ARTIFICIAL EYES Prepared by Dr Khaled Awad Presented

ARTIFICIAL EYES Prepared by : Dr. Khaled Awad Presented by : T. Aisha I. Lubbad

INTRODUCTION An artificial eye is a replacement for a natural eye lost because of injury , disease , trauma, tumor, or end stage ocular disease such as glaucoma, or diabetes can be devastating at any age. Although the replacement cannot provide sight, it fills the cavity of the eye socket and serves as a cosmetic enhancement.

It may have a major impact on one’s selfimage, self-confidence, and self-esteem, not to mention the adjustment required in adapting to monocular (single-eye) vision. There may even be some job restrictions that apply for one-eyed patients (e. g. , commercial drivers, airline pilots, policemen, firefighters, etc. ). Numerous patients have been fitted with prosthetic eyes who are currently employed in the professions mentioned above.

Monocular patients should try to return to their work if possible and lead as normal a life as possible. Although there is some loss of depth perception and peripheral vision, they are not as “handicapped” as many believe.

Before the availability of artificial eyes, a person who lost an eye usually wore a patch. An artificial eye can be attached to muscles in the socket to provide eye movement Today, most artificial eyes are made of plastic, with an average life of about 10 years. Children require more frequent replacement of the prosthesis due to rapid growth changes. As many as four or five prosthesis may be required from infancy to adulthood.

According to the Society for the Prevention of Blindness, between 10, 000 and 12, 000 people per year lose an eye. Though 50% or more of these eye losses are caused by an accident (in one survey more males lost their eyes to accidents compared to females), there a number of inherited conditions that can cause eye loss or require an artificial eye.

Microphthalmia is a birth defect where for some unknown reason the eye does not develop to its normal size. These eyes are totally blind, or at best might have some light perception.

Some people are also born without one or both eyeballs. Called anophthalmia , this presents one of the most difficult conditions for properly fitting an artificial eye. Sometimes the preparatory work can take a year or more. In some cases, surgical intervention is necessary.

Retinoblastoma is a congenital (existing at birth) cancer or tumor, which is usually inherited. If a person has this condition in just one eye, the chances of passing it on are one in four, or 25%. When the tumors are in both eyes, the chances are 50%. Other congenital conditions that cause eye loss include cataracts and glaucoma. One survey showed that 63% of eye loss due to disease occurs before 50 years of age.

There 14/2/2014 are two key steps in replacing a damaged or diseased eye. First, an ophthalmologist or eye surgeon must remove the natural eye. There are two types of operations. The enucleation removes the eyeball by severing the muscles, which are connected to the sclera (white of eyeball). The surgeon then cuts the optic nerve and removes the eye from the socket. An implant is then placed into the socket to restore lost volume and to give the artificial eye some movement, and the wound is then closed.

With evisceration, the contents of the eyeball are removed. In this operation, the surgeon makes an incision around the iris and then removes the contents of the eyeball. A ball made of some inert material such as plastic, glass, or silicone is then placed inside the eyeball, and the wound is closed.

At the conclusion of the surgery, the surgeon will place a conformer (a plastic disc) into the socket. The conformer prevents shrinking of the socket and retains adequate pockets for the prosthesis. Conformers are made out of silicone or hard plastic. After the surgery, it takes the patient from four to six weeks to heal. The artificial eye is then made and fitted by a professional ocularist.

PRIMARY SOCKET PROCEDURE There are three types of eye removal Evisceration - removal of the internal eye contents, but the sclera is left behind with the extraocular muscles still attached. Enucleation - removal of the eyeball, but the adjacent structures of the eye socket and eyelids remain. An intraocular tumor excision requires an enucleation, not an evisceration.

Exenteration - removal of the contents of the eye socket (orbit) including the eyeball, fat, muscles and other adjacent structures of the eye. The eyelids may also be removed in cases of cutaneous cancers and unrelenting infection. Exenteration is sometimes done together with Maxillectomy which is removal of the maxilla or the upper jaw bone/cheekbone

REASONS FOR EYE REMOVAL Cancer of the eye (retinoblastoma, melanomas, any other cancers of the eye or orbit) Severe injury of the eye when the eye cannot be saved or attempts to save the eye have failed End stage glaucoma Painful, blind eye.

In cases of sympathetic ophthalmia (inflammation of the eye) to prevent travel to other eye, in which, if untreated can cause blindness Congenital cystic eye In a deceased person, so the cornea can be used for a living person who needs a corneal transplant by a surgical operation called keratoplasty. Constant infection in a blind, or otherwise useless eye.

