As blind as a bat

(as) blind as a bat 
(humorous) not able to see well

• She's as blind as a bat without her glasses.

The blind leading the blind
a situation in which people with almost no experience or knowledge give advice to others who also have no experience or knowledge

Not a blind bit/the blindest bit of… 

(British English, informal) not any

• He didn't take a blind bit of notice of me (= he ignored me).

• It won't make the blindest bit of difference(= it will make no difference at all).

Turn a blind eye (to something)

to pretend not to notice something bad that is happening, so you do not have to do anything about it

• The authorities were either unaware of the problem or turned a blind eye to it.

Blind (to something)

not noticing or realizing something

• She is blind to her husband's faults.
• I must have been blind not to realize the danger we were in.

Blind faith/obedience

[usually before noun] (of strong feelings) seeming to be unreasonable, and accepted without question; seeming to be out of control

• It was a moment of blind panic.

[usually before noun] (of a situation or an event) that cannot be controlled by reason

• a blind chance
• the blind force of nature