I still have no idea if cybereyes count as having a UDC to hook a smartgun up.
The rule that every device has as UDC and all cyberware are devices runs into cases where it is physically or practically impossible for the cyberware to have a UDC. Bone lacing is another example.
Why would you want to plug a cable directly into your freekin eye to begin with is beyond me...
The book DO let you plug the cable into your datajack (if you have an internal smartlink)
Just like we done in every other edition before things got wireless...
(or into your imaging device if your smartlink is external)
Depending on how you view them style wise, there's no real issue to an eye cable.
If the cyber eyes are a cheap end, goggle looking, Cyclops visor - no one would question whether you could have a UDC on the side.
If you envision high end "almost human" eyes, it still is possible to have a link at the temple like Geordi LaForge's visor contact points.
The ick factor only comes in if you are talking about something like a high end "human" eye with no external hardware what so ever (even then it could be a covered flap like Data's ports on ST:TNG). And I doubt the rules should bow to ick factor. I mean, how's your ick factor when the eye drones are sent out? (Flying eyeballs and a PC with empty sockets? That's nightmare fuel)
Of course this also brings up other style issues - does my embedded commlink look more like Data with hidden ports under little doors? or more like Lobot with a cyber headband in the back?
Personally I have no qualms with internal stuff having a dermal or subdermal (you can transmit through skin if you adhere the wire) hidden UDC for a wired connection but I was trying to find out what the game says on that (as I go to Missions) and it appears that there are at least two different camps.