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At least 1,153 records · Page 64Linked to original sources
PubMed1992

Measurement of retinal nerve fiber layer thickness and its functional correlations with the visual field.

We have developed a technique for stereophotogrammetric measurements of retinal nerve fiber layer thickness at the disc margin. This technique has a reproducibility ranging from 3.9% to 6.0% in normal, ocular hypertensive and high pressure open angle glaucomatous eyes. The presence of a halo or scleral crescent had no effect on the reproducibility of the measurements. The measurements have shown that ocular hypertensive eyes have about an 18% decrease of retinal nerve fiber layer thickness compared to normals. High pressure open angle glaucomatous eyes have about a 43% decrease in retinal nerve fiber layer thickness compared to normals. This technique allows the development of maps of retinal nerve fiber layer thickness so that localized changes at the disc margin can be detected. The thinnest nerve fiber layer occurs primarily in the temporal segment. This technique has also correlated measurements of nerve fiber layer thickness with other measurements of the optic disc, particularly showing a significant correlation with area of pallor as well as measurements of the width of optic disc cup at about halfway between surface and the bottom of the cup. A significant correlation with visual field loss has been shown in high pressure open angle glaucomatous eyes, primarily with the temporal quadrant of the retinal nerve fiber layer and the nasal visual field. The rate of the visual field change in primary open angle glaucoma has been correlated with the initial nerve fiber layer thickness, with the greater the retinal nerve fiber layer thickness the greater the rate of the visual field loss during follow-up. These findings suggest that retinal nerve fiber layer thickness discriminates between normal, ocular hypertensive eyes as well as those with open angle glaucomas and may be useful in following patients with open angle glaucoma prior to development of the visual field loss.

Glaucoma, Open-Angle↗
PubMed1992

Functional evaluation of patients fitted with total knee prostheses.

Degenerative or inflammatory diseases of the knee joint account for a large proportion of diseases affecting the elderly. Treatment aims to eliminate pain, correct the deformity and maintain complete joint mobility. In cases of total joint degeneration, fitting of a joint prosthesis is the technique currently favoured since elimination of pain and correction of the deformity, accompanied by recovery of joint mobility (the fundamental requirements for normal everyday life) can only be obtained if the knee joint is completely replaced. With the discovery of new materials and increasingly sophisticated knowledge about articular mechanics, the knee prosthesis, although more recent than the hip prosthesis, has become ever more widespread to the point that it now represents an irreplaceable aid in the treatment of this common disease. The clinical results obtained are already stable and particularly encouraging and prosthesis design is sophisticated and accurate. There is, however, still the suspicion that current prostheses can be considered "rudimentary" in comparison with the physiological and biomechanical behaviour of the human joint. We therefore wanted to begin an evaluation using a gait analysis system to assess patients fitted with knee prostheses. The first impressions gained in this study are the subject of this article.

Activities of Daily Living↗
PubMed1992

New equipment for stereophlebography.

Discussed in the present article is the complex of the equipment intended for roentgenodiagnosis of the lower limb varicosity and for use in planning the operations on the vessels. The complex includes the automatic stereocassette, constructed as an attachment to the standard roentgenodiagnostic apparatus, and the stereoscope for analyzing the stereophlebograms visually. The article provides a description of this equipment and methods of its employment.

Evaluation Studies as Topic↗
PubMed1992

Historical perspectives of chondromalacia patellae.

Widespread misuse of the term chondromalacia has led to confusion regarding its true meaning. This term should not be used to diagnose patellofemoral pain, but to describe lesions of articular cartilage. Recent advances using stereophotogrammetry to evaluate the patellofemoral joint and its articular cartilage may lead to new insight into the etiology of these lesions.

Cartilage Diseases↗
PubMed1992

A non-invasive technique for the accurate measurement of leg length in animals.

