The FA have released guidance and support for Spectacles and Goggles in Football. 

Can players wear spectacles or goggles when playing football?

 Flying footballs and close physical contact make football a moderate risk sport for eye injuries. Spectacles or goggles may provide protection from injury and can also be worn with those who need to wear prescription lenses.

Polycarbonate Lenses: This is the most important property of all protective spectacles or goggles. Good polycarbonate is virtually unbreakable, and will sustain the impact of a ball or finger.

Sports Band: an elasticised band and not temple pieces should secure the frame. Players must have something that will be secured tight to the head so that the spectacles or goggles won't fall off. A frame with temples will not hold tight enough and a jab from a finger could lift the frame off and potentially damage the eye.
Although sports eyewear is intended to offer the best protection available, there is always the possibility that the wearer may sustain an eye or facial injury due to severe impact or because of the nature of the athletic activity. Referees should ensure that if a request has been made to wear glasses/goggles, that they must not be a danger to himself or to any other player.

Children and Grassroots Football: Whilst The FA recommends Polycarbonate lenses we recognise this may be an issue for children playing in grassroots football. Therefore we encourage referees officiating in grassroots youth football to be tolerant over glasses. However the individual referee has to show concern for all those playing in that game and if s/he feels there is something dangerous in the glasses i.e. sharp edges, etc, then in order to protect players and also the wearer him/herself s/he has the authority to say the glasses can’t be worn.