Blue Gouram eye issue?

[Joeybsmooth]

MY Blue Gouram is missing the black part of his eye. Is there some illness that can do this ( I know that is might be out there ). But it is not like his eye is poked out . Just the pupil is gone.

 

[Delapool]

Anything that could have attacked the fish in the tank?

I've read of single-cell parasites that can infect the eye but didn't see anything on eye loss resulting.

 

[coralbandit]

I have seen some fish with "genetic/birth" issues that have not developed a pupil in their eye before.