ENUCLEATION 18/2/2014 Definition Enucleation is the surgical removal of the eyeball that leaves the eye muscles and remaining orbital contents intact.

Purpose Enucleation is performed to remove largesized eye tumors or as a result of traumatic injury when the eye cannot be preserved. In the case of tumors, the amount of radiation required to destroy a tumor of the eye may be too intense for the eye to bear. Within months to years, many patients who are treated with radiation for large ocular melanomas lose vision, develop glaucoma, and eventually have to undergo enucleation.

The two types of eye tumors that may require enucleation are: Intraocular eye melanoma. This is a rare form of cancer in which malignant cells are found in the part of the eye called the uvea, which contains cells called melanocytes that house pigments. When the melanocytes become cancerous, the cancer is called a melanoma. If the tumor reaches the iris and begins to grow, or if there are symptoms, enucleation may be indicated.

Retinoblastoma is a malignant tumor of the retina. The retina is the thin layer of tissue that lines the back of the eye; it senses light and forms images. If the cancer occurs in one eye, treatment may consist of enucleation for large tumors when there is no expectation that useful vision can be preserved. If there is cancer in both eyes, treatment may involve enucleation of the eye with the larger tumor, and radiation therapy for the other eye.

The conjunctiva (outer covering of eye) is removed with blunt scissors (A). The four rectus muscles are removed from their attachments to the eyeball (B). The optic nerve is severed (C), and the eyeball is removed. A synthetic globe replaces the eyeball in the socket, and the rectus muscles are sutured around it (D).

ENUCLEATION 23/2/2014 Anesthesia The procedure may be performed under general or local anesthesia, according to the surgeon's preference. In either case, the injection is given in the retrobulbar space. An antibiotic (e. g. , cefazolin) and an antiinflammatory (e. g. , dexamethasone) are also given intravenously.

Peritomy, Muscle Identification, and Neurectomy A 360° peritomy is then performed, with care taken to preserve as much of the conjunctiva and Tenon's capsule as possible. The extraorbital muscles are then tagged with 5 -0 Vicryl sutures and are released by resection at their attachments to the globe. A neurectomy is then performed, according to the surgeon's preference, and the globe is delivered. Care should be taken to maintain hemostasis until the implant is placed in the orbit.

Evaluation and Preparation of Tenon's capsule is then inspected for its readiness to accommodate the implant. In order to minimize the risk of implant exposure and subsequent infections, it is important to ensure that the tissues overlying the implant can be closed without tension.

Traditionally, the orbital implant was placed within Tenon's capsule, as first described by Frost (Frost 1887), necessitating the use of a smaller implant. This technique usually required the use of implants with a diameter of 16 mm to 18 mm. However, due to the enophthalmos associated with these smaller implants.

DETERMINATION OF IMPLANT SIZE Proper sizing of the orbit is essential to avoid complications and to achieve an optimum fit of the implant to both the orbit and the artificial eye. An undersized implant may result in enophthalmos or a deep superior sulcus, and may necessitate weight -increasing modifications to the artificial eye which, in turn, induce lower lid sag and restricted motility.

Conversely, an oversized implant increases the risks of wound dehiscence, exposure, and infection, and may complicate the coupling of the artificial eye to the motility peg. An implant is of the proper size when its volume, added to the volume of the implant wrapping material and the volume of the artificial eye, equals the volume of the enucleated globe (Perry 1983).

Refer to a sizing table for determining implant size from the size of the globe. A set of graduated sizing spheres should be used to properly size the orbit. A sizing sphere is of the proper size when it is the largest sphere that allows closure of the conjunctiva and anterior Tenon's capsule without tension.

The diameter of the sizing sphere is noted from markings on its handle, although a calculation must be made to compensate for the thickness of the material used to wrap the implant. A scleral wrapping increases the diameter of the implant by an average of 1. 5 mm. While it is known that the average orbit will accommodate an 18 mm or 20 mm implant wrapped in sclera, each orbit should nevertheless be individually sized.

WRAPPING THE IMPLANT There are several benefits to wrapping the implant. These include: increased motility, ease of insertion, ease of muscle attachment, and decreased risk of exposure. The use of an unwrapped implant allows the rough surface of the hydroxyapatite material to snag on orbital tissues during insertion, and may also cause abrasion of the overlying tissues during movement, thereby increasing the risk of exposure.

