Taking this trait lowers your base Perception by 1 point when attempting to qualify for perks. This means the player must have a base perception of 7 to qualify for all perception based perks (except Infiltrator and HobblerDead Money which require 8 instead of the usual 7 due to the -1). This can be achieved by taking perception 7 at creation, or perception 6 with Intense Training added later to boost it to 7.
Wearing glasses with this trait will actually raise perception by +2 as seen in the Pip-Boy display, thereby nullifying the -1 in terms of compass and skill benefits (though not the damage to base perception, thus requiring the player have 1 more point of permanent perception to take an associated perk). Perception 7 at creation, with this trait (glasses equipped), Intense Training +1 or an implant and a +1 perception hat will still total 10 perception.
In Doc Mitchell's house, where the doctor asks the player their name and lets them adjust appearance options, there is a pair of eyeglasses on the counter over his right shoulder (behind the medical bed). They can be acquired before interacting with the Vit-o-matic Vigor Tester, though not worn until you receive the Pip-Boy 3000.
Unlike the glasses in Fallout 3, the various glasses in New Vegas do not provide a perception bonus. This trait effectively gives them this ability.
If you set your perception to 1 or 10 at character creation, you cannot take this trait.
While most types of glasses grant +2 to Perception with this trait, the Lucky shades grant +3. The reason for this is unknown, as without this trait, the Lucky Shades do not grant any extra Perception.
Biker Goggles are not affected by this perk, even though they have attachments that appear to have glasses and lenses which cover the player's eyes. However, biker goggles are only intended to protect the eyes from wind, dust and other flying particles encountered commonly while riding motorcycles: things not directly related to the functionality of the eyes.