Ultrasound biomicroscopy of the anterior segment

BACKGROUND: New imaging technologies are revolutionizing the understanding and treatment of a wide variety of ocular disorders. Confocal scanning laser ophthalmoscopy, ultrasound biomicroscopy, confocal scanning laser polarimetry, color doppler imaging of blood flow, and optical coherence tomography are providing important information regarding disease pathophysiology, diagnosis, progression, and treatment. METHODS: High frequency (50 MHz), high resolution ultrasound biomicroscopy of the anterior segment was obtained in a wide variety of disorders of the anterior segment. Tissue resolution is approximately 50 microns and the penetration depth is 5 mm. RESULTS: Ultrasound biomicroscopy is capable of imaging the comea, iris, anterior chamber, anterior chamber angle, posterior chamber, and ciliary body with great detail. The structures surrounding the posterior chamber, previously hidden from clinical observation, can be imaged and their normal anatomic relationships assessed. The various forms of angle closure glaucoma, such as pupillary block and plateau iris configuration, can be differentiated. The concave iris found in pigment dispersion and its response to treatment can be assessed. Visualization of anterior segment anatomy in eyes with opaque media is possible. CONCLUSIONS: Ultrasound biomicroscopy assists in the management of eyes with disorders of the anterior segment. Future applications of this technology will yield important information regarding accommodation, normal ocular physiology and disease pathophysiology.     

Ultrasound biomicroscopic analysis of anterior proliferative vitreoretinopathy

PURPOSE: To report the use of ultrasound biomicroscopy for preoperative assessment of anterior proliferative vitreoretinopathy. METHODS: Case report. In a 35-year-old man with tractional retinal detachment and anterior proliferative vitreoretinopathy, we used ultrasound biomicroscopy with UX-02 (Rion Co Ltd, Tokyo, Japan) to perform the preoperative analysis of the ciliary body, anterior vitreous, and detached peripheral retina. RESULTS: In all meridians, the posterior insertion of the vitreous was drawn anteriorly, creating a retinal trough, and the meridian distance between the anterior and posterior vitreous base insertions was reduced. Retinochoroidal detachment was detected posterior to the anterior vitreous base insertion. Based on these imagings, sclerotomy locations were selected. CONCLUSION: Ultrasound biomicroscopy may be useful to assess anterior proliferative vitreoretinopathy preoperatively and to decide on sclerotomy sites.     

Fatal Scedosporium prolificans infection in a leukemic patient

AIM: To establish normative values for the anterior segment in premature infants in relation to postconceptional age and birth weight. METHODS: Anterior segments were measured in 39 premature infants, 25 to 39 weeks' gestational age by use of ultrasound biomicroscopy and a muscle hook with topical anaesthesia. RESULTS: Anterior chamber depth, trabecular-iris angle, angle opening (trabecular-iris) distances at 250 and 500 microns from the scleral spur, and the thickness of the thickest part of the iris showed linear increases in relation to postconceptional age and birth weight. CONCLUSIONS: Ultrasound biomicroscopy is a powerful tool for obtaining precise images and measurement of the anterior segment in preterm neonates. Normative values were established for anterior segment dimensions in relation to postconceptional age and birth weight.     

Antitussive activity of moguisteine enantiomers in guinea-pigs and rats

PURPOSE: We studied a case of Vogt-Koyanagi-Harada syndrome in a patient with a shallow anterior chamber. METHODS: High-resolution, anterior segment ultrasound biomicroscopy was performed to analyze the mechanism of a shallow anterior chamber. RESULTS: Ultrasound biomicroscopy disclosed a slit-like narrow angle and circumferential supraciliary fluid. The ciliary body was rotated anteriorly, and the iris showed anterior bowing consistent with pupillary block. With systemic corticosteroid treatment, the supraciliary fluid disappeared, and the ciliary body reverted to its normal position. CONCLUSION: Ultrasound biomicroscopy was useful in diagnosis and evaluation of the response to corticosteroid treatment in a patient with Vogt-Koyanagi-Harada syndrome accompanied by shallow anterior chamber.     

