Magnetic susceptibility artifact in orbital magnetic resonance imaging

Case report of a 16-year-old boy presenting with total hyphema due to blunt trauma to the left eye. During a subsequent cinematic MRI scan to identify salvageable lateral rectus muscle, the attachment of the left lateral rectus was obscured by a 20-mm diameter signal void. A subsequent CT scan for a suspected metallic foreign body revealed the muscle attachment after all. The theoretical explanations for this finding are discussed.

Neuromuskuläre Wirkzeiten von Rocuronium am Diaphragma, Musculus adductor pollicis und orbicularis oculi in zwei Altersgruppen

OBJECTIVE

Onset time and recovery from non depolarising neuromuscular blockade depends on the tested muscle and is influenced by the age of the patient. This study compares the neuromuscular blocking effect of rocuronium on the diaphragm, adductor pollicis and orbicularis oculi muscle in young and elderly patients.

METHODS

After institutional ethics committee approval and written informed consent, 20 adult patients (ASA I - II), age 18 - 59 and > 65, have been included. Neuromuscular response was measured by accelerography for the adductor pollicis and orbicularis oculi muscle. Monitoring of the diaphragm consisted of measurement of the airway pressure against an occluded tracheal tube during magnetic phrenic nerve stimulation. Onset time and recovery were measured after injection of 0.6 mg/kg Rocuronium.

RESULTS

The adductor pollicis had the fastest onset time ( young 2.3 min, old 2.2 min), followed by diaphragm ( young 3.6 min, old 3.4 min) and orbicularis oculi muscle ( young 3.7 min, old 4.8 min). There was a complete blockade of the diaphragm in 50 % of all patients (Adductor pollicis 100 %, orbicularis oculi 40 %). Neuromuscular recovery, recovery index and TOF 0.8 differed significantly between young and elderly patients. Onset of recovery was earlier at the diaphragm ( young 15.9 min, old 22.0 min) compared to the peripheral muscles (adductor pollicis young 25.6 min, old 37.9 min, orbicularis oculi young 23.8 min, old 27.5 min).

CONCLUSION

2 fould ED95 of rocuronium often results in an incomplete neuromuscular blockade of the diaphragm. Therefore monitoring of the peripheral muscles in patients given a single dose of rocuronium often overestimates the degree of diaphragmatic relaxation, but is a save predictor of recovery. Especially in elderly patients were prolonged neuromuscular blockade should be expected, a neuromuscular monitoring is recommended.

Effect of darkness on upper eyelid position

PURPOSE

To determine the magnitude of upper eyelid retraction induced by sudden darkness in normal subjects and in patients with Graves upper eyelid retraction before and after treatment with guanethidine drops.

METHODS

The study comprised 211 control subjects (n=211 eyes) and 45 patients (n=78 eyes) with Graves upper eyelid retraction. The control subjects were divided in four age groups: 0 to 1 year, 2 to 9 years, 0 to 18 years, and 19 to 61 years. Twenty-one patients with Graves upper eyelid retraction (n=39 eyes) used guanethidine drops for 15 days. Palpebral fissure images of subjects were acquired in photopic conditions and in darkness. For both images, the distance between the mid-pupil and upper eyelid margin was measured.

RESULTS

Darkness induced upper eyelid retraction in all subjects. The increment in the mid-pupil eyelid distance was greater in children. There was no significant difference between the magnitude of eyelid elevation of Graves patients and normal adults. Guanethidine drops did not abolish the eyelid reflex in Graves patients.

CONCLUSIONS

Darkness provokes upper eyelid retraction in control subjects and in patients with Graves upper eyelid retraction. This effect decreases with age and does not result from sympathetic stimulation of the Muller muscle.

[Injection of methylprednisolone directly into the extraocular muscles of eyes with disturbed motility secondary to Graves' ophthalmopathy. Preliminary report]

Aim of the study was to estimate the efficacy of 6-alpha-methylprednisolone injection into involved extraocular muscles in eyes with motility disturbances caused by endocrine ophthalmopathy.

MATERIAL AND METHODS

For further evaluation we qualified 4 patients, 1 female and 3 males, aged: 60, 43, 42 and 64 years, with clinical activity score equal 4, with duration of Graves' ophthalmopathy of mean 2.1 years (0.16 - 5.5). Included were patients with movement restrictions in vertical plane and echographic findings of isolated extraocular muscle involvement (inferior rectus). Each of the patients received 20 mg 6-alpha-methylprednisolone into the muscle belly of inferior rectus, in one case injection was done in both eyes.

