SEARCH · Search PubMed

Results for “Orbit”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources

PubMed1997

Maximal, three-wall, orbital decompression through a coronal approach.

BACKGROUND AND OBJECTIVE: Only limited volume expansion is offered by traditional lateral orbital decompressions in which the anterior segment of the lateral wall is removed to allow lateral soft tissue prolapse. A great deal of additional soft tissue expansion can be obtained, not only laterally, but also posteriorly by removing the deep portion of the sphenoid wing. The authors report their experience in removing this bone through a coronal approach. PATIENTS AND METHODS: The authors performed maximal, three-wall, orbital decompressions through a coronal approach for 20 patients with thyroid-related orbitopathy. A disfiguring proptosis resulting from stable Graves' disease orbitopathy was the indication for surgery in all cases. Through a coronal approach, the lateral rim was left in place and thinned, augmented with specialized orbital rim onlay implants, or repositioned with osteosynthesis systems. The bone over the lacrimal fossa was sculpted to form a "keyhole" for the lacrimal gland, thereby providing additional orbital expansion. Once the medial canthal tendon and lacrimal sac had been elevated from their periosteal attachment, excellent exposure was obtained for medial and inferior orbital decompression. RESULTS: The authors report the results of 20 coronal orbital decompressions during a period of 44 months. Seven cases included lateral rim advancement. Up to 6 mm of retrodisplacement was achieved without rim augmentation, 9 mm with rim augmentation. DISCUSSION: The deep lateral orbital wall can provide significant room for volume expansion. The authors found that up to 6 mm of proptosis reduction can be obtained using the lateral wall alone. The coronal approach provides access to all four orbital walls for deep orbital decompression. The authors' philosophy of treatment in cases without compressive optic neuropathy is evolving toward the use of the lateral wall as the first approach with the incorporation of additional walls as needed.

Adult↗

PubMedDate not supplied

Management of orbital inflammatory disease. A protocol.

A step-by-step practical approach to orbital inflammatory disease is presented. In our hands, this proposed protocol has been useful. In any patient with orbital inflammatory disease, the ophthalmologist must initially rule out a life-threatening bacterial orbital cellulitis. Because the orbital disease presentation may be part of a systemic process, a good history and appropriate systemic work-up are mandatory. If any suspicion of bacterial orbital cellulitis exists, we recommend that intravenous antibiotics be instituted. Concurrently, orbital computerized tomographic scan may be extremely helpful in the work-up. Specifically, three findings--presence of an orbital-mass lesion without sinus involvement or bone erosion, presence of an orbital-mass lesion with sinus involvement or bone changes, or thickened extraocular muscles on CT scan--lead to the differential diagnosis, decision to biopsy, and appropriate treatment.

Biopsy↗

PubMed2026

Orbital involvement in sickle cell disease: A systematic review.

Orbital involvement in sickle cell disease (SCD) is rare but potentially vision-threatening and is often misdiagnosed due to overlap with infectious orbital disease. We conducted a systematic review of case reports and series describing orbital complications in patients with confirmed SCD, following PRISMA and MOOSE guidelines. Across 53 studies, 76 cases were identified. Patients were predominantly male (77.6%), with an average age of 13.2 years. Orbital disease was the initial SCD manifestation in 6.6%. Presentations included periorbital edema in all, proptosis in 64.1%, restricted ocular motility in 56.5%, reduced visual acuity in 28.1%, and bilateral involvement in 38.2%. Laboratory findings commonly included leukocytosis (73%) and raised inflammatory markers (86.7%). Radiologically, orbital subperiosteal hematoma were observed in 70%, combined orbital bone infarction and hematoma in 38.2%, and orbital bone infarction alone in 19.7%. Magnetic resonance imaging is critical for accurate diagnosis. Intracranial hemorrhage was present in 9.2%. Less frequent manifestations included orbital apex syndrome, lacrimal gland disease, and nonspecific soft tissue swelling. Management was primarily conservative (82.9%), and surgery was reserved for vision-threatening or intracranial complications. Complete recovery was achieved in 93.1% of cases. While severe vision-threatening complications are uncommon, early recognition remains critical to optimising outcomes in sickle cell orbitopathy.