Prior to wrapping, the implant is sterilized and soaked in an antibiotic solution (80 mg gentamicin in 100 cc saline). The implant is placed in the scleral shell and the shell is sutured closed with 5 -0 Vicryl sutures. The excess tissue is trimmed and marks are made at the attachment sites of the four rectus muscles and at the anterior pole of the implant

The oblique muscles can be attached, according to the surgeon's preference. Fornix-deepening sutures may be used at this point, as needed, to provide space for the artificial eye to move in concert with this highly motile implant.

CLOSURE The wound should be closed with separate closures of Tenon's capsule and the conjunctiva in order to minimize the risk of exposure. Anterior Tenon's capsule is closed with interrupted 5 -0 Vicryl sutures; the conjunctiva is closed with a running 5 -0 Vicryl suture. Antibiotic ointment is applied to the socket and an acrylic conformer is placed over the conjunctiva, with care taken to avoid undue pressure between the conformer and the wound closure.

DRESSINGS AND POSTOPERATIVE CARE A firm pressure dressing is maintained for 4 to 6 days, oral antibiotics are given for 1 week, and steroids (prednisone 20 mg, adjusted according to patient status) are given 3 times daily for 4 days. Oral postoperative pain medication is also given as needed. The socket is evaluated after removal of the pressure dressing and, if the edema has subsided, the tarsorrhaphy sutures are removed.

Topical antibiotics are applied 4 times daily for 4 weeks. The patient is generally ready for fitting with an artificial eye 6 to 8 weeks postoperatively.

ENUCLEATION SURGERY Enucleation 25/2/2014 refers to removal of the globe (eyeball). Surgery may be done under local stand-by anesthesia (twilight anesthesia) or general anesthesia (patient asleep). It is commonly done either as an outpatient or overnight stay patient. The surgical procedure generally takes about 1 hour. While under anesthesia, the lids are held open and the external coats of the eye (conjunctiva and Tenons) are trimmed away from the eyeball.

The extraocular muscles (responsible for moving the eye into different fields of gaze) are also trimmed away from the eye surface. Lastly the optic nerve is cut and the entire eyeball is removed. Bleeding is controlled by gentle cauterization.

When someone loses an eye, two components are needed: an orbital implant to maintain the volume of the eye socket and an artificial eye or prosthesis. Thus, following removal of the eye, an orbital implant is put into the socket and the tissues are closed over top of it. The extraocular muscles can be hooked up to the implant surface to help keep the implant from migrating and to help with socket movement.

Initially, a temporary prosthetic conformer made of clear plastic is put in place over the orbital implant. This conformer maintains the tissue space behind the eyelids where the prosthetic eye will eventually sit. In approximately 6 -8 weeks, the conformer is removed and a custom made artificial eye (prosthesis) is made for the socket. Eye drops or ointment are required during the first few weeks post-op. Pain is something patients worry about routinely with enucleation surgery.

There may be some discomfort postoperatively in the first few days but how much is variable, as everybody has a different pain threshold. What might be a lot of pain for one person may only be mild to moderate in another. Whatever pain is present (usually not severe) it subsides in the first 3 to 5 days. Pain killers are routinely prescribed after enucleation surgery along with antibiotics

INDICATIONS There is a long and venerable debate about the relative merits of enucleations and eviscerations that began with the first medical report of an evisceration. While this debate is by no means concluded, some consider that an evisceration yields the best cosmetic result because it is less damaging to the structures of the orbit. However, there are many cases in which an enucleation may be indicated

These include cases in which the majority of the contents of the eye must be removed, such as in cases of uveal melanoma, choroidal melanoma, or other malignant intraorbital tumors. Other indications may include objectionable appearance, chronic pain, atrophy bulbi, blindness with unilateral iritis, blindness with unilateral glaucoma, childhood hypoplasia, prophylaxis against sympathetic ophthalmia, and whenever a complete histological examination of the globe is required.

CONTRAINDICATIONS An enucleation is most classically contraindicated after the onset of sympathetic ophthalmia, and in cases of virulent endophthalmitis. However, with improved diagnosis and technique, and considering the relatively rareness of sympathetic ophthalmia, there is some debate as to whether these diseases necessarily contraindicated an enucleation.

An enucleation is also contraindicated in cases where it can be expected that the patient will experience increased psychological trauma from the thought of losing the "entire eye". In the latter case, an evisceration is indicated. Finally, an enucleation is relatively contraindicated in cases where excessive hemorrhaging is expected.