RESULTS

In all cases we were able to archive lessening of the intraocular pressure in secondary position, with slight improvement in ocular motility and bigger range of duction free of diplopia.

CONCLUSIONS

Visual function improvement found by the patients is the best evidence for application of 6-alpha-methylprednisolone into the extraocular muscles of patients with motility disturbances secondary to endocrine ophthalmopathy.

Distribution of the toxin following medial rectus muscular injection of botulinum toxin gel in rabbits

PURPOSE

To determine the distribution of the toxin among individual muscles after intramuscular injection of botulinum toxin gel.

METHODS

One eye of 7 New Zealand white rabbits was randomized into group A, and the contralateral eye was into group B. Eyes in group A received medial rectus intramuscular injection of 2.5 IU of 125I-BTX-A gel in 0.1 ml, and those in group B received equivalent amount of 125I-BTX-A solution by medial rectus intramuscular injection. Four rectus muscles and the levator palpebrae superioris were harvested and the radioactivity of muscles was measured 16 hours after the injection.

RESULTS

In group A, the radioactivity of per gram medial rectus was significantly higher than that of other muscles (P < 0.01), and there was no statistically significant difference in the radioactivity of per gram muscles among other muscles (P > 0.05). In group B, the radioactivity of per gram medial rectus and levator palpebrae superioris was significantly higher than that of other muscles respectively(P < 0.05), and the difference in the radioactivity of per gram muscles between medial rectus and levator palpebrae superioris was not statistically significant (P > 0.05). The radioactivity of per gram medial rectus in group A was higher than that in group B (t=3.731, P-0.01), and there was no significant difference in the radioactivity of per gram muscles among other homonymous muscles (P > 0.05).

CONCLUSION

The toxin dispersed principally in the injected muscle and the local concentration of the toxin was much high following intramuscular injection of botulinum toxin gel.

Extraocular muscle cysticercosis - a clinical challenge to the ophthalmologists

PURPOSE

To report our experience with extraocular myocysticercosis, to highlight the role of ultrasound and orbital computerized tomography (CT) scan in these cases and to discuss the management.

METHODS

This is retrospective study of 35 cases of orbital myocysticercosis confirmed on ultrasound and CT scan of the orbit.

RESULTS

There were 18 males and 17 females. The average age of these patients was 19.6 years. The most common presenting feature was restricted ocular motility with diplopia and recurrent pain and redness. Ultrasound examination and CT scan of the orbit done for all these patients identified the cyst and the affected muscle. All extraocular muscles were noted to be involved in myocysticercosis. However the lateral rectus, medial rectus and the superior oblique were affected to a greater extent. All cases dramatically improved on treatment with albendazole and oral steroids. Surgical excision of cyst was done in 6 cases.

CONCLUSION

A high index of suspicion should be entertained for extraocular muscle cysticercosis, especially in cases of acquired ocular motility disorder with recurrent ocular congestion. Ultrasound and CT scans of orbit play a vital role in diagnosis. Medical therapy with albendazole under cover of steroids is effective in most of the cases.

Lack of Effect of Botulinum Toxin on Cortical Excitability in Patients With Cranial Dystonia

The aim of this study was to verify whether botulinum toxin (BTX)-induced clinical improvement of cranial dystonia is associated with changes in the cortical silent period (SP), a measure of cortical excitability. By transcranial magnetic stimulation (TMS), high-intensity stimuli were delivered with a round coil centered at the vertex during a maximal muscle contraction of the orbicularis oculi. Motor evoked potentials (MEPs) and SPs were obtained from surface electrodes placed over the orbicularis oculi muscle before and 2 to 3 weeks after BTX-A injection into the affected muscles in 10 patients with cranial dystonia and 8 age-matched control subjects. BTX injection improved blepharospasm in all patients. Facial muscle SPs were significantly shorter in patients than in control subjects and did not significantly change after treatment, at the time of maximal clinical improvement. We conclude that the clinical improvement induced by BTX in patients with cranial dystonia is largely symptomatic. It does not appear to result from modulation of abnormal aspects of intracortical excitability, although these may play a role in craniofacial dystonia.

