A medical device for preserving explanted corneas, comprising: a sealed outer main case ; a container , for preserving and viewing a cornea, contained in the sealed outer main case ; wherein the container in turn comprises: a vessel having a base wall , a lateral wall and an upper opening and which inside it forms a preserving chamber ; a supporting unit for a corneoscleral disc positioned in the preserving chamber ; and a first lid removably joinable or joined to the vessel for closing the upper opening ; wherein the medical device is ready for use and also comprises a first locking ring which is joinable or joined to both the first lid and to the vessel , outside them, and is breakable or deformable; wherein when the first lid is joined to the vessel and the first locking ring is joined both to the first lid and to the vessel : in an intact and non-deformed condition, the first locking ring prevents removal of the first lid from the vessel ; and in a broken or deformed condition, the first locking ring allows removal of the first lid from the vessel ; and wherein either: - the first lid is joined to the vessel ; and the first locking ring is intact and non-deformed, and is joined both to the first lid and to the vessel for preventing them from being separated; and wherein the medical device also comprises a second locking ring joinable to the vessel , also inserted in the outer case and separate from the first lid and from the vessel ; or - the first locking ring is separate both from the first lid and from the vessel for, in use, being joined to the vessel and to the lid after a cornea has been inserted in the vessel . a sealed outer main case ; a container , for preserving and viewing a cornea, contained in the sealed outer main case ; wherein the container in turn comprises: a vessel having a base wall , a lateral wall and an upper opening and which inside it forms a preserving chamber ; a supporting unit for a corneoscleral disc positioned in the preserving chamber ; and a first lid removably joinable or joined to the vessel for closing the upper opening ; wherein the medical device is ready for use and also comprises a first locking ring which is joinable or joined to both the first lid and to the vessel , outside them, and is breakable or deformable; wherein when the first lid is joined to the vessel and the first locking ring is joined both to the first lid and to the vessel : in an intact and non-deformed condition, the first locking ring prevents removal of the first lid from the vessel ; and in a broken or deformed condition, the first locking ring allows removal of the first lid from the vessel ; and wherein either: - the first lid is joined to the vessel ; and the first locking ring is intact and non-deformed, and is joined both to the first lid and to the vessel for preventing them from being separated; and wherein the medical device also comprises a second locking ring joinable to the vessel , also inserted in the outer case and separate from the first lid and from the vessel ; or - the first locking ring is separate both from the first lid and from the vessel for, in use, being joined to the vessel and to the lid after a cornea has been inserted in the vessel . - the first lid is joined to the vessel ; and the first locking ring is intact and non-deformed, and is joined both to the first lid and to the vessel for preventing them from being separated; and wherein the medical device also comprises a second locking ring joinable to the vessel , also inserted in the outer case and separate from the first lid and from the vessel ; or - the first locking ring is separate both from the first lid and from the vessel for, in use, being joined to the vessel and to the lid after a cornea has been inserted in the vessel . <EOS>