Histological changes in the orbital region of rats after orbital puncture.

To contribute to the assessment of the degree of discomfort in rats after orbital puncture, we have examined the histological changes in the intraorbital tissues caused by this technique of blood sampling. Orbits were studied from rats euthanized either within 1 min, 4 days, 28 days or 56 days after puncture while under diethyl-ether anaesthesia. The techniques of 2 animal technicians were compared, one using a broken haematocrit capillary and the other using an intact Pasteur's pipette. Non-punctured orbits served as controls. Microscopic slides containing the eye in situ at 2 horizontal levels in the orbital region were examined for 37 parameters; the slides were scored blind and in random order. Orbital puncture caused haemorrhages in the puncture track and, depending on the technique used, also in the periosteum. Four days after puncture, inflammatory reactions were present in the puncture track. Depending on the technique of puncture, these reactions were also seen in the eye muscles and periosteum or in the Harderian gland. Within 4 weeks after puncture, the lesions had healed without detectable scars. The different histological effects of the 2 techniques of orbital puncture are discussed in the light of the characteristics of these techniques.     

The longitudinal orbital CT projection: a versatile image for orbital assessment

The newer generation of CT scanners allows reconstruction of images in coronal, sagittal, and oblique planes from a single set of axial scans. These computer-generated images are described as reformatted. We have found an oblique image reformatted along the plane connecting the apex of the orbit and the center of the globe to be especially useful in assessing orbital disorders. We have named this image the longitudinal orbital projection. This projection allows direct visualization of the inferior rectus muscle and orbital floor in acute and old orbital trauma. With the image produced life size, direct measurements of enophthalmos and proptosis can be made preoperatively and postoperatively, thereby facilitating planning and follow-up. The projection is also useful in combination with other planes of reformation for the localization of tumors. The longitudinal orbital projection is now a routine part of the CT examination of the orbit in our institution. Whereas it already has become an invaluable aid in the diagnosis and follow-up of congenital and acquired orbital lesions, the longitudinal orbital projection promises to clarify the effects of trauma on the inferior rectus muscle and globe position.     

High voltage orbital radiotherapy and surgical orbital decompression in the management of Graves' ophthalmopathy

We report on 2 groups of patients with Graves' ophthalmopathy. A group of 21 patients was treated by high voltage (18 MV) orbital radiotherapy combined with mean doses of corticoids. The results were good or excellent in 12 patients (mean score 6.62 before and 4.0 after, soft tissues greater than proptosis greater than extraocular muscle involvement), without any complications from irradiation. Patients undergoing surgery initially presented less severe symptoms, even 7 patients treated after corticoid and/or radiotherapy failure. The results were satisfactory in all patients (mean score 5.1 before and 2.4 after, proptosis greater than soft tissues greater than extraocular muscle involvement). Both methods showed results within 3 months, and they can be combined.     

Transconjunctival orbital fat repositioning: transposition of orbital fat pedicles into a subperiosteal pocket

Rejuvenation of the lower eyelid complex is based on the principle that the contour changes characterizing aging involve not only prolapse of orbital fat but also descent of the cheek tissues, resulting in accentuation of the orbital rim and tear trough groove. When a deep groove is present along the orbital rim in the area of the tear trough deformity, it is advantageous, rather than removing orbital fat, to reposition the fat over the orbital rim through the opened arcus marginalis onto the superior face of the maxilla. Orbital fat repositioning can be accomplished through a transconjunctival approach. The arcus marginalis is exposed and incised, and a subperiosteal pocket is created over the superior face of the maxilla. The subperiosteal pocket shape and location are customized based on the desired location of the orbital fat pedicle; often the origins of the levator superioris labialis and the levator alae nasi muscles are partially dissected. Medial and central fat pedicles are created and rotated over the orbital rim into the subperiosteal pocket. A 6-0 polypropylene externalized sutured is used to fixate the fat pedicle in position. The suture can be removed after 3 to 5 days. Twenty-four patients were followed clinically after orbital fat repositioning, with follow-up ranging from 6 to 30 months. Although the fat pedicle undergoes some variable resorption, the viability of the graft, the texture and contour of the repositioned fat after a healing period of 1 to 2 months, and the excellent patient acceptance are indicative of the viability of orbital fat repositioning.     

