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Biomedical subjects

W Göbel

Publications and source records attributed to W Göbel.

15 recordsLinked to original sources
PubMed2003

[Diagnosis and follow-up of non-diabetic macular edema with optical coherence tomography (OCT)].

INTRODUCTION: Objective and quantitative follow-up of macular edema with present clinical methods is limited. We studied to what extent optical coherence tomography (OCT) may be clinically useful in diagnosis and follow-up of non-diabetic macular edema. PATIENTS AND METHODS: We evaluated 106 eyes with non-diabetic macular edema retrospectively considering diagnosis, foveal retinal thickness in OCT, fluorescein angiographic findings and visual acuity. RESULTS: In 60 of 61 eyes (98%) the diagnosis of macular edema was confirmed by fluorescein angiography. There was only a minor correlation between visual acuity and foveal retinal thickness (r=0.32, p=0.001). Follow-up of 24 eyes showed a statistically significant decrease of foveal retinal thickness under therapy from 420+/-165 microm to 354+/-165 microm (p=0,035) as well as a small improvement in visual acuity from 0.30 to 0.38 (p=0.025). CONCLUSION: OCT can diagnose macular edema non-invasively and thus may replace fluorescein angiography as an invasive method. The reduction of macular edema in the course of therapeutic measures can be documented objectively with OCT.

Diabetic Retinopathy↗
PubMed2001

[Determination of retinal thickness in relation to the age and axial length using optical coherence tomography].

PURPOSE: It is unknown whether the thickness of the retina depends on axial length or on age. We therefore used optical coherence tomography (OCT) to study this relationship. METHODS AND MATERIALS: We recruited 159 subjects aged 13-92 years (205 eyes) without macular pathology. OCT measurements included three horizontal scans and one vertical scan through the fovea. Axial length was determined by an analog high-resolution biometric unit. RESULTS: There was no correlation between retinal thickness and either axial length or age. Mean retinal thickness in the fovea was 142 +/- 18 microns. In the nasal retina thickness was significantly increased to 266 +/- 17 microns, compared to 249 +/- 18 microns in the temporal retina. Retinal thickness in subjects' two eyes was significantly correlated. CONCLUSIONS: Since retinal thickness does not depend upon age or length of the eye, no corrections are necessary when analyzing pathological retinal thickening, such as in diabetic retinal disease.

Adolescent↗
PubMed2000

[Findings of optical coherence tomography (OPT) before and after macular hole surgery].

PURPOSE: We used optical coherence tomography (OCT) for the staging of macular holes and compared our results with clinical and intraoperative findings. PATIENTS: Between 1 January 1997 and 15 October 1998, 80 patients underwent vitrectomy for idiopathic macular holes. In 36 cases we could record an OCT preoperatively and in 24 cases also postoperatively. OCT measurements were analyzed in a blind fashion independent of the clinical pre- and intraoperative findings. RESULTS: Preoperative OCT staging was in agreement with the intraoperative findings in 24 of 36 cases. However, in 8 cases, the macular hole was judged as stage 3 intraoperatively, while OCT revealed a stage 4 hole. Postoperatively, OCT results were consistent with the clinical findings in all 24 cases. CONCLUSION: OCT scans are a valuable adjunct for the pre- and postoperative analysis of idiopathic macular holes. As the posterior hyaloid surface cannot always be reliably identified in OCT, discrimination between stage 3 and 4 is difficult.

Humans↗
PubMed2000

[Early and late findings with optical coherence tomography (OCT) in patients with postoperative hypotonia].

PURPOSE: To study early and late findings of macular retinal thickness in patients with hypotony following filtering procedures. PATIENTS AND METHODS: 13 patients who had undergone trabeculectomy (9 with antimetabolites) developed ocular hypotony. The macular region appeared normal during biomicroscopy in 8 patients. In the hypotensive phase, macular thickness was measured using optical coherence tomography (OCT). Directly after attempted and successful normalization of intraocular pressure (7 spontaneous, 5 operative, 1 failure) as well as 6 months later, OCT measurements were repeated. Foveal thickness in the hypotonous eye was correlated with visual acuity and foveal thickness in the fellow eye. RESULTS: Intraocular pressure could be raised from a mean of 2.5 +/- 1.3 mmHg to 11.5 +/- 5.5 mmHg and later on to 13 +/- 3.7 mmHg (follow-up). Mean foveal thickness was reduced from 211 +/- 73 microns during hypotony to 170 +/- 44 microns after normalization of intraocular pressure and to 171 +/- 38 microns at late follow-up. Mean visual acuity improved from 0.17 to 0.33 and finally to 0.6. CONCLUSIONS: Despite normal appearance of the macula (8 patients) using biomicroscopy in patients with hypotony, retinal thickness in the fovea is increased. Apart from refractive changes, this retinal thickening can be held responsible for the deterioration of visual acuity in eyes with hypotony. OCT analysis and measurements may be useful to distinguish between retinal thickening that is reversible after normalization of intraocular pressure and cystoid macular edema that leads to permanent visual impairment.

Adult↗
PubMed1997

[Quantitative and objective follow-up of papilledema with the Heidelberg Retina Tomograph].

