Biomedical subjects

K Rohrschneider

Publications and source records attributed to K Rohrschneider.

At least 73 records · Page 4Linked to original sources

PubMed1995

[Fluconazole level in aqueous humor after oral drug administration in humans].

For 2 years fluconazole, a triazole antimycotic, has been available for treatment of systemic mycosis. Compared to amphotericin B fewer severe side effects have been reported. So far, no data have been published as to its penetration into the human eye. In the present study, 20 cataract patients were given 200 mg fluconazole (0.5 to 8 h preoperatively. During the cataract operation 0.1 ml of the aqueous was removed as well as 10 ml serum. With the help of high-pressure liquid chromatography (HPLC), the concentration of fluconazole in each of the samples was determine. If the aqueous humor was removed at least 2h after fluconazole application, concentrations between 2.7 and 5.4 micrograms/ml were reached (mean 3.7 +/- 2.17) In these cases the concentration in the aqueous humor was 80% of the concentration found in the serum at the same time. If the sample of the aqueous humor was collected only 1 h after application, 40% of the concentration in the serum was found in the aqueous humor. These data prove that fluconazole shows an extremely good penetration through the blood-aqueous barrier. After a single dose of 200 mg, a concentration is reached in the eye that surmounts the minimal inhibiting concentration found for Candida species sensitive to fluconazole. Therefore, fluconazole seems to be a good alternative to amphotericin B for the treatment of infections caused by such fungi.

Administration, Oral↗

PubMed1995

[Comparison between local and systemic administration of cyclosporin A on the effective level in conjunctiva, aqueous humor and serum].

Cyclosporine is an important tool for the therapy of immunological diseases of the cornea and conjunctiva, as well as the treatment of patients with high-risk corneal grafts. However, potentially severe systemic side effects are disadvantageous. The purpose of our study was to determine if topical ocular application leads to about the same concentrations in ocular tissues as systemic application. Therefore, the concentration of cyclosporine in conjunctiva, aqueous humor and blood was measured by radioimmunoassay in six patients with systemic administration of cyclosporine and ten patients who received one drop of topical cyclosporine 2% four times prior to cataract surgery. All patients with systemic application showed measurable concentrations of cyclosporine in blood, as did four patients in the group receiving topical cyclosporine. There was no significant difference between both groups concerning cyclosporine concentration in aqueous humor. The level of cyclosporine in the conjunctiva was significantly higher after topical application (P < 0.02). In conclusion, therapy with cyclosporine eye drops results in levels in the conjunctiva and aqueous humor that are comparable to or even higher than those after systemic application if the last application was no more than 18h prior to the measurement. Therefore, topical ocular application of cyclosporine, which reduces or eliminates the drug's systemic side effects, can be used to induce local immunosuppressive activity, particularly in the treatment of superficial immunological diseases and after limbal allograft transplantation.

Administration, Oral↗

PubMed1994

Reproducibility of the optic nerve head topography with a new laser tomographic scanning device.

BACKGROUND: Laser scanning tomography has been shown to be an accurate and reliable method for the assessment of the three-dimensional optic disc topography. The authors investigate the reliability of morphometric measurements with the Heidelberg retina tomograph, a new instrument which was designed based on this technology, which simplifies handling and is much smaller than the laser tomographic scanner. METHODS: Three independent measurements of the optic disc were performed in 39 eyes of 39 patients which were equally divided into the following three groups: glaucoma, glaucoma suspects, and controls. RESULTS: The mean coefficient of variation for measurement in the glaucoma, glaucoma suspect, and control groups was 2.9%, 5.0%, and 3.4%, respectively, for cup area; 4.9%, 4.6%, and 4.6%, respectively, for cup volume; 5.2%, 3.8% and 3.3%, respectively, for mean cup depth; and 5.2%, 4.1%, and 4.0%, respectively, for maximal cup depth. The mean standard deviation for one pixel of the total image was 30 +/- 6 microns, 28 +/- 7 microns, and 22 +/- 6 microns for the three groups, respectively. CONCLUSION: The Heidelberg retina tomograph enables fast and reliable measurement of the optic disc topography and therefore may allow exact follow-up of patients.

Adult↗

PubMed1994

[3-dimensional topography of the optic papilla with laser scanning tomography: clinical correlation of cluster analysis].

