An ocular prosthesis , artificial eyes or eye glass is a type of craniofacial prosthesis that replaces a natural eye that does not exist after enucleation, expenditure contents, or orbital eksentasi. The prosthesis fits with the orbital implant and under the eyelid. Although often referred to as glass eyes, ocular prostheses roughly take the form of convex shells and are made of medical plastic grade plastic. Some ocular prostheses today are made of cryolite glass. The variant of the ocular prosthesis is a very thin hard shell known as a scleral shell that can be worn over damaged eyes or devises. Ocular prosthetic makers are known as ocularists. Ocular prostheses do not not provide vision; this will be a visual prosthesis. A person with an ocular prosthesis is completely blind on the affected side and has a monocular vision (one side).
Video Ocular prosthesis
History
The earliest known evidence of the use of ocular prostheses is that a woman found in Shahr-I Sokhta, Iran dating back to 2900-2800 BC. It has a half-sphere shape and a diameter of more than 2.5 cm (1 inch). It consists of a very light material, perhaps a bitumen paste. Artificial eye surfaces are covered with a thin layer of gold, carved with a central circle (representing iris) and a patterned gold line like sunlight. On both sides of the eye a small hole is drilled, where a golden thread can hold the eyeball in its place. Since microscopic studies have shown that the eye cavity shows a clear trace of the golden thread, the eyeball should be worn during its lifetime. In addition, the earliest Hebrew text refers to a woman wearing an artificial eye made of gold (Jeremiah Ned 41c, comp. Jer. Sanh 13c). The Roman and Egyptian imams were known to have produced artificial eyes at the beginning of the fifth century BC built from clay attached to cloth and worn outside the socket.
The first artificial eyes on the sockets are made of gold with colored enamel, then evolved into the use of glass (thus the name "glass eye") by the Venetians in the latter part of the sixteenth century. It is raw, uncomfortable, and fragile and the methodology of production remained known only to Venice until the end of the 18th century, when Paris took over as an artificial eye making center. However, the center was shifted again, this time to Germany due to their superior glass blowing technique. Shortly after the introduction of the art of making glasses into the United States, German goods became unavailable due to World War II. As a result, the US actually makes artificial eyes of acrylic plastic.
The production of modern ocular prosthetics has evolved from simply using glass into different types of materials. In the United States, ocular prostheses are most often made using PMMA (polymethyl methacrylate), or acrylic. In some countries, Germany in particular, the prosthesis is still most often made from glass.
The limit of realism
Ocularist surgeons are always working together to make artificial eyes look more realistic. For decades, all efforts and investments to improve the appearance of artificial eyes have been dampened by pupillary immobility. One solution to this problem has been demonstrated recently in LCD-based devices that simulate pupil size as a function of ambient light.
Maps Ocular prosthesis
Type of implant and chemical construction
There are many types of implants, classification of shape (Spherical vs egg (oval) shaped), stock vs. custom, porous vs. nonporous, specific chemical makeup, and presence of post or post motility. The most basic simplifications can divide the type of implant into two main groups: not integrated (not porous) and integrated (porous).
Unintegrated implants
Although there is evidence that ocular implants have existed for thousands of years, modern, unintegrated intraconal implants emerged around 1976 (not just glass eyes). Unintegrated implants do not contain unique equipment to attach to extraocular muscles and do not allow the growth of organic tissue into their inorganic substances. The implant has no direct attachment to the ocular prosthesis. Typically, these implants are covered with materials that allow extraocular rectus muscle fixation, such as donor screens or polyester gauze that improve motility implants, but it is not possible for direct mechanical couplings between implants and artificial eyes. Unintegrated implants include acrylic (PMMA), glass, and silicone balls.
Polymetile metakrilate (PMMA)
Polymethyl methacrylate (PMMA) is a transparent thermoplastic available for use as an ocular prosthesis, intraocular lens replacement when the original lens has been removed in cataract treatment and has historically been used as a hard contact lens.
PMMA has a good level of compatibility with human tissue, far more than glass. Although various materials have been used to make implants that were not integrated in the past, polymethyl methacrylate is one of the preferred implants.
