Exposure rates of wrapped and unwrapped orbital implants following enucleation.

PURPOSE: To compare the complication rate of porous polyethylene orbital motility implants with solid acrylic implants following enucleation and identify possible risk factors. METHODS: The authors retrospectively reviewed the charts of a total of 117 consecutive enucleations performed at the University of Illinois at Chicago between March 28, 1994, and May 28, 1999. Data obtained included patient demographics, surgical indication, implant type, attending surgeon, surgical technique, and any reported complications. The primary outcome was presence or absence of implant exposure at the final recorded visit. RESULTS: Of the 117 identified cases, 29 were eliminated due to insufficient follow-up data. Of the 88 remaining cases, 48 patients received porous implants and 40 received solid acrylic implants. Implant exposure developed in four cases. All exposures occurred in unwrapped porous polyethylene implants (n=2) or porous polyethylene implants wrapped in absorbable material (n=2). All exposures occurred in patients younger than 18 years of age, and 75% occurred early after trauma-associated enucleation surgery. CONCLUSIONS: The exposure rate of porous polyethylene implants in this study (9%) was found to be comparable to published rates for hydroxyapatite implants. There were no exposures of unwrapped solid acrylic spheres. Unwrapped porous implants in pediatric patients or following trauma-related enucleation may represent an increased risk for postoperative implant exposure. Absorbable wrapping of porous implants may carry the same risk for exposure as no wrapping. Porous implants wrapped in durable material appear to be as safe as solid acrylic spheres.     

Enucleation with unwrapped porous and nonporous orbital implants: a 15-year experience

PURPOSE: To compare the rates of implant exposure and implant migration among patients who received an unwrapped nonporous spherical implant versus an unwrapped porous spherical implant immediately after enucleation. METHODS: Retrospective analysis of a series of 258 patients who received either an unwrapped nonporous spherical implant (n = 68) or an unwrapped porous spherical implant (n = 190). Actuarial rates of migration of the implant and conjunctival dehiscence leading to implant exposure were computed. RESULTS: Sixty-eight patients received an unwrapped nonporous implant (polymethylacrylate [PMMA]) and 190 patients received an unwrapped porous implant (139 hydroxyapatite [HA] and 51 porous polyethylene [Medpor]). Median follow-up duration in this study was 37.6 months. Implant exposure occurred in 1 of the 68 nonporous implant cases (1.5%) and in 4 of the 190 porous implant cases (2.1%). This difference is not statistically significant (P = 0.85). In contrast, clinically significant implant migration occurred substantially more frequently in the patients who received a nonporous implant. The cumulative actuarial probability of implant migration at 60 months was 15.5% for the nonporous implants versus 0.7% for the porous implants. This difference was statistically significant (P = 0.0003). CONCLUSIONS: Orbital implant migration occurred in a significantly greater proportion of patients who received a nonporous implant than in those who received a porous implant. Implant exposure occurred at a low rate that was not significantly different in the two subgroups.     

带线羟基磷灰石义眼座非包裹植入的临床分析

目的评价带线羟基磷灰石义眼座(HA)无包裹植入的临床疗效。方法对29例眼球摘除术后患者,采用带线羟基磷灰石义眼座作为眼窝植入物,无包裹直接植入。Ⅰ期植入21例。Ⅱ期植入8例。结果分别随访5-18月,4眼术后出现球结膜裂开,2眼术后轻度上睑下垂,1眼术后五月义眼座中度暴露,均经相应治疗后恢复。其他病例手术效果良好,无植入物脱出及移位,义眼座活动度良好。结论带线羟基磷灰石义眼座直接植入术,具有操作简单、材料易得、并发症少等优点,具有良好的应用前景。     

有无巩膜包裹HA义眼台植入术临床对比观察

目的 探讨有无巩膜包裹HA植入术的临床效果.方法 对眶内植入HA义眼台29例,其中有自体巩膜包裹HA义眼台13例,无巩膜包裹义眼台16例,随诊3个月至3年.结果 全部病例效果均良好,均Ⅰ期愈合,未见严重并发症及排斥反应,眼部整形效果理想.结论 无巩膜包裹HA直接植入肌锥中的方法简捷,是一种安全可靠的手术方法,值得推广.     