BACKGROUND The evaluation of optic disc topography is essential for the clinical diagnosis of primary open angle glaucoma. The purpose of this study was (1) to establish a computerized cluster formation of optic nerve head topography based on quantitative three-dimensional parameter values and (2) to describe the resulting clusters according to morphological appearance and visual fields. PATIENTS AND METHODS 337 optic nerve heads (glaucomatous optic neuropathy (n = 99), glaucoma suspects (n = 159), normals (n = 79) were analyzed using laser scanning tomography. A hierarchical cluster analysis was performed based on standardized variables (optic disc area, rim area, area-ratio, cup depth, cup steepness, height variations along the contour-line). Visual fields were tested by computerized static threshold perimetry. RESULTS A seven cluster solution met the optimizing criteria. The characteristic morphology of the clusters can be described as "normal" (N), "normal, large" (NL), "supernormal" (SN), "pseudonormal" (PN), "glaucoma-like-flat" (GF), "glaucoma-like-steep" (GS) and "macropapillary" (M). Visual fields were normal in 180 eyes. 99 eyes had glaucomatous field defects, 58 eyes revealed isolated relative scotomas < 10 db. Presence and degree of visual field defects varied within the automatically classified optic disc groups considerably. Visual field defects were found in 7.7% (SN), 8.3% (N), 18.8% (NL), 33.3% (M), 37% (PN), 64.7% (GF) and 83.3% (GS) respectively. Pseudonormal discs were characterized by a flattening of the height variations along the disc border. CONCLUSIONS (1) Optic nerve heads may be automatically classified based upon a combination of three-dimensional topographic variables. (2) Analysis of optic disc topography and computerized perimetry are supplementary tools in the evaluation of the glaucoma patient. Visual field defects may be present within any cluster. However, the likelyness of the presence of visual field defects differs considerably among the topometrically defined groups of optic nerve heads. Functional damage is to be expected in association with reduced height variations along the disc border, a small rim area and a steep cupping of the optic nerve head.

Cluster Analysis↗

PubMed1994

[Follow-up examinations of papillary morphology with laser scanning tomography].

UNLABELLED: The object of this study was to investigate the perceptibility of changes in the topography of the optic nerve head during follow up with laser scanning tomography (LST), with a minimum observation period of 24 months. METHODS: We evaluated the changes in cup and rim area, cup volume, and mean and maximum cup depth in 50 eyes (8 control eyes, 21 glaucomatous eyes, 21 eyes in which glaucoma was suspected by LST over a mean follow-up time of 36 +/- 10 (range 24-49) months and compared them with the results of computerized static perimetry (Octopus). Changes were considered to be significant if they were larger than three times the maximum deviation measured in one parameter and larger than the maximum deviation in one other parameter [27]. RESULTS: Among 10 eyes that showed increasing cup values, 5 initially presented with striking disc cups, and no pathologic function tests; in none of these eyes was functional loss revealed by perimetry during the follow-up period. Of the 5 glaucomatous eyes in which progression was found on optic disc morphometry, 4 had increasing defects revealed by computerized static perimetry (Octopus 500). CONCLUSION: The results confirm the value of LST. In 6 eyes in which LST revealed a significant increase in the optic cup values, perimetry did not demonstrate progression of the functional loss. Therefore, LST should be used in the follow up of all patients with glaucoma or suspected glaucoma, in addition to conventional computerized perimetry.

Adult↗

PubMed1994

[Coats syndrome in retinitis pigmentosa. Clinical aspects and therapeutic possibilities].

Coats disease itself is a rather rare condition, whereas Coats syndrome has been observed in about 1.2-4.9% of all retinitis pigmentosa (RP) patients. The spectrum of clinical presentations and our therapeutic experience are illustrated with reference to case reports of three patients with clinically and electrophysiologically verified RP and Coats syndrome. As in classic Coats disease, Coats-like changes with RP are defined by aneurysmatic and teleangiectatic vessels and intra- and subretinal lipid deposits leading to exudative retinal detachment. Both entities differ with regard to age of onset, gender, bilaterality and location of the retinal changes. The reports published up to now show that there is no consensus concerning the success of the different treatments of Coats syndrome associated with RP. Laser therapy, cryocoagulation, diathermy and buckling procedures have been suggested for treatment of this complex. As in the therapy of Coats disease, our results confirm that the outcome of laser therapy depends on early detection of Coats-type vascular abnormalities and early initiation of the treatment. Therefore, thorough fundus examination should be regularly performed in all RP patients.

Adolescent↗

PubMed1993

Laser scanning tomography and stereophotogrammetry in three-dimensional optic disc analysis.