UNLABELLED: The Heidelberg retina tomograph (HRT) is a new instrument to analyze the three-dimensional structure of the retina. It is based on confocal laser scanning technology. Scientific interest has so far focused on the follow-up of glaucomatous optic nerve head damage. As parameters such as cup depth and cup volume can be reproduced with a high degree of accuracy, this new instrument may prove to be an excellent tool to follow up swelling of the optic disk. PATIENTS AND METHOD: A total of 21 patients suffering from optic disk swelling of various etiologies were included in a pilot study. Measurements were taken at six different time points. The maximum optic disk elevation and the volume of swelling were evaluated. Visual acuity and the visual field were determined, and fundus photographs were taken. RESULTS: A reduction in optic disk swelling over time may be demonstrated by both morphological parameters and correlates with improvement in fundus changes. The change in the volume of swelling is greater than the change in maximum disk elevation. The course of optic disk swelling differs between patients with anterior ischemic optic neuropathy and those with pseudotumor cerebri. No correlation was found between our measurements with the HRT and functional parameters (visual acuity and visual field). CONCLUSION: The HRT is a good tool for the follow-up of optic disk swelling, particularly optic disk elevation due to increased intracranial pressure.

Follow-Up Studies↗
PubMed1995

[Changes in orbital hemodynamics caused by nitroglycerin and nifedipine. A study using color duplex ultrasound].

Color Doppler imaging has demonstrated orbital hemodynamic changes in diseases such as central vein occlusion, the ocular ischemic syndrome and diabetic retinopathy. Reports of pharmacologically induced changes are, however, rare and inconsistent. In order to verify the sensitivity of color Doppler imaging to demonstrate pharmacologically induced changes in orbital hemodynamics, nitroglycerin and nifedipine served as vasoactive agents with a clear pharmacological spectrum. Twelve healthy volunteers were examined before and after drug application. After the administration of 0.8 mg nitroglycerin, the end diastolic bloodflow velocity was increased in the central retinal artery (before: Vdiastolic 2.2 +/- 1.0 cm/s, after: Vdiastolic 3.1 +/- 1.1 cm/s) as well as the ophthalmic artery (before: Vdiastolic 5.8 +/- 1.7 cm/s, after: Vdiastolic 7.4 +/- 1.8 cm/s). The resistance index of orbital blood flow decreased in all three vessels. After sublingual administration of 10 mg nifedipine, peak systolic blood flow velocity was slightly higher in the ciliary arteries and in the ophthalmic artery (before: Vsystolic 34.7 +/- 4.6 cm/s, after: Vsystolic 37.8 +/- 3.6 cm/s). Blood-flow velocity in the central retinal vein was elevated as well (before: Vmax 3.81 +/- 0.66 cm/s, after: Vmax 4.66 +/- 0.83 cm/s). Those slightly divergent results may be due to the different pharmacological spectrum of the two drugs investigated While nitroglycerin leads to dilatation of venous vessels, nifedipine acts primarily on small arteries. As nifedipine and other calcium channel blockers have been tested in patients with low-tension glaucoma, future color Doppler studies of such a population seem to be promising.

Administration, Sublingual↗
PubMed1994

[Color duplex ultrasound. A new procedure in the study of orbital blood vessels in diabetic retinopathy].

Color Doppler imaging is a new noninvasive technique that allows the measurement of flow velocity in small orbital vessels (both arteries and veins). We compared 59 eyes with proliferative, 47 eyes with nonproliferative and 24 eyes with preproliferative diabetic fundus changes with a control group of non-diabetic patients. The central retinal artery, short ciliary artery and ophthalmic artery of each patient were examined. The systolic, diastolic and mean velocity was obtained for each vessel. Differences between the groups were most prominent in the central retinal artery. The perfusion velocity was significantly lower (P < 0.01) in proliferative eyes (Vsyst 5.7 +/- 1.9 cm/s) than in the control group (Vsyst 9.4 +/- 1.4 cm/s) or the nonproliferative eyes (Vsyst 8.3 +/- 1.9 cm/s). In the preproliferative group the velocity distribution varied widely. Consequently, no statistically significant difference could be deduced in relation to either the control group or the group with proliferative diabetic changes. In the ophthalmic artery and ciliary artery no group showed significant differences from normal. Our measurements indicate a definite correlation between the severity of diabetic retinopathy and a decreased flow velocity, particularly in the central retinal artery. Thus, color Doppler imaging may help to identify those diabetic patients who are at high risk of developing severe diabetic retinopathy so that early photocoagulation treatment can be initiated.

Adult↗
PubMed1993

Retinopathy of prematurity--current diagnosis and management.

Despite advances in ophthalmological care of premature infants, retinopathy of prematurity (ROP) remains a still unsolved problem for paediatricians as well as ophthalmologists. A survey of the current literature concerning drug therapy and surgical management as related to the different stages of ROP is given. The classification system for ROP according to the International Committee is presented as well as our screening policy in relation to the literature. The effectiveness in preventing severe cases of ROP and the toxicity of vitamin E supplementation in high-risk premature infants is still disputed and no recommendations can be given. Cryotherapy is recommended in symmetric cases of stage 3 + ROP. Nevertheless, quite a number of eyes still progress to more severe stages of ROP. Scleral buckling procedures and vitrectomy may lead to anatomical success in a few cases of retinal detachment, however, the visual outcome of such an operation is usually very poor despite reattachment of the central retina.

