Surgical Procedures related to  the Anopthalmic socket



Surgical Procedures: The Anophthalmic patient


1) Loss of an Eye

The three most common indications for enucleation are intraocular malignancy, trauma, and a blind, painful eye. Recommending enucleation is one of the most difficult therapeutic decisions in ophthalmology. In some cases of malignancy, cryotherapy, laser photocoagulation, diathermy, chemotherapy, and radiation therapy may be viable alternatives to surgery. When surgery is chosen, evisceration or exenteration may be alternatives to enucleation. Once the decision is made to perform enucleation or evisceration, the surgeon must choose from several types of implants and wrapping materials. These devices can be synthetic, autologous, or eye-banked tissues. With certain implants, the surgeon must decide when and if to drill for subsequent peg placement. In this review, the authors discuss choices, techniques, complications, and patient consent and follow-up before, during, and after enucleation.

Losing an eye to trauma, tumor, or end stage ocular disease such as glaucoma, or diabetes can be devastating at any age. It may have a major impact on one's self-image, self-confidence, self-esteem, not to mention the adjustment required in adapting to monocular (single eye) vision as there may 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.


2) Primary Socket Procedures

a) Enucleation Surgery

Enucleation is the removal of the globe from the orbit, involving the separation of all connections between the globe and the patient (including transection of the optic nerve).

Enucleation may be

the oldest operation of ophthalmology, and as early

as 2600 BC, there was a Chinese god devoted to the

profession of ocularists.

In 1555, Johannes Lange was first mentioned having performed a “modern” enucleation, although the record does not include a precise description of his procedure. Bartisch, a contemporary and survivor of Lange, described a technique whereby traction was obtained by passing a hook through the globe, and then sharp dissection was used to sever the globe from the orbit. In the 1840s, O’Ferral in Dublin and Bonnet in Paris first used an anatomic approach to the removal of the globe. They described dissection and removal of the extra ocular muscles in an operation that was performed within Tenon’s capsule. In 1846, general anaesthesia allowed surgeons to refine their technique and opened the door to the

development of ocular implants.

Mules introduced the idea of orbital implants, and Frost suggested using a hollow glass sphere. Since that time, investigators have proposed a variety of orbital

implants made of gold, paraffin, glass, ox bone,acrylic, fat, rubber, wire, silk, and rabbit eye.Recently, integrated orbital implants (e.g., hydroxyapatite, porous polyethylene) have been developed.Orbital volume replacement (implants) were commonlyused by the end of the 19th century. The nextchanges focused on implantation technique. In 1972, Soll suggested implant placement posterior to Tenon’s capsule. Building on Helveston’s work, heused donor sclera to wrap orbital implants.In1978, Smith and Petrelli proposed the use of dermis fat grafts for volume augmentation in patients with volume loss, contracted sockets, and implant extrusion.

Surv Ophthalmol 44 (4) January–February 2000

MOSHFEGHI ET AL

Enucleation 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 post-operatively 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.

b) Evisceration Surgery -

Evisceration involves removal of the contents ofthe eye, while maintaining an intact sclera shell attached to the extra ocular muscles. Some authors recommend complete removal of the cornea, while others believe it may be retained. Enucleation is the treatment of choice when there is a possibility of intraocular malignancy or the chance of developing sympathetic ophthalmia. Thus, when evisceration is being considered, it is important to perform ophthalmic ultrasonography to rule out intraocular malignancy. Evisceration is often the procedure of choice for blind, painful eyes secondary to endophthalmitis.Advantages of evisceration over enucleation include preservation of orbital anatomy and enhanced cosmesis and mobility.

Evisceration, like enucleation, can be done under local stand-by (twilight anesthesia) or general anesthesia 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.


Which is best: Enucleation or Evisceration? . There is less anatomical disruption to the eye socket with evisceration and the end results (appearance, movement) are superior in most cases then with enucleation. However, there are some situations where one simply cannot have an evisceration. In any eye that has a tumor (e.g. melanoma) or suspected tumor - an enucleation is the only option. If the diseased eye has end stage glaucoma, end stage diabetes, is a post trauma eye, has a known history without suspicion of a tumor, an evisceration is suitable and becoming increasingly common because of the ease of surgery and the excellent cosmetic results.

c) 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.