Integrated implant (porous)
The porous nature of the integrated implant allows fibrovascular ingrowth along the implant and thus also the insertion of the post or post. Since direct mechanical coupling is thought to increase artificial eye motility, efforts have been made to develop so-called 'integrated implants' that are directly connected to the artificial eye. Historically, implants directly attached to the prosthesis were unsuccessful due to chronic inflammation or infection arising from unpaired implant materials. This led to the development of a quasi-integrated implant with a specially designed anterior surface that was supposedly better to move the motility implant into the artificial eye through the closed conjunctiva and capsule of Tenon. In 1985, problems associated with integrated implants were considered largely solved by the introduction of spherical implants made of porous calcium hydroxyapatite. This material allows for fibrovascular ingrowth within a few months. Porous enubation implants are now manufactured from a variety of materials including natural and synthetic hydroxyapatite, aluminum oxide, and polyethylene.
The surgeon can change the porous implant contour before insertion, and it is also possible to modify the contours in situ, although this is sometimes difficult.
Hydroxyphosphate (HA)
Hydroxyapatite implants are round and made in different sizes and different materials (Coralline/Synthetic/Chinese).
Since its introduction in 1989 when an implant made from hydroxyapatite received the approval of the Food and Drug Administration, spherical hydroxyapatite implants have gained wide popularity as enucleation implants and at one point are the most commonly used orbital implants in the United States. The porous nature of this material allows fibrovascular ingrowth throughout the implant and allows the insertion of coupling devices (PEGs) by reducing the risk of inflammation or infection associated with earlier integrated exposure type implants.
hydroxyapatite is limited to established (stock) bulbs (for enucleation) or granules (for building defects).
One of the main disadvantages of HA is that it must be covered with exogenous materials, such as sclera, polyethylene terephthalate, or vicryl mesh (which has a weakness in creating a rough implantable network interface that can cause technical difficulties in implantation and erosion of the tissue above it by the extrusion end stage ), because direct suturing is not possible for muscle attachment. Scleral cover carries the risk of infection transmission, inflammation, and rejection.
A recent study shows that HA has a faster rate of fibrovascularization than Medpor.
Porous polyethylene (PP)
MEDPOR is a high density porous polyethylene (Medpor) Implants made from linear high-density polyethylene. Development in polymer chemistry has enabled the introduction of new biocompatible materials such as porous polyethylene (PP) to be incorporated into the field of orbital implant surgery. Porous polyethylene enucleation implants have been used since at least 1989. These are available in dozens of round and non-spherical spheres and various plain sizes or blocks for individual intraoperative adjustment. The material is hard but easily shaped and allows direct muscle stitching to be planted without wrapping or additional steps. In addition, the smooth surfaces are less abrasive and irritating than other materials used for similar purposes. Polyethylene also becomes vascularized, allowing the posting placement of titanium motility that joins the implant into the prosthesis in the same way that the pegs are used for hydroxyapatite implants.
PP has been shown to have good results, and in 2004, it was the most commonly used orbital implant in the United States. Porous polythilene meets several criteria for successful implants, including little tendency to migrate and anatomical defect recovery; it is available, cost-effective, and can be easily modified or custom-fit for any defects. PP implants need not be closed and therefore avoid some of the problems associated with hydroxyapatite implants.
Bioceramic
Bioceramic prosthetics are made of aluminum oxide (Al 2 O 3 ). Aluminum oxide is a ceramic biomaterial that has been used for more than 35 years in the field of orthopedics and teeth for a variety of prosthetic applications due to its low friction, durability, stability, and inertia. Aluminum ocular oxide implants can be obtained in a spherical shape and not round (egg-shaped) and in various sizes for use in anophthalmic sockets. It received the approval of the US Food and Drug Administration in April 2000 and was approved by Health and Welfare, Canada, in February 2001.
Aluminum oxide has previously been shown to be more biocompatible than HA in cell culture studies and has been suggested as a standard reference material when biocompatibility studies are needed to investigate new products. Previous exposure levels associated with bioceramic implants (2%) were less than most reports on porous HA or polyethylene implants (0% to 50%).
Conical orbital implant (COI) and multipurpose conical orbital implant (MCOI)
A safe and effective ball (still popular and easy to use) comes with a pyramid or COI implant. The COI has unique design elements that have been incorporated into the overall cone shape, including flat anterior surfaces, superior projections and preformed channels for the rectus muscle. 5-0 Vicryl sewing needles can be skipped with little difficulty directly through the implant to be tied to the anterior surface. In addition, this implant has a slightly hidden slot for the superior rectus and bulge to fill the superior fornix.