Intravenous acyclovir treatment for extensive herpetic keratitis in a liver transplant patient

BACKGROUND: The different clinical forms of glaucoma share in common an optic nerve head neuropathy. MATERIALS AND METHODS: Review article. RESULTS: For a long time, a high intraocular pressure (IOP) has been considered to be the only risk factor associated with glaucoma. By extension it has even been considered that glaucoma was equivalent to a high IOP, and thus only an affection of the anterior segment of the eye. The fact to consider glaucoma as an affection of the posterior segment has changed our conceptual approach of this disease. It has allowed us to look for other risk factors associated with this affection. CONCLUSIONS: The existence of different potentially treatable risk factors opens new therapeutical perspectives for glaucoma.     

Delivery, distribution, and neuronal uptake of exogenous mannose-terminal glucocerebrosidase in the intact rat brain

OBJECTIVE: To show the utility of ultrasound biomicroscopy (UBM) in imaging small ocular foreign bodies of the anterior segment. DESIGN: Retrospective case series. PARTICIPANTS: Twelve eyes of 12 consecutive patients evaluated in the emergency department or referred to specialty services at 1 institution between August 1994 and November 1997 were examined. INTERVENTION: Ocular ultrasound biomicroscopy was performed. MAIN OUTCOME MEASURES: Detection and localization of an ocular foreign body were measured. RESULTS: An intraocular or superficial foreign body was detected by UBM in 9 (75%) of 12 eyes. The foreign body was classified as corneal in two eyes, subconjunctival in two, intrascleral in three, and intraocular in two eyes. The foreign body was not visible by ophthalmic physical examination in seven of the nine eyes with a confirmed ocular foreign body. In the remaining two eyes, UBM was used to determine the depth of a visible foreign body. In three of the eyes with a confirmed foreign body, computed tomography and/or contact B-scan ultrasonography was obtained and failed to show a foreign body. Six of the foreign bodies were nonmetallic. CONCLUSIONS: Clinical detection of ocular foreign bodies after trauma can be hindered by small size, haziness of the optical media, poor patient cooperation, or hidden location. Ultrasound biomicroscopy is a valuable adjunct in the evaluation of suspected ocular foreign bodies, especially in cases involving small, nonmetallic objects.     

Ciliary body is not hyperplastic in Weill-Marchesani syndrome

PURPOSE: To demonstrate the in-vivo morphology of the ciliary body in Weill-Marchesani syndrome which might be of pathophysiological importance for the spherical shape of the crystalline lens. METHODS: Three juvenile patients with Marchesani syndrome were examined by ultrasound biomicroscopy of the anterior segment. RESULTS: The in-vivo configuration of the ciliary body in these Weill-Marchesani patients with normal axial length of the eye showed no signs of hyperplasia, and was even relatively small. CONCLUSION: Spherophakia and hyperplasia of the ciliary body are not necessarily associated with the syndrome, as supposed by Marchesani and other investigators. Instead, spherophakia might be regularly accompanied by a small ciliary body in Weill-Marchesani syndrome.     

Role of ligaments and facets in lumbar spinal stability

STUDY DESIGN: The issue of segmental stability using finite element analysis was studied. Effect of ligament and facet (total and partial) removal and their geometry on segment response were studied from the viewpoint of stability. OBJECTIVES: To predict factors that may be linked to the cause of rotational instabilities, spondylolisthesis, retrospondylolisthesis, and stenosis. SUMMARY OF BACKGROUND DATA: The study provides a comprehensive study on the role of facets and ligaments and their geometry in preserving segmental stability. No previous biomechanical study has explored these issues in detail. METHODS: Three-dimensional nonlinear finite element analysis was performed on L3-L4 motion segments, with and without posterior elements (ligaments and facets), subjected to sagittal moments. Effects of ligament and facet (partial and total) removal and their orientations on segment response are examined from the viewpoint of stability. RESULTS: Ligaments play an important role in resisting flexion rotation and posterior shear whereas facets are mainly responsible for preventing large extension rotation and anterior displacement. Facet loads and stresses are high under large extension and anterior shear loading. Unlike total facetectomy, selective removal of facets does not compromise segmental stability. Facet loads are dependent on spatial orientation. CONCLUSIONS: Rotational instability in flexion or posterior displacement (retrospondylolisthesis) is unlikely without prior damage of ligaments, whereas instability in extension rotation or forward displacement (spondylolisthesis) is unlikely before facet degeneration or removal. The facet stress and displacement distribution predicts that facet osteoarthritis or hypertrophy leading to spinal stenosis is most likely under flexion-anterior shear loading. Selective facetectomy may restore spinal canal size without compromising the stability of the segment. A facet that is more sagittally oriented may be linked to the cause of spondylolisthesis, whereas a less transversely oriented facet joint may be linked to rotational instabilities in extension.     