 CONFORMERS

It is necessary to choose a conformer that occupies the fornices. It should not be so small that it falls out or so large that it places tension on the wound. Patel and co-workers devised a standardized set of conformers and symblepharon rings that allow the surgeon to find the ideal fit.

Conformers can be left in until the patient is ready for prosthetic fitting.

Molgat and colleagues described the development of customized conformers for patients with severely contracted socket and orbital volume deficit undergoing buccal  mucous membrane fat grafts.

Anatomic information was obtained from computed tomographic scanning. They found their prostheses toprovide maximal orbital volume restoration and sufficientvertical forniceal support.

d) 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.

 

3) Orbital Implants


Prior to 1885 orbital implants were not used. The eye was removed by enucleation or evisceration and the socket was left to heal in its own. The result was an unsightly sunken depression of the eyelids into the eye socket. The use of an orbital implant was a major breakthrough in anophthalmic socket surgery. The implant improved postoperative cosmesis by filling orbital volume and also reducing the chance of socket contractions due to scar tissue formation. Over the last 100 years a variety of materials have been used for the orbital implant including: gold, silver, cartilage, bone, fat, cork, sponge, rubber, paraffin, wool, asbestos, as well as a variety of others in an attempt to find the most biocompatible implant (Figure 1). 

 

Enucleation can be performed without implant placement, but this is unusual and will yield a poor cosmetic

result.

Many different types of implants have

been advocated.  In general, implants replace the volume lost by the enucleated eye, impart motility to the prosthesis, and maintain cosmetic symmetry with the fellow eye

There are two major groups of orbital implants:

1. integrated vs. non integrated,

2) buried vs. exposed. It is important to realize that no

matter what type of implant is employed after enucleation, during the ensuing years the orbital contents

tend to contract toward the orbital apex (nasal

and inferiorly). This process is the likely cause of the

superior sulcus deformity and limits the ability of

pegged implants to yield superior motility over time.

1. Non integrated Implants

Non integrated 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. Materials used as non integrated implants include glass, rubber, silicone, steel, gold, silver, acrylic, and polymethylmethacrylate (PMMA).

Compared to no implant, these devices provide both volume replacement and improved cosmesis. Imbrication of the rectus muscles in front of aspherical implant imparts motility to the implant and prosthesis. Like a ball-and-socket joint, when theimplant moves, the prosthesis moves.

2. Integrated Implants

a. Hydroxyapatite

The hydroxyapatite orbital implant is commonly

used during enucleation surgery .It is formed from a salt of calcium phosphate that is present in the mineralized portion of human bone. It is reported to be nontoxic, nonallergenic, and biocompatible.Its porous structure allowsintegration of fibrovascular tissues into the stroma of the implant.86,243 Sires and associates postulate that pore orientation in the hydroxyapatite sphere may influence the degree of vascularization and that poor vascularization might result in implant extrusion. Fibrovascular ingrowth and density changes have been assessed by a variety of radiographic techniques, but contrast-enhanced magnetic resonance imaging with surface coil appears to be the modality of choice Jamell and coworkers have demonstrated how magnetic resonance imaging with contrast enhancement shows early peripheral vascularization of the implant, with vascularization of the central core not occurring until later.121 It is important to identify the central avascular zone when plans are made to drill for peg placement. Implants whose gadolinium-enhanced magnetic resonance imaging revealed greater than 75% vascularization were found to bleed during drilling. Dutton advocates drilling additional holes in the implant at the site of the scleral windows before it is inserted into the socket.77This feature is designed to increase vascularization of the implant.Fibrovascular coupling—between host tissue and the hydroxyapatite implant—is said to aid in preventing migration and extrusion.243Because of its rough surface, the hydroxyapatite implant is usually wrapped with donor sclera or other material. These materials are also used to anchor the extraocular muscles to the implant.

A variety of shapes and sizes have also 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 (Figure 4a). 


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 (Figure 4b)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.