Humans↗

PubMed2003

Orbital exenteration: results of an individualized approach.

PURPOSE: The authors report and evaluate their experience with an individualized approach to orbital exenteration. METHODS: Retrospective chart review was performed on a consecutive series of 25 orbital exenteration patients at a tertiary care center. The cases were classified into two groups for the retrospective analysis: Total exenteration procedures involved the removal of the entire orbital contents including the periorbita (13 cases), and subtotal procedures preserved at least a quadrant of the orbit or the orbital tissues posterior to the globe (12 cases). RESULTS: The total exenteration group had a lower rate of clear surgical margins and a higher rate of systemic metastasis, whereas patients in the subtotal exenteration group had fewer surgical complications and better functional and aesthetic results. CONCLUSIONS: The surgical planning for orbital exenteration should take into account the location, extent, and biological behavior of the orbital disease process and the reconstructive and prosthetic options for the exenterated socket. When an individualized approach to orbital exenteration is used, subtotal procedures can offer improved functional and aesthetic results while still maximizing the chances for a surgical cure.

Aged↗

PubMedDate not supplied

[Orbital pseudotumour imitating a proliferative process].

INTRODUCTION: Orbital pseudotumour is a non-specific inflammatory process of the orbit of unknown origin. It is a rarely diagnosed disease particularly in children, which imitates a neoplastic process. Typical clinical picture is a tumour localized in the orbit, causing various degree of exophtalmus and a decrease of globe mobility and vision. The extent of intraorbital changes are revealed by imaging studies (USG, TK, MR). Diagnosis is based on histopathology of tumour sample. In treatment steroid therapy, radiotherapy or chemotherapy in resistant cases are used. Relapse and malignant transformation are observed. CASE REPORT: We present a case of a 5-years old girl with orbital pseudotumour. In the histopathological examination there a small lymphoid cells, immunohistochemically there is mixed lymphocytic T and B infiltration (CD 3 (+), CD 20 (+), bcl (+), CD 43 (-)). She was treated with steroid therapy, and achieved complete regression of the tumour. At present she is regularly oncologically examined because of the possibility of malignant transformation. CONCLUSIONS: 1. Orbital pseudotumour should be included in the differential diagnosis of children with an orbital tumour 2. Corticosteroids seem to be the treatment of choice in orbital pseudotumour 3. Children with orbital pseudotumour should be regularly oncologically examined because of the possibility of malignant transformation.

Child↗

PubMed1996

Connectional networks within the orbital and medial prefrontal cortex of macaque monkeys.

The intrinsic cortico-cortical connections within the orbital and medial prefrontal cortex (OMPFC) were demonstrated with retrograde and anterograde tracers injected into each of the architectonic areas that constitute this region. Although many of the connections linked neighboring areas, others selectively connected relatively distant areas. Most, but not all, of the connections were reciprocal. Altogether, the connections formed at least two distinct networks within the OMPFC. The "orbital" prefrontal network linked most of the areas within the orbital cortex, with very few connections to medial prefrontal areas. Areas Iam, Iapm, Ial, 12l, 12m, and 12r in the caudal and lateral parts of the orbital cortex (which received inputs from several sensory modalities) had convergent connections with areas 13l, 13m, and 13b in the central orbital cortex, with further connections to the rostral orbital area 11l. For the connections between areas Iapm, Iam, Ial, 13m, 13l, and 11l, rostrally directed fibers arose mainly in layer V, whereas caudally directed fibers originated mainly in layer III. The "medial" prefrontal network selectively involved medial areas 14r, 14c, 24, 25, 32, and 10m, rostral orbital areas 10o and 11m, and agranular insular area Iai in the posterior orbital cortex. Two orbital areas, 13a and 12o, had substantial connections to both networks and may serve as points of interaction between them; otherwise there were relatively few interconnections. The two networks also had distinct connections with other cortical regions, with limbic structures, and with the mediodorsal thalamic nucleus. Their role in guidance of affective behaviour is discussed.

