Biomedical subjects

M Reim

Publications and source records attributed to M Reim.

At least 127 records · Page 7Linked to original sources

PubMed1992

[Surgical anatomy, physiology, biochemistry and questions on the inlay technique].

The chemical identification of collagens and proteoglykans adds to the knowledge of the fine structure of the cornea as seen in histological sections and with the electron microscope. Chemical properties of collagens and proteoglykans help to understand the microscopical appearance of the tissue and some special functions of the cornea, such as transparency, stromal hydration, cohesion, elasticity and shear force resistance. Understanding mechanical properties of the cornea may be valuable for corneal and especially refractive surgery. A review of recent literature on intrastromal implants to be used for optical correction of refractive errors showed, that the resulting problems of corneal nutrition and also those of hydration may be solved by the time. But presumably proteolytic processes around intrastromal implants still prevent longterm tolerance of such implants.

Biomechanical Phenomena↗

PubMed1991

Retinal blood flow in diabetic children and adolescents.

A total of 209 diabetic children and adolescents aged 6-17 years (mean, 12.6 +/- 2.3 years) were examined by ophthalmoscopy, video fluorescein angiography and hemoglobin (HbA1c) test. Microaneurysms were found in 26% of the children (ophthalmoscopy, 11%; angiography, 23%). The prevalence of retinopathy was 16% in patients aged 6-10 years, 27% in those aged 11-13 years and 36% in those aged 14-17 years. Only five diabetics aged 11-17 years showed lesions other than microaneurysms (hard exudates, intraretinal hemorrhages or retinal capillar leakage). Retinal blood flow was quantified using video fluorescein angiography. The arm-retina time (ART) and the arteriovenous passage time (AVP) as parameters of the retinal microcirculation were obtained using an image analysing system. The mean value for ART was 9.7 +/- 2.5 s and that for AVP was 1.43 +/- 0.52 s. AVP was significantly shorter in diabetic children and adolescents with good glycemic control (HbA1c, less than 7%; AVP, 1.35 +/- 0.44 s) than in those with bad glycemic control (HbA1c, greater than or equal to 9%; AVP, 1.65 +/- 0.51 s).

Adolescent↗

PubMed1991

Retinal capillary blood flow measurement with a scanning laser ophthalmoscope. Preliminary results.

The scanning laser technique in combination with digital image analysis allows direct objective measurement of flow velocities in perimacular capillaries. In addition, the complete macular network of capillaries can be observed. By means of digital frame-to-frame picture analysis of digital recordings, blood flow velocities and morphologic data have been measured. The mean flow velocity in perimacular capillaries observed with the scanning laser ophthalmoscope in healthy subjects (n = 21) amounted to 3.28 +/- 0.45 mm/second. In patients (n = 13) with diabetes mellitus (no or background retinopathy), the mean flow velocity was significantly reduced (2.89 +/- 0.57 mm/seconds) compared with healthy subjects. Morphologic data of the perifoveal capillary bed showed a significant reduction of capillaries in patients with diabetes mellitus when compared with healthy subjects.

Adult↗

PubMed1991

[Collection and processing of ophthalmologic findings with a personal computer].

In a recently presented paper we proved that it is easy possible to store and analyse data form patients in a strabological department by using purchable data base programs and personal computers. The new program, we now use, has the opportunity to show all inputs in a special data field (i.e. the diagnosis field) in alphabetical order on the screen. For standardization in the data file we have created a special record. In all fields all possible and allowed inputs are entered. When entering new data of a patient, the user only has to select and to transfer the data from one field into the other. This has three advantages: 1. Time is saved when entering data, because it is not necessary to encode the data in an alphanumerical code. 2. The presentation of the data on the monitor is easy understandable. 3. It is not possible to enter no standardized data.

Electronic Data Processing↗

PubMed1991

[Silver nitrate burn after Credé's preventive treatment. A roentgen analytic and scanning electron microscopy study].