EVISCERATION SURGERY Evisceration 2/3/2014 surgery refers to the removal of the inside contents of the eye (cornea, iris, lens, vitreous, and retina). The white shell of the eye (sclera) is left in place. The extraocular muscles are left attached to the eye surface and the optic nerve is not cut. Once the contents of the eye are removed, an implant is placed into the scleral shell. The sclera, Tenons, and conjunctiva are then closed over the implant and a temporary (clear plastic) conformer is put in place.

The real artificial eye (prosthesis) is made in about 6 -8 weeks. Evisceration, like enucleation, can be done under local stand-by (twilight anaesthesia) or general anaesthesia and may be performed as an outpatient or as an overnight stay visit. Like enucleation, pain is variable and dependant upon one's pain threshold. Generally, there is some pain but usually it is not severe. It settles in the first 3 to 5 days.

INDICATIONS An evisceration is indicated in the cases listed above, where an enucleation is not specifically indicated. Some surgeons prefer an evisceration over an enucleation wherever possible. Classically, the clearest indication for an evisceration has been in cases of virulent endophthalmitis, to reduce the risk of the infection spreading via the optic nerve sheath. In addition, an evisceration is often less psychologically traumatic for the patient because it involves the loss of what is perceived as only a portion of the eye, as compared with the entire eye.

CONTRAINDICATIONS An evisceration is contraindicated in cases where an intraorbital neoplasm is suspected, in cases where acute trauma may prevent complete removal of the uveal tissue, and in cases where a complete histological exam is needed.

4/3/2014 EXENTERATION SURGERY Exenteration is a more radical procedure than enucleation, evisceration or secondary orbital implantation. It involves removal of all the tissues within the entire eye socket. The conjunctiva, globe, extraocular muscles and orbital fat are all taken out. In these situations there is no place to put an orbital implant or artificial eye as described above. An oculo-facial prosthesis can be made however, to cover the eye socket opening. Although it does not move, it looks much better than an empty eye socket

SECONDARY ORBITAL IMPLANT SURGERY In some individuals who previously had an enucleation procedure years ago, the orbital implant may have shifted out of position, become exposed, infected, or is simply too small. In this situation a secondary surgery can be performed to remove the first implant (secondary orbital implant surgery

Secondary orbital implant surgery can be more challenging than enucleation or evisceration especially if the surgeon tries to localize and reconnect the extraocular muscles. It is therefore usually done under general anesthesia as an overnight stay patient. The post-operative healing is similar to enucleation and evisceration surgery.

SECONDARY IMPLANTATION : Anesthesia : The procedure may be performed under general or local anesthesia. An antibiotic and an anti-inflammatory are also given intravenously. Removing the implant.

Dissection of the muscle. Preparation of the orbit : The socket is then inspected for scarring that may have contributed to the migration of the primary implant, and all such scars are remove to allow proper placement and to prevent migration of the new implant

Determination of implant size : Proper sizing of the orbit is essential to avoid complication and to achieve an optimum fit of the implant to both orbit and artificial eye. Wrapping Dressings the implant. and postoperative care.

INDICATIONS A secondary implant has been traditionally indicated in cases of chronic exposure, migration, or extrusion of the primary implant. In recent years, however, a rapidly growing number of patients are requesting secondary implants using the Bio-eye HA orbital implant in order to recover lost motility and to counteract lid sag via a motility/support peg.

In most cases, the motility provided by the Bio-eye HA orbital implant is equal to or better than that provided by the primary implant. If the rectus muscles can be identified and attached directly to the implant, even greater motility can be expected. Fortunately, the rectus muscles can usually be identified because check ligaments attached to the fornices and Tenon's capsule prevent them from retracting too deeply after they are cut from the globe.

If a socket containing a previously placed implant shows no motility, then damage to the rectus muscles or to the innervation to the rectus muscles is expected. There is no known implant design that will improve the motility of either the socket or the artificial eye in such cases.

CONTRAINDICATIONS A secondary implant is contraindicated in cases where there are no complications with the primary implant and where cosmesis and artificial eye motility is satisfactory

GENERAL COMPLICATION Exposure Early exposures : if the exposure occurs within the first 6 months postoperatively, and if it is small (<= 3 mm). If it widens, a graft should be considered. If the exposure does not widen and remains stable, continue to observe it, unless the patient complains of increased mucous discharge. this is related to surgical technique and not related to the chemical properties of the implant.