The latest model is a multipurpose orbital conical implant designed to overcome postoperative anophthalmic orbital problems that are at risk for developing socket abnormalities including enophthalmos, retraction of the upper eyelid, deepening of the superior sulcus, backward slope of the prothesis, and stretching of the lower eyelid.1 after discharge of content or enucleation, These problems are generally considered secondary to the lack of orbital volume also handled by MCOIs. The conical shape of a conical polyethylene implant cone polyethylene (MCOI) (Porex Medical) more closely matches the orbital anatomical form of a round implant. A wider anterior portion, combined with a narrower and longer posterior portion, allows for a more complete and natural replacement of lost orbital volumes. This shape reduces the risk of superior sulcus deformity and puts more volume in the muscle cones. Muscles can be placed in any location the surgeon wants with this implant. It is advantageous for muscle cases that are damaged or lost after trauma, and the remaining muscles are diverted to improve postoperative motility. And to anticipate future post placement there is a 6 mm diameter surface, which eliminates the need to shave a flat anterior surface before placing the pegs.
Both implants (COI and MCOI) consist of an interconnection channel that enables the growth of host connective tissue. Complete vascularisation implants reduce the risk of infection, extrusion, and other complications associated with non-integrated implants. And both implants produce superior motility and postoperative cosmesis.
Put a stake (motility post)
In a hydroxyapatite implant, a secondary procedure may insert a peg or an external round screw into the implant. The prosthesis is modified to accommodate the pegs, creating the ball-and-socket joints: once the fibrovascular ingrowth is complete, small holes can be drilled to the anterior surface of the implant. After the conjunctiva in this hole, a peg may be mounted with a rounded end corresponding to the corresponding dimple on the posterior surface of the artificial eye. These pegs directly transfer motility implants to the artificial eye. However, motility pegs are installed only in a small percentage of patients. This may be partly the result of problems associated with post placement, whereas hydroxyapatite implants are assumed to produce superior artificial eye motility even without pegs.
Polyethylene also becomes vascularized, allowing the posting placement of titanium motility that joins the implant into the prosthesis in the same way that the pegs are used for hydroxyapatite implants.
Implant movement
Movement of implants and prostheses is an important aspect of the overall cosmetic appearance after enucleation and is essential for the ideal purpose of forming a similar human eye in all aspects of a normal human eye. There are several enhanced eye movement theories, such as using integrating prosthetic materials, grouping implants, covering the implants (eg with sclera tissue), or sewing the eye muscles directly into a prosthetic implant. The transmission efficiency of movement from implant to prosthesis determines the level of prosthetic motility. The movement is transmitted from unusual traditional spherical implants through surface tension at the conjunctiva-prosthetic interface and fornice movement. Integrated pseudo implants have irregularly shaped surfaces that create indirect coupling mechanisms between implants and prostheses that impart greater movement to the prosthesis. Integrating the implant into the prosthesis directly via an external coupling mechanism is expected to increase further motility.
Despite the reasons that hydroxyapatite orbital implants with no motility spikes produce superior artificial motility, when the same surgical technique is used implanted implantable implants (hydroxyapatite) implants and a closed donor of nonporous (acrylic) spherical enucleation implants produces comparable artificial eye motility. In two studies there was no maximum amplitude difference between hydroxyapatite and acrylic or silicone enucleation ball implants, thus indicating that the implant material itself may have no bearing on the implant movement as long as the muscles are attached directly or indirectly to the implant and the implant is not pegged. Unintelligent artificial eye motility can be caused by at least two forces. (1) The scouring force between the posterior surface of the artificial eye and the conjunctiva covering the implant may cause the artificial eye to move. Since this force may be roughly the same in all directions, this will result in a comparable horizontal and vertical artificial eyepiece. (2) The artificial eye usually fits in the conjunctival space (probably not in the superior fornix). Therefore, any movement of the conjunctival fornix will cause artificial eye movements, whereas the lack of fornice movement will limit its motility. Imbrication of the rectus muscle above an unintegrated implant is traditionally thought to provide movement to the implant and prosthesis. Like ball-and-socket joints, when the implant moves, the prosthesis moves. However, because the so-called spheres and sockets are separated by the capsule layer of Tenon, the contaminated muscles, and the conjunctiva, the mechanical efficiency of transmission of movement from implant to prosthesis is suboptimal. In addition, the concern is that the blurring of the recti over an unintegrated implant may actually result in implant migration. The recent myoconjuctival enucleation technique is an alternative to muscle imbrication.