Parameters of drug antagonism: re-examination of two modes of functional competitive drug antagonism on intraocular muscles

There are two distinct kinetic functional pharmacological procedures by which the equilibrium affinity constant, KB, of a competitive reversible blocker is obtained. The classical method on an organ system requires the study of the parallel displacement of the agonist concentration-response curve in the presence of the blocker. In the second method, the agonist-evoked functional mechanical response is reduced to half by the blocker IC50 (the concentration required for 50% inhibition). In relation to these parameters the role of the ionization constant pKa and liposolubility log Pc or log D of blockers was examined. On the ciliary muscle from human eye, IC50/KB ratios for (+/-)-atropine, its quaternary analogue (+/-)-methylatropine, (-)-scopolamine, (+/-)-cyclopentolate, (-)-tropicamide, (+/-)-oxybutynin and pirenzepine were 15, 23, 4.4, 2.6, 1.66, 1.46 and 1.71, respectively. The ratios on the iris sphincter were comparable with those of ciliary muscle. When compared with large proportions of ionized molecules with water soluble properties of (+/-)-atropine and (+/-)-methylatropine, relatively high amounts of un-ionized and/or with greater partitioning of all other blockers in the lipoid barrier correlated well to low IC50/KB ratios, as predicted by the classical theory of competitive drug antagonism. It was hypothesized that due to receptor biophase access, the reduction of the mechanical response of the agonist by the highly ionized water-soluble antagonist at IC50 represented time-distorted "pseudoequilibrium" estimation, where a higher concentration of the blocker was needed. On the other cholinergic effectors, like that of rat anococcygeus muscle or frog rectus abdominus muscle, IC50/KB ratios of respective blockers atropine or (+)-tubocurarine and hexamethonium were close to 1. Thus physicochemical properties, which affect the distribution coefficient log D and the tissue morphology (where asymmetric distribution of receptors may occur), appeared to be a critical factor in the analysis of the affinity parameters of the competitive reversible blocker. On the intraocular muscles, two functional pharmacological procedures for obtaining KB and IC50 values were not kinetically equivalent.

Augenmuskeloperationen bei endokriner Orbitopathie - Dosis-Wirkungs-Beziehung und funktionelle Ergebnisse

BACKGROUND

Strabismus in thyroid ophthalmopathy is based on a loss of the contractility and distensibility of the external ocular muscles. Different therapeutic approaches are available, such as recession after pre-. or intraoperative measurement, adjustable sutures, antagonist resection, or contralateral synergist faden-operation.

PATIENTS AND METHODS

26 patients with strabismus in thyroid ophthalmopathy were operated between 2000 and 2003. All patients were examined preoperatively, then 1 day and 3 - 6 months (maximum 36 months) postoperatively. Before proceeding with surgery, we waited at least 6 months after stabilization of ocular alignment and normalization of thyroid chemistry.

RESULTS

Preoperative vertical deviation was 10-44 PD (mean 22), 3 months postoperatively it was 2-10 PD (mean 1.5). Recession of the fibrotic muscle leads to reproducible results: 3.98 +/- 0.52 PD vertical deviation/mm for the inferior rectus. In the case of a large preoperative deviation a correction should be expected, which might not be sufficient in the first few days or weeks; a second operation should not be carried out before 3 months. 7 patients were operated twice, 1 patient need three operations. 4 patients (preop. 0) achieved no double vision at all; 15 patients (preop. 1) had no double vision in the primary and reading positions; 3 patients (preop. 0) had no double vision with a maximum of 5 PD; 1 patient (preop. 7) had double vision in the primary or reading position even with prisms; and 2 patients (preop. 17) had double vision in every position.

CONCLUSIONS

We advocate that recession of the restricted inferior or internal rectus muscle is precise, safe and effective in patients with thyroid ophthalmopathy. The recessed muscle should be fixed directly at the sclera to avoid late over-correction through a slipped muscle. The success rate in terms of binocular single vision was 76 % and 88 % with prisms added.

Costenbader Lecture. The efficacy of rectus muscle transposition surgery in esotropic Duane syndrome and VI nerve palsy

BACKGROUND

Partial tendon transposition was first described by Hummelshein in 1907. Full tendon transposition was reported by Schillinger in 1959. Recently, full tendon transposition with posterior augmentation was reported by Foster in 1997. I will review current thinking concerning the anatomy and physiology of rectus muscle transposition and present our current clinical experience with this procedure in Duane syndrome.

METHODS

A retrospective review of vertical rectus muscle transposition procedures in patients with VI Nerve palsy was performed comparing the postoperative field of single binocular vision, amount of improved abduction, and change in the primary esotropic angle. In addition, a consecutive series of vertical rectus muscle transposition cases for the treatment of esotropic Duane syndrome is presented, evaluating the improvement and head position, abduction, and reduction of the primary position esotropia.

