Time filter

Source Type

Thanos S.,Institute of Experimental Ophthalmology | Thanos S.,University of Munster | Bohm M.R.R.,Institute of Experimental Ophthalmology | Bohm M.R.R.,University of Munster | And 6 more authors.
Progress in Retinal and Eye Research

Neuroprotection is an emerging challenge in ophthalmology due to the particularly exposed location of retinal neurons and to the steadily increasing rate of intraocular surgical and pharmacological treatments applied to various eye diseases. Within few decades neuroprotection has developed from strongly contested approaches to being recognized and introduced as a potentially clinical application. One of the groups of putative substances for neuroprotection comprises αA- and αB-crystallins, which are types of heat-shock proteins and are considered to be molecular chaperones. The β/γ-crystallins form their own superfamily and are characterized as proteins with a distinct structure containing four Greek key motifs. Besides being abundant in the ocular lens, crystallins are also expressed in both the developing and mature retina. Crystallins are dramatically up-regulated in numerous retinal pathologies, including mechanical injury, ischemic insults, age-related macular degeneration, uveoretinitis, and diabetic retinopathy. Crystallins of the α family are thought to play a crucial role in retinal neuron survival and inflammation. Crystallins of the β/γ superfamily are also small proteins with a possible emerging role in retinal tissue remodeling and repair. One of the typical retinal diseases associated with crystallins is the experimental glaucomatous neuropathy that is characterized by their expression. Another typical retinal disease is the atrophy that occurs after mechanical injury to the optic nerve, which is associated with the need to regrow retinal axons. We have shown in regenerative models in vivo and in vitro that βB2-crystallin actively supports the regenerative growth of cut retinal axons, thereby offering targets for neuroprotective and regenerative treatments. In this review we discuss the discovery that βB2-crystallin is clearly up-regulated in the regenerating retina in vitro. βB2-Crystallin is produced and secreted during axon elongation, while β/γ-crystallins promote axon growth both in vivo and in vitro by acting either directly by uptake into cells, or indirectly by enhancing the production of ciliary neurotrophic factor from astrocytes to synergistically promote axon regrowth. We also discuss methods to induce the continuous production of crystallins at the site of injury and repair based on the use of transfected neural progenitor cells. This review ultimately leads to the conclusion that the postinjury fate of neurons cannot be seen merely as inevitable, but instead should be regarded as a challenge to shaping the neuroprotective and regenerative conditions that promote cell survival and axon repair. © 2014 Elsevier Ltd. Source

Kannengiesser M.,Institute of Experimental Ophthalmology | Zhu Z.,Institute of Experimental Ophthalmology | Langenbucher A.,Institute of Experimental Ophthalmology | Janunts E.,Institute of Experimental Ophthalmology
Zeitschrift fur Medizinische Physik

Purpose: No commercially available device for measuring individual IOL surface topographies exists on the market. The purpose of this paper is to show the applicability of clinically available corneal topographers for measuring individual IOLs consisting of a spherical surface on one side and a freeform surface on the other side. Methods: Three measurement principles (Placido rings: Tomey TMS-2N, Scheimpflug: Oculus Pentacam, optical coherence tomography: Tomey CASIA) are applied in determining the IOLs' surface and compared against the design data used for producing the surfaces. Spherical and freeform IOLs are measured and analysed in both radius of curvature (ROC) and higher-order residual parameters by analysing the residuals. Results: Repeatability and reproducibility measurements show a sub-μm precision for the TMS-2N system, while the Pentacam's values are located around 10. μm and the CASIA system's values gather around 20. μm. The TMS-2N system works best at detecting a sample's ROC and residual properties within the range of 8 mm to 13.5 mm mean ROC. In this range, the deviations from the theoretical ROC are about 45 μm. The Pentacam doesn't have this limitation, but faces problems with exporting measurements of freeform surfaces. In some circumstances the program crashes and prevents the export. If being able to export the Pentacam measurements show an average deviation of 100 μm from the theoretical ROC value. The CASIA system shows high amounts of noise which makes it not applicable in this field, having deviations of several 100 μm from the theoretical ROC value. Residual comparison for the higher-order samples shows sub-μm precision for the TMS-2N, about 1 μm precision for the Pentacam and several μm for the CASIA system. The values for the customized samples are slightly increased, several μm for the TMS-2N, up to 30 μm for the Pentacam system and around 75 μm for the CASIA system. Conclusion: The TMS-2N system is an appropriate device for measuring individual IOL surface topographies for ROCs between 8 mm to 13.5 mm. The Pentacam and CASIA induced relatively high level of variation and noise. Future application of the TMS-2N in this field will reveal its long-term statistics.© 2012. Source

Discover hidden collaborations