Ocular toxicity following topical application of anesthetic cream to the eyelid skin

BACKGROUND AND OBJECTIVE: The use of topical anesthetic cream in the periorbital region may be of clinical value. The potential for toxic effects from such use has not been studied in a controlled manner. This study was performed to evaluate the potential ocular toxicity of anesthetic cream topically applied to the eyelid in an animal model. MATERIALS AND METHODS: Ten rabbits underwent periorbital eutectic mixture of local anesthetics (EMLA) (2.5 percent lidocaine and 2.5 percent prilocaine) application and were observed for evidence of gross or microscopic ocular toxicity. Baseline external and anterior segment examinations were performed, including biomicroscopy and fluorescein staining, after which a standard quantity of EMLA cream (0.75 g) was applied along the upper eyelid and covered with an occlusive dressing. After 1 hour of treatment, the eyelid and anterior segment were examined for evidence of adverse reaction. The eyelids were excised and examined histopathologically. RESULTS: No significant adverse effects were noted on external lid and anterior segment examination. The histopathologic findings were within normal limits. CONCLUSIONS: This study suggests that external application of EMLA cream to the eyelid does not induce local toxicity in the rabbit model. The external application of EMLA cream may be safe in the periorbital region.     

APE/Ref-1 responses to oxidative stress in aged rats

OBJECTIVE: To compare iridocorneal angle grading systems on the basis of gonioscopy and ultrasound biomicroscopy (UBM). DESIGN: Original cross-sectional observational study. ANIMALS: 22 dogs. PROCEDURE: Gonioscopy, goniophotography, and UBM were performed on 38 eyes from dogs without clinical evidence of glaucoma in the eyes examined. RESULTS: Predominant gonioscopic grades derived from goniophotographs were considered normal (n = 26) and mild (12). Ultrasound biomicroscopy angle measurements ranged from 16 to 38 degrees (mean +/- SD, 26.2 +/- 4.5 degrees). Ciliary clefts depicted on UBM images were graded as open (n = 4), compact/narrow (23), and closed (11). Significant differences were not found between UBM-derived ciliary cleft grades and goniophotography-derived dysgenesis grades, nor between UBM-derived ciliary cleft grades and subjective gonioscopic grades. CLINICAL IMPLICATIONS: Because gonioscopy allows evaluation of the anterior face of the ciliary cleft, whereas UBM provides cross-sectional information of the iridocorneal filtration angle, UBM may yield more information regarding pathogenesis and prognosis of, and preferred management approaches to, glaucoma. Ultrasound biomicroscopy may also be useful as a predictor of glaucoma or to diagnose early stages of glaucoma.     

A biomechanical evaluation of graft loading characteristics for anterior cervical discectomy and fusion. A comparison of traditional and reverse grafting techniques

STUDY DESIGN: A biomechanical study of graft loading characteristics for anterior cervical discectomy and fusion comparing the amount and location of transmitted forces. OBJECTIVES: To evaluate the difference between traditional iliac grafting and reverse iliac grafting used for anterior cervical discectomy and fusion in the amount and location of forces applied to the grafts. SUMMARY OF BACKGROUND DATA: Traditional fusion after anterior cervical discectomy involves placing a tricortical iliac crest strut into the disc space with the cortical portion facing anteriorly and the cancellous portion posteriorly. Recently, reverse iliac grafting has been introduced in which the cortical portion is placed in the posterior disc space and the cancellous portion in the anterior disc space. There is no biomechanical or clinical study showing an advantage of using one technique over the other. This study is the first to produce data supporting one technique as biomechanically superior. METHODS: Five fresh cadaveric cervical spines were tested using pressure-sensitive film placed between the bone graft and the vertebral endplate after an anterior discectomy was performed. A 10-pound load was applied to the cervical spine at predetermined sagittal positions. Recordings were made at neutral, 10 degrees of flexion, and 10 degrees and 20 degrees of extension after traditional and reverse iliac grafting. RESULTS: Graft forces were identical in both traditional and reverse grafting in the location and amount of force applied. Total force increased to the maximum in flexion and gradually decreased in more extended positions. The location of the forces was completely anterior with flexion, moving to the posterior portion of the graft with positions of extension. With 10 degrees of flexion, the load applied to the grafts was 20.4 N. In the neutral position, the load was 12 N. The loads decreased further with extension with forces of 11 N in 10 degrees extension, and 4 N in 20 degrees of extension. CONCLUSIONS: The optimal position of the tricortical iliac graft for an anterior cervical fusion is with the stronger cortical portion placed in the anterior disc space and the weaker cancellous portion placed in the posterior disc space. In this traditional position, the graft will best resist the loads applied to the cervical spine, preventing graft collapse.     