Late exposure : If the exposure occurs later than 6 months postoperatively, and vascularization of the implant is confirmed, the exposure should simply be observed, unless the exposure widens or there is increased discharge. Most large exposure (> 3 mm) will be accompanied by increased discharge. In some cases, even large exposure can remain stable for long periods of time if the implant is well vascularized.

INDICATIONS Enucleation There is a long and venerable debate about the relative merits of enucleations and eviscerations that began with the first medical report of an evisceration. While this debate is by no means concluded, some consider that an evisceration yields the best cosmetic result because it is less damaging to the structures of the orbit. However, there are many cases in which an enucleation may be indicated

These include cases in which the majority of the contents of the eye must be removed, such as in cases of uveal melanoma, choroidal melanoma, or other malignant intraorbital tumors. Other indications may include objectionable appearance, chronic pain, atrophy bulbi, blindness with unilateral iritis, blindness with unilateral glaucoma, childhood hypoplasia, prophylaxis against sympathetic ophthalmia, and whenever a complete histological examination of the globe is required.

Evisceration An evisceration is indicated in the cases listed above, where an enucleation is not specifically indicated. Some surgeons prefer an evisceration over an enucleation wherever possible. Classically, the clearest indication for an evisceration has been in cases of virulent endophthalmitis, to reduce the risk of the infection spreading via the optic nerve sheath. In addition, an evisceration is often less psychologically traumatic for the patient because it involves the loss of what is perceived as only a portion of the eye, as compared with the entire eye.

Secondary Implantation A secondary implant has been traditionally indicated in cases of chronic exposure, migration, or extrusion of the primary implant. In recent years, however, a rapidly growing number of patients are requesting secondary implants using the Bio-eye HA orbital implant in order to recover lost motility and to counteract lid sag via a motility/support peg.

In most cases, the motility provided by the Bio-eye HA orbital implant is equal to or better than that provided by the primary implant. If the rectus muscles can be identified and attached directly to the implant, even greater motility can be expected. Fortunately, the rectus muscles can usually be identified because check ligaments attached to the fornices and Tenon's capsule prevent them from retracting too deeply after they are cut from the globe.

If a socket containing a previously placed implant shows no motility, then damage to the rectus muscles or to the innervation to the rectus muscles is expected. There is no known implant design that will improve the motility of either the socket or the artificial eye in such cases.

CONTRAINDICATIONS 11/3/2014 Enucleation An enucleation is most classically contraindicated after the onset of sympathetic ophthalmia, and in cases of virulent endophthalmitis. However, with improved diagnosis and technique, and considering the relatively rareness of sympathetic ophthalmia, there is some debate as to whether these diseases necessarily contraindicated an enucleation.

An enucleation is also contraindicated in cases where it can be expected that the patient will experience increased psychological trauma from the thought of losing the "entire eye". In the latter case, an evisceration is indicated. Finally, an enucleation is relatively contraindicated in cases where excessive hemorrhaging is expected.

Evisceration An evisceration is contraindicated in cases where an intraorbital neoplasm is suspected, in cases where acute trauma may prevent complete removal of the uveal tissue, and in cases where a complete histological exam is needed.

Secondary Implantation A secondary implant is contraindicated in cases where there are no complications with the primary implant and where cosmesis and artificial eye motility is satisfactory.

ORBITAL IMPLANT A 16/3/2014 variety of shapes and sizes have been tried in an attempt to promote some motility to the socket. In 1985 a new concept in eye socket implants began to evolve when a researcher (Dr. Arthur Perry, San Diego, CA) began to study sea coral as an ocular implant. Through a patented hydrothermal process the calcium carbonate component of sea coral was turned into calcium phosphate and a substance known as hydroxyapatite was made. Hydroxyapatite has the same chemical structure and porous structure as human bony tissue.

The implant material (corralline hydroxyapatite) is biocompatible, non-toxic and non-allergenic. The body’s tissue recognizes the material as similar and because of the porous nature, tissue will grow into it. The implant becomes more fixed and therefore resists migration. The implant allows attachment of the extraocular muscles which in turn leads to improved orbital implant motility.

The orbital implant can also be directly attached to the prosthesis through a peg, protruding from the implant allowing a wide range of prosthetic movement as well as the darting eye movements commonly seen when people are engaged in conversation. The increased range and fine darting movements allow a more life-like quality to the prosthetic eye.

