.

- “Assessment of the accommodation response over sustained near visual tasks with different electronic devices, using a Hartmann-Shack aberrometer”. A. Moulakaki, A. Rechioni, J. Esteve-Taboada, A. Del Águila-Carrasco, R. Montés-Micó.

- “Alternative method for optical design of intraocular lenses”. G. Zoulinakis, A. Moulakaki, E. Papadatou, T. Ferrer-Blasco.

- “Optical power distribution on spherical monofocal intraocular lenses”. G. Zoulinakis, E. Papadatou, A. Moulakaki, T. Ferrer-Blasco.

- “Predicting subjective depth-of-field of the accommodating eye with objective methods”. J. Zapata-Díaz, R. Iskander, N. López-Gil, J. Alfonso, H. Radhakrishnan.

- “Ocular straylight of hydrophilic and hydrophobic multifocal intraocular lenses: a literature review”. G. Labuz, N. Reus, T. van den Berg.

- “Comparison of a trifocal toric and a bifocal toric intraocular lens under simulated conditions of decentration and tilt”. E. Papadatou, G. Zoulinakis, A. Moulakaki, D. Madrid-Costa, T. Ferrer-Blasco.

- “Visual response to multifocal spherical correction”. I. Sisó-Fuertes, R. Montés-Micó, J. Alfonso, H. Radhakrishnan.

07/10/2015

Author: Grzegorz Łabuz, Rotterdam Ophthalmic Institute, University of Murcia

Ocular straylight is caused by inhomogeneities in the ocular media that scatter light. An increased straylight level leads to several visual difficulties and decreases quality of vision. An intraocular lens (IOL) is considered as a new source of straylight once implanted in the eye. However, IOL contributions differ across optical designs and materials, particularly in case of multifocal IOLs.

The ESCRS poster appeared to address this issue showing that the hydrophilic material presents less straylight by comparison to the hydrophobic one. This might result in decreasing the risk of optical side effects like disability glare after multifocal IOL implantation, and consequently, improving patient satisfaction. How this difference can be understood, and whether other IOL factors play a role, is currently under studies. 

28/09/2015

Author: Cari Pérez Vives, PhD, Medical Affairs, Alcon Management (Switzerland)

During the ESCRS congress, as Medical Affairs at Alcon Management (EMEA) I was involved in several activities, such as:

Medical & Commercial booth: medical affairs is managing the medical booth including “Meet the expert”, where over 40 surgeons met 7 experts on various topics: Biometry, General Cataract, Cataract Refractive Surgery and Refractive Surgery (fig. 1). Medical affairs also supports the marketing team by reviewing all the promotional material, publications distributed in the congress as well as developing some interactive activities, like the visual simulator touch screen for PanOptix (fig. 2).

Alcon events, such as training for Alcon employees on new products, Toric master meeting, ORA/Verion and Toric IOLs Advisory Board, Ultrasert & PanOptix launch event, INFOCUS event and different symposium about refractive and cataract refractive surgery. The role of Medical Affairs in all these events is to cooperate as team player on topic definition and medical review on scientific presentations (fig. 3 & 4).

Scientific coverage of most relevant talks about Alcon products and main competitors. These activities are summarized in a report with the main highlights and are shared with all Alcon employees involved.

Competitive intelligence: attending to competitors’ symposiums and booths to collect information about the main insights, launches, messaging and activities from the main competitors. 

18/9/2015

Author: Danilo Andrade de Jesus, Wrocław University of Technology

Ageye fellows have met once again to receive training in Vision Sciences. This time an optical and illumination design software, named Zemax OpticStudio was chosen. The course was organized by Professor Norberto of University of Murcia as a local training and Dr Ian Wallhead was invited to run the course for 4 days on Calabardina, Spain. The main purpose of this course was to bring the student who is new to Zemax to a competent level in order to design simple optical systems, analyse their performance and perform basic optimizations. The design skills learned during these days were applied to the design of different eye models.

Figure – Dr. Ian and Ageye fellows during the course (a) and Navarro’s Eye Model designed using Zemax Optic Studio (b).     

