My guess is that the experience of an arahant can still be described by the same verse:
“cakkhuñca paṭicca rūpe ca uppajjati cakkhuviññāṇaṁ“, because:
(1) For a living arahant, there is still a cakku pasada rupa and a hadaya vatthu.
(2) Elsewhere Lal has explained that paticca in this context is “coming together” — not the same as “pati + icca” as in paticca samuppada. Thus, for an arahant, there is still paticca in this sense.
We know that cakkhuviññāṇaṁ for an arahant is pure and vastly different from that of ours; it’s just not fathomable to us. If someone can make up a special term to describe that to help him understand better then it’s all good (perhaps something like “cakkhuñāṇaṁ” (without the “vi“)).
Anyhow, it is much easier to draw the distinction between an arahant and us in the subsequent verse: there is NO “tiṇṇaṁ saṅgati phasso” for arahants, but there is for us. And this point can serve us better in terms of practice — to work to reduce “san“.
Best,
Lang