Although it is generally accepted that integrating prostheses into porous implants with post insertion improves prosthetic movement, there is little evidence available in the literature documenting the rate of improvement. And although porous implants have been reported to offer increased implant movement, it is clearly more expensive and distracting, requires wrapping, and subsequent imaging to determine vascularization and clustering to provide better transmission of implant motion to the prosthesis, and also susceptible to implant exposure.
The age and size of the implant may also affect motility, since in studies comparing patients with hydroxyapatite implants and patients with implanted nonporous implants, implant movements appear to decline with age in both groups. The study also showed an increase in the movement of larger implants irrespective of the material.
Surgical procedure
Basically surgery follows these steps:
- Anesthesia
- conjunctival peritomy
- The anterior fascia separation of the sclera
- Pass sutures through rectus muscle
- Rectus muscle is inserted from the globe
- Play and elevate the globe
- Open Tenon capsule to visualize optic nerve
- Cauterization of necessary blood vessels
- Divide the nerve
- Remove the eye
- Hemostasis is achieved by cautery or digital pressure.
- Enter the orbital implant.
- If necessary (hydroxyapatite) cover the implant with the wrapping material before
- Put muscles (if possible) directly (PP) or indirectly (HA) for the implant.
- Create fenestration in the wrapping material if necessary
- For HA implants, drill a 1 mm hole as a place of muscle insertion
- Tenon fascia images on implants
- Close facia Tenon in one or two layers
- Conjunctival sutures
- Insert a temporary ocular conic until the prosthesis is received (4-8 weeks later)
- After vascularization implants, an optional secondary procedure may be performed to place a particular post or post.
Also under anesthesia
- Create a conjunctival incision on the post insertion site
- Make a hole into the implant to insert a peg or post
- Change prosthesis to receive pegs/posts.
Surgery is performed under general anesthesia with the addition of additional subconjunctival and/or retrobulbar anesthesia that is injected locally in some cases. The following is a description of the surgical procedure performed by Custer et al. :
Conjunctival peritomy is performed on the corneal limbus, preserving as many healthy tissues as possible. Anterior anterior fascia apart from sclera. Blunt dissection in four quadrants between the rectus muscles separates the fascia within Tenon.
Stitches can pass through the rectus muscle before disinserting from the eyeball. Some surgeons also sew one or both oblique muscles. Traction or clamp sutures can be applied to horizontal rectus muscle insertion to help rotate and lift the eyeballs during subsequent surgery. Tenon capsules can be opened posteriorly to allow optical nerve visualization. Vortex venous and posterior ciliary vessels may be dried before dividing the nerve and removing the eye. Alternatively, the optic nerve can be localized with clamps before transection. Hemostasis is achieved by cautery or digital pressure.
The orbital implant is inserted at the time of enucleation. Suitable sized implants should replace the volume of globes and leave enough room for ocular prostheses. Enucleation implants are available in various sizes that can be determined by using implant sizing or calculated by measuring the eyeball volume or axial length of the contralateral eye.
