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Biomedical subjects

K P Boergen

Publications and source records attributed to K P Boergen.

At least 19 recordsLinked to original sources
PubMed1997

[Measuring saccades in endocrine orbitopathy].

Thyroid-associated ophthalmopathy (TAO) is evaluated mainly by orthoptic examination and morphometric parameters such as ultrasound, CT scanning or magnetic resonance imaging. Inflammatory changes of the extraocular muscles lead to an impairment of eye movement. Recent evidence suggests that saccades are altered by changes to the extraocular muscles. Although of potential interest, this phenomenon has so far received little attention. To determine the role of saccades as a potential diagnostic tool for assessing the function of the affected muscles, we have begun to analyze saccadic parameters in patients with TAO. Preliminary results of this study are reported in the present paper. For registration of both horizontal and vertical eye movements, we used the "Ober-2-Apparatus," which uses the infrared technique. Horizontal and vertical saccades with an amplitude of 10 degrees were analyzed in 20 healthy persons and 30 patients suffering from TAO. Patients showed changes in the quality of saccades, such as the appearance of glissades and additional correctional saccades as well as quantitative changes, such as an increase in the maximum speed and latency. Our current data suggest the presence of saccadic alterations in TAO. Our ongoing studies are designed to evaluate whether characteristic changes can be assigned to certain stages of the disease and whether assessment of saccadic changes in a promising tool for early detection and functional follow-up in patients with TAO.

Adult↗
PubMed1997

[Functional eye muscle changes in endocrine orbitopathy].

BACKGROUND: To determine the functional changes in the extraocular muscles in patients with thyroid-associated ophthalmopathy (TAO). PATIENTS AND METHODS: Horizontal saccades with an amplitude of 20 degrees were carried out over a period of 2 min. Eight patients with acute TAO and five patients with chronic TAO were compared with ten age-matched healthy individuals. Ocular movements were recorded using the "Ober 2" system based on infrared technology. For evaluation of fatigue effects, the parameters of the first five and the last five saccades were analysed. RESULTS: A significant difference of four and five, respectively, out of nine tested saccadic variables including maximum velocity (Vmax) was found both before and after fatigue. In comparison to normal subjects, patients with chronic TAO revealed mildly increased reduction of Vmax after fatigue. Results in patients with acute TAO were related to the action of the most severely affected muscle. On active contraction of the medial rectus muscle (adducting saccades), Vmax was not significantly decreased after fatigue. On passive elongation of the medial rectus muscle (abducting saccades), however, Vmax was initially markedly decreased and increased significantly after fatigue. CONCLUSIONS: Functional changes of extraocular muscles in patients with TAO can be demonstrated by saccadic analysis. The inverse change in velocity after fatigue in acute disease indicates an improvement of muscle elasticity during exertion and strongly supports the concept that early impairment of bulbar motility in active TAO results from contracture of myofilaments. Thus, analysis of the fatigue effect may help to differentiate between acute and chronic disease.

Graves Disease↗
PubMed1997

[Photoscreening for early detection of amblyogenic eye changes].

BACKGROUND: Congenital and early acquired ocular changes impairing the optic input induce amblyopia when left untreated. Amblyopia treatment must start early to be efficient. Therefore it seems necessary to employ screening tests in preverbal childhood. PATIENTS AND METHODS: The reliability of two commercially available photoscreening devices, the "Visiscreen 100" (Vision Research Corp.) and the "MTI-Photoscreener" (Medical Technology Inc.), was tested. 180 children from a kinder-garten and 120 infants from our outpatient clinic were screened. The results were compared to the findings of a full ophthalmologic and orthoptic examination. RESULTS: The efficacy of the photoscreening depended on the skill of the examiner and on the age of the children tested. The rate of interpretable photographs was 94% in the older group and 63.3% in the infants. The mean sensitivity for detection of amblyogenic factors was 63% in the older and 80% in the infant group. The mean negative predictive value was 90%, and 75%, respectively. CONCLUSION: Modern photoscreening techniques can help to detect amblyogenic factors in early childhood. However, in addition to the non-interpretable photographs, about 20% of the affected children are missed. Therefore, photoscreening cannot be recommended for countries with a high number of ophthalmologists, such as Germany. Instead, an ophthalmologic and orthoptic investigation in early childhood would be preferable.

