Opto-mechanical design of a dispersive artificial eye

We present an opto-mechanical artificial eye that can be used for examining multi-wavelength ophthalmic instruments. Standard off-the-shelf lenses and a refractive-index-matching fluid were used in the creation of the artificial eye. In addition to dispersive properties, the artificial eye can be used to simulate refractive error. To analyze the artificial eye, a multi-wavelength Hartmann-Shack aberrometer was used to measure the longitudinal chromatic aberration and the possibility of inducing refractive error. Off-axis chromatic aberrations were also analyzed by imaging through the artificial eye at two discrete wavelengths. Possible extensions to the dispersive artificial eye are also discussed.

[Analysis of ocular prosthetic care on the territory of Russia]

The results of ocular prosthetic help analysis in different regions of the country is presented based on estimation of number of patients who need ocular prostheses; analysis of quality and quantity of produced prostheses in the country; evaluation of demand for glass and plastic prostheses and price determination; study of regulations.

The universal implant for evisceration surgery

The Universal implant is a quasi-integrated buried orbital implant designed to provide the same motility advantages as does an Iowa implant, but is simpler to implant and associated with fewer complications. The protruding mounds on the implant are keyed to corresponding indentations on the posterior prosthetic surface, allowing more life-like motility. We describe a straight-forward technique for its use as an evisceration implant and report the results in 24 patients. The Universal implant is simple to use and the lock-and-key mechanism obtained between implant and prosthesis provides the patient with a high degree of life-like motility. Its cost is significantly lower than the more popular hydroxyapatite implant and it does not require a drilling procedure for coupling.

Cosmetic conformers

The loss of an eye is an emotionally traumatic event. A prosthetic eye is usually not fitted until the socket has healed (about 6 weeks after surgery). This period, during which a clear conformer is fitted, can be particularly traumatic, especially for the newly anophthalmic patient. The authors have designed interim acrylic prosthetic conformers to help patients overcome some of these problems while preserving the necessary characteristics of ideal postoperative conformers.

Implant-retained prosthetic rehabilitation of orbital defects

OBJECTIVE

To evaluate the use of endosseous transcutaneous implants to retain removable facial prostheses for the rehabilitation of orbital defects.

SETTING

Tertiary referral center.

PATIENTS

Six patients with a history of facial defects secondary to orbital exenteration for cancer ablation.

OUTCOME MEASURES

Clinically noted functional and cosmetic results, patient reports of satisfaction, and complications encountered.

RESULTS

Twenty-three of 25 implants were integrated (postoperative period, 13 to 65 months; mean, 44.2 months), representing an integration success rate of 92%. All patients were successfully wearing implant-retained prostheses after 48.3 months (post-prosthesis delivery period, 1 to 48.3 months; mean, 24.5 months). Overall patient satisfaction was very high.

CONCLUSIONS

Implant-retained prosthetics represent a safe and effective treatment option. It is anticipated that this treatment will become the standard of rehabilitative care for patients with orbital defects.

The hydroxyapatite orbital implant: a prospective study

The hydroxyapatite orbital implant was first released for use as an orbital implant in humans in August 1989. It has been shown to be well tolerated, providing good motility of the artificial eye with a low complication rate when used as a primary implant. This prospective study evaluated the hydroxyapatite orbital implant used as both a primary and a secondary implant. Sixty patients were implanted between October 1992 and November 1994, 28 being implanted as a primary procedure at the time of enucleation or evisceration, and 32 as a secondary procedure. Seven patients underwent second-stage drilling and pegging of the implant. The mean follow-up time was 13 months (range 2-26 months). A standardised operative and post-operative protocol was followed. The patients were evaluated post-operatively for the amount of enophthalmos, degree of upper lid sulcus deformity, motility of the prosthesis, location of the implant in the socket, socket status and the presence or absence of discharge, position of the drill hole and coverage of the implant. Complications and their management were documented. Both patient and surgeon made a subjective assessment of cosmesis and the patient's satisfaction with the overall result was noted. The results of this study show the hydroxyapatite orbital implant to provide excellent motility of the artificial eye and good cosmesis with a low rate of complications when used both as a primary and as a secondary implant.