Heritability of quantitative orbital traits

We conducted a study of 63 couples and their 242 normal children from northeastern Brazil (no facial malformations or deformities) to evaluate the heritability of 4 quantitative traits of the orbital region adjusted by covariance for sex, age, (age)2, sex x age, and sex x (age)2. The heritability is estimated as 0.514 for the mean horizontal diameter of the palpebral fissures, 0.454 for the interpupillary distance, 0.390 for the internal intercanthal distance, and 0.337 for the external intercanthal distance. The heritability of the first principal component of the orbital region is estimated as 0.418.     

Ribozyme catalysis via orbital steering

Orbital steering is invoked to explain how the three-dimensional structure of a small self-cleaving RNA, the hammerhead ribozyme, both prevents and enhances RNA autocatalysis. Within the conserved catalytic core of the ribozyme, the position of the 2' oxygen atom of the G8 ribose is observed to be aligned almost perfectly with the phosphorus atom and the 5' oxygen atom of the adjacent A9 phosphate group for self-cleavage via an in-line attack mechanism. Despite this apparent near-perfect atomic positioning, no cleavage takes place. The explanation proposed is that a network of hydrogen bonds in the ribozyme core orients or steers the orbitals containing the electron lone pairs of the attacking nucleophile (the 2' oxygen atom) away from the A9 phosphorus atom, eliminating overlap with the vacant phosphorus d-orbitals despite the near-perfect in-line positioning of the oxygen atom, thus preventing catalysis. Because of the near-perfect atomic positioning of the 2' oxygen atom relative to the phosphate group, orbital steering effects in this case are fortuitously uncoupled from conformational, distance and orientation effects, allowing an assessment of the catalytic power due purely to orbital steering. In contrast, a conformational change at the cleavage site is required to bring the 2' oxygen atom and the scissile phosphate group into atomic positions amenable to an in-line attack mechanism. In addition, the conformationally changed structure must then steer the lone-pair orbitals of the correctly positioned 2' oxygen atom toward the scissile phosphorus atom in order for cleavage to take place. We estimate that fulfillment of each of these two required changes may contribute separately an approximately 1000-fold rate enhancement, potentially accounting for a significant fraction of the catalytic power of this ribozyme. Orbital steering therefore appears to be a general phenomenon that may help to explain catalysis in both ribozymes and protein enzymes in a unified manner.     

Pure orbital blowout fracture: new concepts and importance of medial orbital blowout fracture.

Pure orbital blowout fracture first occurs at the weakest point of the orbital wall. Although the medial orbital wall theoretically should be involved more frequently than the orbital floor, the orbital floor has been reported as the most common site of pure orbital blowout fractures. A total of 82 orbits in 76 patients with pure orbital blowout fracture were evaluated with computed tomographic scans taken on all patients with any suspicious clinical evidence, including nasal fracture. Isolated medial wall fracture was most common (55 percent), followed by medial and inferior wall fracture (27 percent). The most common facial fracture associated with medial wall fracture was nasal fracture (51 percent), not inferior wall fracture (33 percent). This finding suggests that the force causing nasal fracture is an important causative factor of pure medial wall fracture as the buckling force from the medial orbital rim. Of patients with medial wall fractures, 25 percent had diplopia and 40 percent had enophthalmos. On plain radiographs, diagnostic signs were found in 79 percent of medial wall fractures and in 95 percent of inferior wall fractures. On computed tomographic scans, late enophthalmos was expected in 76 percent of medial wall fractures. Therefore, the medial orbital blowout fracture may be an important cause of late enophthalmos, because it has a high incidence of occurrence, a low diagnostic rate, and a high severity of defect. Among the causes of limitation of ocular motility, muscle traction of the connective septa and direct muscle injury were found frequently, but true incarceration of the muscle was extremely rare in all fractures. The medial and inferior orbital walls are clearly demarcated by the bony buttress, which is an important structure supporting these orbital walls. Its buttress was closely correlated with the fracture of these orbital walls. Most orbital blowout fractures without collapse of the bony buttress had a trapdoor fracture with or without small fragments of punched-out fracture.     

