Potenzial von fMRT für die Funktionsüberprüfung des pathologischen Sehsystems

Abstract

Current developments in functional magnetic resonance imaging (fMRI) of the human visual system have generated a set of powerful approaches that are of great promise for modern ophthalmology. These make it possible to perform an objective spatially resolved test of visual function in patients with strong visual impairment and even to investigate the functional organisation of the visual cortex in the blind. As a consequence, they open a broad field of applications for functional assessment in ophthalmology and provide fundamental insights into the interplay of pathology and plasticity in the human visual system. This is highlighted by current studies investigating patients with acquired or congenital defects of the macula, or with visual pathway abnormalities, extended retinal damage, and complete blindness. Therapeutic approaches targeting the restoration of visual input are expected to benefit from these fMRI applications, either for the estimation of the success rate of a planned retinal therapy or as an objective high-level biomarker for the readout of therapy success.

Population receptive field and connectivity properties of the early visual cortex in human albinism

“…When inspected at higher spatial resolution, as demonstrated electrophysiologically in an albino green monkey (Guillery et al, 1984), these superimposed maps form hemifield dominance domains that are reminiscent of ocular dominance domains in a normal visual system. Despite the substantial aberrant input to the visual cortex, major aspects of visual function are preserved (Eick et al, 2019;Hoffmann et al, 2017;Hoffmann and Dumoulin, 2015;Klemen et al, 2012;Wolynski et al, 2010). This is taken as evidence for adaptive mechanisms that make the erroneous visual input available for perception and highlights the importance of albinism as a powerful model to study the foundation of visual pathway formation and the scope of plasticity in humans.…”

Sehschärfe, Kontrastempfindlichkeit, Farbensehen: Gedanken zu psychophysischen Untersuchungen in der Neuroophthalmologie

“…[2,3]), kann nur durch psychophysische "subjektive" Untersuchungen bestimmt werden, wie gut der Patient tatsächlich sieht. Zudem stehen für die Sehbahn jenseits der Netzhaut, etwa Sehnerv und visueller Kortex, trotz Fortschritten in der Entwicklung der funktionellen Magnetresonanztomografie [4] weit weniger bildgebende Untersuchungsmöglichkeiten zur Verfügung wie für Netzhaut und Vorderabschnitt des Auges. Folglich kommt psychophysischen Untersuchungsverfahren eine besondere Bedeutung zu.…”