" Cornea lives for over 40 hours after the death of the person. For donation, the eye must be removed within four hours of the death of a person."

Lives for 40 hours but must be removed after 4 hours? Why?

Dear Student,

Although cornea can survive for 40 hours after death, but it is better to have transplantion of cornea within 4- 6 hours. 

 The concept of organ donation is based on the fact that after death of a person, his /her organs and their tissues take time to be considered as dead. It is so because minute capillaries supplying blood to tissues contain oxygenated blood even after death. When tissues utilises all the oxygen and  no more oxygen is left behind, then the organ loses its function and considered as dead.

 Same case is with the  cornea (tissue).