eye. however, the motility peg is mounted in only a minority of patients. this may partially be the result of problems associated with peg placement, whereas hydroxyapatite implants are assumed to yield superior artificial eye motility even without the peg. polyethylene also becomes vascularized, allowing placement of a titanium motility post that joins the implant to the prosthesis in the same way that the peg is used for hydroxyapatite implants. implant movement implant and prosthesis movement are important aspects of the overall cosmetic appearance after enucleation and are essential to the ideal objective of crafting a lifelike eye similar in all aspects to the normal fellow eye. there are several theories of improved eye movement, such as using integrating prosthetic material, pegging the implant, covering the implant (e.g. with scleral tissue), or suturing the eye muscles directly to the prosthetic implant. the efficiency of transmitting movement from the implant to the prosthesis determines the degree of prosthetic motility. movement is transmitted from traditional nonporous spherical implants through the surface tension at the conjunctival–prosthetic interface and movement of the fornices. quasi-integrated implants have irregularly shaped surfaces that create an indirect coupling mechanism between the implant and prosthesis that imparts greater movement to the prosthesis. directly integrating the implant to the prosthesis through an externalized coupling mechanism would be expected to improve motility further. despite the reasoning stating that hydroxyapatite orbital implants without a motility peg would yield a superior artificial eye motility, when similar surgical techniques are used unpegged porous (hydroxyapatite) enucleation implants and donor sclera-covered nonporous (acrylic) spherical enucleation implants yield comparable artificial eye motility. in two studies there were no differences in maximum amplitude between hydroxyapatite and acrylic or silicone spherical enucleation implants, thus indicating that the implant material itself may not have a bearing on implant movement as long as the muscles are attached directly or indirectly to the implant and the implant is not pegged. the motility of a nonintegrated artificial eye may be caused by at least two forces: the rubbing force between the posterior surface of the artificial eye and the conjunctiva that covers the implant may cause the artificial eye to move. because this force is likely to be approximately equal in all directions, it would cause comparable horizontal and vertical artificial eye amplitudes. an artificial eye usually fits snugly in the conjunctival space (possibly not in the superior fornix). therefore, any movement of the conjunctival fornices will cause a similar movement of the artificial eye, whereas lack of movement of the fornices will restrict its motility. imbrication of the rectus muscles over a nonintegrated implant traditionally was thought to impart movement to the implant and prosthesis. like a ball-and-socket joint, when the implant moves, the prosthesis moves. however, because the so-called ball and socket are separated by layers of tenon's capsule, imbricated muscles, and conjunctiva, the mechanical efficiency of transmission of movement from the implant to the prosthesis is suboptimal. moreover, the concern is that imbrication of the recti over nonintegrated implants actually can result in implant migration. the recent myoconjuctival technique of enucleation is an alternative to muscle imbrication. although it is generally accepted that integrating the prosthesis to a porous implant with peg insertion enhances prosthetic movement, there is little available evidence in the literature that documents the degree of improvement. and although the porous implants have been reported to offer improved implant movement, these clearly are more expensive and intrusive, requiring wrapping, and subsequent imaging to determine vascularization and pegging to provide for better transmission of implant movement to the prosthesis, and also are prone to implant exposure. age and size of the implant may also affect the motility, since in a study comparing patients with hydroxyapatite implants and patients with nonporous implants, the implant movement appeared to decrease with age in both groups. this study also demonstrated improved movement of larger implants irrespective of material. surgical procedure essentially the surgery follows these steps: anesthesia conjunctival peritomy separation of the anterior tenon's fascia from the sclera pass sutures through rectus muscles rectus muscles disinserted from the globe rotate and elevate the globe open tenon's capsule to visualize optic nerve cauterize necessary blood vessels divide the nerve remove the eye hemostasis is achieved with either cautery or digital pressure insert orbital implant. if necessary (hydroxyapatite) cover the implant with wrapping material before attach the muscle (if possible) either directly (pp) or indirectly (ha) to implant. create fenestrations in wrapping material if necessary for ha implants drill 1 mm holes as muscle insertion site draw tenon's fascia over implant close tenon's facia in one or two layers suture conjunctiva insert temporary ocular conformer until prosthesis is received (4–8 weeks later) after implant vascularization an optional secondary procedure can be done to place a couple peg or post. also under anesthesia: create conjunctival incision at the peg insertion site create hole into implant to insert peg or post modify prosthesis to receive peg/post. the surgery is done under general anesthesia with the addition of extra subconjunctival and/or retrobulbar anesthetics injected locally in some cases. the following is a description of the surgical procedure performed by custer et al.: the conjunctival peritomy is performed at the corneal limbus, preserving as much healthy tissue as possible. anterior tenon's fascia is