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• To match the side that the prosthetic arm will be fitted.
• As twinned pairs (Tactical borg will often walk with a "left-eye" and a "right-eye" on either side of a subject, for example)
• As @Einer says, if someone has a pre-existing deficiency in one eye, it's reasonable to presume the Borg will replace that eye as a priority
• Handedness seems to be hard-wired into human (and alien) brains. It makes sense not to fight against an existing predisposition when there's a completely free choice.

• To match the side that the prosthetic arm will be fitted.
• As twinned pairs (Tactical borg will often walk with a "left-eye" and a "right-eye" together for example)
• As @Einer says, if someone has a pre-existing deficiency in one eye, it's reasonable to presume the Borg will replace that eye as a priority
• Handedness seems to be hard-wired into human (and alien) brains. It makes sense not to fight against an existing predisposition when there's a completely free choice.

Regarding the side of the head that the device is fitted to, there are a couple of possible reasons:

• To match the side that the prosthetic arm will be fitted.
• As twinned pairs (Tactical borg will often walk with a "left-eye" and a "right-eye" on either side of a subject, for example)
• Handedness seems to be hard-wired into human (and alien) brains. It makes sense not to fight against an existing predisposition when there's a completely free choice.

Tactical Drones, for example seem to have long-lens type eyepieces on their right whereas Medical Drones appear to have a microscoping eyepiece with multiple lenses. Normal 'labor/maintenance-type' drones seem to have the bog-standard holographic eyepieces that we see in TNG: I, Borg whereas the Borg Queen's eyepiece seems to be wholly internal.

Tactical Drones, for example seem to have long-lens type eyepieces on their right whereas Medical Drones appear to have a microscoping eyepiece with multiple lenses. Normal 'labor/maintenance-type' drones seem to have the bog-standard holographic eyepieces that we see in TNG: I, Borg whereas the Borg Queen's eyepiece seems to be wholly internal.

Regarding the side of the head that the device is fitted to, there are a couple of possible reasons:

• To match the side that the prosthetic arm will be fitted.
• As twinned pairs (Tactical borg will often walk with a "left-eye" and a "right-eye" on either side of a subject, for example)
• As @Einer says, if someone has a pre-existing deficiency in one eye, it's reasonable to presume the Borg will replace that eye as a priority
• Handedness seems to be hard-wired into human (and alien) brains. It makes sense not to fight against an existing predisposition when there's a completely free choice.

Tactical Drones, for example seem to have long-lens type eyepieces whereas Medical Drones appear to have a microscoping eyepiece with multiple lenses. Normal 'labor/maintenance-type' drones seem to have the bog-standard holographic eyepieces that we see in TNG: I, Borg whereas the Borg Queen's eyepiece seems to be wholly internal.

You'll note that the eyepieces became far more elaborate in First Contact (and then Voyager) as their budget grew. Gil Mosko, makeup artist for TNG, Voyager and First Contact describes the evolution of the eyepieces over time;

Tactical Drones, for example seem to have long-lens type eyepieces on their right whereas Medical Drones appear to have a microscoping eyepiece with multiple lenses. Normal 'labor/maintenance-type' drones seem to have the bog-standard holographic eyepieces that we see in TNG: I, Borg whereas the Borg Queen's eyepiece seems to be wholly internal.

Gil Mosko, makeup artist for TNG, Voyager and First Contact describes the evolution of the eyepieces over time. The side chosen appears to be totally random, as part of an effort to create a "unique feel" for the alien nature of the Borg.