Here's a few things that helped me when I was at university during the pandemic.

1. Make sure your room is well lit. Natural light is best, but artificial light is better than nothing.
2. If you have a tv, try watch some of your lectures on that instead of on your computer/phone. Focusing on stuff that's a bit further away is easier on the eyes.
3. Just listen to the audio. I know a lot of lectures have vital visual components, but if you can avoid looking at a screen completely that's a big win for eye comfort.

I hope some of these help.

In case anyone's interested, this illustration is the album art for "All Our Favorite Stories" by Dog Is Dead (often shortened to D.I.D.). I recommend listening if you're into indie rock music.