cakkhu = eye
cakkháyatanam = the organ of the eye, the sense of sight. [not the eye itself, a kind of internal thing]
cakkhundriyam = the organ of the eye, the faculty of sight. [not the eye itself, a kind of internal thing]
SN56.14 wrote:‘Cha ajjhattikāni āyatanānī’ tissa vacanīyaṃ. Katamāni cha? Cakkhāyatanaṃ…pe… manāyatanaṃ – idaṃ vuccati, bhikkhave, dukkhaṃ ariyasaccaṃ.
"And what, bhikkhus, is the noble truth of suffering ? It should be said : the six internal sense bases. What six ? The eye base ... the mind base. This is called the noble truth of suffering."
"ajjhattikāni āyatanānī" is here translated into "six internal sense bases", which seems to make things difficult to understand.
ajjhattiko means: Relating or belonging to the individual or self, personal, internal, subjective.
Thus it should be understood as: What is the noble truth of suffering? It should be said: the six sense bases related to a self.
The ability/faculty of sight (cakkhundriyam) is not affected. But the sense of sight changes. From "this form is mine, I am this form, this form is my self" to "this form is not mine, I am not this form, this form is not my self" and for the arahant it isn't even that, it's just "form".
For example, the puthujjana sees: "this is my body, I am this body, it is my self"
the sekha sees: "this is not my body, I am not this body, it is not my self"
the asekha sees: "this form is form, depending on this form there is the term "body"
This is only an example to illustrate what I mean! Pleas don't take it too literally.
I don't see anywhere that the six sense bases cease before the death of the body. Maybe because I usually do not draw a distinction between the six senses and the six sense bases. But we could say the internal six sense bases have ceased after enlightenment, leaving the abilitiy to see untouched. This would then only mean that the six sense bases are no longer related to a self (refering to ajjhattiko). Things would be seen as they are: not-self.
But imho this shouldn't be discussed too much (in detail), because it easily leads to confusion . In the end it is again the well-known statement of the Buddha:
sabbe dhamma anatta
best wishes, acinteyyo