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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Ocular prosthesis | 4/6 | https://en.wikipedia.org/wiki/Ocular_prosthesis | reference | science, encyclopedia | 2026-05-05T07:31:20.544903+00:00 | kb-cron |
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. In addition to this, although the porous implants have been reported to offer improved implant movement, these are more expensive and intrusive, require wrapping and subsequent imaging to determine vascularization and pegging to provide for better transmission of implant movement to the prosthesis, and 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 == Enucleation and orbital implantation 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.: