question: How do prosthetics, including a glass eye, move with the body?
comment: I know glass eyes have a depression in the back that is fitted to a group of muscles so it twitches with the muscles that control both eyes.
passages: 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.
   Artificial Vision/Prosthetic Eyes Visual prosthesis has been a topic of experiments since the late 20th century. Notable characters using artificial vision include all characters from the Ghost in the Shell series who use prosthetic bodies e.g. Batou's ranger eyes, Saito's left eye, and Motoko Kusanagi's artificial eyes, Geordi La Forge from the "" series who made use of a VISOR and later; ocular implants, RoboCop from the RoboCop series, Spike Spiegel from the Cowboy Bebop anime series, and the Illusive Man from the Mass Effect series of videogames. 
   Though there is evidence that ocular implants have been around for thousands of years, modern nonintegrated spherical intraconal implants came into existence around 1976 (not just glass eyes). Nonintegrated implants contain no unique apparatus for attachments to the extraocular muscles and do not allow in-growth of organic tissue into their inorganic substance. Such implants have no direct attachment to the ocular prosthesis. Usually, these implants are covered with a material that permits fixation of the extraocular recti muscles, such as donor sclera or polyester gauze which improves implant motility, but does not allow for direct mechanical coupling between the implant and the artificial eye.
   In optics field, was involved in two projects, one to develop an innovative technique to cut lenses for glasses and one to model rigid scleral contact lenses in the 3D space, and then mill them. These contact lenses are worn by patients who have severe injuries in the eye (explosion, piece of glass, etc.). This last project is a joint project between EyePrint Prosthetics and .
  
  Section::::Applications.:Materials science.
   Production of modern ocular prosthetics has expanded from simply using glass into many different types of materials. In the United States, most custom ocular prostheses are fabricated using PMMA (polymethyl methacrylate), or acrylic. In some countries, Germany especially, prostheses are still most commonly made from glass.
  
  Section::::History.:Limits of realism.
   Ocularist surgeons have always worked 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 the immobility of the pupil. One solution to this problem has been demonstrated recently in a device based on an LCD which simulates the pupil size as a function of the ambient light.
  
  Section::::Implant types and chemical construction.
   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.
  
  Section::::Surgical procedure.
  
  Essentially the surgery follows these steps:
  
  BULLET::::- Anesthesia
  
  BULLET::::- Conjunctival peritomy
  
  BULLET::::- Separation of the anterior Tenon’s fascia from the sclera
  
  BULLET::::- Pass sutures through rectus muscles
  
  BULLET::::- Rectus muscles disinserted from the globe
  
  BULLET::::- Rotate and elevate the globe
  
  BULLET::::- Open Tenon’s capsule to visualize optic nerve
   In April 2009, Ebeling flew five programmers and hackers from Graffiti Research Lab, Free Art and Technology Lab, and openFrameworks to Los Angeles and in the living room of his home created the EyeWriter, an open source, DIY device which enables individuals with paralysis to communicate and create art using only the movement of their eyes. The EyeWriter project was conceptualized and first created for Tempt One, a Los Angeles-based graffiti artist who was diagnosed with Amyotrophic lateral sclerosis (ALS) in 2003. Tempt1 wrote his first piece of graffiti after seven years using the EyeWriter on April 10, 2009.
   Section::::History.
   In hydroxyapatite implants a secondary procedure can insert an externalized, round-headed peg or screw into the implant. The prosthesis is modified to accommodate the peg, creating a ball-and-socket joint: after fibrovascular ingrowth is completed, a small hole can be drilled into the anterior surface of the implant. After conjunctivalization of this hole, it can be fitted with a peg with a rounded top that fits into a corresponding dimple at the posterior surface of the artificial eye. This peg thus directly transfers implant motility to the artificial eye.
   The implantation procedure takes several hours, with the person receiving the implant under general anaesthesia. The surgeon removes the vitreous humor and any membranes on the retina where the implant will be placed. The implant is attached to the surface of the retina with a tack. The cables connecting the implant to the processor are run through the pars plana, a region near where the iris and sclera touch.
  
  Section::::Device.
   The Argus implant's primary external element is a digital camera mounted on eyeglass frames, which obtains images of the user's surroundings; signals from the camera are transmitted wirelessly to a computerised image processor. The processor is in turn connected by cables to the implant itself, which is surgically implanted on the surface of the person's retina and tacked into place. The implant consists of 60 electrodes, each 200 microns in diameter.
  
  Section::::History.
   Rob Spence, a Toronto-based film-maker, who titles himself a real life "Eyeborg", severely damaged his right eye in a shooting accident on his grandfather's farm as a child.
  
  Many years later, in 2005, he decided to have his ever deteriorating and now technically blind eye surgically removed, whereafter he wore an eye patch for some time before he later, after having played for some time with the idea of installing a camera instead, contacted professor Steve Mann at the Massachusetts Institute of Technology, an expert in wearable computing and cyborg technology.
   The earliest known evidence of the use of ocular prosthesis is that of a woman found in Shahr-I Sokhta, Iran dating back to 2900–2800 BCE. It has a hemispherical form and a diameter of just over 2.5 cm (1 inch). It consists of very light material, probably bitumen paste. The surface of the artificial eye is covered with a thin layer of gold, engraved with a central circle (representing the iris) and gold lines patterned like sun rays. On both sides of the eye are drilled tiny holes, through which a golden thread could hold the eyeball in place. Since microscopic research has shown that the eye socket showed clear imprints of the golden thread, the eyeball must have been worn during her lifetime. In addition to this, an early Hebrew text references a woman who wore an artificial eye made of gold (Yer. Ned. 41c; comp. Yer. Sanh. 13c). Roman and Egyptian priests are known to have produced artificial eyes as early as the fifth century BCE constructed from painted clay attached to cloth and worn outside the socket.
   Joseph Rizzo and John Wyatt at the Massachusetts Eye and Ear Infirmary and MIT began researching the feasibility of a retinal prosthesis in 1989, and performed a number of proof-of-concept epiretinal stimulation trials on blind volunteers between 1998 and 2000. They have since developed a subretinal stimulator, an array of electrodes, that is placed beneath the retina in the subretinal space and receives image signals beamed from a camera mounted on a pair of glasses. The stimulator chip decodes the picture information beamed from the camera and stimulates retinal ganglion cells accordingly. Their second generation prosthesis collects data and sends it to the implant through RF fields from transmitter coils that are mounted on the glasses. A secondary receiver coil is sutured around the iris.
   Living with an ocular prosthesis requires care, but oftentimes patients who have suffered from 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.
  
  Section::::Notable people with prosthetic eyes.
  
  BULLET::::- Baz Bastien – Canadian ice hockey player, coach "(right eye)"
  
  BULLET::::- Mokhtar Belmokhtar – Algerian smuggler, kidnapper, weapons dealer, and terrorist; lost his eye mishandling explosives "(left eye)"
   Training and registration varies significantly worldwide.
  
  There is not a specific training program of study to call a person an "ocularist" at the present time. Therefore, this field is practiced in many places by maxillofacial prosthodontists, dentists who have undergone 3–4 years of specialty residency training. There are also technicians who practice this field as well after learning how to make artificial eyes through an apprenticeship program. There are also people who use the title of ocularist who have had no formal training in the fitting, manufacture, and delivery of ocular prosthetics.
   The two part system of orbital implant and ocular prosthesis provides a stable, and well tolerated aesthetic restoration of the eye socket. Although vision is not restored by removal of the eye with placement of an orbital implant and ocular prosthesis, a natural appearance can result. The implant, along with the attached, visible ocular prosthesis, can be moved by intact extraocular muscles that will track or move simultaneously with the other eye. The eyelids are able to move and blink over the prosthesis as well.
  
  Section::::See also.
  
  BULLET::::- Eye gouging
  
  BULLET::::- Phantom eye syndrome
  
  Section::::External links.
   The style of the eyewear frames is similar to the basic designer-like frames made famous and worn by Buddy Holly. The multifunction plastic titanium framed glasses are controlled by pressing tactile buttons on the sidebar of the frame to activate the camera or determine the darkness of the sun glass lens. If a prescription eye glass lens is needed, a prescription lens with a Nominal Base Curve of 2 diopters can be installed by an optometrist.
  
  Section::::Hardware.
   The porous nature of integrated implants allows fibrovascular ingrowth throughout the implant and thus also insertion of pegs or posts.
  
  Because direct mechanical coupling is thought to improve artificial eye motility, attempts have been made to develop so-called 'integrated implants' that are directly connected to the artificial eye.
  
  Historically, implants that directly attached to the prosthesis were unsuccessful because of chronic inflammation or infection arising from the exposed nonporous implant material.
   In addition, there is an accommodating lens that was approved by the US FDA in 2003 and made by Eyeonics, now Bausch & Lomb. The "Crystalens" is on struts and is implanted in the eye's lens capsule, and its design allows the lens' focusing muscles to move it back and forth, giving the patient natural focusing ability.
   In the early 20th century, Moritz von Rohr and Zeiss (with the assistance of H. Boegehold and A. Sonnefeld), developed the Zeiss Punktal spherical point-focus lenses that dominated the eyeglass lens field for many years. In 2008, Joshua Silver designed eyewear with adjustable corrective glasses. They work by silicone liquid, a syringe, and a pressure mechanism.
   Ophthalmotrope
  
  An ophthalmotrope is an apparatus for demonstrating the movements of the eye and the action of the different muscles which produce them, consisting essentially of a model eyeball to which are attached strings and pulleys to duplicate the line force of the muscles.
   Similar in function to the Harvard/MIT device, except the stimulator chip sits in the primary visual cortex, rather than on the retina. Many subjects have been implanted with a high success rate and limited negative effects. Still in the developmental phase, upon the death of Dobelle, selling the eye for profit was ruled against in favor of donating it to a publicly funded research team.
  
  Section::::Ongoing projects.:Intracortical visual prosthesis.
   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.
  