Surgical Revision of Orbital Prosthesis

David J. Woods, MD

CASE PRESENTATION

51 yo AA Male Discharge from behind prosthetic implant OD x 1 month. Referred for revision of extruding orbital implant

POH:Enucleation OD for Eye tumor at five years oldFirst orbital implant as long as I can rememberAt least three different orbital implantsCurrent PMMA implant placed around 1995

PMHx:CVA - October 2003Depression, Hypertension, Hypercholesterolemia, borderline diabetes

Allergy: NKDAMedications: Bacitracin Ophth Ung bid, dilantin, Lisinopril, Vioxx, Escitalopram

ExamODEOM:Limited motility of prosthesisExternal: Proptotic prosthesis Lids:wnlConj:2x4 mm buttonhole scant mucus, no infection Extruding PMMA implant

OS20/30 vision, Normal exam

Case PresentationAssessment: Extruding Orbital PMMA implant s/p enucleationMultiple past revisions

Questions:What risk factors does this patient have for orbital implant extrusion?What are the surgical options and recommendations?

Exposure and Extrusion of ImplantMay Occur if . . .

placed too far forward

compromised wound healing(infection, diabetes, radiation, burn)

closure of anterior Tenon's fascia is not satisfactory

poorly fitting prostheses or conformers (Contracted socket)

pressure points between the implant and prosthesis

Surgical OptionsDermis-fat graft For Limited ConjunctivaUnpredictable reabsorption of volume in adultsAppear to grow with orbit in children

Inert spherical implants (glass, silicone, or methyl methacrylate)comfort and low rates of extrusion motility only through passive movement of the socket.

Buried motilityfront surface projections push the overlying prosthesis with a direct force probably improve prosthetic motility. may pinch conjunctiva, lead to a painful socket or erosion

Biointegrated implants (Hydroxyapatite and porous polyethylene)allow for drilling and placement of a peg Drilling usually 6-12 months after enucleationexcellent motility, some report even w/o peggingpossibly higher rate of postoperative exposure

Secondary Orbital ImplantSurgical TechniqueSelect Smaller Implant by 1-2 mmConsider opening muscle cone if contracture present Place new implant posterior to all layers of Tenons Resuture rectus muscles or old scleral shell to implant in anatomic fashionPass muscle suture ends through conjunctival fornicesTenons and Conj closed in separate layersPlace Conformer; Tarsorrhaphy

Porous biomaterial & polymersHydroxyapetite Biologic, inert, porousUse since 1985

Porex Medpor SpheresSynthetic polymerPores allow rapid ingrowth

Implant Placementwithin Tenon's capsule or posteror in the muscle cone

Reinforcement with homologous sclera or autogenous fascia

Should include tight closure of Tenon's fascia over implant prevent later extrusion

Muscles sutured into the normal anatomic locations allow superior motility and prevent migration

Goals

Implant GoalsComfortMotility Appearance

sufficient volume (Maintain with Conformer)centered within the orbitconjuctiva and fornices sufficient to hold a prosthesis

Contracted Sockets: fornices inadequate to retain a prosthesis

Causes include:Radiation treatment

Consequence of extrusion

Severe initial injury (alkali burns or extensive lacerations)

Poor surgical techniques excessive sacrifice of conjunctiva and Tenon's capsule, traumatic dissection within the socket causing scar

Multiple socket operations

Removal of the conformer or prosthesis for prolonged periods

Exposed implantssubject to infection

rarely spontaneously close

should be covered with scleral patch grafts or autogenous tissue grafts to promote conjunctival healing

Surgical Anophthalmos

The Anophthalmic SocketProcedure of choice varies with multiple indicationsfirst described over 4 centuries ago

Enucleation: removal of the entire globe Often indicated for primary malignancy not amenable to other local therapies

Evisceration: removal of the intraocular contents leaving the sclera and extraocular muscles intact. should not be performed in cases of suspected intraocular malignancy.

Exenteration: removal of globe and all parts of orbital tissues

Contracted SocketsProstheses or Conformeracrylic or silicone conformer is placed in the conjunctival fornicesmaintain the conjunctival space anophthalmic socket without a conformer or prosthesis can contract in a matter of daysSurgically placed inflatable conformers available for children

Treatment of Contracted SocketsReconstruction procedures: incision and/or excision of the scarred tissues and placement of a graft to enlarge the fornices. Full-thickness mucous membrane grafting is preferred, (matches conjunctiva histologically)Buccal mucosal grafts possible option

Thank You