A novel, non-invasive technique for accurate measurements in animals (Kyniklometry) is presented. Kyniklometry (derived from greek ŏ kúvikloz the rabbit) determines the distance between soft tissue landmarks in conscious rabbits, in particular the rear lower leg. Each measurement consists of six subsequent and independent estimations of this distance, with a technical error of 79 microns (study I), respectively 83 microns (study II). The angle of the relaxed sitting animal's knee is approximately 45 infinity, and remains individually almost constant during subsequent measurements. The precision of the device was compared with X-ray stereophotogrammetry (technical error 30 microns). Five female New Zealand White rabbits were measured for 13 consecutive days at 24-hour-intervals both by kyniklometry and X-ray stereophotogrammetry (study I). The mean increment of 5 kyniklometric series of ten (3rd to 13th day) 24-hour-increments was 0.988 mm, the mean 24-hour-variance was 0.244 mm2. Sixty point five percent of this variance could be explained by parallel right/left leg soft tissue variation. Only 5% of the variance was explicable by the technical error. The 24-hour-correlation between kyniklometry and X-ray stereophotogrammetry was significant with r = 0.889 and p less than 0.001. Kyniklometric measurements were also performed in 5 female rabbits for 56 days at 24-hour-intervals (study II). We found spontaneous periodicity once every 8 to 14 days. There was a diurnal variation of rear lower leg increment with maxima in the early morning hours.

Animals↗
PubMed1992

Articular geometry of the glenohumeral joint.

Little quantitative data exists defining the true shape of the humeral head and glenoid articular surfaces. This study uses a precise stereophotogrammetry (SPG) technique and provides highly accurate quantitative results for determining the three-dimensional geometry of glenohumeral joint articular surfaces, including their "sphericity", surface areas, cartilage thickness, and the difference in these quantities between the genders. Results indicate that glenohumeral joint surfaces may be approximated by a section of a sphere with small deviations from sphericity of less than 1% of the radius. Furthermore, results indicate that mating humeral head and glenoid articular surfaces are quite congruent and have radii within 2 mm in 88% of cases, and within 3 mm in all cases measured. The lack of anatomic stability of this joint is therefore not attributable to the relative shallowness or lack of congruence of the joint but rather to the small surface area of the glenoid which does not enclose the humeral head. Cartilage thickness results may partially explain perceptions of glenohumeral incongruity obtained from roentgenographic measurements where the glenoid appears flatter than the corresponding humeral head. Only when the actual articular cartilage surfaces are analyzed is it determined that the actual articulating surfaces do conform.

Aged↗
PubMed2003

Effect of denture adhesive on stability of complete dentures and the masticatory function.

This study examines the effects of denture adhesive on the retention and stability of complete dentures and the masticatory function. The authors estimated the stability of complete dentures from 3-dimensional (3-D) denture movement and rotational denture movement and additionally the masticatory function from cycle time and chewing time. Six edentulous subjects who participated in this study had old and newly fabricated complete dentures. Upper denture movement was recorded using a 3-D motion capture system while chewing 3 kinds of food (peanuts, fish paste, raisins). Both the new and old dentures showed that using a denture adhesive contributes to reducing 3-D denture movement, rotational denture movement and chewing time during chewing the various foods. The cycle time in new and old dentures was statistically unaffected by applying denture adhesive. There was no statistically significant difference in improvement in 3-D denture movement or rotational denture movement between the new and old dentures, for any of the foods. This study observes the overall effect of denture adhesive during use for both dentures. The results of this study suggest that denture adhesive contributes to reducing denture movement and so improves chewing function.

Adhesives↗
PubMed2004

[Three-dimensional reconstruction on facial soft tissue using three-dimensional grating projection technique].

PURPOSE: The purpose of this study is to establish a method to reconstruct the facial soft tissue three-dimensionally. METHODS: By ATOS three-dimensional opticalmetry, which used in industry, 3D data on facial profile of a patient with mandibular hyperplasia was achieved quickly. RESULTS: Three-dimensional data of facial profile was accurate and the images were reconstructed with verisimilitude. CONCLUSIONS: Traditional device of grating projection was modified by using two CCD cameras to obtain grating images.3D data on facial profile were achieved quickly and accurately.

Adult↗
PubMed1992

Roentgen stereophotogrammetric analysis of prosthetic fixation in the hip and knee joint.

