The human body is perfectly made and no one part cannot work without the other in its perfection. Yes, some people have had the unfortunate mishap to lose a limb or two, and some were born without too. Yet, missing one limb has not stopped people from achieving great things like Nick Vujicic who was born with any limbs, but found purpose in life. Now, the eye is one of those parts of the body that no one would prefer to give over another. Compared to a kidney, a lung, or part of the liver for extremes, no one would prefer to donate an eye. In fact, the bible calls the eye the lamp of the body (Mt6:21-23) and it can have conditions that are good and bad, but if the conditions of the heart are bad no one is willing to take it out. The bible tells us that in the process of healing the eye is a vital part for it to happen (Mt13:15). With a little faith this blind man received his sight again when he encountered Jesus in Matthew 9:28-30. The eye is closely linked to the heart, so whatever you allow to go through it, it will eventually end up in the heart.
Matthew 5:28-29
28 But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart. 29 If your right eye causes you to stumble, gouge it out and throw it away. It is better for you to lose one part of your body than for your whole body to be thrown into hell.
So, taking your physical eye is not something that we are not too willing to do no matter what, but Jesus made it clear that because of the gravity of the act of impurity we need to consider. The people of Beth Shemesh, after the Philistines sent over the ark of the covenant with golden rats and tumors for sins, died when they looked inside the ark (1Sam6:19). These people of Beth satisfied their lustful desires to see inside of what they knew did not please God. Plucking out those desires from the flesh are not so easy to do, but the bible tells us that we do need to flee (2Tim2:22). But, not just from sexual immorality do we need to flee from, there are other things from which our eyes needs to be hid from. For example, when we look at the conflicts in the homes between parents and their children it can be attributed to a haughty spirit (Prv30:11-13).