Animals↗

PubMed2006

The effects of sensory loss and walking speed on the orbital dynamic stability of human walking.

Peripheral sensory feedback is believed to contribute significantly to maintaining walking stability. Patients with diabetic peripheral neuropathy have a greatly increased risk of falling. Previously, we demonstrated that slower walking speeds in neuropathic patients lead to improved local dynamic stability. However, all subjects exhibited significant local instability during walking, even though no subject fell or stumbled during testing. The present study was conducted to determine if and how significant changes in peripheral sensation and walking speed affect orbital stability during walking. Trunk and lower extremity kinematics were examined from two prior experiments that compared patients with significant neuropathy to healthy controls and walking at multiple different speeds in young healthy subjects. Maximum Floquet multipliers were computed for each time series to quantify the orbital stability of these movements. All subjects exhibited orbitally stable walking kinematics, even though these same kinematics were previously shown to be locally unstable. Differences in orbital stability between neuropathic and control subjects were small and, with the exception of knee joint movements (p=0.001), not statistically significant (0.380p0.946). Differences in knee orbital stability were not mediated by differences in walking speed. This was supported by our finding that although orbital stability improved slightly with slower walking speeds, the correlations between walking speed and orbital stability were generally weak (r(2)16.7%). Thus, neuropathic patients do not gain improved orbital stability as a result of slowing down and do not experience any loss of orbital stability because of their sensory deficits.

Algorithms↗

PubMed2005

Differential effects of orbital and laminar shear stress on endothelial cells.

OBJECTIVE: Laminar shear stress is atheroprotective for endothelial cells (ECs), whereas nonlaminar, disturbed, or oscillatory shear stress correlates with development of atherosclerosis and neointimal hyperplasia. The effects of orbital and laminar shear stress on EC morphology, proliferation, and apoptosis were compared. METHODS: ECs were exposed to orbital shear stress with an orbital shaker (210 rpm) or laminar shear stress (14 dyne/cm 2) with a parallel plate. Shear stress in the orbital shaker was measured with optical velocimetry. Cell proliferation was assessed with direct counting and proliferating cell nuclear antigen staining; apoptosis was assessed with transferase-mediated deoxyuridine triphosphate nick end labeling staining. Cell surface E-selectin and intercellular adhesion molecule expression were assessed with fluorescence-activated cell sorting. Akt phosphorylation was assessed with Western blotting. RESULTS: Orbital shear stress increased EC proliferation by 29% and 3 [H]thymidine incorporation two-fold compared to 16% and 38% decreases, respectively, in ECs treated with laminar shear stress (P < .0001 and P = .03, analysis of variance). Cells in the periphery of the culture well aligned to the direction of shear stress similar to the shape change seen with laminar shear stress, whereas ECs in the center of the well appeared unaligned similar to ECs not exposed to shear stress. Shear stress at the bottom surface of the culture well was reduced in the center of the well (5 dyne/cm 2) compared to the periphery (11 dyne/cm 2); the Reynolds' number was 2066. ECs were seeded differentially in the center and periphery of the wells. ECs in the center of the well had increased proliferation, increased apoptosis, reduced Akt phosphorylation, increased intercelluar adhesion molecule expression, and reduced E-selectin down-regulation, compared with ECs in the periphery of the well. CONCLUSION: Although the orbital shaker does not apply uniform shear stress throughout the culture well, arterial magnitudes of shear stress are present in the periphery of the well. ECs cultured in the center of the well exposed to low magnitudes of orbital shear stress might be a model of the "activated" EC phenotype. CLINICAL RELEVANCE: The perfect in vitro model to study and assess treatments for atherosclerosis and neointimal hyperplasia does not exists. An extensive body of literature describing effects of laminar shear stress on endothelial cells has contributed to our understanding of the interactions between shear stress and blood vessels. Laminar shear stress is atheroprotective, whereas oscillatory or disturbed shear stress correlates with areas of atherosclerosis and neointimal hyperplasia in vivo. This study describes the orbital shear stress model, its effects on endothelial cell proliferation and apoptosis, and suggests that activation of the intracellular Akt pathway is associated with these differing effects of laminar and orbital shear stress on endothelial cells.