Following Credé's prophylaxis with silver-nitrate, the cornea of a newborn presented greyish-brown, lime-like plaques on the nasal part of the right eye. A paracentral ulcerating stromal opacification undermined these appositions, when the patient was admitted to the eye-clinic at Aachen. In the material taken in a lamellar keratectomy scanning electron microscopical examination was able to prove the existence of granules, previously described in light-microscopy. These granules measured 100 to 300 nm in diameter and were placed up to 110 microns deep into the corneal stroma of the specimen. An earlier chemical analysis of necrotic material showed no silver specific reaction. By means of EDX-Analysis these granules could be identified as silver-containing. This was once reassured by a newly developed modification of van-Kossa's-staining-method. The fact that the granular deposits contained mainly silver proves that the onset of a sodium-chloride-irrigation did not promote an intended therapeutic silver-chloride-precipitation and therefore had no effects on the silver-nitrate's penetration abilities. Injuries by silver-nitrate-solutions used for Credé's prophylaxis are seldom but still reported. The mechanism of injury in this case of a child, born by sectio remains unknown. Neither the use of an unusual silvernitrate solution, that was taken from a disposable ampoule (Mova-Nitrat) was reported, nor any corneal injury during sectio mentioned.(ABSTRACT TRUNCATED AT 250 WORDS)

Burns, Chemical↗

PubMed1991

[Hemodynamic findings in patients with retinitis pigmentosa].

The hemodynamic status of 26 patients with retinitis pigmentosa was examined using video fluorescein angiography. The hemorheological parameters hematocrit, plasma viscosity, erythrocyte aggregation and erythrocyte rigidity were determined. The results were compared to a matched pairs-group. Video angiography showed for retinitis pigmentosa patients a normal arm-retina time and a significant increase of the arteriovenous passage time. The rheological parameters for both groups were within the reference range. Interestingly the hemodynamic disturbance of microcirculation could be demonstrated already in early stages with no ophthalmoscopic symptoms and no atrophy of retinal vessels detectable at the time. The results indicate that disturbance of the retinal hemodynamics in early stages of retinitis pigmentosa may play a role in the pathogenesis of the disease.

Adolescent↗

PubMed1991

[Testing vision in children].

Measurement of visual acuity in children is more difficult than in adults. Children tend to riet when the threshold is reached and become inattentive. However the exact determination of visual acuity in children is important in some situations (Screening, Amblyopia). In this paper we examined whether an automated procedure is more exact than measurement by an examiner. Three series of experiments were done. In n = 173 we measured visual acuity first by an examiner using an optotype projector and second by an automated procedure (computer, keyboard, television screen). Both, the examiner and the computer used the same test-procedure and threshold criterion (DIN-Norm). The correlation coefficient was 0.84. In n = 53 children (age 4 to 7) visual acuity was measured by an examiner without a special strategy. Afterwards visual acuity was measured by the automated procedure. The correlation coefficient was 0.1. In n = 63 children (age 5-7) visual acuity was measured by an examiner using a strategy and a threshold criterion. Afterwards the automated procedure was used. The correlation coefficient was 0.69. The results show, that without a strategy and defined threshold criterion it is not possible to compare the measurements of visual acuity in different times. An automated procedure presented in this paper guaranties constant test conditions in an optimal way.

Adult↗

PubMed1991

[Video fluorescein angiography studies in acute anterior ischemic optic neuropathy].

Acute anterior ischemic optic neuropathy (AION) is a circulatory disorder of the short posterior ciliary arteries and their branches. 74 patients with AION were examined with video fluorescein angiography for disturbance of the retinal circulation. The armretina time (ART) was slightly (15%, p less than 0.01) increased in patients with AION (12.9 +/- 3.9 s) as compared to healthy persons (11.2 +/- 3.3 s). The prolonged ART was more prominent in the 26 (35.1%) diabetic patients (14.2 +/- 3.9 s). Because of the ART being only moderately prolonged and since the Doppler ultrasonography of the carotid arteries showed in only 3 patients an occlusion or a hemodynamically relevant stenosis of greater than or equal to 50%, prolonged ART may play a considerable role in the course of AION in only few patients. The retinal arteriovenous passage time (AVP) is considerably (77%, p less than 0.01) increased in AION (2.57 +/- 0.89 s) as compared to healthy persons (1.45 +/- 0.40 s). In patients with duration of symptoms less than 10 days (2.78 +/- 0.96 s) the AVP was increased (p less than 0.01) as compared to patients with duration of symptoms between 11 and 30 days (2.11 +/- 0.46 s). The comparison between the eye with AION and the not affected eye showed no difference in ART but an increase of AVP in the eye with AION. The AVP in AION patients without and with diabetes was not different. No differences in ART and in AVP were found between arteriitic and non-arteriitic patients with AION. The results indicate that the retinal microcirculation is disturbed in patients with arteriitic and non-arteriitic AION. This condition may worsen the in AION affected microcirculation of the optic nerve head through the mechanism of decreased blood flow in the retinociliary anastomoses.

