Schraermeyer Lab

Experimental Vitreoretinal Surgery

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Scientific Results

Finding the leaky sites in choroidal neovascularization

Recently we reported the clinicopathologic findings of leaky sites in pathological vessels after submacular removal of choroidal neovascular membranes (CNV´s). As the site that causes fluid exudation from neovascular vessels is unknown, specific attention was focused on the formation of fenestrations, cellular junctions, and morphologic alterations which can cause endothelial leakage. A newly discovered type of pathological capillary, called a labyrinth capillary, is responsible for the permanent leakage of fluid. Due to the small vessel lumen, thrombocytes cannot enter these capillaries to close the leakages. Currently we are developing strategies of how to target these vessels specifically.

Unravelling the mystery of the Stiles-Crawford Effect

The Stiles-Crawford Effect of the first kind (SCE I) was regarded as one of the most important discoveries in visual science of the last century but is still not fully understood. The SCE describes the phenomenon that light entering the eye near the edge of the pupil produces a lower photoreceptor response compared to light of equal intensity entering near the center of the pupil.
Very recently we showed that unique Müller cells in the center of the fovea guide the light based on the incident angle by their specific anatomy and thereby reduce light transmission through the retina, causing the SCE I.

Preclinical results of a new pharmacological therapy approach for Stargardt disease and dry age-related macular degeneration

Stargardt disease (SD) and dry age-related macular degeneration (AMD) are marked by the accumulation of lipofuscin in the retinal pigment epithelium (RPE). This results in the progressive deterioration of the RPE and retina leading to vision loss and finally blindness. Thus, removal of lipofuscin from the RPE may be a potential strategy to ameliorate the clinical symptoms. Currently no treatment is available for either disease. We discovered that a small molecule belonging to the tetrahydropyridoether class of compounds (Remofuscin®) is able to remove lipofuscin from the RPE of SD mouse models (pigmented and albino Abca4-/- mice), does not show any toxicity in ERG and slows down the degeneration of photoreceptors in SD mice. Moreover, Remofuscin® accumulates specifically in RPE pigments. Therefore it is a promising drug for the treatment of SD and dry AMD.

A valid ultrastructural rat choroidal neovascularization model developed by overexpression of VEGF

We developed a CNV model by subretinal injection of a high-capacity adenovirus vector encoding for human VEGF-A165 (HC Ad.VEGF) into rats (Long Evans). Scanning laser ophthalmoscopy (SLO), fluorescein angiography (FA), indocyanine green angiography (ICG) and optical coherence tomography (OCT), immuno-cytochemistry and electron microscopy were performed. This rat model resembles human CNV and is being used to study new therapeutical options, for example inhibition of fibrosis in the preclinical status.