RESULTS

In VI Nerve palsy patients, vertical rectus transposition surgery produces 41 degrees to 71 degrees of binocular visual field with 10 degrees to 21 degrees of binocular field in abduction. In esotropic Duane syndrome the surgical procedure produces 42 degrees to 66 degrees of binocular field and a correction of approximately 15 degrees of face turn. Variability in the efficacy of the procedure is related to the degree of ipsilateral medial rectus contracture.

CONCLUSION

Vertical rectus transposition with posterior fixation can create a binocular diplopia-free field of 40 to 70 degrees in patients with VI Nerve palsy and about 40 to 65 degrees in patients with Duane syndrome. Partial rectus muscle transposition is an effective procedure in cases where surgery on multiple rectus muscles has been or will be required. Orbital wall fixation of the lateral rectus muscle is an effective and reversible method to inactivate a lateral rectus muscle and may be useful in cases of Duane syndrome with marked anomalous innervation and severe cocontraction.

Role of Exogenous and Endogenous Trophic Factors in the Regulation of Extraocular Muscle Strength during Development

PURPOSE

Weak eye muscles can cause ophthalmic disorders, and in particular, strabismus. Exogenous trophic factors such as cardiotrophin (CT)-1 and insulin-like growth factor (IGF) have been shown to increase the contractile force of adult heart and skeletal muscles, respectively. In the current study, the effects of endogenous and exogenous trophic factors on extraocular muscle strength and mass were examined in the developing chicken.

METHODS

Superior rectus and superior oblique muscles of hatchling chicks were treated in vivo either to increase levels of trophic factors CT-1, IGF-I, glial cell line-derived neurotrophic factor (GDNF), or brain-derived neurotrophic factor (BDNF), or to decrease their levels with neutralizing antibodies and binding proteins. Forty-eight hours after factors were injected into the orbit, the contractile force of dissected muscles was measured in vitro and the morphology of muscle fibers was compared between control and treated muscles.

RESULTS

Treatment with CT-1 or IGF-I significantly increased the mean single-twitch force generation and these trophic factors increased muscle fiber diameters when compared to control muscles. A cocktail of antibodies and binding proteins, directed against endogenous IGF-I, GDNF, and CT-1, significantly decreased mean single-twitch force. This cocktail slightly, but significantly, reduced muscle fiber diameters within treated extraocular muscles.

CONCLUSIONS

Endogenous trophic factors regulate and/or maintain extraocular muscle force through a rapid mechanism that appears to involve changes in muscle mass and specifically enlargement of muscle fiber diameters. CT-1 and IGF-I may be considered promising candidate trophic factors for therapeutic strengthening of eye muscles in the developing extraocular muscle system.

Surgery and botulinum toxin in congenital esotropia

BACKGROUND

In a previous study we investigated the advantages and drawbacks of early and delayed injection of botulinum toxin as primary treatment of infantile esotropia with nystagmus in abduction (IENA). We carried out a further study to investigate the role and efficacy of surgery in this condition and to determine the possible effect of previous injection of both medial recti with botulinum toxin in patients requiring a final horizontal surgical correction.

METHODS

Review of the records of 44 patients (24 girls and 20 boys) with IENA seen between 1979 and 1998 who had undergone at least one horizontal surgical procedure. The outcomes in the 16 patients who had previously received botulinum toxin were compared with those in the 28 patients for whom surgery was the primary treatment.

RESULTS

There was a negative correlation between the pretreatment esotropic angle and age (Pearson's r = -0.45, p < 0.05). The first visit to a surgical specialist took place very late (mean age 43 months [standard deviation (SD) 39 months]). Of the 35 children seen during the period in which botulinum toxin was available, 20 (57%) had additional factors inducing unsteadiness of binocular vision (e.g., moderate to severe initial relative amblyopia, initial ametropia). Administration of 5 units of botulinum toxin before 18 months of age destabilized dissociated vertical deviation. Overall, 39 patients (89%) had a final residual deviation of less than 10 prism dioptres. The first surgical correction was horizontal and vertical-torsional in 30 patients (68%). A total of 23 patients (52%) required some retreatment (botulinum toxin or surgery or both). Children treated initially with botulinum toxin had less surgery than those with initial surgery (mean recession or resection 8.9 mm [SD 4.5 mm] vs. 14.2 mm [SD 4.0 mm]) as well as fewer horizontal muscles operated (mean 1.6 [SD 0.6] vs. 2.3 [SD 0.6]).

