He's not a normal Uchiha so I don't think he's losing his eyesight since it was aa transplant. I belive he activated his MS by means unknown.
that doesnt mean nothing them eyes are from an uchiha
Yeah and when Sasuke and Madara took their brothers eyes they don't lose vision which is a transplant.
Since it's not known if Kakashi is losing his vision or not all I can base it on is the fact that it seems when a transplant is done the effects of blindness is nulled. Like I said they never mentioned Kakashi losing his eyesight so we can only speculate.