An entire eye cannot be transplanted although corneas can be transplanted, which involve replacing the clear front part of the eye which is a common and successful procedure.
Transplanting the entire eye and restoring functional vision through a complete eye transplant is not possible.
The reason why we can't have an eye transplant is because the transplanted eye cannot send the signal to the brain through the optic nerve which is why it's not currently possible to restore vision with a whole eye transplant.
A blind person can sometimes see again with surgery, although it also depends on the type and cause of the blindness.
If the blindness is caused by cataracts, which is a clouding of the eye lends, it can be effectively treated with cataract surgery and can restore sight to people who were previously considered blind from cataracts.
Other eye conditions that can result in blindness such as some forms of retinal degeneration, can often be treated through emerging treatments such as gene therapy or even bionic eye implants.
Bionic eye implants are still in clinical trials although they do offer some hope for restoring some vision in some people.
If the person is completely blind and it's another cause then surgery cannot fix it and the person won't be able to see again.
If the blindness is a result of damage to the cornea, which is the clear front part of the eye, then a corneal transplant can restore a persons vision.
And in some cases of inherited retinal diseases, gene therapy may also be able to correct the genetic defect and improve vision.
Bionic eye implants, involve implanting a device which can stimulate the retina or brain to create a sense of vision.
Although they are still experimental devices and are currently in clinical trials and they are not a perfect replacement for natural eyesight, but they can help people distinguish light, shapes and movement.
And even emerging treatments such as stem cell therapy and other surgical interventions hold promise for certain conditions, but they are also still in development.