separated from the sclera. blunt dissection in the four quadrants between the rectus muscles separates deep tenon's fascia. sutures may be passed through the rectus muscles before their disinsertion from the globe. some surgeons also suture one or both oblique muscles. traction sutures or clamps may be applied to the horizontal rectus muscle insertions to assist in rotating and elevating the globe during the ensuing dissection. tenon's capsule may be opened posteriorly to allow visualization of the optic nerve. the vortex veins and posterior ciliary vessels may be cauterized before dividing the nerve and removing the eye. alternatively, the optic nerve may be localized with a clamp before transection. hemostasis is achieved with either cautery or digital pressure. the orbital implant is inserted at the time of enucleation. an appropriately sized implant should replace the volume of the globe and leave sufficient room for the ocular prosthesis. enucleation implants are available in a variety of sizes that may be determined by using sizing implants or calculated by measuring globe volume or axial length of the contralateral eye. in the past, spherical nonporous implants were placed in the intraconal space and the extraocular muscles were either left unattached or were tied over the implant. wrapping these implants allows attachment of the muscles to the covering material, a technique that seems to improve implant movement and reduce the incidence of implant migration. porous implants may be saturated with antibiotic solution before insertion. because the brittle nature of hydroxyapatite prevents direct suturing of the muscles to the implant, these implants are usually covered with some form of wrapping material. the muscles are attached to the implant in a technique similar to that used for spherical non-porous implants. the muscles may be directly sutured to porous polyethylene implants either by passing the suture through the implant material or by using an implant with fabricated suture tunnels. some surgeons also wrap porous polyethylene implants either to facilitate muscle attachment or to reduce the risk of implant exposure. a variety of wrapping materials have been used to cover porous implants, including polyglactin or polyglycolic acid mesh, heterologous tissue (bovine pericardium), homologous donor tissue (sclera, dermis), and autogenous tissue (fascia lata, temporalis fascia, posterior auricular muscle, rectus abdominis sheath). fenestrations in the wrapping material are created at the insertion sites of the extraocular muscles, allowing the attached muscles to be in contact with the implant and improving implant vascularization. drilling 1 mm holes into the implant at the muscle insertion sites is performed to facilitate vascularization of hydroxyapatite implants. tenon's fascia is drawn over the implant and closed in one or two layers. the conjunctiva is then sutured. a temporary ocular conformer is inserted at the completion of the pro- cedure and is worn until the patient receives a prosthesis 4 to 8 weeks after surgery. an elective secondary procedure is required to place the coupling peg or post in those patients who desire improved prosthetic motility. that procedure is usually delayed for at least 6 months after enucleation to allow time for implant vascularization. technetium bone or gadolinium-enhanced magnetic resonance imaging scans are not now universally used, but they have been used to confirm vascularization before peg insertion. under local anesthesia, a conjunctival incision is created at the peg insertion site. a hole is created into the porous implant to allow insertion of the peg or post. the prosthesis is then modified to receive the peg or post. some surgeons have preplaced coupling posts in porous polyethylene implants at the time of enucleation. the post may spontaneously expose or is externalized in a later procedure via a conjunctival incision. aftermath of surgical procedures regardless of the procedure, a type of ocular prosthesis is always needed afterwards. the surgeon will insert a temporary prosthesis at the end of the surgery, known as a stock eye, and refer the patient to an ocularist, who is not a medical doctor, but board certified ocularist by the american society of ocularists. the process of making an ocular prosthesis, or a custom eye, will begin, usually six weeks after the surgical procedure, and it typically will take up to three visits before the final fitting of the prosthesis. in most cases, the patient will be fitted during the first visit, return for the hand-painting of the prosthesis, and finally come back for the final fitting. the methods used to fit, shape, and paint the prosthesis often vary between ocularist and patient needs. living with an ocular prosthesis requires care, but oftentimes patients who have had incurable eye disorders, such as micropthalmia, anophtalmia or retinoblastoma, achieve a better quality of life with their prostheses. the care required for an ocular prosthesis, outside of regular polishes and check-ups with ocularists, typically revolves around maintaining moisture of the prosthesis and cleanliness. notable people with prosthetic eyes bhumibol adulyadej – king of thailand; lost his eye in a 1948 car crash (right eye) baz bastien – canadian ice hockey player, coach (right eye) mokhtar belmokhtar – algerian smuggler, kidnapper, weapons dealer, and terrorist; lost his eye mishandling explosives (left eye) sammy davis jr. – american singer (left eye) peter falk – american actor (right eye) tex avery – influential american animation director (left eye) ry cooder – famous musician best known for his slide guitar work. (left eye) nick griffin – bnp leader (left eye) leo mckern – actor (left eye) carl ouellet – canadian professional wrestler (right eye) claus schenk graf von stauffenberg – german career army officer and resistance leader (left eye) robert thurman – writer (left eye) mo udall – politician (right eye)