In the past, non-porous implants were placed in the intraconal space and the extraocular muscles were either unattached or tied over the implant. Wrapping this implant allows muscle attachment to the cover material, a technique that seems to improve implant motion and reduce the incidence of implant migration. Porous implants may be saturated with antibiotic solutions before insertion. Because the fragile nature of hydroxyapatite prevents direct suturing from muscle to implant, this implant is usually covered with some form of wrapping material. The muscles attach to the implant in a technique similar to that used for non-porous implants. Muscles can be sewn directly into either porous polyethylene implants by passing stitches through implant materials or by using implants with tunnel fabrication. Some surgeons also wrap either porous polyethylene implants to facilitate muscle attachment or to reduce the risk of implant exposure. Various 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 ). Fenestration in the wrapping material is made at the insertion point of the extraocular muscles, allowing the attached muscles to make contact with the implant and repair the vascularization implant. Drilling of 1 mm hole into the implant at the site of the muscle insertion is done to facilitate vascularization of the hydroxyapatite implants. Fasia Tenna is pulled over the implant and closed in one or two layers. The conjunctiva is then stitched. An ocular conic conic is inserted at the completion of the procedure and is used until the patient receives the prosthesis 4 to 8 weeks after surgery. Elective secondary procedures are needed to place pegs or clutch posts in patients who want an increase in prosthetic motility. The procedure is usually delayed at least 6 months after enucleation to allow time for vascularization implants. Magnetic bone scans or magnetic resonance imaging reinforced by bone Technetium are not now universally used, but they have been used to confirm vascularization prior to post insertion. Under local anesthesia, conjunctival incisions are made on the post insertion site. Holes are made into porous implants to allow for the insertion of pegs or pegs. The prosthesis is then modified to receive pegs or pegs. Some surgeons have placed coupling pegs in porous polyethylene implants at the time of enucleation. Posts may spontaneously expose or be externalized in the next procedure through the conjunctival incision.
After the surgical procedure
Regardless of the procedure, the type of ocular prosthesis is always required afterwards. The surgeon will enter a temporary prosthesis at the end of the operation, known as the stock eye, and refer the patient to an ocular, who is not a medical doctor but an ocular certified board by the American Society of Ocularists. The process of making ocular prostheses, or special eyes, will begin, usually six weeks after the surgical procedure, and will usually take up to three visits before the final prosthesis is installed. In most cases, the patient will be installed during the first visit, return for hand painting of the prosthesis, and finally return for the final installation. The methods used to adjust, shape, and repaint prostheses often vary between the ocularist and patient needs.
Living with ocular prostheses requires treatment, but often patients with untreatable eye disorders, such as micropthalmia or retinoblastoma, achieve better quality of life with their prostheses. Treatment required for ocular prostheses, outside of regular polishing and examination with ocularists, usually revolves around maintaining moisture prosthesis and hygiene Removing ocular prostheses to clean out ocular offices is not necessary, but some patients prefer it. Patients find that after they adjust their ocular prosthesis, they barely feel the difference in feelings between their artificial eyes and their native eyes.
Famous people with prosthetic eyes
- Baz Bastien - Canadian ice hockey player, trainer (right eye)
- Mokhtar Belmokhtar - Algerian smuggler, kidnapper, arms dealer and terrorist; lost his eyes of abuse handling error (left eye)
- Helen Keller - Reformed American social deformator (both eyes)
- Sammy Davis Jr. - American singer (left eye)
- Peter Falk - American actor (right eye)
- Tex Avery - influential American animation director (left eye)
- Leo Fender - Architect of the instrument; founded what is now known as Fender Musical Instruments Corporation, and is famous for creating, among other instruments, Fender Stratocaster and Fender Precision Bass (left eye) .
- Ry Cooder - A renowned musician famous for his slide guitar work. (left eye)
- Nick Griffin - leader of the BNP (left eye)
- Ben Dreyfuss - author ( left eye )
- Jeff Healey - Canadian blues guitarist (both eyes)
- Leo McKern - actor (left eye)
- Carl Ouellet - Canadian professional wrestler (right eye)
- Park Jie-won - South Korean politician (left eye)
- Claus Schenk Graf von Stauffenberg - German career army officer and resistance leader (left eye)
- Dean Shiels - a Northern Ireland footballer who lost his eyes during a minor accident ( right eye ).
- Robert Thurman - author of (left eye)
- Mo Udall - politician (right eye)
- Ben Underwood - California student (both eyes)
- Henry Lee Lucas - serial killer (left eye)
- Fetty Wap - American rap star (left eye) (no longer using prosthesis)
- Alice Walker - author (right eye)
References
External links
- Mind Map: Adjusting and Adapt to Eye Loss
- Personal stories about having artificial eyes
- Make up Eye Prosthesis
- Artificial Eye History
- Ocular Prosthetic
- Eyeform Optician Ocular Prosthesis Information
- A FourDoc (a brief online documentary) about the latest glasses maker in the UK.
- How the Prosthetic Eye is made
- Prosthetic Maxillofacial American Academy
- Introduction to Self-Lubricating Prostheses
Source of the article : Wikipedia
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