Thanks Tonatiuh & garagefarm!
Still not happy with this, but I need to move on.
The main challenges were the same as with the LW version, namely achieving a smooth sclera/cornea transition which illuminates when catching the light, accompanied by sharp caustics. I couldn’t get anything useful out of the caustics (ultimately I had to abandon them in LW as well), and the transition is prone to noisy artefacts, which isn’t helped by a shadow being cast by the cornea that shouldn’t really be there.
I’d have preferred using the Translucent BSDF on the sclera instead of the cornea, but strangely that made the bumps appear inverted at the terminator. Otherwise that would have been a more elegant solution than the one I arrived at:
Any way to slow that .gif down to its native 24fps by the way? It’s playing so fast here that it’s dropping frames.