Eye Removal Surgery
An eyeball may need to be removed for a number of reasons:
- a painful blind eye
- an unsightly blind eye
- an eye with a malignant tumour (e.g. choroidal melanoma)
There are 2 types of eye removal surgery:
- Enucleation (removal of the whole eyeball)
- Evisceration (removal of the contents of the eye)
In enucleation surgery the whole eyeball is removed from the eye socket. The lining of the eyeball (the conjunctiva) is opened and the six extraocular muscles that move the eyeball are detached from the surface of the eye. The optic nerve is then detached form the back of the eyeball. The eye can then be removed.
The volume of the eyeball (7mls) is partly replaced by insertion of a spherical orbital implant at the the time of surgery. This is usually made of acrylic or a porous material (bioceramic, hydroxyapatite or Medpor).
After the socket has healed (usually 6-8 weeks later) an artificial eye can be custom-made and fitted by a specially trained prosthetics expert (an ocularist).
Evisceration surgery removes all of the contents of the eyeball but leaves the sclera (the tough outer coat) behind. This remains attached to the extraocular muscles and can be used to cover an orbital implant sphere.
Evisceration is usually a less invasive procedure than enucleation. Less of the eye socket tissues are disrupted.
Patients undergoing evisceration have potentially better artificial eye movements and less hollowing of the eye socket and upper eyelid (upper eyelid sulcus deformity).
To choice of whether a patient undergoes enucleation or evisceration will be down to surgeon and patient preference in many cases.
It is essential to perform an enucleation if a malignant tumour is diagnosed or suspected. This allows the tumour to be removed in it’s entirety and eliminates the risk of spillage of tumour cells into the eye socket.
An enucleation is also preferred if the eyeball is very shrunken in size or if an infection is suspected of involving the sclera.
Sympathetic ophthalmitis (SO)
This is a rare severe inflammation of the eyes that can be triggerred by exposure of the contents of the eyeball to the immune system. The immune system can launch an attack on the eyeball and cause sight-threatening inflammation. This can happen after any surgery that involves entering the eyeball (intraocular surgery).
In view of the above risk some surgeons prefer to perform enucleation rather than evisceration. The theoretical risk of sympathetic ophthalmitis affecting the only remaining eye is indeed only a theoretical one.
Statistically there is very little difference in the risk of SO between the 2 procedures. In many cases the potential advantages of evisceration (a shorter less invasive procedure and potential cosmetic and artificial eye movement benefits) make this the procedure of choice.