Laser scanning tomography (LST) and computed stereophotogrammetry (CSP) are sophisticated diagnostic tools for the three-dimensional analysis of optic nerve head topography. The two methods are based on different physical principles. To compare the information about the shape of the cup of an optic nerve head obtained by LST and CSP, we evaluated the volume profile (VP; i.e., the cross-sectional area of the cup from top to bottom) in 36 discs of 36 patients (20 control group discs C, 16 glaucoma discs G). The Spearman correlation coefficient between the photogrammetric and the laser scanning VP-slope measurements was rs = 0.931; P < 0.001 (rs = 0.935 G, P < 0.001; rs = 0.910 C, P < 0.001). The results suggest that confocal laser scanning provides readings of the shape of the optic disc cup that are similar to the measurements of computed stereophotogrammetry.

Adolescent↗

PubMed1993

Reproducibility of topometric data acquisition in normal and glaucomatous optic nerve heads with the laser tomographic scanner.

The reproducibility of optic disc cup measurements was analyzed in 24 eyes of 24 patients [8 normals, 8 glaucoma patients, 8 glaucoma suspects] using the Laser Tomographic Scanner. The mean coefficient of variation in triple measurements was 5.0% for the cup area, 5.4% for the rim area, 7.0% for the cup volume, 4.0% for the mean cup depth, and 4.3% for the maximum cup depth. Mean reliability between two of the three measurements performed in each eye was better than 0.988 for the cup area, 0.995 for the cup volume and 0.996 for the mean cup depth readings. These results suggest that laser scanning tomography allows highly reproducible measurements in living eyes and adds an important tool to the ophthalmologist's armamentarium for the diagnosis and follow-up of glaucoma patients.

Female↗

PubMed1993

[Prognosis of intralenticular lead foreign bodies].

BACKGROUND: The prognosis of intraocular foreign bodies consisting of lead remains controversial. While experiments have shown that infected lead becomes sterile when fired from rifles, both the total absence as well as presence of severe inflammation have been observed following perforating injuries with lead. Furthermore, alterations of the ERG have been described in experimental settings. This case report is presented in order to clarify the long term prognosis of intralenticular lead particles. PATIENT AND METHOD: The 69-year-old patient suffered from a bilateral perforating injury caused by a bullet during World War II (1942). The right lens was extracted due to a secondary cataract several weeks following the injury. The left lens remained clear despite a paracentrally located metallic foreign body. The patient underwent extracapsular cataract extraction in 1992 because of an opacity of the posterior capsule which was well separated from the foreign body. Preoperatively the ERG was normal. An energy dispersive X-ray microanalysis in a scanning electron microscope was performed in order to determine the chemical composition of the foreign body, and X-ray diffraction with a Gandolphi camera was used for its structural characterisation. The foreign body consists of lead. However, its surface is probably altered to lead oxide, hydroxide or carbonate, which hindered further reaction of the lead. Calcium phosphate was deposited on the walls of the foreign body. CONCLUSION: Our report shows that lead in the lens remains inert for several decades and does not cause alterations in the ERG. Therefore, intralenticular lead outside of the optical axis may be left in situ unless a secondary cataract develops.

Aged↗

PubMed1993

[Determination of retinal nerve fiber density in vivo using laser polarimetry].

BACKGROUND: A direct in vivo measurement of the retinal nerve fiber layer thickness enables new possibilities for the detection of nerve fiber defects. Using the principle of polarimetry the Nerve Fiber Analyzer has been told to measure directly the nerve fiber layer thickness in vivo. PATIENTS AND METHODS: We measured the nerve fiber layer thickness along a peripapillary circle and investigated the reproducibility in 10 independent measurements of 10 left eyes of ten normals. RESULTS: The nerve fiber layer thickness measurements varied between 10 and 130 microns for single pixel measurements. The coefficient of variation was 11.9 +/- 2.6 percent for a peripapillary circle while the temporal, nasal, superior and inferior quandrants were 19.2 +/- 3.6%, 19.5 +/- 4.7, 14.3 +/- 5.6 and 16.4 +/- 5.5 percent, respectively. Mean coefficient of variation in 10 time evaluation of 5 single examinations of 5 different eyes was 1.8 +/- 1.1%. CONCLUSIONS: The first investigations demonstrate a good reproducibility of the measurements observed by the Nerve Fiber Analyzer. Supplementary to three-dimensional optic disc topography and perimetry, nerve fiber layer thickness assessment may become an additional tool for diagnosis and follow-up of early glaucoma. The option of measuring along circle segments or areas instead a peripapillary circle consisting of a single pixel would increase the clinical value and reproducibility. Further studies are warranted to evaluate the accuracy of this new method of polarimetry.

