Just rewatched “The Naked Now” not having seen it for at least a decade. Forgot about the talk with Crusher about his condition and how they bring it full circle when the metaphasic radiation temporarily heals his optic nerves. I’ll be funny next post, I swear.
The VISOR (an acronym for Visual Instrument and Sensory Organ Replacement) allows him to see infrared and ultraviolet. Not to mention lots of other useful environmental info.