What I take from this thread and the reference to the graduated deed-example table in the book is that blinding an opponent for the long term is perhaps too much for a deed, even on the higher scale of the die.
The 7+ result example actually includes the possibility of being permanently blinded (24 hours of blindess followed by a Fort save against the attack the Deed landed with).
Since we're here, talking, (well, we're not here per se... nor talking... and I'm pretty much alone writing in this thread presently... Damn!) what would you allow for trying to blind someone with sand in the face? If that's in the book too, I apologize in advance.
With a Deed, I might grant the character a +2 or +1d to his attack roll for having sand to throw in the target's face... but the attack would deal no damage.
Without a Deed, I might use an opposed Agility Check (monster using his HD as his bonus to the roll) to see if the character could pull off the sand in the eyes trick.
And... How about taking in the opponent's strength to consider the result? Say the PCs are fighting a 1 hit die opponent and the warrior throws sand in his face, hoping to blind him and succeeds on his deed die, perhaps that could work and the critter is blind for a couple of rounds; but if the warrior throws sand in the face of the 15 hit die dragon, perhaps it doesn't work as well?
Other than the above mention of me using a critter's HD as their "ability modifier" for most opposed rolls, I don't like the idea of using HD to represent a lot of things about a critter... just being a big, tough, or well trained sort of thing/person doesn't make your eyes any less susceptible to painful irritation by coarse, gritty particles.
Now, as the book suggest, you might adjust the usefulness of a blinding attack either up or down the scale relative to the number of eyes or sight-organs a monster has (i.e. cyclopes are out of luck when it comes to eye jabs, but a roiling ball-like creature with a thousand eyes is nigh-impossible to blind).