The hydroxyapatite implant, also known as the Bio-Eye™ (integrated Orbital implants, San Diego) is called a “porous implant. ” Since its introduction, a number of other “porous implants” have been introduced. One such implant (popularized by Dr. D. R. Jordan - University of Ottawa Eye Institute, Ottawa, Ontario, Canada) is a synthetic variety of hydroxyapatite (FCI 3 HA implant) that has similar qualities to the original Bio. Eye™ but less expensive.

A recent study has shown that HA has a more rapid rate of fibrovascularization than Medpor (porous polyethylene). It is available in Canada and other parts of the world but due to patent restrictions is unavailable in the United States. Another synthetic porous implant that has become increasingly popular is a type of porous plastic known as Porous Polyethylene (Medpor™ - Porex Surgical Inc, Cooledge Park, GA).

This material is a synthetic man-made material that previously has been used in a wide range of cranio-facial reconstructive procedures and facial fractures, with few problems. Its properties demonstrate high tensile strength, malleability, biocompatibility and fibrovascular ingrowth. The porous polyethylene orbital implants are also cheaper than the original Bio-Eye™, and are available in spherical, egg, conical or mounded shapes.

Aluminum oxide (Al 2 O 3) another man-made biomaterial that has been in use for more than 30 years as an implant in orthopedics and dentistry has also been studied extensively (Dr. D. R. Jordan University of Ottawa Eye Institute, Ottawa, Ontario, Canada) and is emerging as an orbital implant in Canada, Europe and several other parts of the world. The aluminum oxide implant, also known as the Bioceramic Implant (FCI, Issy-Les-Moulineaux, Cedex, France) looks identical to the Bio-Eye™ hydroxyapatite with multiple interconnected pores. Like the synthetic HA and porous polyethylene, it is less expensive than the Bio-Eye™.

There is evidence that human osteoblasts and fibroblasts appear to grow better on aluminum oxide than hydroxyapatite, suggesting it may be more biocompatible than hydroxyapatite and better tolerated in the eye socket.

IMPLANT TYPES AND CHEMICAL 18/3/2014 CONSTRUCTION There are many different types of implants, classification ranging from shape (spherical vs oval shaped), stock vs custom, porous non porous, and the presence of a peg or motility post. The most basic simplification can be to divide implant types into two main groups : non-integrated (non-porous) and integrated (porous)

NON-INTEGRATED IMPLANT 1 - non-porous implants contain no unique apparatus for attachment to the extraocular muscles. 2 - don’t allow in-growth of organic tissue into their inorganic substance. 3 - no direct attachment to ocular prosthesis. 4 - usually, these implants are covered with a material that permits fixation of the extraocular recti muscles, such as donor sclera which improves implant motility. 5 - non-integrated implants include the acrylic (PMMA), glass, and silicon spheres

Plymethyl methacrylate (PMMMA) : PMMA is a transparent thermoplastic available for use as ocular prosthesis, replacement intraocular lens when the original lens has been removed in the treatment of cataract and has historically been used as hard contact lenses. PMMA has a good degree of compatibility with human tissue, much more than glasses.

INTEGRATED IMPLANT 1 - the porous integrated implants allows fibrovascular ingrowth throughout the implant. 2 - and thus also insertion of beg. Because direct mechanical coupling (PEG) is thought to improve artificial eye motility. Direct connected to the artificial eye. 3 - implants that directly attached of the prosthesis were unsuccessful because of chronic inflammation or infection arising. 5 - integrated implants include the hydroxyapatite, aluminum oxide and polyethylene.

Bioceramic : 1 - Bioceramic prosthetics are made of alminum oxide (Al 2 O 3). 2 - Low friction, durability, stability, and inertness. 3 - more biocompatible than HA.

IMPLANT SIZE Proper 23/3/2014 implant sizing is crucial. Implant that provides about 65 -70% of volume replacement is ideal, the remaining 35 -30% being Contributed by the prosthesis. A smaller implant has a higher tendency to displace or migrate And develop superior sulcus deformity. A larger implant is known to improve both cosmoses and motility. However, an inappropriately large Implant may produce tension on the conjunctival wound and result in Wound gape and implant exposure.

Implant sizing has mostly been Empirical and is often decided in the operating room. Generally, a 16 -18 Mm implant is used in infants, 18 -20 mm in older children, and 2022 Mm in adults. There are implant sizers that may help gauge the Appropriate size. A recent trend is to use the axial length of the fellow Eye (axial length in mm - 2 = implant diameter in mm) to choose the Implant size.

One should remember to deduct an additional 2 -mm From the axial length if the implant is traditionally wrapped but not When the scleral cap technique is used.