Equipment Design↗

PubMed1993

[Bilateral choroid osteoma].

BACKGROUND: Choroidal Osteoma is a rare, typically monolateral benign ossifying tumor of the choroid found in healthy females aged 10 to 30 years. In contrast, multiple idiopathic sclerochoroidal calcifications occur in elderly otherwise healthy subjects. Local or generalized distortions of calcium phosphate metabolism may cause secondary choroidal calcifications. PATIENT: We report on a 56-year-old woman, who underwent removal of a histologically verified osteoma 2 years ago. Ophthalmoscopically, there were multiple prominent choroidal tumors in the inferior midperiphery of both eyes. Ultrasonography showed high reflectivity and marked shadowing posterior to the lesion. CT-scan demonstrated the presence of calcifications. The patient neither belonged to the age group, in which choroidal osteomas are typically found, nor were the lesions located in the typical manner as reported in literature. The location in the inferior choroid has not yet been described for idiopathic sclerochoroidal calcifications. The presence of secondary choroidal calcifications was very unlikely, as there was no history of ocular inflammation or systemic disease such as hyperparathyreoidism or chronic renal failure. CONCLUSION: Thus, despite the lack of histologic examination, one may assume the rare incidence of bilateral choroidal osteomas in atypical inferior localisation in our patient.

Choroid↗

PubMed1993

[Goniotrepanation combined with sinus surgery as a transitional measure in spontaneous carotid artery-cavernous sinus fistulas].

Two patients with spontaneous, angiographically proven fistulas showed progressive ocular symptoms which precluded waiting for spontaneous occlusion of the fistulas. On the other hand, endovascular therapy of the carotid-cavernous fistulas was not possible because the arterial supply of the fistulas came from both internal carotids. Therefore filtering surgery was performed in the affected eyes. Postoperatively, intraocular pressure decreased to normal values in both patients and the symptoms resolved. The visual acuity increased in one patient and remained the same in the other. In conclusion, filtering surgery is an important therapeutic tool to preserve visual function in eyes with carotid-cavernous fistulas that display progressive ocular symptoms but cannot be treated by embolization.

Aged↗

PubMed1993

[Comparison of two laser scanning tomography systems for three-dimensional analysis of the optic papilla].

The Heidelberg retina tomograph (HRT) allows three-dimensional topographic analysis of the optic disc based on the same confocal laser tomographic scanning principle as the laser tomographic scanner (LTS). We evaluated the reproducibility attained with the HRT and compared the data acquired with the two instruments. To determine the reproducibility of the data acquisition with the HRT, we measured 27 glaucomatous discs five times each. The mean standard deviation was 0.075 mm2 for the cup area, 0.035 mm3 for the cup volume and 0.018 mm for the mean cup depth. In addition, 50 eyes were examined with both instruments. Measurements of the optic disc area and cup area demonstrated slightly increased values obtained with the HRT (mean difference 4.1% and 6.6%, respectively), while the values for cup volume and cup depth were 15.5% and 13.9% larger than those obtained with the LTS. The comparison between LTS and HRT demonstrates good agreement of the reproducibility concerning three-dimensional topometric data relating to the optic nerve head. The differences between the measurements may be due to a modified optical pathway enabling direct assessment of the intraocular focus position in the HRT. In conclusion, the improved and simplified method of laser scanning tomography as used in the HRT yields reproducible and reliable measurements of the optic nerve head. In addition, this instrument makes it possible to obtain high-quality images without pupil dilatation with a significantly shorter examination time.

Equipment Design↗

PubMed1992

Are large optic nerve heads susceptible to glaucomatous damage at normal intraocular pressure? A three-dimensional study by laser scanning tomography.

To evaluate the effects of the presence of glaucomatous visual field defects and of intraocular pressure elevations on optic nerve head topography, we analyzed 148 left optic nerve heads of 148 patients using laser scanning tomography. The optic discs are classified according to computerized static perimetry and documented IOP readings: 101 discs show normal visual fields (36 normal discs, 22 ocular hypertensives, 28 normotensive glaucoma suspects and 15 ocular hypertensive glaucoma suspects), 47 discs (34 high-pressure glaucoma discs, 13 normal-tension glaucoma discs) demonstrate glaucomatous visual field damage. A two-way analysis of variance discloses significant differences (P < 0.01) between the groups of optic discs classified according to perimetry for most topometric parameters evaluated except for disc area. Classification according to documented IOP (cut off at 21 mmHg) results in larger disc areas in normotensive discs compared to hypertensive optic nerve heads in the study population. Results suggest that large discs may be susceptible to glaucomatous visual field damage at statistically normal IOP readings.