Animals↗

PubMed2005

Idiopathic orbital hemorrhage related to the inferior rectus muscle: a rare cause for acute-onset diplopia and unilateral proptosis.

PURPOSE: To report 6 patients with spontaneous orbital hemorrhage in relation to the inferior rectus muscle. DESIGN: Retrospective observational case series. PARTICIPANTS: Six patients with acute onset orbital pain, diplopia, and proptosis referred to the orbital clinic at the Royal Victorian Eye and Ear Hospital, January 1995 through December 2004. METHODS: Review of clinical history, imaging studies, and follow-up. MAIN OUTCOME MEASURES: Resolution of proptosis and diplopia and imaging studies of the orbit, including computed tomography (CT), magnetic resonance imaging (MRI), or both. RESULTS: Six patients (4 men, 2 women; mean age, 68 years) were referred with acute onset of unilateral proptosis and diplopia. None of the patients had a history of bleeding disorder. Visual acuity and intraocular pressure were normal; 3 patients showed marked limitation in upgaze on the affected side. Imaging studies of the orbit by CT, MRI, or both showed inferior orbital hemorrhage either within (4 patients) or adjacent to (2 patients) the inferior rectus muscle, possibly within the muscular sheath. Symptoms resolved completely in all but 1 patient, who had persistent diplopia in extreme upgaze. Follow-up CT, MRI, or both showed complete resolution in 3 patients and mild persistent inferior rectus muscle thickening in 2 patients. CONCLUSIONS: Acute onset proptosis and diplopia may be secondary to spontaneous orbital hemorrhage within the inferior rectus muscle or its sheath with no other orbital or systemic pathologic features. Symptoms resolved spontaneously over the course of days to weeks, and orbital imaging showed complete resolution or mild persistent enlargement of the muscle without significant symptoms.

Acute Disease↗

PubMed2001

Electronic structure of 3d[M(H2O)6](3+) ions from Sc(III) to Fe(III): a quantum mechanical study based on DFT computations and natural bond orbital analyses.

The metal-donor atom bonding along the series of 3d[M(H2O)6](3+) ions from Sc(3+) to Fe(3+) has been investigated by density-functional calculations combined with natural localized bond orbital analyses. The M-OH(2) bonds were considered as donor-acceptor bonds, and the contributions coming from the metal ion's 3d sigma-, 3d pi-, and 4s sigma-interactions were treated individually. In this way, the total amount of charge transferred from the water oxygen-donor atoms toward the appropriate metal orbitals could be analyzed in a straightforward manner. One result obtained along these lines is that the overall extent of ligand-to-metal charge transfer shows a strong correlation to the hydration enthalpies of the aqua metal ions. If the contributions to the total ligand-to-metal ion charge transfer are divided into sigma- and pi-contributions, it turns out that Cr(3+) is the best sigma-acceptor, but its pi-accepting abilities are the weakest along the series. Fe(3+) is found to be the best pi-acceptor among the 3d hexaaqua ions studied. Its aptitude to accept sigma-electron density is the second weakest along the series and only slightly higher than that of Sc(3+) (the least sigma-acceptor of all ions) because of the larger involvement of the Fe(3+) 4s orbital in sigma-bonding. The strengths of the three types of bonding interactions have been correlated with the electron affinities of the different metal orbitals. Deviations from the regular trends of electron affinities along the series were found for those [M(H2O)6](3+) ions that are subject to Jahn-Teller distortions. In these cases (d(1) = [Ti(H2O)6](3+), d(2) = [V(H2O)6](3+), and d(4) = [Mn(H2O)6](3+)), ligand-to-metal charge transfer is prevented to go into those metal orbitals that contain unpaired d electrons. A lowering of the complex symmetry is observed and coupled with the following variations: The Ti(3+)- and V(3+)-hexaaqua ions switch from T(h)() to C(i)() symmetry while the Mn(3+)-hexaaqua ion moves to D(2)(h)() symmetry. The loss of orbital overlap leading to a diminished ligand-to-metal charge transfer toward the single occupied metal orbitals is compensated by amplified bonding interactions of the ligand orbitals with the unoccupied metal orbitals to some extent.