Role of macrophage overactivation in the development of acute pancreatic injury in rats

PURPOSE: To report quantitative changes in the anterior chamber configuration after small-incision cataract surgery with implantation of a posterior chamber intraocular lens by means of ultrasound biomicroscopy. METHODS: We examined the anterior chamber configuration of 20 eyes of 20 patients before and 3 months after small-incision cataract surgery (phacoemulsification and aspiration plus foldable intraocular lens implantation through a 3.0- to 4.0-mm self-sealing wound) by means of ultrasound biomicroscopy. The following variables were measured: the anterior chamber depth at the center of the cornea, the angle-opening distance 250 microns from the scleral spur (AOD250), the angle-opening distance 500 microns from the scleral spur (AOD500), and the trabecular-iris angle. RESULTS: The anterior chamber depth at the center of the cornea, AOD250, AOD500, and trabecular-iris angle increased significantly after surgery. The preoperative anterior chamber depth at the center of the cornea and trabecular-iris angle were negatively correlated with the differences between the postoperative and preoperative values (P < .01). The preoperative values of all variables examined were negatively correlated with the ratios of the postoperative value to the preoperative value (P < .002). CONCLUSIONS: The present results showed that small-incision cataract surgery significantly deepened the anterior chamber and widened its angle. The more shallow the preoperative anterior chamber was, the greater the postoperative change of the chamber was; and the more narrow the preoperative angle was, the greater the postoperative change of the angle was.     

Surgical treatment of spinal tumor (analysis of 32 cases)

With the advance of spinal surgery in the last decade, surgical treatment of spinal tumors has been no longer limited to simple laminectomy. The principles of surgical treatment of spinal tumors include: (1) anterior approach for the anterior lesion and posterior approach for the posterior lesion; (2) combined anterior and posterior approach for extensive lesions and (3) internal fixation for spinal stability. 32 cases of spinal tumors were treated on the basis of the above guiding principles and 84% (27/32) showed excellent or good results.     

Accommodation and presbyopia in the human eye. Changes in the anterior segment and crystalline lens with focus

PURPOSE: To characterize changes in the sagittal dimensions of the human crystalline lens and anterior segment as a function of accommodation, to determine the potential age dependence of these changes, and to evaluate these changes in relation to the development of presbyopia. METHODS: Scheimpflug slit-lamp photography, as well as a variety of standard ophthalmologic methods, was used to collect information about lens and anterior segment sagital dimensions in a population of 82 adults with refractive error < or = magnitude of 2.0 diopters and at least 0.25 diopter of accommodation for subjects 18 to 70 years of age. Data were analyzed statistically for dependence on accommodation, age, and age dependence of accommodative rate. RESULTS: The rate of change per diopter of accommodation for each measured variable within the lens is independent of age for the entire adult age range. With increasing accommodation, the lens becomes thicker and the anterior chamber shallower along the polar axis. This increase in sagittal lens thickness is entirely because of an increase in the thickness of the lens nucleus. Because the anterior and posterior halves of the nucleus increase in thickness at approximately the same rate with accommodation, the increase in lens thickness results from equal changes in the lengths of the anterior and posterior portions. CONCLUSIONS: Because changes along the sagittal axis of the anterior segment with accommodation are independent of age, any explanation of presbyopia that relies on simple changes in the rates of lens thickening and anterior chamber shallowing with age does not hold. In light of other age-related changes in the anterior segment and lens (e.g., increased sharpness of lens curvature, increased lens sagittal thickness, decreased anterior chamber depth), it appears that compensatory mechanisms to preserve far vision with age also preserve the rate of change per diopter of sagittal spacings.     

