In The Two Towers, the elf Legolas, at a distance of five leagues, observed once, “there are one hundred and five [riders on horses]. Yellow is their hair, and bright are their spears. Their leader is very tall.” In 2014, a viral video made the claim that this was impossible, based on the equation θ≈1.22λ/d, where θ is the angular size of the Airy disk produced by a point source of light, λ is wavelength, and d is the diameter of the pupil. My idea is that, in a material with a high refractive index, λ would be proportionally less than it is in air, resulting in a smaller θ, and with it an image with better resolution.
(This post’s image and alt text are not my work; Wikipedia user Inductiveload released them into the public domain.)
The Airy disk is caused by diffraction at the entrance pupil to the lens. Even a perfect lens would be affected. The vitreous humor (which is behind the lens) cannot restore image degradation that already occurred when light passed the pupil.