He wears a VISOR, a half-moon shaped device allowing LaForge, who was born blind, to see. Sometime between Star Trek VII: Generations and Star Trek: First Contact he received ocular implants which replaced the VISOR giving him a more 'normal' appearance.
Geordi was born February 16, 2335 at the African Confederation, Earth to parents Captain Silva LaForge and Commander Edward M. LaForge. He attended Starfleet Academy, from 2353 to 2357.
In 2357 he was assigned as an ensign aboard the USS Victory under Captain Zimbata and in 2363-2364 was promoted to lieutenant junior grade and named chief con officer, USS Enterprise D (NCC-1701-D) under Jean-Luc Picard.
In 2365 he was promoted to a full lieutenant and transferred from command to the operations division and named chief engineer and in 2366 he was promoted again to lieutenant commander (sometime between Star Trek:The Next Generation seasons two and four).