The astigmatism of the eye ==> some quantic problems.
No one photon can be 5 m wide on the mirror of the Mount Palomar, simply because the geometrical defects of the mirrors limit the size of the real entry pupil to what can really be focused on the quantic absorber of this one photon. The same restriction applies to the photons passing by our pupil, to be absorbed by the retinal in one opsin.
However a category of geometrical defects in the eye cannot be solved by restricting the effective pupil by the Abbe condition, it is astigmatism. No more one focus, but two quasi-focal distances according to two perpendicular directions. However ONE retinal in ONE opsin absorbs the entire photon, it is about 5 to 9 Å wide x 18 Å long, with no depth of field. Even from a far star.
In the Newtonian background of received ideas, such a punctual convergence through an astigmatic eye is just impossible.
As soon as we admit the existence of the absorber in quantum physics (sure, we are a minority to admit it), we are compelled to admit that the astigmatism of the eye modifies the shape and the angles of the aerial Fermat spindle incoming in the eye, to an elliptical cross-section, instead of a circular one. And that, statistically on all photons incoming in an astigmatic eye, that will be absorbed by an opsin, a quantic reaction, a small one.
An experimental testing? No idea. And you? Have you better ideas?