01/08/2015

Author: Alejandra Consejo, Wrocław University of Technology

The aim of this work is studying whether there exists a relation between the outer limbus outline and its corresponding inner outline. The limbus has been traditionally calculated as a border line between the cornea and the sclera. However nowadays it is considered that it is not a distinct border but rather a region [1]. Four young subjects (eight eyes) were recruited for the study. The data was acquired using Eye Surface Profiler (ESP, Eaglet Eye BV, Netherlands), a new 3D technology based on the principle of profilometry. Raw 3D profilometry data was fit with the 12th radial order Zernike polynomial expansion [2], from which semi-meridional curvature was calculated. This local curvature was analytically calculated using the first and the second derivative of Zernike polynomials. The two largest changes in local curvature for every semi-meridian were used to demarcate the limbus. The amplitude of the curvature ‘kicks’ localized for every semi-meridian was calculated and plotted using an intensity colorscale which varies from dark blue (lower values) to dark red (highest values). Finally, Wilcoxon test is applied to analyze the data. As Fig 1. suggests it is reasonable to assume that there is no relation between the inner limbus and its correspondent outer limbus. The results of Wilcoxon test confirm that no statistically significant differences (p-value<0.001) between outer and its corresponding inner limbus are observed. Because this is a curvature based calculation, mathematically, wherever the change in curvature sign is localized the curvature should go to infinity. In reality, this means that a single pixel can have a decisive influence in the magnitude of the peak which could lead to misrepresented results. With the proposed curvature based method it is not possible to ascertain if there is a relation between outer and its correspondent inner limbus. Extrapolating scleral topography is not as straight forward as extrapolating corneal periphery (for example, for simulating contact lens behaviour on eye).

Fig. 1. Left: Limbus demarcation (female, 27-years-old). Colorful points mark the amplitude of the change in curvature for each semi-meridian. Right: Example of semi-meridian (corresponding to ) intensity curvature calculation.

This work has been accepted and will be presented in the conference IONS Valencia, Spain, 24-26^th of September 2015

References

[1] D. R. Iskander, "A parametric approach to measuring limbus corneae from digital images," IEEE Trans. Biomed. Eng., vol. 53, pp. 1134-1140 (2006)

[2] RJ. Noll, “Zernike polynomials and atmospheric turbulence”. J Opt Soc Am, 66(3):207-211 (1976)

13/07/2015

Author: Eleni Papadatou, M.Sc., University of Valencia

A number of designs regarding contact lenses have been developed in order to improve the vision of the presbyopes. The majority of these designs use the concept of ‘’simultaneous vision’’ which corresponds to lenses that have multiple powers positioned in front of the pupil at the same time. Such lenses, in compare with monofocal lenses, yield more complex power profiles which should be carefully evaluated. Although manufacturers normally provide some parameters for the design of the lenses, yet is not common to provide detailed power profiles.^1,2

In order to determine the power profiles of lenses there are several approved methods (ISO 18369) including small-aperture focimetri, Moire deflectometers^* and Hartmann-Shack devices. The lab of GIO is equipped with a device based on the phase-shifting Schlieren method which has been demonstrated to be more accurate than the previous ISO mehods.³ Taking advantage of this new technology is possible to obtain the corresponding power profiles of contact lenses.

Using these information, we are able to characterize complex profiles of multifocal contact lenses. Furthermore, we can investigate the effect that various parameters (e.g. pupil diameter) can have on power profiles and how can influence the optical performance.

* First commercial deflectometer:  https://www.youtube.com/watch?v=9WLB3tmnmoU

References

1.Plainis, S., Atchison, D. A., & Charman, W. N. (2013). Power profiles of multifocal contact lenses and their interpretation. Optometry & Vision Science,90(10), 1066-1077

2.Montés-Micó, R., Madrid-Costa, D., Domínguez-Vicent, A., Belda-Salmerón, L., & Ferrer-Blasco, T. (2014). In vitro power profiles of multifocal simultaneous vision contact lenses. Contact Lens and Anterior Eye, 37(3), 162-167.

3.Joannes, L., Hough, T., Hutsebaut, X., Dubois, X., Ligot, R., Saoul, B., ... & De Coninck, K. (2010). The reproducibility of a new power mapping instrument based on the phase shifting schlieren method for the measurement of spherical and toric contact lenses. Contact Lens and Anterior Eye, 33(1), 3-8.

Figure 1:  Illustration ofMoiré deflectometry technique with two identical gratings and a position-sensitive detector.

06/07/2015

Author: Zoulinakis Georgios, University of Valencia

There are two different types of multifocal IOLs, the refractive and the diffractive ones. The first have zones (rings) of different refractive power while the second ones have a diffractive pattern on one of their surfaces. This diffractive pattern, according to its architecture, diffracts the light and focuses the light in more than one foci.

In order to design this type of lens in an optical design program we need to create this pattern on an IOL surface. For this, we developed a code in Matlab R2012b (The Mathworks, Inc.). With this code we can create the surface we want (Figure 1a) and control all the parameters like curvatures, asphericities, diffractive parameters etc. The code produces a text file of point coordinations that can be inserted into the software in order to be simulated and ray traced.