OCULAR PROSTHESIS: otherwise known as an artificial eye, is a plastic prosthesis used when an eye is surgically removed. During surgery, a ball implant is inserted into the eye socket to fill the area the eye once occupied. An ocular prosthesis is then molded to fit in front of the implant. It occupies the space between the eyelids and the skin (conjunctiva) covering the implant

The ocular prosthesis is generally made four to six weeks after surgery in order to allow the socket tissues to heal adequately. Prior to that time, a thin plastic plate, called a conformer, is sometimes worn in place of the prosthesis. This prevents shrinkage of the tissue and helps to prepare the socket for ocular placement. Until the ocular prosthesis is fitted, the upper eyelid can be droopy in appearance. The prosthesis will help support the eyelid and allow the lids to open and close normally.

SCLERAL COVER SHELL PROSTHESIS: also known as a "cover shell", is a thin, plastic prosthesis used when an eye is malformed as a result of a birth defect, or becomes non-functioning due to subsequent illness or injury. In such cases, the nonfunctioning eye is left within the eye socket. A prosthesis can then be molded to fit between the lids and the blind eye

Scleral cover shells fit directly over the malformed eye. Sometimes a "trial shell" is fashioned to allow the eye to grow accustomed to the direct contact of the prosthesis. Cover shells impart a better cosmetic appearance by closely resembling the remaining good eye, while leaving the affected eye in the socket.

TYPES OF OCULAR PROSTHESIS 1 - Artificial Eye : - patients who had one of their eyeballs enucleated or had grossly phthisical eyes, have been provided with artificial eyes. These are Snellen type of preformed eyes which vary in thickness from 2 -10 mm and in size from 12 x 14 to 28 x 30 mm, the vertical side being the smaller one with a notch on the upper nasal border

2 - Moulded Eye : -In patients where a satisfactory fitting is not possible with the conventional type of artificial eyes described above, a moulded eye affords better results. Moulded eye is prepared from an impression of the socket.

3 - Cosmetic Contact Shell: -This is an opaque contact lens painted for all the anterior segment details including conjunctiva and sclera. It requires all the fitting techniques and procedure of a scleral contact lens. This is given in cases who have normal or nearly normal shape of the eyeball having total corneal opacity or a disfigured eye where useful vision is not possible. These are extremely thin shells varying in thickness from 0. 50 -2. 50 mm depending upon the contour and shape of the eyeball

4 - Cosmetic Contact Lens : -This is akin to a cosmetic shell except that the pupillary area is left clear for visual purposes and is suitably powered to correct the refractive error. The scleral portion in such cases is also transparent. 5 - Spectacle Prosthesis : -It is an ocular prosthesis attached to a spectacle frame and is indicated in cases whose sockets are markedly contracted beyond reasonable repair and cannot retain even the smallest eye or have been subjected to exentration

Before we deliver the prosthetic, we check seven basic considerations for assuring proper fit and life-like results: 1) Size and lid contour. 2) Proper posterior fit of the prosthesis over the anterior tissues in the ocular cavity for comfort and motility. 3) Color of the sclera (white). 4) Position and plane of the iris. 5) Color of the iris and pupil size. 6) Movement of the artificial eye. 7) Patient comfort and a pleasing cosmetic result.

FABRICATING OCULAR PROSTHESIS Prosthetic eyes are made of an acrylic plastic material called methyl methacrylate. It can be formed into any size and shape, it's durable, and is well-tolerated by the surrounding eye tissues. The prosthesis is made through the following series of steps

Sometimes the process begins by taking an impression of the eye socket to duplicate the exact nature of the space the prosthesis will fit into. The impression of the eye socket is used to make a wax model. Using the model, we determine the correct positioning of the iris (the colored part of the eye), the outer curvature, and the extent to which the eyelids will open The iris is hand painted from direct observation of the unaffected eye.

The wax model is then used to prepare a master mold which is filled with acrylic plastic to create a cast of the prosthesis. The prosthesis is further colorized and vessels are added to simulate a natural appearance. It is then covered with a clear plastic protective coating and is cured once more The prosthesis is now ready for a polishing to give it a perfectly smooth surface and wet-looking appearance.

Finally, the prosthesis is complete. Its appearance is deceivingly real, while the underside is an exact replica of the socket. It fits snugly and comfortably in place.

