how can i cut the iris from the sclera but keep the imbral ring and its transparency?

[split swallow]

i have a complete eye texture and I want to separate the irisis from the sclera but maintain the whole imbral ring and its transparency but have the sclera beneath removed and not showing like in this iris only example where the imbral ring is maintained and has transparency.

If i used the pen tool and removed the iris and full imbral ring there would be sclera and veins underneath the transparent parts of the imbral ring and thats what i want to avoid without removing the outer areas of the ring. I dont know if im explaining this correctly

[austere tulip]

I'm not sure if you're not doing a great job with the explanation 🙂

You want to split the white part of the eye (sclera) from the blue bit (iris) but with a half decent 'vignette' sort of effect so it looks more gradual and not 'cut out'