Long-term stability of Teflon orbital implants

Teflon orbital floor implants have become controversial owing to reports of implant-related complications. To determine the actual incidence of Teflon implant-related complications and factors associated with complications, we conducted a long-term follow-up study of 77 selected patients. We obtained data on 35 implants in 31 patients with a mean follow-up period of 16 years, representing an experience of 528 patient-implant years. The short-term complication rate (within 1 month of surgery) was 3.9 percent. The long-term complication rate was 2.8 percent. Concomitant antral packing and implantation of Teflon sheet were associated with a markedly higher risk of implant pocket infection. There was no case of implant migration with proper fixation. Facial growth was normal in three children in the series. We conclude that Teflon sheet is well-tolerated in the orbit in the long term. The low complication rate can be further reduced with proper fixation of the implant and avoidance of antral packing at the time of implantation.     

Rigid fixation of internal orbital fractures

When large portions of the internal orbit are destroyed (two to four walls), standard bone-grafting techniques for immediate and late orbital reconstruction may not yield predictable eye position. Critical bone support is most often deficient inferomedially. CT analysis of orbital volume in cases where eye position was unsatisfactory reveals that displacement of bone grafts is one mechanism of the unsatisfactory result. Other mechanisms include undercorrection and bone-graft resorption. In order to minimize postoperative bone-graft displacement, titanium implants were used to span large defects in the internal orbit to provide a platform for bone-graft support. Twenty-six implants were placed in immediate and 12 were placed in late orbital reconstructions. More reliable bone-graft position resulted. Two late infections have occurred resulting in implant removal in a 3-year period.     

The surgical management of orbital neurofibromatosis

Orbitofacial neurofibromatosis may cause severe soft-tissue deformity along with pulsating exophthalmos. The orbit is enlarged, and the greater wing of the sphenoid is absent. The eye in some cases may be functionally useless, immobile, displaced, and blind. In these, orbital exenteration with soft-tissue excision and orbital reconstruction is recommended. External cover is provided by the thin eyelid skin, and a prosthesis ultimately allows a very satisfactory end result. Four such cases with a minimum of 2 years of follow-up are presented.     

Thermal orbital injuries from disposable cauteries

Forty rabbits divided in six groups and three brands of hot wire cautery with temperature ranging from 190 degrees C to 1035 degrees C were used in this experiment. A surgical procedure resembling a cosmetic blepharoplasty was performed on a total of 60 lower eyelids of the rabbits. The remaining eyelids were either shams or normal controls. Cautery application to orbital fat was carefully controlled, i.e., 10 or 20 seconds in single or double applications. Gross observation and microscopic examination of the biopsied specimens taken at 3 hours, 2 days, and 2 weeks after the procedures were performed. Evidence of thermal injury to the lacrimal gland and extraocular muscle damage was found. Although no evidence of thermal injury to the optic nerve was found, it was conceivable that either by a direct transfer of heat or by an indirect inflammatory and compressive effect the health of the optic nerve might be threatened. It is strongly recommended that hot wire cautery be used with extreme caution when working with orbital tissues.     

Ultrastructure of cultured human orbital fibroblasts

The fine structure of cultured human orbital fibroblasts was investigated by transmission electron microscopy. One culture was derived from a patient with severe Graves' ophthalmopathy, the other from a donor without inflammatory orbital disease. Despite their known differences in metabolism, orbital fibroblasts from either source revealed no ultrastructural differences. The cells had extensive thin cytoplasmic processes. The perinuclear areas contained multiple assemblies of Golgi membranes, modest amounts of rough endoplasmic reticulum, intermediate filaments, and lysosome-like structures. Glycogen deposits were noted both in the perinuclear cytoplasm and in the thin processes. These ultrastructural features of orbital fibroblasts are the same as those of fibroblasts from other anatomic regions.     

Fragment molecular orbital calculations for biomolecules

Exploring biomolecule behavior, such as proteins and nucleic acids, using quantum mechanical theory can identify many life science phenomena from first principles. Fragment molecular orbital (FMO) calculations of whole single particles of biomolecules can determine the electronic state of the interior and surface of molecules and explore molecular recognition mechanisms based on intermolecular and intramolecular interactions. In this review, we summarized the current state of FMO calculations in drug discovery, virology, and structural biology, as well as recent developments from data science.