Appeal judges ruled the original sentence "unduly lenient" and said the case was a stark example of what might happen when excessive alcohol was consumed.
The Court of Criminal Appeal in Edinburgh heard that Jason Clark, 18, and Rhys Wilkinson, 17, both of Kilmarnock, were first offenders from stable and supportive families.
"Yet on the evening of 28 December 2008, they perpetrated a most vicious assault on a defenceless victim with very grave consequences for the rest of his life," said Lord Hamilton, the Lord Justice-General, sitting with lords Eassie and Bannatyne.
Clark and Wilkinson admitted attempting to murder John Dale, 50, in Old Street, Kilmarnock, as they returned from a Hibernian v Kilmarnock football match in Edinburgh. Both teenagers had been drinking.
Mr Dale was walking home carrying a bottle of milk when the pair knocked him to the ground and punched and kicked him on the head and body. They then positioned his unconscious body so they could take running kicks at his head.
Mr Dale suffered multiple facial fractures and required extensive reconstructive surgery. He also sustained brain damage and will require care for the rest of his life, the court heard. Even everyday tasks such as getting out of bed and washing and dressing were beyond him. He was blinded in one eye, and now has only partial sight in the other.
Sentences of three years and four months were imposed on each youth by Lord Brailsford, but the Crown appealed those as too lenient. Lord Hamilton said the pair should have been given seven and a half years, which would be discounted to five years because they had pleaded guilty.