Journal Article↗

PubMed2006

Lone-pair orbital interactions in polythiaadamantanes.

The electronic structures of a series of polythiaadamantanes from thiaadamantane through 2,4,6,8,9,10-hexathiaadamantane (HTA) have been analyzed using density functional theory calculations in conjunction with Hückel and natural bond orbital analysis. The effects of multiple sulfur p-type lone-pair orbital interactions on ionization potentials, hole mobilities, and electronic coupling have been determined. An overall increase in the average energy of the lone-pair orbitals as the number of sulfur atoms increases is predicted, with the exact positioning of the HOMO depending on specific lone-pair interactions. Separation of through-bond (TB) and through-space (TS) interactions between intramolecular sulfur atoms has been performed using localized molecular orbitals and model systems based on interacting hydrogen sulfide molecules. TB interations were found to reduce orbital splitting, while TS interactions were found to increase orbital splitting. TS interactions were more or less constant from one polythiaadamantane to the next, and the contributions of TB effects to individual orbital energies vary depending on the relative orientation of sulfur atoms as determined by the sigma molecular framework. Electronic coupling between intermolecular sulfur lone-pair orbitals was determined by investigating unique dimer pairs observed in the crystal structure of HTA. Electronic coupling is not as strong as expected given the short intermolecular S-S distances observed in the crystal structure. In general, B3LYP/6-31G(d) and B3LYP/6-311+G(d,p) give very similar orbital energies and splittings.

Journal Article↗

PubMed1999

Vasculature of the orbital rete in the Japanese deer (Cervus nippon).

The vasculature of the orbital rete (rete mirabile ophthalmicum) in Japanese deer (Cervus nippon) was studied using corrosion casting, scanning electron microscopy, and histology. The orbital rete is a flat, triangular- or leaf-shaped arterial network, which consists of a complex of small arterioles, that intermixes with a similar complex of the supraorbital vein at the base of the orbital cavity. Blood to the retina passes through the orbital rete. The orbital retial arterioles leave the parent external ophthalmic artery at right angles forming T-shaped bifurcations, and follow a tortuous, undulating course. Each retial arteriole is connected by side branches and forms a rope-ladder-like network. Some of the side branches are surrounded by a groove representing the intra-arterial cushion that regulates blood flow at branching sites. The central retinal artery supplying the retina originates from the orbital rete. The ciliary arteries supplying the choroid arise from the external ophthalmic artery proximal to the orbital rete. The anatomical specializations of the orbital rete may involve buffering the blood pressure and flow to the retina and regulating ocular tissue temperature as in the carotid rete. In addition, the orbital rete may help dampen the tension that the vessel exerts on the retina, by stretching in response to eyeball movement.

Journal Article↗

PubMed1971

On the concept of orbital steering in catalytic reactions.

Angular displacement from linear overlap of but a few degrees in the transition state of the enzyme-substrate complex has been postulated to be of great kinetic significance ("orbital steering"). The concept of orbital steering is shown to have evolved from the orientation parameters of an equation previously proposed to evaluate the kinetic importance of propinquity. This equation is shown to be naive. Arguments provided against the concept of orbital steering include: (a) force constants predicted from orbital steering are about 100 times those experimentally determined from displacement of nuclei in a direction normal to the axis of a covalent bond (for example, at room temperature vibrational bending amplitudes of +5 degrees or more are common); (b) because of the lessened directionality of orbitals containing nonbonded electron pairs, the force constants in transition states should be even smaller than in the case of a covalent bond; and (c) molecular orbital calculations predict shallow total energy minima for orbital alignment. The experimental rate data offered as a basis for the concept of orbital steering are shown to find rationalization in the previously observed dependence of DeltaSdouble dagger on kinetic order and the energy requirements for the freezing-out of single bonds in the transition state leading to the formation of medium-size ring compounds from extended ground states. It is concluded that if orbital steering does exist, experimental and theoretical evidence to support this concept have yet to be presented.

