Relevance of Laser Flare Photometry in Retinal Pathologies. / Relevanz der Laser-Flare-Photometrie bei retinalen Pathologien.

Laser flare photometry provides a non-invasive and objective measurement of the Tyndall effect in the anterior chamber. The laser flare value (measured in photon number per millisecond [pc/ms]) thus quantifies the extent of disruption to the blood-aqueous barrier and can be used in clinical applications to monitor uveitis therapy or to measure the postoperative degree of inflammation. Standardised performance must be observed during measurement. Publications of the last 35 years on laser flare photometry deal not only with the measurement procedure but also with its use in clinical practice for different ophthalmological pathologies. Likewise, various influencing factors have already been investigated and described that must be considered when measuring and evaluating laser flare values. The focus of this article is the relevance of laser flare photometry in retinal pathologies. In recently published studies, the level of objective tyndallometry in primary rhegmatogenous retinal detachment is shown to depend on lens status, symptom duration, and extent of retinal detachment. The greater is the area of the retina affected, the greater the disruption of the blood-aqueous barrier appears to be. Elevated laser flare values have also been considered as a predictor for the development of proliferative vitreoretinopathy (PVR). However, based on current knowledge, this assumption must be put into perspective. According to current data, objective tyndallometry can be used to monitor the progression of intraocular inflammation and to quantify the blood-aqueous barrier, and the values correlate with the extent and anatomical features, as well as the symptom duration in retinal detachment. Many influencing factors have already been identified. But further evaluation is desirable and needed. It is still unclear whether laser flare values can be used in the future as a predictor for sequelae such as PVR development.

Retinal and Choroidal Ultra-Widefield OCT - Technology, Insights, and Clinical Relevance. / Retinale und choroidale Ultra-Weitwinkel-OCT ­ Technologie, Einblicke und klinische Bedeutung.

As one of the most state-of-the-art procedures for retinal and choroidal imaging, ultra-widefield optical coherence tomography (UWF-OCT) offers significant gains in terms of information pertaining to peripheral retinal lesions and their differential diagnoses. In particular, it enables the presence of minimal accumulations of subretinal fluid to be assessed in detail and then documented. It also enables choroidal expansion of choroidal lesions to be precisely measured. Similar to conventional OCT, its only limitations relate to patient compliance and opacities of the ocular media. While the pupil width is somewhat less important here, the quality of the images is nevertheless better with the patient under medication-induced mydriasis. Used in combination with UWF fundus photography, UWF-OCT is a helpful tool for assessing and monitoring peripheral retinal and choroidal lesions.

Regenerative approaches as alternatives to donor allografting for restoration of corneal function.

A range of alternatives to human donor tissue for corneal transplantation are being developed to address the shortfall of good quality tissues as well as the clinical conditions for which allografting is contraindicated. Classical keratoprostheses, commonly referred to as artificial corneas, are being used clinically to replace minimal corneal function. However, they are used only as last resorts, as they are associated with significant complications, such as extrusion/rejection, glaucoma, and retinal detachment. The past few years have seen significant developments in technologies designed to replace part or the full thickness of damaged or diseased corneas with materials that encourage regeneration to different extents. This review describes selected examples of these corneal substitutes, which range from cell-based regenerative strategies to keratoprostheses with regenerative capabilities via tissue-engineered scaffolds pre-seeded with stem cells. It is unlikely that one corneal substitute will be best for all indications, but taken together, the various approaches may soon be able to supplement the supply of human donor corneas for transplantation or allow restoration of diseased or damaged corneas that cannot be treated by currently available techniques.

A new tool for the transfection of corneal endothelial cells: calcium phosphate nanoparticles.

Calcium phosphate nanoparticles (CaP-NP) are ideal tools for transfection due to their high biocompatibility and easy biodegradability. After transfection these particles dissociate into calcium and phosphate ions, i.e. physiological components found in every cell, and it has been shown that the small increase in intracellular calcium level does not affect cell viability. CaP-NP functionalized with pcDNA3-EGFP (CaP/DNA/CaP/DNA) and stabilized using different amounts of poly(ethylenimine) (PEI) were prepared. Polyfect®-pcDNA3-EGFP polyplexes served as a positive control. The transfection of human and murine corneal endothelial cells (suspensions and donor tissue) was optimized by varying the concentration of CaP-NP and the duration of transfection. The transfection efficiency was determined as EGFP expression detected by flow cytometry and fluorescence microscopy. To evaluate the toxicity of the system the cell viability was detected by TUNEL staining. Coating with PEI significantly increased the transfection efficiency of CaP-NP but decreased cell viability, due to the cytotoxic nature of PEI. The aim of this study was to develop CaP-NP with the highest possible transfection efficiency accompanied by the least apoptosis in corneal endothelial cells. EGFP expression in the tissues remained stable as corneal endothelial cells exhibit minimal proliferative capacity and very low apoptosis after transfection with CaP-NP. In summary, CaP-NP are suitable tools for the transfection of corneal endothelial cells. As CaP-NP induce little apoptosis these nanoparticles offer a safe alternative to viral transfection agents.