Social isolation induces preference for odours of oestrous females in sexually naive male staggerer mutant mice

PURPOSE: To evaluate Sturge-Weber-associated glaucoma using ultrasound biomicroscopy. METHOD: Case report. Clinical examination combined with ultrasound biomicroscopy was performed in a patient with Sturge-Weber-associated glaucoma. RESULTS: In the patient's left eye, which had Sturge-Weber-associated glaucoma, a 360-degree supraciliary effusion, dilated superficial and intrascleral vessels, and an open angle were detected by ultrasound biomicroscopy. CONCLUSION: The presence of dilated intrascleral vessels and supraciliary fluid support the hypothesis of increased episcleral venous pressure as the cause of elevated intraocular pressure in this syndrome.     

Bone disease after liver transplantation should not be underestimated

PURPOSE: To report the management and outcome of cataract surgery and intraocular lens placement in a child with unilateral posterior lenticonus. METHODS: Case report. A 7-year-old boy with a best-corrected visual acuity of RE, 20/200, posterior lenticonus, and cataract underwent a pars plana lensectomy, vitrectomy, posterior chamber intraocular lens insertion into the ciliary sulcus, and central anterior capsulotomy. RESULT: At 2 years of follow-up, best-corrected visual acuity was RE, 20/40. CONCLUSION: This technique allowed complete removal of the opaque posterior lenticonus plaque while preserving the peripheral anterior capsule for sulcus fixation of the posterior chamber intraocular lens.     

Assessment and surgical management of posterior fossa epidermoid tumors: report of 28 cases

OBJECTIVE: The management of a series of 28 patients operated on for posterior fossa epidermoids is reviewed, emphasizing the need for long-term follow-up. We discuss the rationale for a comprehensive classification system that may allow the comparison of results from homogeneous series. METHODS: We grouped the tumors to differentiate the surgical management according to various tumor sites and the degree of extension. Twenty patients harbored tumors located in the cerebellopontine angle, five patients harbored tumors in the fourth ventricle, and three patients harbored tumors in the posterior fossa basal. In 17 patients, extensions of tumors outside the posterior fossa included the following regions: the suprasellar/ chiasmatic (n = 5), the parasellar/temporobasal (n = 5), and the mesencephalic/pineal (n = 7). Tumor extension was also defined by the number of regions involved. Pre- and postoperative magnetic resonance imaging and computed tomographic findings collected in 17 and 28 patients, respectively, were carefully evaluated. RESULTS: Clinical features and surgical approaches varied according to location and growth pattern. Fifty-seven percent of the tumors were completely removed. A higher total removal rate was achieved in patients with tumors confined to the primary location. One patient (3%) died in the perioperative period. Approximately half of the patients presented with transient mild focal deficit impairments resulting from the manipulation of the nervous structure over a wide area. There was a higher rate of surgical complications with fourth ventricle and mesencephalic extended cerebellopontine angle tumors. The mean follow-up period was 8.6 years. Thirty percent of the patients with subtotal removal experienced symptomatic recurrences after 8.1 years, whereas all patients with total removal were still asymptomatic. The recurrence-free survival rate was 95% at 13 years for patients with total removal compared with 65% for patients with subtotal removal. Problems of identification of tumor regrowth are discussed. CONCLUSION: By assessing posterior fossa epidermoids, we determined that location and extension play a major role in the prognosis. Our data suggest that more aggressive surgery is called for at first operation, and that a second operation should be planned when regrowth becomes symptomatic and/or tends to extend outside its original site.     