Hydroxyapatite implants--a new trend in enucleation and orbital reconstructive surgery

As treatment modalities evolve in ophthalmology one must assess and re-evaluate current methods of therapy in the care and treatment of the patient facing the loss of an eye. With the advent of Hydroxyapatite Orbital Implants, new challenges face the ophthalmic nurse in caring for the patient undergoing enucleation and reconstructive surgery. Integrated orbital implants are used to replace the volume of the orbit when the eye is removed due to enucleation, evisceration, or as secondary orbital implants. Various materials have been used in the past to replace orbital volume, with the most common being silicone or polymethylmethacrylate. Hydroxyapatite is a new orbital implant material which has unique interconnected porous matrix derived from marine corals with a mineral composition similar to bone. This orbital implant undergoes fibrovascular ingrowth by the patient's own tissue, becoming truly integrated and less likely to reject, migrate or extrude. The hydroxyapatite implant may be inserted with a variety of surgical techniques, all of which are more complex than standard enucleation implant techniques and have special considerations for the ophthalmic registered nurse.

Hydroxyapatite orbital implants: indications for use and nursing considerations

1. An orbital implant made of coralline hydroxyapatite is available as an enucleation, evisceration, or secondary orbital implant. This material is naturally occurring, nontoxic, nonallergenic, biocompatible, and resistant to infection. 2. Special nursing considerations, beginning with meticulous aseptic technique, are necessitated by the special preparation of the hydroxyapatite sphere for implantation. It is important to assess the patient's understanding of the surgical procedure, postoperative care regimen, and the importance of keeping follow-up appointments. 3. Coralline hydroxyapatite orbital implants undergo fibrovascular ingrowth, making them truly integrated orbital implants. Unique possibilities for prosthetic rehabilitation provide a significant improvement over previously available enucleation implants.

Methylmethacrylate implants: a scanning electron microscopic study

Two methylmethacrylate orbital implants used for 34 and 5 years, respectively, were examined with a scanning electron microscope. One of the implants was a combination of a prosthesis and an implant containing a magnet. The magnetic force had decreased markedly, and rust crystals were apparent. The methylmethacrylate surface was irregular and rough.

Improved prosthetic motility following enucleation

Enucleation is the beginning of a long-term relationship between the ophthalmologist and the patient to provide a comfortable, cosmetically acceptable, anophthalmic socket. The ideal socket should have a low risk of implant extrusion, normal volume, and normal motility of the prosthesis. Aspheric motility implants provide good motility, but pressure points between implant and prosthesis may lead to discomfort or extrusion. Spherical volume implants minimize pressure between implant and prosthesis, but have been criticized for inability to transmit motility to the prosthesis. The authors describe a modification of the traditional sphere implant technique that provides improved motility, ease in prosthetic fitting, and a comfortable socket.

The argument against imbricating the rectus muscles over spherical orbital implants after enucleation

Upper eyelid ptoses with migrated spherical implants resulting from imbrication of the rectus muscles over the implants after enucleation appears to constitute a syndrome. Traditionally shaped artificial eyes cannot reduce this type of ptosis. Spherical implants 18 mm in diameter do not fill Tenon's space. Imbricated muscles slip off the sphere, usually to the inferior nasal side. The sphere is displaced into the superior temporal quadrant of Tenon's space. A rolling motion is imparted to all tissues. The superior fornix and upper lid are pulled forward and downward. The inferior fornix is stretched into a rounded trough. The lower eyelid is pulled downward and backward. There is little motility to move the artificial eye. There are several better alternative types of surgery, some involving buried quasi-integrated muscle cone implants. More eye fitters will now fit these implants properly because of the educational efforts of the American Society of Ocularists. Two of those are most favored by the author because the surgical methods of their implantations do not contribute to ptosis and the resulting motility and general cosmesis are typically very good to excellent. In the order of preference they are: 18 or 16 mm diameter acrylic spheres in evisceration. The quasi-integrated implant which has become known is the Iowa Implant, specifically designed for imbrication of the rectus muscles after enucleation.

