There are a few different types of eye movements.

One's normally wander around to capture different details and forth a complete mental picture. These movements are fairly random and involuntary.

You can also decide to focus on some object of interest, on which case you'd voluntarily move your eyes in its direction, similarly to reaching out your hand.

There's also a mostly involuntary type of movement where, after focusing on a specific object, you'd move your eyes to track it, if it starts moving quickly. That's a hunting instinct I believe.

Finally, actually focusing at the proper distance is pretty automatic.

There are also considerations around the cooperation between both eyes, but I couldn't really help you with that, and I'm sure I'm missing other things.

You might get interesting answers at r/askscience, by the way.

Interesting question. You have to think about it because you need to "tell" your eyes where to look at any given time. It happens with minimal thinking and effort but if you don't consciously look in a specific direction, your eyes will just sit there (or just close).

I think it's also different if you have some sort of visual impairment. If you have severe nystagmus, your eyes are constantly moving in there isn't much you can do about it. Now then, I'm not an expert, but I don't think severe nystagmus makes you visually impaired, that's just an example. Though I do know it can blur vision.

In my experience, I would liken it to breathing. It's typically something you do involuntarily, but you can take control over that function at any given time for any given reason.

Good question.

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Eyes move on their own with no/little sensation of movment when looking at things. Intentionally wiggling eyes about feels like a low key workout in the face holes and is easier if the eyes are defocused.

I would compare it to things like breathing and blinking. You sort of do it automatically, but you can consciously choose to focus on this object or that one, or at this spot in your visual field. If you don't focus, the eyes will usually look straightish ahead or will try to track something moving. This is what other people say though; I don't see enough significantly moving things to verify the last point. However, unlike breathing and blinking, there is no need to do it, technically, so it doesn't feel like something you have to do. So, for example, if I don't focus on something for a while, I do not get metaphorical screeching red alerts from my brain like I do when I stop breathing.

It took me the longest time to learn how to roll my eyes. I can move my eyes just fine, but I didn't see other people doing it, so I guess my brain just never put in any effort in to copying the movement. But when I do, it feels pretty weird. I'm pretty sure I roll my eyes differently than other people, but when I roll them, I feel a slight pressure on the sides of them. So like when they go to the right, I feel a little bit of pressure on the right side of my eyeballs. I honestly have no idea if this is normal.

But rolling the eyes, at least the way I do, is pretty extreme when it comes to eye movements, so everyday focusing and other eye movements don't feel like anything. Sometimes stuff around my eyes, like my eyebrows or eyelids, moves just a bit when I put my eyes in a certain direction.

Note: I don't know much about how eyes move, like the muscles and instincts involved. Above is mostly based on my personal experience with a little bit of what people have told me.

I'm thinking some muscle control & signals from the brain. When I visit my ophthalmologist, I just move my eyes in the direction they tell me. I think also there is some natural movement when focusing on an object. When a doctor held a pen in front of my eyes, both eyes should naturally move inwards as the pen moves closer. to the nose. Oddly, only my left eye does that & my right eye moves in the opposite direction. Lastly, I've had a doctor notice that my eyes will also dance around similar to Dancing Eye Syndrome.

I really like the hand analogy... tschuess! (Are you Swiss? I am, but like in the US)

it’s like a hand movement, like rolling your eyes, you do it consciously, I didn’t know how to until I was about 5