Journal Article↗

PubMed2002

Thyrotropin receptor expression in orbital adipose/connective tissues from patients with thyroid-associated ophthalmopathy.

The TSH receptor (TSHR) is the autoantigen responsible for the hyperthyroidism of Graves' disease. However, whether this receptor plays a role in the development of Graves' ophthalmopathy (GO) is unclear. Expression of TSHr is augmented in orbital tissues from patients with GO, and in newly differentiated adipocytes derived from precursor cells within the orbit. Our recent studies suggest that interleukin-6 (IL-6), a cytokine elevated in the circulation of Graves' patients, stimulates TSHr expression in vitro in orbital preadipocyte fibroblasts. This cytokine might play a role in the pathogenesis of GO by stimulating TSHr expression within the fatty connective tissues of the orbit, allowing the receptor to act there as an autoantigen. Whether IL-6 also stimulates adipogenesis in the orbit is unclear at present, but such an effect could contribute to the increased volume of orbital adipose/connective tissue characteristic of this condition. Other cytokines, including IFN-gamma and TGF-beta, inhibit TSHr expression and adipogenesis by orbital fibroblasts, effects that would seem to favor disease remission. The initiation and subsequent clinical severity of GO may therefore be influenced by competing inhibitory and stimulatory cytokine effects occurring simultaneously within the orbit. Some of these may impact the expression of TSHr, the putative orbital autoantigen in this condition.

Adipose Tissue↗

PubMed2006

Stiff three-frequency orbit of the hydrogen atom.

We study a stiff quasiperiodic orbit of the electromagnetic two-body problem of Dirac's electrodynamics of point charges. The delay equations of motion are expanded about circular orbits to obtain the variational equations up to nonlinear terms. The three-frequency orbit involves two harmonic modes of the variational dynamics with a period of the order of the time for light to travel the interparticle distance. In the atomic magnitude, these harmonic modes have a frequency that is fast compared with the circular rotation. The quasiperiodic orbit has three frequencies: the frequency of circular rotation (slow) and the two fast frequencies of two mutually orthogonal harmonic modes. Poynting's theorem gives a mechanism for a beat of the mutually orthogonal fast modes to cancel the radiation of the unperturbed circular motion by interference. The nonradiation condition for this destructive interference is that the two fast frequencies beat at the circular frequency. The resonant orbits have magnitudes in qualitative and quantitative agreement with quantum electrodynamics (QED), as follows: (i) the orbital angular momenta are integer multiples of Planck's constant to a good approximation, (ii) the orbital frequencies agree with a corresponding emission line of QED within a few percent on average, (iii) the orbital frequencies are given by a difference of two linear eigenvalues, viz., the frequencies of the mutually orthogonal fast modes, and (iv) the angular momentum of gyration of the variational motion about a resonant circular orbit is of the order of Planck's constant.

Journal Article↗

PubMed2003

Flat panel detector-based cone beam computed tomography with a circle-plus-two-arcs data acquisition orbit: preliminary phantom study.

