Twenty-month-old Nicholas Holderman accidentally fell on his parents' keys while playing at their home, forcing one of them through his eyelid.
His parents, Chris and Staci, called for emergency services as soon as they heard his screams. The little boy was rushed by helicopter from the family home in Perryville, Kentucky, to hospital.
Doctors observing Nicholas removed the key during surgery without the toddler suffering any damage to his brain, even though they believed that the kid's right eye had been ruptured.
However, they were astounded when just 15 minutes after the operation they discovered that the boy's eyesight was unaffected.
The kid's mother revealed that the accident took place while Nicholas was playing with brothers Caleb and Isaac in the living room on September 2.
"I'll never forget that moment. Nothing can prepare you for something like that. We knew that he was injured seriously," the Telegraph quoted her as saying.
His brother Isaac said: "When I looked at it close I saw the key in his eye."
Their father added: "It was a very horrifying sight to see this happen to your baby."
Nicholas was allowed home just after six days in hospital, and he is now said to have made a full recovery.
His parents have revealed that his eyesight is perfect.
His father said: "Fifteen minutes later for another doctor to say nothing was wrong, we knew it was a miracle from the Lord."
Nicholas' mother added: "We all grin and look at him and are so thankful, and are reminded every day of what a miracle it truly is."