Amblyopia↗
PubMed1997

Investigations on subjective and objective cyclorotatory changes after inferior oblique muscle recession.

PURPOSE: To determine subjective and objective cyclorotatory changes after surgery for oblique muscle disorders and to analyze the mechanisms of the well-known, long-term, postoperative, subjective cyclotorsional changes. METHODS: Twenty-six patients underwent unilateral inferior oblique muscle recession for strabismus sursoadductorius (inferior oblique overfunction). Subjective and objective cyclodeviation were examined before surgery with and without diagnostic occlusion, as well as 1 day, 3 days, and 4 months after surgery. Subjective cyclodeviation was assessed by Harms' tangent scale. Objective cycloposition was measured by means of fundus cyclometry, a novel method using an infrared scanning laser ophthalmoscope. RESULTS: Diagnostic occlusion did not lead to significant changes in either objective or subjective cyclodeviation. Preoperative objective excycloposition was nearly equally distributed between affected eyes and fellow eyes. Early surgically induced incyclorotatory effects were more pronounced objectively than subjectively. On long-term follow-up, a reduction in the incyclorotatory effect was found to be smaller subjectively than objectively. A significant difference between subjective and objective cycloposition was seen early after surgery, and a significant difference between subjective and objective cyclorotatory change was found immediately after surgery and on long-term follow-up. CONCLUSIONS: Long-term regression of the incyclorotatory effect after inferior oblique muscle recession was confirmed objectively and subjectively and can be explained as a cessation of preoperatively required binocular compensatory innervation. The authors conclude that the difference between objective and subjective regression is caused by sensory cyclofusion.

Adolescent↗
PubMed1996

Amblyopic quasi-blindness for image structure.

Human amblyopes display reduced contrast sensitivities, suffer from perceptual distortion, and their letter acuities are worse than is predicted from grating visibility. We sought the origin of these dysfunctions by measuring normal and amblyopic sensitivities to various forms of well-defined image distortion, namely band-limited phase quantization, phase quantization with additional amplitude modulation, and grey-scale modification. Our results prove the existence of an amblyopic quasi-blindness to image structure, that cannot be explained in terms of contrast detection. We discuss these findings within the computational scheme of image decomposition into local amplitude and local phase values. they are consistent with the assumption of amblyopic eyes beings impaired in processing local phase but having the local amplitude (or "energy", possibly at reduced gain) at their disposal. Phrased in physiological terms, we propose a scheme of complex-cells-only vision in amblyopia. We also provide a demonstration of how amblyopic eyes may see the test stimuli and natural images by generating local amplitude and phase representations at limited phase resolution.

Amblyopia↗
PubMed1996

[Effect of strabismus operation of corneal topography].

BACKGROUND: In order to determine the short- and long-term influence of strabismus surgery on corneal curvature, a prospective study was carried out measuring corneal topography before and after operation. PATIENTS AND METHODS: Corneal topography was performed using a computer assisted videokeratoscope. 77 eyes of 74 patients were examined 1 day before and 1 day as well as 3 months after surgery. Data of the semimeridians at 0 degree, 90 degrees, 180 degrees and 270 degrees in the 3-, 5- and 7-mm zone and of the corneal center were analyzed. Objective refraction, induced astigmatism and simulated keratometer reading were evaluated. 39 horizontal recess-resect procedures. 12 inferior rectus recessions, 10 horizontal resections. 10 inferior oblique recessions and 6 other procedures were performed. RESULTS: The spheric equivalent of objective refraction decreased by 0.23 D. The absolute astigmatism increased by 0.16 D, the maximum change was 1 D. Changes of objective refraction were statistically not significant. The simulated keratometer reading increased by 0.2 D postoperatively and returned to the initial value after 3 months. With few exceptions, corneal topographic changes were small, statistically not significant and nearly disappeared after 3 months. Corneal flattening tended to occur in the semimeridian of resection while corneal steepening was observed at the site of recession. CONCLUSIONS: The influence of strabismus surgery on corneal astigmatism is usually small and mostly transitory. In a few cases, however, the induced astigmatism persists. Patients should be informed about this possibility preoperatively.

