Enucleation & Evisceration
Removal of an eye (an enucleation), or the inside of an eye (an evisceration), may be necessary for a variety of reasons. Regardless of the underlying disorder, and whether the eye sees or not, the decision to have an eye removed can be difficult and emotionally demanding. Nevertheless, skilled surgery combined with first class prosthetic care can lead to a very acceptable aesthetic result, and in many cases the symmetry and colour match between the artificial and the fellow eye can be very good indeed.
What are the possible treatments for an eye that does not see?
In general, it is better to avoid surgery if possible, with painted contact lenses, or shells (acrylic artificial eyes) worn over a blind eye often looking as good as a real eye. However, if a blind eye becomes painful in spite of the use of drops, or a contact lens or shell cannot be tolerated, or the patient does not have the manual dexterity required to remove the lens or shell each evening, then surgery should be considered as this addresses both the discomfort and allows an artificial eye to be worn continuously with only a very occasional need for its removal for cleaning.
How is an eye removed?
Essentially, there are two approaches:
- . An enucleation: this involves the removal of the entire eyeball (this includes the white part of the eye referred to as the ‘sclera’). In its place a permanent solid spherical implant (or ‘ball’) is placed deep within the socket to compensate for the loss of volume, and the muscles which move the eye are reattached to this implant. The superficial membranes (including the conjunctiva) are stitched over the front surface of this implant (or ball, which remains permanently covered), and once the surface inflammation has settled (within a few weeks), an artificial eye, or ‘prosthesis’ (similar to a shell) can be worn on top. This is held in place by the eyelids. The deeper ball implant typically remains in place for life and usually requires no further attention. For some patients who are not suitable for such an implant, a dermis fat graft is used instead. This is taken from the abdomen or the upper outer quadrant of the buttock area.
- . An evisceration:in this operation the white part of the eye (the sclera) is not removed, but used as a natural wrapping material to cover the ball implant. This operation is easier to perform but cannot be undertaken for patients who have an eye tumour. It offers the advantage of a more rapid recovery for the patient.
I have heard that removal of an eye can cause inflammation in the other eye. What is this called and why does it occur?
An exceptionally rare form of inflammation, called ‘sympathetic ophthalmitis’, can occur in the healthy eye any time after an open eye injury or an operation on the other eye that exposes the uvea, the pigmented layer of the eye. This occurs because the exposed contents of an injured eye can activate the body’s immune system against the same tissues in the healthy eye. Although treatable in the vast majority of patients, such an inflammatory problem can rarely lead to loss of sight in the good eye.
The removal of an eye using the evisceration method (but not an enucleation) carries this theoretical risk of such an inflammation. It should be noted however that such eyes have usually had previous injury or surgery, and the other normal eye is therefore already at risk, even before the eye is removed. The true likelihood of developing sympathetic endophthalmitis in the good eye after an evisceration is very difficult to determine, but is considered to be in the order of 1: 50,000. However, sympathetic endophthalmitis is treatable, and overall many more eviscerations are now performed than enucleations for the reasons outlined above.
How long do I stay in hospital, and when is the artificial eye first fitted?
Evisceration and enucleation are usually day case procedures and thus patients can be discharged a few hours after their surgery. The eye dressing is removed at home, 5 days later and a review is scheduled for one week later.
The artificial eye, or ocular prosthesis, is designed and fitted by specialised colleagues called ocularists or ocular prosthetists.
During the healing phase after surgery, the patient wears a clear plastic shell (a surgical conformer) inserted behind the eyelids to maintain the shape of the socket during the healing process. During this interval any socket inflammation and swelling gradually resolve. The bespoke artificial eye is then made, using the colour and characteristics of the fellow normal eye as a template. It is usually fitted as soon as the socket has completed healed 6 weeks after the operation. It is important that the artificial eye is not fitted too soon as this can disrupt the wound and predispose to exposure of the buried implant.