Hydroxypropyl methylcellulose (HPMC) lubricant facilitates insertion of porous spherical orbital implants

The insertion of an orbital implant in the posterior Tenon's space or in the eviscerated sclera must be smooth, without entrapment or dragging of adjacent soft tissue. Anterior Tenon's fascia and conjunctiva must be closed without undue tension that could lead to subsequent postoperative implant exposure. Current methods to prevent tissue drag include passing the implant via a cut "thumb" from a surgeon's glove, the use of a prepackaged rigid plastic funnel, or a specialized orbital implant introducing forceps, e.g., Carter sphere injector. We recommend also coating the porous implant with an inert semisynthetic viscoelastic polymer, thus enabling easy placement. We illustrate this in a typical case.     

Magnetic orbital implants.

Sixty-six consecutive cases undergoing enucleation with the insertion of the Roper-Hall magnetic implant at the Birmingham and Midland Eye Hospital (BMEH) were followed up to re-establish the rate of extrusion. It was possible to study the records of all 66 patients. An extrusion rate of 1.5% was found.     

Complications of supramid orbital implants

PURPOSE: To determine the incidence and risk factors of complications associated with Supramid orbital implants. METHODS: A retrospective chart review was performed to document complications in a series of 41 patients receiving Supramid implants during orbital reconstruction or fracture repair. Implant size, duration of time between trauma and implant insertion, and history of prior orbital surgery were examined as possible risk factors for the development of complications. RESULTS: Four patients had hemorrhage within the implant capsule. An orbital abscess developed in a single patient. All but one complication appeared 7.8 to 10 years after implant insertion. Patients who had complications had a longer duration of time between trauma and implant insertion than those in whom complications did not occur (P =0.0019). Complications were more frequent among patients with larger (>600 mm2) implants and a history of orbital surgery. CONCLUSIONS: Spontaneous infection or hemorrhage may occur within the capsules of Supramid orbital implants, even many years after surgery. The insertion of larger implants in the late repair of extensive bony orbital defects may predispose patients to these complications. Implant removal and marsupialization of the implant capsule to the maxillary sinus appears to be curative without causing significant postoperative enophthalmos.     

Perspective on orbital enucleation implants

The philosophy and design of orbital enucleation implants have evolved significantly over the past 50 years. Animal studies and improved imaging techniques have changed our understanding about the physiology and anatomy of the post-enucleation orbit. Changes in implant design and biomaterials have reduced complication rates. It is our impression that for many ophthalmic professionals in training, the rational behind the current thinking in implant design and biomaterials is unclear. This is in part related to the older literature on orbital enucleation implants, which is scattered and at times contradictory. This review aims to present the historical information in a coherent and concise form; provide evidence based review of changes in the practice patterns of enucleation; identify areas of continuing controversy; and highlight gaps in the scientific literature about orbital implants, in particular, the poor understanding of implant and prosthesis motility.     

Late infection of hydroxyapatite orbital implants

BACKGROUND: Exposure and minor complications of hydroxyapatite orbital implants are common. Infection appears to be rare and fibrovascular ingrowth into hydroxyapatite implants may make infection and extrusion less likely than with other types of orbital implant. METHODS: We describe three cases of chronic low-grade infection of hydroxyapatite implants, occurring late after apparently uncomplicated surgery, with tiny or inapparent areas of conjunctival loss or exposure. RESULTS: Two of the three cases grew Staphylococcus oureus on culture. All three implants ultimately needed to be removed. A characteristic histological pattern was seen, with abrupt transition between vascularized and abscessed implant. CONCLUSIONS: Chronic infection of hydroxyapatite implants can occur late, in the absence of large conjunctival defects, or other obvious risk factors.While exposure of the implant to pathogens through a breach in the conjunctiva may have been a factor, it appeared that the infection may have arisen in an avascular portion of the implant prior to the conjunctival breakdown in one or more of these cases.     

