Enucleation

This procedure (Figure 9.2) involves the removal of the entire globe by severing the attachments of the extra-ocular muscles and optic nerves. This is the technique of choice in the presence of an intra-ocular tumour as histological specimens are easily obtained. There is no associated risk of sympathetic ophthalmitis. The surgery requires care to

Figure 9.1 Evisceration. (a) 360° peritomy, anterior chamber opened, cornea removed, two triangles of sclera excised at 3 and 9 o'clock; (b) evisceration spoon used to remove contents of globe, scleral shell cleaned; (c) scleral shell closed with 5/0 Vicryl.

Figure 9.1 Evisceration. (a) 360° peritomy, anterior chamber opened, cornea removed, two triangles of sclera excised at 3 and 9 o'clock; (b) evisceration spoon used to remove contents of globe, scleral shell cleaned; (c) scleral shell closed with 5/0 Vicryl.

prevent socket contracture or late post operative fat atrophy.

A 360° peritomy is made in the conjunctiva and Tenon's capsule is carefully separated from the globe. The four rectus muscles are identified and tagged with double ended 5/0 Vicryl sutures. The two oblique muscles are cut or the inferior oblique may be tagged and sutured to the inferior border of the lateral rectus, 10mm posterior to its free edge. The optic nerve is sectioned with scissors or a snare. The globe is removed and the socket packed, using gauze soaked in iced saline to achieve haemostasis.

An ocular implant is generally inserted, either within Tenon's capsule or posterior to the posterior part of Tenon's capsule. Deep

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Figure 9.2 Enucleation. (a) 360° peritomy; (b) four rectus muscles disinserted, oblique muscles cut, optic nerve divided, globe removed; (c) wrapped spherical orbital implant inserted, rectus muscles saturated to implant; (d) tenons capsule closed, muscle sutures brought out through conjunctiva; (e) conjunctiva closed.

Figure 9.2 Enucleation. (a) 360° peritomy; (b) four rectus muscles disinserted, oblique muscles cut, optic nerve divided, globe removed; (c) wrapped spherical orbital implant inserted, rectus muscles saturated to implant; (d) tenons capsule closed, muscle sutures brought out through conjunctiva; (e) conjunctiva closed.

placement of the orbital implant in this site posterior to Tenon's capsule allows a larger volume to be implanted and reduces the incidence of implant migration or extrusion. The orbital implant may be of inert material, for example silicone ball or one that allows fibrovascular ingrowth, for example Medpor and Hydroxyapatite. Implants are wrapped in a synthetic mesh or donor sclera. The four rectus muscles are attached to the implant. The superior rectus should not be placed too anteriorly to minimise the incidence of upper lid retraction or ptosis.When using Hydoxyapatite, holes should be made in the wrap to allow the attachment of the extra ocular muscles and to facilitate fibro-vascular ingrowth. Muscle sutures are then placed through the conjunctival fornices to improve prosthesis mobility. Tenon's capsule and conjunctiva are closed carefully in two layers. A conformer, with a large central drainage hole should be inserted post operatively and left in place until a prosthesis is fitted at approximately six weeks.

Enucleation is not appropriate in the presence of endophthalmitis nor where a malignant tumour may have spread to extra-ocular structures. In this case an exenteration should be performed. An orbital implant is normally inserted at the time of primary enucleation but may be avoided in the presence of intraocular malignancy or in a very inflamed orbit where the incidence of post operative extrusion is high.

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