Back in SR2 you could put them in either cybereyes or ears. Not sure if 3rd had that. Still imagining that creepy image of someone inserting a huge jack into his eye is just discomforting
According to SR2 p. 247-248 cyberears would
...accept a minor additional adjustment (one feature of 0.2 essence cost or less) without additional impact on the users's system (Cosmetic modification, Damper, High Frequency, Low Frequency and/or Recorder) and Eyes would
...accept additional vision enhancements up to 0.5 essence cost without further essence loss (Camera, Cosmetic Modification, Flare Compensation, Low-Light and/or Thermographic). Cyberlimbs could be fitted with
...spurs and hand razors at no additional loss to the users's system. You could also built-in a smartlink in your cyberlimb for half essence cost (back in SR2 smartlink was bodyware that used a subdermal induction pad in the users palm to link with the smartgun).
In SR2 you placed headware in the cranium, internal headware inside the brain, ear modificaitons in the ears, vision enhancements in eyes and bodyware in the body.