Cone beam computed tomography (CBCT) has been investigated in the past two decades due to its potential advantages over a fan beam CT. These advantages include (a) great improvement in data acquisition efficiency, spatial resolution, and spatial resolution uniformity, (b) substantially better utilization of x-ray photons generated by the x-ray tube compared to a fan beam CT, and (c) significant advancement in clinical three-dimensional (3D) CT applications. However, most studies of CBCT in the past are focused on cone beam data acquisition theories and reconstruction algorithms. The recent development of x-ray flat panel detectors (FPD) has made CBCT imaging feasible and practical. This paper reports a newly built flat panel detector-based CBCT prototype scanner and presents the results of the preliminary evaluation of the prototype through a phantom study. The prototype consisted of an x-ray tube, a flat panel detector, a GE 8800 CT gantry, a patient table and a computer system. The prototype was constructed by modifying a GE 8800 CT gantry such that both a single-circle cone beam acquisition orbit and a circle-plus-two-arcs orbit can be achieved. With a circle-plus-two-arcs orbit, a complete set of cone beam projection data can be obtained, consisting of a set of circle projections and a set of arc projections. Using the prototype scanner, the set of circle projections were acquired by rotating the x-ray tube and the FPD together on the gantry, and the set of arc projections were obtained by tilting the gantry while the x-ray tube and detector were at the 12 and 6 o'clock positions, respectively. A filtered backprojection exact cone beam reconstruction algorithm based on a circle-plus-two-arcs orbit was used for cone beam reconstruction from both the circle and arc projections. The system was first characterized in terms of the linearity and dynamic range of the detector. Then the uniformity, spatial resolution and low contrast resolution were assessed using different phantoms mainly in the central plane of the cone beam reconstruction. Finally, the reconstruction accuracy of using the circle-plus-two-arcs orbit and its related filtered backprojection cone beam volume CT reconstruction algorithm was evaluated with a specially designed disk phantom. The results obtained using the new cone beam acquisition orbit and the related reconstruction algorithm were compared to those obtained using a single-circle cone beam geometry and Feldkamp's algorithm in terms of reconstruction accuracy. The results of the study demonstrate that the circle-plus-two-arcs cone beam orbit is achievable in practice. Also, the reconstruction accuracy of cone beam reconstruction is significantly improved with the circle-plus-two-arcs orbit and its related exact CB-FPB algorithm, as compared to using a single circle cone beam orbit and Feldkamp's algorithm.

Algorithms↗

PubMed1998

Paranasal sinus endoscopy and orbital fracture repair.

Although excellent results may be achieved in the management of many orbital floor injuries with standard transconjunctival or transcutaneous approaches, visualization of the posterior edge of the orbital floor or medial wall defect may be challenging at times. We describe our experience using endoscopic examination of the orbital floor through maxillary sinus approaches during the repair of selected orbital floor fractures. Owing to the posterosuperior angulation of the orbital floor, these approaches allow better visualization of the posterior edge of fractures involving the posterior portion of the orbital floor than do the standard transconjunctival approaches, and they facilitate confirmation that all orbital soft tissues have been elevated from the fracture site. We have used these techniques successfully in 9 patients with fractures involving either the posterior portion of the orbital floor or the medial wall or both.

Baseball↗

PubMed1997

Secondary squamous cell carcinoma of the orbit.

OBJECTIVE: To evaluate the origin and biological behavior of secondary orbital squamous cell (SCC) and mucoepidermoid carcinoma. METHODS: A retrospective review of 30 consecutive patients with SCC and mucoepidermoid carcinoma of the orbit seen over a period of 8 years at a large ophthalmic hospital in Saudi Arabia. RESULTS: A total of 51 secondary orbital tumors were seen in the 8-year period from 1983 through 1991; 30 (60%) of the 51 cases were SCC. There were 16 male and 14 female patients, with an age range of 38 to 80 years and a mean age of 65 years. In 28 (93%) of the 30 patients, the tumor originated in the conjunctiva. Orbital involvement by conjunctival SCC was the most common cause of secondary orbital tumors encountered in patients older than 19 years. Four patients had concomitant paranasal sinus involvement, 4 patients exhibited intraocular invasion, and 2 others were found to have intracranial extension of the SCC. Six (20%) of the 28 patients developed regional lymph node metastases during the course of their illness. All patients were treated by orbital exenteration, with or without radiation therapy. Seven (23%) of the 28 patients died of their disease. CONCLUSIONS: Orbital SCC is an aggressive and life-threatening condition. Most cases result from secondary extension of conjunctival SCC, a common disease in Saudi Arabia. Several factors contribute to the aggressiveness of conjunctival SCC in this geographic location, including continual exposure to UV rays, chronic irritation, and genetic factors. Delay in presentation for treatment, inadequate initial resection of conjunctival lesions, and the aggressive mucoepidermoid carcinoma variant of SCC are also factors contributing to orbital invasion.

Adult↗