Keratoprosthesis. Results, complications, and management

Thirty-one cases of keratoprosthesis were followed for periods of from 1 to 84 months (average 35 months). The Cardona through-and-through device was implanted, covered with periosteum, and exteriorized through an opening in the upper lid. Visual results varied from 20/20 (1 of 31 cases) to counting fingers (5 of 31 cases). While 12 of the 31 cases achieved 20/40 or better at some point in the postoperative course, only 5 of 31 maintained this level of acuity over a long-term period. Severe complications included retroprosthetic membrane (18 out of 31), vitreitis (7 out of 31), dislocation (5 out of 31), extrusion (3 out of 31), and endophthalmitis (5 out of 31). Fifteen of the 31 patients required subsequent surgical revision. Despite the frequency and severity of complications, 17 out of 31 patients achieved sufficient improvement in visual acuity to enable them to function without assistance for periods of 1 to 7 years.

The anophthalmic socket

Following enucleation or evisceration surgery, the anatomy and physiology of the orbit are changed. These changes affect not only the cosmetic appearance of the anophthalmic patient but also the function of the socket and the prosthesis. Surgical techniques for primary enucleation and evisceration surgery and correction of early and late complications are described. During the course of this century many operations and prosthetic devices have been advocated. A brief summary of these is given as well as detailed surgical descriptions of techniques the author believes have proven successful over the years.

Surgical treatment of the denervated or sagging lower lid

Paralytic ectropion of the lower eyelid and increased curvature of the lower eyelid associated with anophthalmos both cn be optimally treated by use of an autogenous fascia lata sling. Some patients also have problems with prosthesis retention due to lower eyelid deformity with a shortened inferior fornix. In some instances, it is also necessary to perform a horizontal shortening operation on the lower eyelid. In anophthalmic patients, the relationship between prosthesis size and weight and a sagging lower lid is discussed. In some patients when the lower eyelid is elevated, the patient then has an upper lid ptosis for which it is necessary to perform an appropriate levator shortening operation. Surgical technique and illustrative pre- and post-operative photographs are shown.

Histological and scanning electron microscopic study of tissue invasion of Bangerter nylon implant after enucleation

An incidentally extirpated Bangerter-type nylon implant was examined by light microscopy and scanning electron microscopy. Three months after implantation, the implant was densely filled with tissues, which were shown by light microscopy to be muscle cells in the margin of the implant; the muscle cells were fixed there at the time of implantation, and fibrocytic cells were inside the implant. Scanning electron microscopy showed interlacing fibrous cells with erythrocytes and leukocytes among the nylon fibers, lamellar accumulation of fibrous cells around nylon fibers, and a smooth surface of the margin of the nylon implant. This invasion of fibrous cells into the nylon implant is one reason why the Bangerter type of nylon implant rarely falls out of the orbital socket.

Complications associated with use of tantalum-mesh--covered implants

In 1948, ophthalmologists started implanting plastic spheres partially covered with tantalum mesh (eg, the Valley Forge Implant) in anophthalmic sockets. Numerous patients have developed complications ten to 15 years after surgery: pain ("pinching" or "deep"), headache, heavy mucopurulent discharge and diffuse conjunctival inflammation, migration of the implant, thinning or erosion of tissues covering the implant (extrusion), and inability to wear an artificial eye. Management includes refabrication of the artificial eye and replacement of the implant with a dermis-fat graft or a silicone ball plus scleral graft. Tantalum-mesh--covered orbital implants should probably not be used.

Prosthetic correction

Fitting a comfortable and cosmetically attractive prosthetic device is a challenge, one which many people in the ophthalmic field seem to hesitate to undertake. Based on my experience, I provide practical guidelines for this important task. Artificial eyes which are required after enucleation are not discussed, but contact lenses and shells for disfigured blind or seeing eyes are.

Cosmetic eye modified to retain vision

A patient with bilateral ocular injuries with hypotony and light perception vision was fitted with scleral shells modified to allow light to pass through the central 4-mm area. This modification, allowing the patient to retain light perception with the prosthesis in place, aided in the rehabilitation of this patient by encouraging his independent ambulation, providing clues to time, place, and direction, and offering an enhanced cosmetic effect.

Terylene implant for enucleation and eviseration: a long-term follow-up

A terylene implant, to which the tissues can be sutured directly, has been used after enucleation and evisceration since 1958. An advantage is that it can be implanted in the orbit as a secondary procedure some time after enucleation. It is easy to insert, gives fair motility and is well tolerated. It is a satisfactory implant for routine use.