5) Artificial Eye Motility: Implant Pegging Procedures


a) To peg or not to peg? One of the many advantages of porous implants (hydroxyapatite,) is the ability to integrate them with the overlying artificial eye through a peg system. By coupling the orbital implant to the artificial eye a wide range of prosthetic eye movements as well as darting eye movements commonly seen in conversational speech can occur. These movements impart a more life-like quality to the prosthetic eye. To peg or not to peg, is up to the surgeon and patient. They are certainly not for everyone and with all due respect, not all eye socket surgeons are equally skilled at putting them in. Before considering a peg the implant has to be fully vascularized (minimum of 6 months, in some this may take a year or more) and, the socket has to be a healthy one. Patients with diabetes, previous radiation, systemic disease such as Systemic Lupus Erythematosis (SLE) or, individuals on medications such as steroids, are not good candidates for pegging, because their socket tissue simply does not have good blood flow.


Pegs are not fool proof and do have their own inherent set of problems above and beyond those of the implant. A meticulous peg placement technique is required to obtain excellent results - a fact not appreciated by many. The pegs must be central and straight. They must also be flush with the implant with no exposed portion to ensure a good result. Once pegged - the individuals do require regular follow up initially to be sure the peg is sitting well. With time the follow-ups can decrease (yearly) if all is well. The most worrisome problem associated with pegging is introduction of infection to the implant, requiring implant removal.

Other potential peg problems include discharge, pyogenic granuloma (excess healing tissue) around the peg, peg falling out, poor transfer of movement, clicking, conjunctival overgrowth, poor fitting or loose sleeve, part of sleeve shaft visible, peg drilled on an angle, peg drilled of center, HA visible around peg hole, and excess movement of peg.


Thus, although pegs allow a more lifelike quality to the artificial eye, they are not for everyone.

b) Peg Variations (Figure 6a)

A hole was drilled into the implant and a standard peg was put in place. To obtain a more secure fit between the orbital implant and peg, a peg and sleeve system was designed. Following drilling of a hole into the implant, a sleeve is screwed into the implant until it is tight and flush with the implant surface. A peg is then placed into the center of the sleeve. In more recent years titanium has replaced polycarbonate as a peg and sleeve material since it is better tolerated in the socket tissue (more biocompatible). 


6) Socket Reconstructive Procedures


a) Volume Augmentation - some degree of sunkenness is common in artificial eye patients. The appropriate selection of an adequate implant size at the time of enucleation or evisceration is the first step in decreasing the sunken appearance of the artificial eye patient. However, if there remains some sunkenness, techniques are available to decrease it. One option is to undergo a second surgical procedure to implant a second implant (sled or floor implant) into the eye socket, underneath and behind the first. A general anaesthetic is required to put these volume augmentation implants into position. They are designed to slip in underneath and posterior to the first implant. They can be secured in position by glue, wire or a mini plate system used in facial reconstruction. The surgery is short (45 minutes) and patients are discharged with a patch in place on the day of surgery or the following morning. The artificial eye remains in position but may require an adjustment in the first few weeks. Pain is not a big factor as there is very little disruption to the socket tissues (Figure 7a,b).




Another technique to decrease a sunken appearance involves the use of "dermal fat grafts. A graft of fat just beneath the skin ("dermal fat") can be harvested from the hip of the patient. This fat is then implanted into the sunken appearing upper lid (sulcus). The hip incision lies beneath the underwear or bathing suit area. The fat is trimmed and implanted into the sunken appearing upper lid (sulcus) making a 1-inch long eyelid skin crease incision. A pocket is made for the fat graft, which is then implanted followed by skin closure. This procedure is routinely done under local or local stand-by anaesthesia (twilight anaesthesia) as a day patient. It is not painful and has good to excellent results. Over correction is required as some fat atrophy does occur in the first 3 months. 


Lastly, to balance the sunken appearance of the artificial eye, removal of a small amount of skin and fat from the upper lid of the opposite seeing eye can be performed. This is a very simple and quick procedure that is routinely done as an outpatient. Sometimes it can be performed with nice results even prior to consideration of the "floor implants" or "fat graft technique" described.

b) Fornix Reconstruction - After many years of wearing an artificial eye, recurring socket infection and/or scarring secondary to trauma, the pocket behind the lower lid where the artificial eye sits ("inferior fornix") can become shallow. This may be associated with a retracted appearing lower lid (a lower lid that looks too low) as well as artificial eye fitting problems with the artificial eye recurrently falling out (Figure 8) .


