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, 24-26th 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 Eye37(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 Eye33(1), 3-8.

 

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