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Does the foveal shape influence the image formation in human eyes?

: Frey, K.; Zimmerling, B.; Scheibe, P.; Rauscher, F.G.; Reichenbach, A.; Francke, M.; Brunner, R.

Volltext ()

Advanced Optical Technologies 6 (2017), Nr.5, S.403-410
ISSN: 2192-8584
ISSN: 2192-8576
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer IOF ()

In human eyes, the maximum visual acuity correlates locally with the fovea, a shallow depression in the retina. Previous examinations have been reduced to simple geometrical fovea models derived from postmortem preparations and considering only a few superficial ray propagation aspects. In the current study, an extended and realistic analysis of ray-optical simulations for a comprehensive anatomical realistic eye model for the anterior part and realistic aspherical human foveal topographical profiles deduced from in vivo optical coherence tomography (OCT) are presented, and the refractive index step at the transition from vitreous to retinal tissue is taken into account. The optical effect of a commonly shaped (averaged) and an extraordinarily shaped foveal pit were both compared to the analysis of an assumed pure spherical boundary layer. The influence of the aperture size, wavelength, and incident angle on the spot size and shape, as well as the axial focal and latera l centroid position is investigated, and a lateral displacement of about 2 μm and an axial shift of the best focal position of less than 4 μm are found. These findings indicate only small optical effects that are laterally in the range of inter-receptor distances and axially less than the photoreceptor outer segment dimension.