To correct this, an initial assessment by the ocularist can be performed to determine if a modified custom made prosthesis might be of some benefit. If not a, a fornix deepening surgical procedure is required. One such surgery involves borrowing some of the lining from the inside of the mouth (mucous membrane) and using it to create a deeper lower lid pocket. Hard palate mucosa (from the palate of the mouth) can also be used as well as ear cartilage or donor sclera. These surgeries are done under local stand-by anaesthesia (twilight anaesthesia) or general anaesthesia. They generally take 1-1½ hours and are very well tolerated. If hard palate mucosa is used - hot foods and liquids may be difficult to tolerate for a few weeks.

7) Eyelid Reconstructive Surgeries


a) Ptosis of the upper lid - Ptosis refers to "drooping". A droopy upper lid or "ptotic upper lid" is not uncommon. After several years of wearing an artificial eye, and removing it on numerous occasions, it is possible for the upper lid elevation muscle (levator aponeurosis) to become thin and stretch. As a result, the upper lid falls and becomes "ptotic" (Figure 9).


If the lid droop is mild, an adjustment to the artificial eye may elevate the lid and correct the droop. If the lid remains droopy, a simple, quick, painless operation can be performed referred to as "levator advancement". The surgery takes approximately 15-30 minutes and is done under local freezing as an outpatient. Post-op there may be some minor bruising and swelling in the first week.

b) Lower lid laxity - After many years of wearing an artificial eye, the lower lid, (which supports the weight of the artificial eye) may become lax (loose). As a result the lower sags downward. To correct this, a minor lid tightening procedure can be performed. Under local anaesthesia as an outpatient, a snip is made in the lateral part of the lid and the firm part of the lid (tarsal plate) is reconnected to the bony orbital rim. This procedure, commonly referred to as a "tarsal strip" is simple to do. It takes about 15 minutes and relatively pain free. The sutures used are dissolvable and only rarely cause some tenderness while absorbing.

c) Entropion repair - Entropion refers to an inward turning of the lid (Figure 10).

 In the artificial eye patient it may be seen on the upper and lower lid. As entropion occurs, when the lashes become more vertical in the upper and lower lid, and may end up resting on the prosthetic eye. Surgery for upper or lower lid entropion is available, generally as an outpatient under local anaesthesia. The surgeries usually last 30 minutes and the goal is to rotate the lashes either in the upper or lower lid back to a more normal position. The sutures used are absorbable and dissolve over 3-6 weeks depending upon what type is used. Post-op there may be mild swelling and bruising. Pain is not a major concern but some minor discomfort may be present.

d) Ectropion repair - Ectropion refers to an outward turning of the lower lid. After several years of artificial eye wearing and tissue laxity development in the lower lid, the lower lid may not only sag downward but may, in some instances turn away from the artificial eye (become ectropic). Like entropion, this problem can be corrected by a very straightforward outpatient procedure under local anaesthetic with absorbable sutures. The goal is to return the eyelid to a more normal position so that it sits against the artificial eye. Surgery lasts 15-30 minutes and may be associated with some minor lid swelling and bruising.

8) Concluding remarks about Artificial Eyes


Eye contact is an essential part of human interaction. It is extremely important for the artificial eye patient to maintain a natural, normal-appearing prosthetic eye. In recent years major developments have taken place in reconstruction of an eye socket following enucleation/evisceration or secondary implant surgery. The ideal orbital implant has been sought for more than a century. Porous materials (hydroxyapatite) are currently the preferred orbital implants primarily because of the vascularization and tissue integration that can occur. These implants are less likely to migrate than previously used plastic implant and are associated with a higher degree of motility especially when coupled to the overlying artificial eye through a peg system. Which implant is best is currently a matter of debate. The ideal porous implant is one that is biocompatible, non-toxic, non-allergenic, inexpensive and stable over time.


This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.

References:

American Society of Ocularists

Darius M. Moshfeghi, MD,

Andrew A. Moshfeghi, MD,

and Paul T. Finger, MD

David R. Jordon, MD

Ottawa, Ontario

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