INTERPRETATION

Surgery with or without further interventions is a reasonable approach for IENA with delayed diagnosis and in cases associated with unsteadiness of binocular vision or with nonhorizontal deviations. Initial treatment with botulinum toxin, injected into both medial recti, is effective, reducing the amount of further horizontal surgery and favouring postoperative stability, except in children under 18 months, in whom injection of 5 units induces unbalanced dissociated vertical deviation.

[Treatment of strabismus associated with psychomotor impairment using botulinum toxin]

PURPOSE

Strabismus is associated with 80% of people with psychomotor retardation. Surgical treatment is difficult owing to brain instability. The aim of this study is to determine the efficacy of a direct application of botulinum toxin in cases strabismus related to psychomotor retardation.

METHODS

This is a retrospective, longitudinal, observational study of treatment of strabismus associated to brain damage (under the Laws of Health of Mexico) using a direct application technique of botulinum toxin, considering age, type of strabismus, number of toxin applications, response and cause of brain damage.

RESULTS

We analyzed 30 patients, age: 3.5 years old (S.D.: 2), follow-up 12.7 (S.D.: 2.3 months). Eighty percent of the patients had moderate psychomotor retardation and 20% had a severe retardation. The response was good in 44% and moderate in 24%, there were no cases without response. The patients were treated with 1.7 (S.D.:1) injections of toxin. Age and type of strabismus was not related to success of treatment (X2: 9.4; 7.8 to null hypothesis). First application of toxin determines the response to treatment (Fisher test: <0.05). Moderate retardation was related to better response. Bad results were related to unstable brain disease.

CONCLUSIONS

The difficulty and prognosis of surgical treatment of strabismus in patients with brain damage and psychomotor retardation, causes us to consider the use of botulinum toxin as the first choice for this cases.

Myotoxic effects of the skeletal muscle-specific immunotoxin, ricin-mAb35, on orbicularis oculi muscle after eyelid injections in rabbits

PURPOSE

The authors recently demonstrated that a single injection of the immunotoxin ricin-mAb35 has potent and long-lasting myotoxic effects in extraocular muscles. The myotoxicity of injected ricin-mAb35 was tested in the eyelids of rabbits to determine its potential for use in the treatment of benign essential blepharospasm and other dystonias.

METHODS

The immunotoxin ricin-mAb35 was injected in one eyelid of adult rabbits. After 1 week, 1 month, or 6 months, the rabbits were euthanized, and the eyelids were prepared for histologic examination of inflammatory cell infiltrate with immunohistochemical localization of cd11b and myosin heavy chain isoform expression. Muscle loss was quantified by analysis of muscle fiber cross-sectional area and total myofiber number.

RESULTS

Within the first week after a single injection of ricin-mAb35, some edema developed, which resolved by the second week. Otherwise, the eyelids were normal in appearance. A short-lived inflammatory response was seen at 1 week, but this resolved 1 month after treatment. One week after injection, there was a significant decrease in the total number of orbicularis oculi myofibers in the ricin-mAb35-treated eyelids. This myofiber loss remained significant 1 month later and was maintained 6 months after the initial injection.

CONCLUSIONS

Direct injection of the immunotoxin ricin-mAb35 resulted in significant, acute muscle loss in the orbicularis oculi of rabbits that was maintained for up to 6 months. Physiologic studies are needed to demonstrate concomitant loss of muscle strength, but these results suggest that ricin-mAb35 injection holds promise as a muscle-weakening agent in the eyelid.

Antimuscarinic Action of Oxymetazoline on Human Intraocular Muscles

At 10 microM or 100 microM concentration of oxymetazoline, the activity of carbachol was competitively blocked on the isolated human iris sphincter or ciliary muscles. On the ciliary muscle, the dissociation constant K(B) of 5.2 microM was obtained. The value is approximately equal to that on the iris sphincter. Even though it is a weakly active antimuscarinic drug with potent alpha-adrenoceptor-mediated vasoconstriction activity, the therapeutic benefit in ocular decongestion recovery may be partly related to the weak anticholinergic activity.

Botulinum toxin for the treatment of congenital entropion

PURPOSE

To describe a case of congenital entropion presenting with ulcerative keratitis that was successfully treated with a single injection of botulinum toxin.

DESIGN

Interventional case report.

