Lear: the earliest reference to sight comes in Act One, Scene One after Lear has failed to see the truth about his three daughters. Kent tries to warn the King that he is behaving foolishly ‘See better, Lear’
Kent begs Lear to let him remain ‘the true blank of thine eye’
In response Lear dismisses Kent ‘out of my sight’
Kent is able to see Cordelia's true love for Lear, so Kent tries to help Lear see her love, but Lear's stubbornness keeps his vision clouded.
After the storm, Lear’s ability to see more clearly is apparent when he meets Gloucester.
In IV.6, the black humour of the references to sight heightens the pathos of old men suffering. It also comes as a relief as there is reason for Lear’s madness as he has seen what has happened to him and how he has been deceived.
Gloucester’s blinding is the physical manifestation of the mental torture Lear endured on the heath.
Gloucester's blindness prevents him from seeing the goodness of his son Edgar and the evil of his son Edmund.
Gloucester’s physical blindness symbolises the metaphorical blindness that grips both Gloucester and the play’s other father figure, Lear.
The parallels between the two men are clear: both have loyal children and disloyal children, both are blind to the truth, and both end up banishing the loyal children and making the wicked ones their heirs.
Only when Gloucester has lost the use of his eyes and Lear has gone mad does each realize his tremendous error.