Adult↗

PubMed1992

[Further development of a streak retinoscope with calibrated collimator].

Development and rationale of a new streak retinoscope have been discussed in an earlier paper. In contrast to classical retinoscopy this retinoscope determines the refraction by forming the narrowest streak in the test person's pupil with a calibrated collimator. In addition to the first prototype the extension of the lamp according to variation of the refraction is measured electronically and the data are transposed into a computer. This allows to freely choose a working distance in a range from about 30 to 120 cm and therefore it is possible to examine restless patients. Accuracy of the measurement was less than or equal to 0.25 D for Ametropia from -0.5 to 5.0 D in a working distance of 30 cm or from -4.0 to -1.5 D in 100 cm. In most persons it is not necessary to use additional glasses during refraction by choosing the adequate distance. Therefore this method can help to refract kids and other persons which could not be refracted by use of glasses. In addition this method excludes the accommodation of the patient as apposed to regular refractometers.

Calibration↗

PubMed1992

Depth position of spontaneous venous pulsations in ocular hypertensives and control-group discs.

Spontaneous venous pulsation can be observed at the site of entry of retinal veins into the physiological cup of the optic disc. Although it has been speculated that spontaneous vessel pulsation is related to primary open-angle glaucoma, no evaluation has been done on the depth position of such a pulsation inside the cup and its relationship to the intraocular pressure. Using laser scanning tomography, we measured the depth position of the maximal spontaneous vessel pulsation inside the optic cup in 24 discs of 24 patients, including 15 ocular hypertensives and 9 controls. The two groups did not differ significantly in age or refraction. The depth position of the maximal venous collapse, however, showed a significant difference between the two groups (p < 0.005), the mean value being 301 +/- 95 microns beyond the first retinal vessel reflection in the control-group eyes and 507 +/- 193 microns in the ocular hypertensive discs. The location of the depth position of the maximal venous collapse within the excavation could be a parameter that indicates the individual pressure tolerance of the ocular tissues.

Adult↗

PubMed1991

[Volumetric analysis of the optic papilla using laser scanning tomography. Parameter definition and comparison of glaucoma and control papilla].

We performed a three-dimensional structure analysis of the optic disc in 65 eyes of 65 patients (38 glaucoma patients, 27 control-group patients) using laser scanning tomography. Patients classified as glaucoma showed at least 3 points with a relative scotoma of -10 db loss or greater compared to age matched controls on static 30 degrees computerized perimetry. Control-group patients showed no relative scotoma outside the blind spot area compared to age matched controls. One way analysis of variance revealed statistically significant differences between the glaucoma (G) and the control-group (C) for excavation volume (+0.57 +/- 0.37 mm3 G/0.31 +/- 0.27 mm3 C, p less than 0.01), for the 3rd moment of the frequency distribution of excavation depths readings (-0.01 +/- -0.12 G/-0.13 +/- -0.09 C, p less than 0.001), area ratio (0.75 +/- 0.15 G/0.57 +/- 0.16 C, p less than 0.001), depth area ratio (0.35 +/- 0.24 G/0.18 +/- 0.12 C, p less than 0.001). A stepwise discriminant analysis classified 32 of 38 (84.2%) glaucoma discs and 21 of 27 (77.8%) control-group discs by a linear combination of 5 out of 15 topographic parameters. The results suggest that a combination of topographic parameters may provide an objective optic disc classification.

Computer Graphics↗

PubMed1991

[Effects of acetazolamide (Diamox, Glaupax) on tear production].

In view of personal clinical observations, it appeared possible that a therapy with the carboanhydrase inhibitor acetazolamide leads to a reduction of tear production and induces a dry eye syndrome. Tear secretion was therefore measured by Schirmer tests in a control group of 66 patients after cataract surgery and in a test group of 20 patients who were treated with acetazolamide (Diamox, Glaupax) on the day after the cataract operation. The results were subjected to a statistical analysis with 3-factor anova. The cataract operation induced a significant increase of tear flow. Independent of this effect, administration of the carboanhydrase inhibitor caused a significant decrease of tear production, both in the operated eyes and the untouched fellow eyes.

Acetazolamide↗