METHODS

A 3-week-old female infant with a corneal ulcer of the left eye since birth presented for evaluation. She was found to have entropion of the left lower lid. The pretarsal orbicularis muscle was injected with 5 units of botulinum toxin.

RESULTS

Four days after treatment, the entropion had resolved and the corneal epithelial defect had healed. There was no recurrence of the entropion 7 months after botulinum toxin injection.

CONCLUSIONS

Injection of botulinum toxin can effectively treat certain cases of congenital entropion.

A novel in vitro model for screening and evaluation of anti-asthenopia drugs

Patients suffering asthenopia are steadily increasing with an expanding use of visual display terminals such as computers. An attempt was made to develop an in vitro model for asthenopia. Ciliary muscle removed from eyeballs of a rabbit was stimulated with acethylcholine, resulting in contraction of the muscle. Repeated stimulations caused decreased contraction, which may be related to fatiguing of ciliary muscle and hence asthenopia. Treatment of the repeatedly stimulated muscle with cyanocobalamin restored contraction dose-dependently. Thus, the model developed in this study can be used to screen drug candidates for treating asthenopia.

Persistent diplopia after retrobulbar anesthesia

PURPOSE

To determine the causative factors of persistent diplopia after retrobulbar anesthesia.

SETTING

Strabismus Section, Department of Ophthalmology, Seoul National University, Seoul, South Korea.

METHODS

Prism and alternate cover tests in the diagnostic positions of gaze and ductions/versions were performed in 28 patients with persistent diplopia 6 months after retrobulbar anesthesia. The Lancaster test, Bielshowsky head tilt test, double Maddox rod test, fundoscopic examination for torsion, forced duction test, force generation test, tensilon test, thyroid function test, and/or orbit computed tomography were performed when necessary.

RESULTS

Most of the patients (26 patients, 93%) did not have diplopia before retrobulbar anesthesia. Of the 14 patients with extraocular muscles imbalance, 12 patients showed vertical rectus overaction (11 superior recti, 1 inferior rectus) and 2 patients, mild vertical rectus underaction. Nine patients were presumed to have a sensory strabismus related to the preoperative poor vision, but this went unnoticed preoperatively. Three patients showed a small vertical deviation without any specific causative factors.

CONCLUSIONS

Fifty percent of the cases of diplopia were associated with either direct trauma or anesthetic myotoxicity to the extraocular muscles, in which overactions were more common than underactions. Thirty-two percent of the patients were presumed to have sensory strabismus, which suggested the importance of preoperative examination for strabismus as well as providing an explanation about the risk of postoperative diplopia before surgery.

Effect of retrobulbar injection of lidocaine on saccadic velocities

PURPOSE

To determine whether exposing the extraocular muscles (EOMs) to lidocaine via retrobulbar injection for cataract surgery has a demonstrable negative effect on subsequent function of the muscle.

SETTING

York Finch Eye Associates, Humber River Regional Hospital, and Toronto Western Hospital Research Institute, Toronto, Ontario, Canada.

METHODS

This study comprised 37 eyes that had phacoemulsification and posterior chamber intraocular lens implantation; 13 eyes had retrobulbar lidocaine with hyaluronidase and 24 eyes, topical anesthesia. The postoperative saccadic velocities were compared with the preoperative velocities using a sensitive recording device. The results were compared within and between the retrobulbar lidocaine and topical anesthesia groups.

RESULTS

No detectable decrement in postoperative saccadic velocities was detected in any patient, and no difference was found between the groups.

CONCLUSIONS

Exposing EOMs to lidocaine for cataract surgery had no detectable negative effect on saccadic velocities 1 week after surgery.

Localized Inferior Orbital Fibrosis Associated with Porcine Dermal Collagen Xenograft Orbital Floor Implant

We describe the clinical features, treatment, and histologic changes of a case of severe localized orbital inflammation associated with the use of porcine dermal collagen xenograft (Permacol) as an orbital floor implant in a 14-year-old boy. After uneventful blowout fracture repair with normal forced duction testing after insertion of a Permacol implant, progressive elevation and depression deficit developed in the postoperative period. There was no improvement after removal of the Permacol implant. Exploratory surgery revealed gross fibrosis of the inferior rectus muscle accounting for the abnormal ocular motility. Biopsy of the inferior rectus muscle showed chronic granulomatous inflammation suggestive of foreign body reaction. Although porcine dermal collagen xenograft has been suggested as an implant for orbital floor repair because of its reported high strength, ease of handling, and high biocompatibility, we believe that further studies are necessary before it can be recommended for this use.