Adolescent↗
PubMed1996

Discordant monozygotic twins with the Schimmelpenning-Feuerstein-Mims syndrome.

The Schimmelpenning-Feuerstein-Mims syndrome (SFM), characterized by linear nevus sebaceous and ocular and neurologic abnormalities, is a sporadic condition without known familial cases or etiology. We report the occurrence of SFM in only one of two monozygotic (MZ) twins. After considering a variety of possible causative mechanisms, we suggest that a postzygotic dominant lethal mutation in mosaic form may best explain SFM and the discordancy for SFM in these MZ twins.

Abnormalities, Multiple↗
PubMed1996

Functional prognosis in A and V patterns: a retrospective analysis of surgery on oblique muscles.

Treatment of A and V patterns through surgery on the overacting oblique muscles was evaluated. A retrospective analysis of 330 operated cases with A and V patterns was performed. Surgery on the overacting oblique muscles proved to be successful in treating the vertical incomitance in these patterns, especially after the introduction of maximal recession of the inferior oblique muscle in cases with marked V patterns that used to show undercorrections with the usual 8-mm recession. Little was found in the literature about the binocular vision in these patterns. We therefore evaluated cases with special regard to the functional point of view. We found that about one-third of the patients had had simultaneous perception preoperatively and that more than two-thirds did so postoperatively.

Child↗
PubMed1995

[The initial clinical manifestations of rhabdomyosarcoma].

Unilateral proptosis, dislocation of the globe and impairment of motility in childhood are known to be typical presenting signs of rhabdomyosarcoma of the orbit. In a retrospective analysis of 17 patients with rhabdomyosarcoma (1974-1993) only 8 patients presented with typical signs. 9 patients did never show the typical signs which initially lead to a wrong diagnosis in many cases. A 5-year-old boy complained of a conjunctival cyst in the lower fornix of the left eye. Two weeks later the cyst was replaced by a solid tumor. The tumor was not completely resectable, histology revealed an embryonal rhabdomyosarcoma. Presenting signs and symptoms of orbital rhabdomyosarcoma show a sometimes misleading variety including conjunctival cyst formation. In any recent onset of unilateral rapidly progressing alterations of the lid, the conjunctiva or the caruncle in childhood the physician should consider a rhabsomyosarcoma of the orbit.

Adolescent↗
PubMed1993

[Detection, localization and modulation of hyaluronic acid/CD44 receptor expression in patients with endocrine orbitopathy].

Accumulation of hyaluronic acid within the orbital tissues represents a histological hallmark of Graves' ophthalmopathy. The hyaluronic acid/CD44-receptor plays a key role in the binding and metabolism of hyaluronic acid, and affects numerous cellular functions of potential relevance to the pathogenesis of Graves' ophthalmopathy, including cell proliferation, migration, and adhesive interactions between connective tissue components and immunocompetent cells. Using a highly sensitive immunoperoxidase technique and monoclonal antibodies directed against the standard CD44 molecule, we examined the expression and modulation of hyaluronic acid/CD44 receptors in cryostat sections of orbital biopsy specimens derived from patients with severe Graves' ophthalmopathy and normal individuals. Modulation of CD44 by cytokines and affinity-purified IgGs derived from patients with Graves' ophthalmopathy was studied in extracts of fibroblast monolayers following stimulation in vitro, using SDS-polyacrylamid gel electrophoresis and immunoblotting. Strong immunoreactivity for CD44 was present in all specimens derived from patients with Graves' ophthalmopathy and was detected in fibroblasts residing in retroorbital connective tissue, in extracellular matrix components and in mononuclear cell infiltrates. By contrast, in normal orbital specimens, CD44 immunoreactivity was faint and present only in occasional connective tissue cells. Recombinant IL-1 alpha, TNF alpha, IGF-1 and GO-IgGs significantly stimulated CD44 expression in Graves' retroocular fibroblasts (range: 168 to 588%; all p < 0.05). By contrast, EGF, IL-6, control IgGs and 15% fetal calf serum failed to alter CD44 expression. Treatment of monolayers with IFN gamma resulted in weak inhibition of CD44 expression. In conclusion, the hyaluronic acid/CD44 receptor is expressed at elevated levels in Graves' orbital connective tissue in situ.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1992