We have checked that the code creates correctly spherical/aspherical lenses that have same simulations as the ones from the software. After that we have been able to design diffractive IOLs (bifocal) which when simulated in the software.

Soon we will be able to advance it even more and produce a database of diffractive IOL simulations of different architectures.

Figure 1: Matlab images for apodization function, diffractive profile and IOL surface with diffractive pattern

03/07/2015

Author: Sonia Gholami, Rotterdam Ophthalmic Institute

In one study (Marsack et al., 2004), it has been shown that the visual Strehl ratio (VSR) metric accounts for 81% of the variance in high-contrast logMAR visual acuity (VA) which makes this metric a strong predictor of visual performance in normal eyes. We have applied this method and investigated the correlation between the VA and the VSR of cataract eyes. The VSR versus visual acuity (logMAR VA) plot shows a very similar relationship for both groups (Fig. 1).

We furthered the study to computing lenticular VSR by subtracting the corneal Zernike coefficients from the ocular ones (see post on 2.2.2015). A rather high correlation with visual acuity (Fig. 2), convinced us to apply this method on a group of cataract eyes which are listed by the ophthalmologists to be operated on. This will help us to find out whether the lenticular VSR is a factor which is considered unconsciously in making decision for cataract surgery.

Figure 1 : Ocular VSR vs. logMAR VA in cataract and non-cataract eyes

Figure 2: Lenticular VSR vs. logMAR VA in cataract eyes

29/06/2015

Author: Matt Jaskulski, University of Murcia

We presented the results of our most recent study about the influence of the longitudinal chromatic aberration on the depth of field during the ARVO 2015 conference in Denver, CO.

Concepts

If the eye is focused at a given distance, then objects located either nearer or further away will produce blurred images on the retina. Although theoretically a perfectly clear and in-focus retinal image is formed only when the object is precisely optically conjugate with the retina, a slightly defocused image will also be interpreted in this way by the brain as long as it is positioned within the optical extent of the depth-of-focus (DOF). Related to the DOF is the depth-of-field (DOFi). It can be defined as the „projection of the dioptric interval of the depth-of-focus into free space”. The observer is unable to detect blurring of objects within this interval and perceives them with maximum visual acuity.

The longitudinal chromatic aberration (LCA) is the dependence of the refractive power of the eye with wavelength and is one of the important cues for the accommodative system that affects its response and accuracy. 

Measurements

We measured aberrations of 7 young subjects while showing them a target at 3 different distances to make their eyes accommodate. We used a custom­-made adaptive optics system equipped with a 1024-lenslet Hartmann-Shack sensor, a deformable mirror (Mirao 52­e, Imagine Eyes), and a Badal system controlled by the subject. The target was presented on on an OLED microdisplay that was covered with color filters.

Results

The figure above shows that there is no difference between the eye's response to B&W and green stimuli. The DOFi extend in these cases right up to the „ideal response” line. This confirms the statement that the eye accommodates only the minimum amount, enough to place the target within its depth of field and see it relatively clearly. The fact that the LAG and DOFi for polychromatic stimuli don't differ from those for monochromatic green indicates that they are not influenced by the presence of the LCA.

16/06/2015

Author: Juan F. Zapata-Díaz (The University of Manchester)

In last decade, the depth-of-focus (DoF) of the human eye has become an important issue to address due to the hypothetical improvement that could represent on the new approaches to correct presbyopia. Nevertheless, DoF of the human eye has been widely studied in last century.

Some of the findings achieved by researchers were the factors that may influence DoF of the human eye. These factors could be categorized as internal and external factors. External factors refer to the characteristics of the environment where the subject is placed while internal factors are the optical and neural characteristics of the subject’s visual system that influence DoF.

External factors are: luminance of the test field; and contrast, spatial frequency and target detail. Internal factors are: pupil size; optical aberrations; refractive state; retinal eccentricity; and age.

Apart from these factors, DoF has been found to be influenced by a neural factor associated to subjects’ blur sensitivity and that could be responsible for the large differences between objectively and subjectively measured DoF, and for the wide variability among subjects.

09/06/2015

Author: Irene Sisó Fuertes, University of Manchester

Usually accommodation is treated as a static process but it is not. During an accommodative response the refractive power undergoes small amplitude fluctuations. These fluctuations in accommodative response increase during accommodation and decrease with advancing age.

There exists a controversy when it comes to the mechanism and significance of the fluctuations. It is still uncertain whether they simply represent a background noise of the accommodative system or play a role in the accommodation steady-state, maintaining focus and retinal contrast whilst fixating on a fixed target. Therefore, studies that look into the impact of microfluctuations of accommodation and other higher order aberrations on the retinal image quality are warranted on a large age range of patients to understand their role in the eye further.