Hello and welcome to the community.
They generally have an eye issue when the water parameters aren't, ot weren't good, but it could be from an injury, like a twig end of a DW or stone, possibly a fight with another fish.
Check the water parameters, even if it is from an injury, keeping the water in the top condition, is needed for good healing.
Are there any other fish acting sluggish, hiding, clamped fins, or seeming unwell or getting any cloudiness in the eyes?
The article in my signature link has helpful fish keeping information and very useful for keeping healthy fish.
You may also want to try Epsom salt if you think it was an injury, and all the other fish are doing well.
New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?
Start here - Aquarium Advice Article
FW Favorites right now Clown Loaches, any shrimp - SW Vase Red Mangroves