[Comparative study of deep lying drusen of the papilla with the scanning laser ophthalmoscope and fundus camera].

We examined four patients with the suspected diagnosis of optic disc drusen by scanning laser ophthalmoscopy (SLO) and fundus photography. In all four cases the autofluorescence that distinguishes optic disc drusen was observed with the SLO, but not with the fundus camera. Three of the four examined patients, children or adolescents, were spared further diagnostic procedures to clarify the underlying cause of the swollen optic disc.

Adolescent↗
PubMed1991

[Normal and disordered visual development with preferential looking].

Normal and disturbed development of grating acuity in preverbal infants has been studied using the Teller acuity card procedure. The results of 195 normal and 34 premature children are in good accordance with those reported in the literature. In more than 86% no interocular differences of grating acuity could be detected in these groups. On the other hand the incidence of interocular acuity differences reached 30% in 37 cases showing monolateral convergent squint. This is much higher than has been reported in current literature and may indicate that grating and Snellen acuity correlate better than expected in infants' squint amblyopia. As to the problem of monitoring early amblyopia therapy by PL, four longitudinal cases are presented.

Amblyopia↗
PubMed1990

[Congenital fibrosis syndrome. Considerations on etiology, genetics and surgical therapy].

Fibrosis syndrome has been a well-known clinical entity for more than a century. Nevertheless, there are still some unresolved questions concerning its etiology, chronological course, and optimal timing of surgery. On the basis of their experience in 12 cases (2 unilateral, 10 bilateral, 7 with eye muscles and/or lid surgery), the authors attempt to help answer these questions.

Adolescent↗
PubMed1990

[Normal and defective development of visual stimulus processing: psychophysical and electrophysiologic test results].

Two methods were developed for the assessment of normal and disturbed visual development in infancy and early childhood: the preferential looking procedure (PL) as a psychophysical method and measurement of visual evoked potentials (VEP) as an electrophysiological principle. Both methods test visual functions, but on different levels of the visual system. Proper interpretation of the methods requires direct comparison. This was accomplished over a 12-months period in infants and young children with normal and disturbed visual development in the first year of life. For normal infants older than 4 weeks we found accurately configurated VEP responses and rapidly increasing visual accuity, ranging from 0.4 cpd (age 2.5 weeks) to 10 cpd (36 weeks) and better. There was a close agreement between the VEP and PL results, possibly due to our conservative interpretation of VEP acuity, which was not extrapolated from the VEP amplitude versus spatial frequency function, but defined by the relationship to the simultaneously registered noise level of the responses. The last response that could be differentiated from this noise level was defined as VEP acuity in analogy to the acuity definition of the Teller acuity cards. In visually impaired children there was a delay in visual development. Visual deficits in congenital cataract were much more marked than in congenital squint. Infants with congenital cataract showed a nearly newborn stage when tested shortly after lensectomy. With our preliminary results is was not possible to determine any statistical relationship among the psychophysical, electrophysiological and clinical findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Attention↗
PubMed1990

[Endocrine orbitopathy--symptoms, diagnosis, therapy].

The diagnosis of graves ophthalmopathy is still essentially an ophthalmological problem, because the etiopathological links to the troubles of the thyroid gland are not yet fully understood. The typical signs and symptoms of the disease, the diagnostic and therapeutic possibilities of the ophthalmologist are described.

Graves Disease↗