HOW PROSTHETIC EYES ARE MADE 1 - Clear Conformer The first step in fitting an artificial eye or scleral shell is to fit a clear acrylic conformer. This conformer fits inside the eye socket and opens the eyelids, so that both eyes are equal in shape and in overall appearance

2 - Alginate Impression The second step in the process is to take an impression of the eye socket, allowing a comfortable and acurate fit. The impression allows us to match the volume and lid contours of the fellow eye and also allows for excellent movement in the final prosthesis

3 - Cast of Impression The impression is then duplicated within a material called castone, inside a stainless steel cast. This cast is used for making the white acrylic blank that will be the base of the prosthesis. The white blank is then processed using our specialized acrylic processo

4 - Iris Painting All painting is done by hand with dry pigments in our specially designed paint room. The iris is painted on a flat acrylic disc, layer by layer. We use advanced techniques combined with careful attention to create a realistic and accurate match. This is one of the most important steps to matching a prosthesis to one's existing eye

5 - Lathe Cutting A clear acrylic dome, similar to a cornea, is added over the painted surface. This dome brings up the depth and magnifies the detail of the iris. A specially designed lathe is used to cut a series of angles into the clear acrylic cap, allowing for a precise machined blend between the painted iris and the sclera portion of the prosthesis

6 - White Blank This white blank is the exact size and shape of the molded clear conformer. It will be fit for comfort, lid size and shape, and movement. A well fit ocular prosthesis will move (track) right along with the orbital implant which is attached to the ocular muscles.

7 - Positioning Iris While the patient is wearing the white blank, the iris position and plane are marked. This step ensures that the position of the completed prosthesis will match the natural eye. The completed iris and positioned blank are then prepared for attachment

8 - Attaching Iris The iris is carefully attached with acrylic at the exact plane and position illustrated. This perfect line-up is very important for the finished overall cosmetic result

9 - Preparing for Veining The excess acrylic and positioning lines are then trimmed away, leaving a white blank with attached iris. The prosthesis is now prepared for the veining

10 - Veining The veining of the sclera (white of eye) is done with a frayed red silk thread. This thread is carefully applied to match the veins on the natural eye. This step is done in our colorcorrected paint rooms

11 - Completed Veining Once the veining is applied, the sclera is carefully tinted with our dry pigments to match the surface patterns and colors of one's existing eye. Notice how natural and realistic the eye looks at this stage

12 - Acrylic Capping After the veined prosthesis is allowed to completely dry, a final cap of clear acrylic is applied. This final cap seals in all of the veining and pigments and also provides the prosthesis with its final polished surface. The prosthesis is then ground to the correct shape

13 - Final Adjustments The prosthesis is polished with pumice, leaving a smooth durable finish for patient comfort. Following the polish with pumice, the prosthesis is finely polished with a high-speed wheel to remove all scratches and give it the final shiny finish

14 - Completed Prosthesis The final prosthesis is then fit, adjusted and evaluated for size and contour, iris color and pattern, iris position and plane, scleral tinting and veining, movement, patient comfort and overall pleasing cosmetic result

15 - Completed Prosthesis The entire process of making a custom ocular prosthesis takes 3 -4 appointments, which can be done over the course of 2 -3 days depending on one's schedule.

ARTIFICIAL EYE CLEANING Cleaning Your artificial eye need only be cleaned occasionally. You may sleep with your artificial eye in, in fact it is advisable to do so. However, when it is removed, it should be cleaned by using hard contact lens cleaner, as the most common problem is irritation and watering caused by a protein build up.

If not cleaned correctly this protein will collect upon the surface of the artificial eye as a crystalline coating which will eventually make the artificial eye feel gritty. The socket lining and the inner surface of the eyelids may become inflamed and sore with discharge in extreme cases A HARD contact lens cleaner should be used to clean the artificial eye (it is not recommended that hand soap or washing-up liquid are used as cleaners).

THE CLEANING PROCEDURE IS AS FOLLOWS: Remove artificial eye and place it on palm of hand. Put a few drops of hard contact lens solution onto the artificial eye and gently rub over all surfaces. Rinse the artificial eye thoroughly in sterile saline ensuring all the cleaner has been removed. The artificial eye is now ready to be reinserted.

GENERAL POINTS It is very important to wash hands thoroughly before inserting or removing the artificial eye for any reason. The artificial eye should be removed and cleaned when it becomes sticky, dry and uncomfortable to wear. The frequency of this may vary from a few days to a couple of months. If dropped the artificial eye is unlikely to break, however, to minimise the risk of scratching or fracture great care must be taken when inserting and removing the artificial eye. It is recommended that the artificial eye should be checked and polished annually.