Using highly accurate roentgen stereophotogrammetric analysis (RSA), migration and cyclic displacement of prosthetic components can be assessed. In arthroplasty of the knee, all tibial components migrate during the first year but stabilize thereafter in a majority of cases. They also display inducible displacement in response to external forces. The effects of alterations in design or different modes of fixation may be readily detected using this noninvasive method. Three patients, who later developed mechanical loosening, migrated continuously and were identified by RSA already during the first year, indicating a clinical significance of continuous migration in terms of future mechanical loosening. Also in the hip, abnormally migrating femoral and acetabular components may be identified at an early stage. Using conventional clinical assessment, ten years and a large number of patients are often needed, while with RSA, new prosthetic devices may be assessed at a much earlier stage.

Cementation↗
PubMed2002

Three-dimensional shape analysis of the scoliotic spine using MR tomography and rasterstereography.

Rasterstereography delivers only indirect information about the three-dimensional shape of the spine. Therefore, validation with radiologic methods is necessary, in particular in severe scolioses above 50 AE Cobb. Comparison with conventional a.p. radiographs yielded satisfactory results for scolioses up to 50 AE Cobb, but only in frontal view, i.e. in two dimensions. A true three-dimensional validation is possible only with MR tomography, however this is difficult due to severe technical limitations. In the present study 26 patients with Cobb angles between 26 AE and 116 AE were examined both with MR tomography and rasterstereography. Comparing the shape of the spinal midline as measured by the two methods we found that a) the gross 3-d shape of the spinal midline is well reproduced by the rasterstereographic model, b) the lateral rms error is about twice as large as with conventional radiographs and c) that the rms errors increase with increasing Cobb angle. This means that the rasterstereographic model reconstruction must be modified for severe scolioses.

Adolescent↗
PubMed2002

The effect of posture on Quantec measurements.

The effect of moving the patient's centre of gravity from one extreme to the other, where the weight is entirely supported on the left or right foot at either extreme, was investigated in 33 patients attending for surface topography measurements with the Quantec Spinal Measurement System. Average changes of about 20 were seen in the measured curvature of the lower spine line and pelvic tilt, but there was considerable variation between individual patients. When such extremes of stance were included, the reproducibility of measurements of the curvature of the lower spine, pelvic tilt and vertical alignment was poorer, but not to the extent that a significant improvement in reproducibility would be expected if the patient's centre of gravity was closely controlled with, for example, a force platform.

Analysis of Variance↗
PubMed2002

Monitoring the thoracic sagittal curvature in kyphoscoliosis with surface topography: a trend analysis of 57 patients.

Records of Quantec measurements of tlie kypliotic curvature of the back were reviewed for all patients attending the children's orthopaedic clinic who were referred for back shape measurements. Of these, 57 children had five or more preoperative visits allowing trends to be calculated. Linear trends were found in 30 of the patients, with gradients ranging from 1.1 degree/yr to 7.2(0)1/yr. On average, the scatter of measurements about the trend line, or about the mean value in the other 27 cases, compared well with that expected from repeatability studies but the amount of scatter varied from one patient to another. This may well be due to sampling. Where such measurements are monitored for evidence of change in an individual patient, the possibility of larger than average scatter about any emerging trend should be considered.

Analysis of Variance↗
PubMed2002

Accuracy of rasterstereography versus radiography in idiopathic scoliosis after anterior correction and fusion.

Rasterstereography enables to reduce the number of radiographs in the conservative treatment of idiopathic scoliosis (Cobb angles below 50 degrees). The aim of the present study was to evaluate the use of rasterstereography in severe scoliosis before and after anterior surgery. The results show that the accuracy (as compared to radiographs) is lower in the pre-operative rasterstereographs. However, after operation the Cobb angles were less than 50 degrees in all cases and the accuracy of the rasterstereographs was similar to that of non-operated scolioses. This finding might allow a significant reduction of post-operative radiographs.

Adolescent↗
PubMed1992

[Forces and turning moments of hip and knee joints in locomotion].

In order to be helpful to orthopedic surgeons in planning operations, and providing quality control, gait analysis must provide information on forces and moments at major joints because kinematic data alone have proved to be unsatisfactory. A practical procedure for this purpose was developed and applied to 20 children and young adults, using the inverse dynamic approach. Segmental body volumes were obtained by stereophotogrammetry. Together with density values, this permits individual calculation of segmental mass center positions even in the presence of severe deformity. Segmental anatomical coordinate systems were defined and tagged by skin markers. Subsequent stereophotogrammetric gait recording by high-speed cameras and 3D force plates allowed the calculation of reactive forces and moments with their changing values over each gait cycle. For the two peaks of force transmission in the early and late stance phases, vector diagrams demonstrate 3D components of forces and moments as related to the anatomy of the thigh and shank of a normal young adult. The peak reaction force component in the longitudinal axis during initial loading about reaches body weight, the anteroposterior force 2/5th and the mediolateral component 1/25th of body weight.

