VISOR

The VISOR is a device that allows Geordi Laforge to see, in spite of him being blind from birth. It scans through the EM spectrum at a much greater range of frequencies than those that the normal human eye can detect. The device transmits the data through data ports implanted in the sides of his head.

In TNG "Encounter at Farpoint", Geordi says that using the device is painful, but the prescribed medical treatments would interfere with the device. This aspect of the device's operation is never addressed again in the series.