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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Ocular prosthesis | 5/6 | https://en.wikipedia.org/wiki/Ocular_prosthesis | reference | science, encyclopedia | 2026-05-05T07:31:20.544903+00:00 | kb-cron |
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 to suit both 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. It is generally recommended to leave the prosthesis in the socket as much as possible, though it may require some cleaning and lubrication, as well as regular polishing and check-ups with ocularists.