This horribly, bloody, terrible event that happens had to have a specific purpose.
we can see without our eyes.
"O dear son Edgar,
The food of thy abused father's wrath!
Might I but live to see thee in my touch,
I'ld say I had eyes again!"- act IV scene I
He was blind metaphorically, and wrongly accused his righteous son, until he was blinded literally, and saw the truth.
"What, art mad? A man may see how this world goes
with no eyes. Look with thine ears: see how yond
justice rails upon yond simple thief. Hark, in
thine ear" -act IV scene VI
Lear, in his mad, primal state, half lost his mind tells Gloucester still how there is life to see beyond what we experience only through our eyes.
"Met I my father with his bleeding rings,
act V scene III
His newly lost eyes, became his guide.
Gloucester pleads with his son, Edgar to let him stay and rot under a tree, and Edgar replies,
Their going hence, even as their coming hither-"act V scene II
Men must endure.
This disturbing and unsettling play has a purpose in its gruesomeness. Even though our own mistakes create the misery in our lives, we must still go on.