Cryosurgery↗
PubMed1989

[Surgical therapy of backache].

Apart from disc prolapse, there is a range of other disorders associated with low back pain, for which, when all conservative efforts have failed, surgical treatment should be offered. It must be emphasized, however, that the indication for surgery needs to be rigorously applied, since the most common cause of failure of surgical therapy is an erroneous surgical indication. Here, the clarification of the cause of the pain and not the diagnosis per se is decisive. In particular in degenerative disorders of the lumbar spine in the elderly, the diagnoses established often have little pathological value. Unfortunately, in many cases the real cause of low back pain still cannot be clarified with certainty. Our experience to date, however, in particular with the use of modern implants, shows that, in cases of lumbar spinal stenosis especially, tumors and pronounced segmental instability, excellent results can be achieved with surgery.

Back Pain↗
PubMed1989

Compaction stasis due to gravitational red cell migration and floatational plasma skimming. Reversal of the fahraeus effect due to pathological RCA-formation in plastic tubes and mesenteric venules.

A horizontally aimed microscope was directed at isolated rat mesentery preparations as well as artificial microchannels cast in polyester blocks. They were perfused with aggregating red cell suspensions containing about 7 g/l of bovine fibrinogen at various perfusion pressures. The effects induced by gravitational influences were monitored by measuring the local red cell concentration (video-densitometry) and velocity profiles (IPM-dual slit velocimetry). At low perfusion pressures, sedimentation during maintained flow occurs, leading to a relative red cell slowing compared with plasma. Consequently, a progressive deposition of red cells at the bottom of vessels occurs and finally, blocking of the vessel by aggregated red cells is seen. Thus, the well-known phenomenon of compaction stasis must be attributed not merely to a transmural plasma loss but also to gravitationally induced haemoconcentration.

Animals↗
PubMed1979

Pharmacokinetics of primidone and its active metabolites in the dog.

In dogs, the metabolism of primidone and the pharmacokinetics of the drug itself as well as its metabolites phenobarbital and phenylethylmalonic acid diamide (PEMA) was followed after single oral doses of 30 mg/kg (0.14 mmole/kg). Primidone was rapidly absorbed, so that maximal serum concentrations were reached after 2 hr, the concentration fell then with a half-life averaging 5 hr in Beagles and 10 hr in Mongrels. PEMA appeared in plasma with a ka of 0.003--0.005 min-1, reached maximal concentrations after about 6.5 hr in Beagles and 12 hr in Mongrels. The elimination half-life averaged 7.5 hr in Beagles and 14 hr in Mongrels. After single oral doses, phenobarbital could only be detected in low concentrations in some Beagles. Phenobarbital had an elimination half-life of 32 +/- 4.8 hr in Beagles and of 70 +/- 16 hr in Mongrels. During continued treatment with daily doses of 30--50 mg/kg primidone, steady-state concentrations of about 15 micrograms/ml (65 nmole/ml) were reached after 6--8 days, the PEMA concentrations showed rather pronounced fluctuations around average values of 8--10 micrograms/ml (39--49 nmole/ml), whereas the concentrations of primidone mainly remained below 5 micrograms/ml (23 nmole/ml). In mice, the anticonvulsant potency of the 3 drugs was determined: Elevations of the electroconvulsant threshold by 40 V were produced by 0.01 mmole/kg of phenobarbital, 0.017 mmole/kg of primidone or 0.37 mmole/kg of PEMA. Taking the anticonvulsant potency of the 3 drugs into consideration, phenobarbital is responsible for more than 85% of the total anticonvulsant activity during continued medication of primidone. The penetration of primidone and its metabolites into the cerebro-spinal fluid was followed: phenobarbital reached steady state levels already after 1--1.5 hr, primidone and PEMA not before 2.5 hr. The concentrations in CSF roughly corresponded to the free drug in plasma. On account of the similarities in metabolism and pharmacokinetics of primidone in dog and man, the former species seems to be a suitable model in epilepsy research. Differences between both species are most pronounced in the Beagle.

Animals↗
PubMed1978

Consecutive gas chromatographic determination of phenytoin, phenobarbital, primidone, phenylethylmalondiamide, carbamazepine, trimethadione, dimethadione, ethosuximide, and valproate from the same serum specimen.

A quantitative gas-liquid chromatographic procedure is described for the consecutive determination of phenytoin, phenobarbital, primidone, phenylethylmalondiamide, carbamazepine, trimethadione, dimethadione, ethosuximide and valproate from a single serum specimen of 1.2 ml. After extraction from serum by two different procedures, the anticonvulsants are chromatographed without further purification on a 3% OV 17 column either with or without derivative formation by means of "on-column" methylation. Multiple internal standards are employed in order to enhance the reproducibility of drug-concentration measurement.

Anticonvulsants↗