Radiation absorption properties of orbital implants

A 5-year-old girl presented with a large swelling measuring 50 × 35 mm in the left upper lid. The mass was firm to hard in consistency. Fine-needle aspiration showed a few spindle-shaped cells arranged in clusters. The mass was excised in toto and the histopathological examination revealed dermatofibroma, which is an extremely rare condition affecting the eyelid.     

Exposure of tantalum mesh orbital implants

This retrospective study of 195 enucleations with tantalum mesh implants reviews the role of demographic, preoperative, and operative factors in subsequent implant exposure or extrusion. Fourteen implants (7.2%) became exposed, two of which subsequently extruded. Significant associations were found between implant exposure and history of prior orbital infection, and suturing of the inferior oblique to the lateral rectus muscle. The average age at enucleation was 20.4 years for those whose implant became exposed, which was significantly less than the average age of 38.7 years for those without exposure of the implant. No association was found between implant exposure and gender, preoperative diagnosis, proptosis, chemosis, sharp trauma to the orbit, orbital fracture, previous orbital surgery, implant size, closing of posterior Tenon's capsule, or muscles sutured to the implant. Because of the high exposure rate, it is recommended that the use of tantalum mesh implants be discontinued.     

Radiation absorption properties of orbital implants

PURPOSE: To determine the radiation absorption properties (RAP) of three commonly used orbital implant materials, namely, methylmethacrylate (MM), hydroxyapatite (HA), and porous polyethylene (PP). METHODS: Eighteen (18)-mm spheres of MM, HA and PP were tested with 1.25 MV gamma-rays from cobalt-60, 6 MV X-rays, and 9 MeV, 12 MeV, and 16 MeV electron beams. The implants were immersed in a water phantom, and the measurements were obtained on X-omat V(R) film; the scanning was done with a computerized laser densitometer, CADSCAN(R). RESULTS: The RAP of all three materials appeared to be very close to those of water. The density of the MM implant was calculated to be the closest to that of water at all photon and electron energies. PP had a higher transmission than water at all electron energies (9, 12 and 16 MeV); the transmission through HA, however, was lower than through water. CONCLUSION: When postoperative radiation is indicated for an orbit containing an implant, the RAP of the allograft material play a significant role in the planning of the radiation treatment. Our study indicated that MM implants have RAP equivalent to those of water when treatment of orbital tumors is undertaken at the commonly used photon and electron energies. The RAP of the other allografts were either higher or lower, which may lead to unreliability in irradiation planning.     

羟基磷灰石义眼台植入的手术体会

目的比较巩膜包裹羟基磷灰石(hydmxypatite，HA)义眼台植入法与带线HA义眼台直接植入法的疗效。方法眶内植入HA义眼台共58眼，用自体或异体巩膜包裹义眼台后眶内植入40眼，用带线义眼台直接植入眼眶18眼，随访3月-4年。结果义眼台暴露7眼12％(7／58)，Ⅰ期1眼，Ⅱ期6眼；6眼采用巩膜包裹植入法15％(6／40)，1眼采用带线义眼台直接植入法5．6％(1／18)。结膜囊狭窄1眼。结论HA义眼台植入术后主要并发症是义眼台暴露，用带线义眼台直接植入发生这种并发症的机率变小。     

Pericranium grafts for exposed orbital implants

PURPOSE: To report the use of autologous pericranium grafts to cover exposed orbital implants. METHODS: A two-center consecutive case series of exposed orbital implants covered with autologous pericranium grafts. A patch of pericranium was harvested from the parieto-occipital region and was placed over the implant within a pocket between the implant and the Tenon capsule, followed by layered closure of Tenon and conjunctiva. RESULTS: Four patients (2 women, 2 men) with a mean age of 37 years (range, 26 to 45 years) were included in the study. The mean follow-up period was 9.5 months (range, 7 to 12 months). In all cases, there was no recurrence of exposure and no donor site morbidity. A small pyogenic granuloma, arising from the conjunctival suture line, developed in one case. CONCLUSIONS: Autologous pericranium is a useful covering material for exposed orbital implants and may be used as an alternative to frontal periosteum.