Transcutaneous PCO2 monitoring during laparoscopic cholecystectomy in pregnancy

The management of narrowing spinal fragments in the operative treatment of spinal fractures remains an open question, in particular when the procedure is performed by a posterior approach. This article describes the use of intraoperative ultrasonography during spinal surgery. From 1990 to 1997, 116 spinal fractures were treated operatively at our clinic. Stabilization of the spine was achieved with the AO fixateur interne and the AO USS, respectively (Synthes, D-79224, Umkirch, Germany). For 60 cases who had a fractured posterior vertebral surface dislocated into the spinal canal, we used intraoperative ultrasonography to monitor the repositioning of the narrowing fragments. The patients underwent pre- and postoperative computed tomography scans (CT). In six cases, color-coded duplex sonography was performed intraoperatively to view the A. spinalis anterior. In 58 cases, the spinal canal and the fractured posterior surface of the vertebrae were visualized successfully. The sonographic image was inconclusive in two cases with severely damaged fragments. Identical findings were observed on the intraoperative ultrasound image after completion of repositioning and on the postoperative CT scan. In six cases, the A. spinalis anterior was viewed by color-coded duplex sonography with a different flow before and after fracture repositioning. Intraoperative ultrasound is a valuable means of monitoring the restoration of the spinal canal by a posterior approach. The method is easy to perform and can be repeated as often as required. Color-coded duplex sonography allows further visualization of the A. spinalis anterior.     

Optimization of the scintigraphic segmental anatomy of the lungs

Accurate and reproducible reporting of lung scintigraphy is predicated on a sound knowledge of the segmental anatomy of the lungs. A limited amount of hard data exists about the true segmental anatomy of the lungs. A virtual model of human lungs was created using a CT-based dataset and a Monte Carlo simulation technique to examine the optimal projections for the visualization of each segment in the lungs. METHODS: Segmental anatomy of the lungs was modeled using CT, cadaveric lungs and standard anatomical texts. The emission, scatter and attenuation of photons was modeled within these virtual lungs and the surrounding tissues. Single segmental lesions were created in eight projections and submitted for blinded reporting to four experienced nuclear medicine physicians to obtain the best views for each segment. RESULTS: The anterior and posterior oblique projections yielded the best views for 10 of 18 segments, with the laterals contributing four views, the anterior contributing two views and the posterior contributing one view. The majority of basal segments (six of nine) were best seen in the anterior and posterior oblique projections. CONCLUSION: This model overcomes the major problems associated with experimentation in the normal human and has the potential to provide answers to the major problems of scatter, attenuation and "shine-through" in lung scintigraphy.     

Transient osteoporosis of the hip in pregnancy

STUDY DESIGN: Fresh calf lumbar spines were used to perform flexibility tests in multiple loading directions to compare the stabilizing effects of anterior and posterior rigid instrumentations. OBJECTIVE: To compare the biomechanical flexibility of anterior and posterior instrumentation constructs using an unstable calf spine model. SUMMARY OF BACKGROUND DATA: Unstable burst fractures of the thoracolumbar spine can be managed anteriorly or posteriorly. Controversy persists, however, on the merit of anterior fixation versus that of posterior fixation in terms of how much stability can be achieved. METHODS: Fifteen fresh calf spines (L2-L5) were loaded with pure unconstrained moments in flexion, extension, axial rotation, and lateral bending directions. After removal of L3-L4 disc and endplates to create an 1.5-cm anterior and middle column defect, testing was performed on five specimens after anterior Kaneda rod fixation, anterior University Plate fixation, or posterior ISOLA pedicle screw fixation (AcroMed, Cleveland, OH). Testing was repeated after inserting a polymethylmethacrylate block to stimulate an interbody anterior graft with instrumentation. RESULTS: All fixation devices provided a significant stabilizing effect in flexion and lateral bending. In extension, all constructs except ISOLA (AcroMed) without graft were stiffer than the intact specimen. In axial rotation with no graft, only the Kaneda device significantly reduced the flexibility from that of the intact specimen. The interbody graft provided additional rigidity to the ISOLA (AcroMed) instrumentation construct in flexion and extension and to the Kaneda construct in lateral bending. There was no significant effect of grafting in axial rotation. CONCLUSIONS: A short, transpedicular instrumentation, such as ISOLA (AcroMed), provided less rigid fixation in flexion and extension without the anterior structural graft. The Kaneda rod and University plate with grafting provided a significant stabilizing effect in all directions compared with the intact specimen. When no graft was inserted, the Kaneda device was more effective in preventing axial rotation than the other devices. In lateral bending, the University plate provided more rigid fixation than the Kaneda device without grafting.