~~ What was,  what is  Blinded?   What was opened?~~

11Cor. 3: 14.  But their minds were blinded:

Eph. 1: 18 The eyes of your understanding being enlightened

Eph. 2: 3.  Among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others.

So see that the 'mind' and the 'eyes' are the same thing.  If you are blind, then it means your mind is darkened; not understanding truth.  It causes you to fulfill the lusts of the flesh and the mind.

Eph. 3: 4.  Whereby, when ye read, ye may understand my knowledge in the mystery of Christ)

See again it speaks of the 'knowledge'.

Romans 1: 21.  Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.
 22.  Professing themselves to be wise, they became fools,

See here it says their heart was DARKENED.  This means their mind was blinded.

Romans 11: 10.  Let their eyes be darkened, that they may not see, and bow down their back alway.

This is also speaking of their mind being blinded.

Eph. 4: 18.  Having the understanding darkened, being alienated from the life of God through the ignorance that is in them, because of the blindness of their heart:

This says their understanding was darkened because of the blindness of their HEART.  OR MIND.

Compare this to our first verse > the mind was blind; so this heart being blind is the mind being blind; which means lack of light, or enlightment, which is darnened.

So at one time they had their minds, or understanding, or eyes enlightened;  but then their foolish heart or mind or eyes were again darkened or blinded.

So when Adam and Eve had their eyes opened, it opened their mind up to evil.  Then God through Jesus gave us light or opened our blinded eyes; but then their foolish heart turned back to Egypt or law, and their understanding was again darkened or blinded.

Go back to 11Cor. 3.  It tells that reading the O.T. or law is what blinded their minds.

11Cor. 3: 14.  But their minds were blinded: for until this day remaineth the same vail untaken away in the reading of the old testament; which vail is done away in Christ.
 15.  But even unto this day, when Moses is read, the vail is upon their heart.