Adolescent↗
PubMed2006

Individual case photogrammetric calibration of the Hirschberg Ratio (HR) for corneal light reflection test strabometry.

PURPOSE: The HR (prism diopters [PD] per mm of corneal light reflection test [CLRT] asymmetry for strabometry) varies in humans from 14 to 24 PD/mm, but is totally unpredictable. Photo(grammetric) HR calibration in (of) each case facilitates acceptable strabometry precision and accuracy. METHOD: Take 3 flash photos of the patient with both the preferred eye and then the deviating eye fixating straight ahead and then again with the deviation eye fixing at (+/-5-10 PD) the strabismic angle on a metric rule (stick) one meter away from the camera lens (where 1 cm = 1 PD). RESULTS: On these 3 photos, make four precise measurements of the position of the CLR with reference to the limbus: In the deviating eye fixing straight ahead and fixating at the angle of deviation. Divide the mm difference in location into the change in the angle of fixation to determine the HR for this patient at this angle. Then determine the CLR position in both the deviating eye and the fixing eye in the straight ahead primary position picture. Apply the calculated calibrated HR to the asymmetry of the CLRs in primary position to determine the true strabismic deviation. CONCLUSIONS: This imaging method insures accurate Hirschberg CLRT strabometry in each case, determining the deviation in "free space", under conditions of normal binocular viewing, uncontaminated by the artifacts or inaccuracies of other conventional strabometric methods or devices. So performed, the Hirschberg CLRT is the gold standard of strabometry.

Blinking↗
PubMed2006

[A method of iris image quality evaluation].

Iris image quality evaluation plays a very important part in iris computer recognition. An iris image quality evaluation method was introduced into this study to distinguish good image from bad image caused by pupil distortion, blurred boundary, two circles appearing not concentric, and severe occlusion by eyelids and eyelashes. The tests based on this method gave good results.

Humans↗
PubMed2006

Biometry of primate lenses during immersion in preservation media.

PURPOSE: The purpose of this study was to assess the condition of human lenses (obtained from an eye bank) and of fresh monkey lenses, and to determine the effects of maintaining these lenses in various liquid preservation media. METHODS: Freshly excised human and monkey lenses were maintained for 5 h in one of four solutions (Balanced Saline Solution [BSS], Ringer's Solution, Dulbecco's Modified Eagle Medium with Ham's F-12 [DMEM/F-12/F-12], and Tissue Culture Medium 199 [TC-199]) using a custom-designed, temperature-regulated testing cell. A modified optical comparator and digital camera were used to photograph magnified lens profiles and measure lens diameter and thickness. Lens volume was then calculated assuming rotational symmetry about the optical axis. RESULTS: Seven of the 33 human lenses exhibited extensive swelling and separation of the capsule from the lens cell mass prior to the incubation. During incubation, for 12/22 of the remaining human and 27/27 of the monkey lenses, thickness increased by 1.0-1.8%, diameter decreased by 0.7-1.6% and the volume was essentially unchanged. Substantial swelling and capsular separation were observed in 10 of the 22 human lenses, 7/10 for those maintained in salt solutions, and 3/12 for those in tissue culture media. Lens volumes increased by an average of 6.8%, due to an 8.7% increase in the thickness, while the diameter decreased by 0.9%. These changes appeared to be independent of postmortem time and donor age. CONCLUSIONS: Culture media are more effective than simple salt solutions in maintaining lens physical integrity during short-term incubations. Substantial uptake of water, accompanied by separation of the capsule from the lens cell mass, occurs at various stages during storage and experimental manipulations in >60% of human lenses obtained from the eye bank. Data obtained with such lenses will not be representative of the true ex vivo state. It is recommended that lenses be assessed to determine if swelling has taken place before acceptance of data.

Adult↗