Thank you for making your comics accessible, and for caring about how users with vision impediments might engage with them.
I would suggest, if you are really inclined to make these accessible, to create transcripts. You could make a simple HTML page called "Transcript" for each comic and place the link under the image.
Transcripts are considered an acceptable accessibility alternative in video media where captioning isn't practical. I think this could translate well to comics. Ypsi's answer touches on how screenreaders would read it like a script, so if you start your comics with scripts, you'd just need to add a few more details for each scene to come to life.
There are other benefits for transcripts:
- Plaintext shows up in search engines, so if a reader can't remember which comic a scene was in, they could Google the details, and Google would likely make a decent match
- Sometimes comics are difficult to understand - not necessarily the fault of the artist, it might be that the reader comes from a cultural or other context (perhaps a young age) where they don't immediately grasp what is going on. A transcript could help them find a written description, which could be translated easily.
More info on transcripts at w3.org.