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.