Your eyes fail you due to physics. I'll explain:
When we are young our eyeballs are roughly the same size as when we are adults. The difference between the two ages lies in the ability of our pupils to dilate with increasingly poorer light. As darkness approaches, everyone's pupils dilate to let in more photons. The distance across the pupil is known as 'aperture'. Increasing aperture means more photons incident upon the fovea, the part of the eye that sees details and colours. But as our pupils dilate, the greater aperture also lets more photons fall on the 'rods', those super-keen detectors that are able to detect movement and low light, but whose array prevents us from seeing details in darkness...at least not nearly as well as when it's light.
But wait! There's more!! As apertures expand, so too does the ability of the optical system, in this case our eyeballs, to separate small details that are very close together. This is called 'resolution'. Larger telescopes can separate tiny, faint, and very close stellar systems that are called binary stars, even triplets. It is thought that a great number of star systems are actually multiples, and that our solar system might be in a small majority.
There are stories of astronomers in modern times pointing out the planet Jupiter to their young children and saying a pair of binoculars would show anywhere from one to four small moons, appearing as tiny dots of light, around Jupiter. The parents are amazed to hear their children say, "Yes, I can see three!" Without binoculars. That is because of the wider aperture, approaching 8mm in some children, that actually allows them to see the Jovian moons.
Logically, and since we accept that our pupils will often only dilate to about 5.5-6mm when we are north of about 60, we don't get the same amount of light falling on our details patch, the fovea. We have to compensate indoors by having more lights on, and often we need 'reading glasses' that magnify everything. Further, our smaller apertures prevent us from separating closely set details, meaning that our ability to 'define' a scene is impaired. 'Definition' is at the heart of a good optical system.