Aged↗

PubMed1991

Retinal circulation times in diabetes mellitus type 1.

Video fluorescein angiography was performed in 124 patients between 18 and 65 years of age (mean 35.0, SD 12.3 years) with juvenile-onset, insulin-dependent diabetes mellitus (type 1). The arm-retina time (ART) and the retinal arteriovenous passage time (AVP) were measured by means of a picture analysis system to quantify the retinal microcirculation. Glucose metabolism was assessed by the blood level of haemoglobin A1c. The ART 11.5, SD 3.4 s) was similar to that in normal persons (11.2, SD 3.3 s), while the AVP was significantly longer in the diabetics (AVP = 2.35, SD 0.87 s) than in normal persons (AVP = 1.45, SD 0.40 s). The patients with severe diabetic retinopathy showed the most impressive change in AVP. The diabetics with good glycaemic control, that is, with glycosylated haemoglobin (HbA1c) less than or equal to 8.0 g/dl, had a shorter AVP than patients with bad glycaemic control (HbA1c greater than or equal to 9.5 g/dl). The group with a history of diabetes for less than five years showed circulation parameters similar to those of normal persons. The AVP in this group was significantly shorter than in groups with a history of diabetes for five or more years.

Adolescent↗

PubMed1991

Retinal microcirculation in patients with diabetes mellitus: dynamic and morphological analysis of perifoveal capillary network.

The new scanning laser technique allows one to quantify the retinal microcirculation. A digital image analysing system was used to study capillary blood flow velocities and morphological parameters of perifoveal intercapillary areas and foveal avascular zones in normal and diabetic subjects. Diabetic patients showed a significant reduction in capillary blood cell velocities in comparison with normal subjects. Perifoveal intercapillary areas and foveal avascular zones were significantly increased in all stages of diabetic retinopathy, and both parameters increased with progressing diabetic retinopathy. Significant changes in the perifoveal intercapillary areas were observed between normal subjects and patients with no retinopathy.

Adult↗

PubMed1991

[Hemodilution in patients with central retinal vein thrombosis. A placebo-controlled randomized study].

A randomized placebo-controlled study was conducted in 40 patients with acute retinal vein occlusion, 19 of whom received iso-(Hct greater than or equal to 42%) or hypervolemic (Hct less than 42%) hemodilution over 10 days with daily infusion of 250 ml hydroxyethyl-starch (MW 200,000/0.5, 10% HAES-steril) in combination with pentoxifylline (oral: 1200 mg/day; i.v.: 300 mg/day; Trental). After this 10-day trial of hemodilution rheological therapy was continued with pentoxifylline (oral: 1200 mg/day; Trental). The control group of 21 patients received no hemodilution or rheological therapy. After 10 days 35 patients underwent laser coagulation. Clinical, hemodynamic and rheological data of all patients were recorded before therapy, after 10 days but before laser coagulation, and after 6 weeks. In the group treated with hydroxyethyl-starch in combination with pentoxifylline, 10 patients had an improvement of central vision by two or more lines after 6 weeks. In the control group only 4 patients showed central vision improved by two or more lines after 6 weeks. In the treated group the retinal circulation and rheological data were significantly improved after 10 days of hemodilution therapy.

Adult↗

PubMed1991

[Hemodilution in acute arterial circulatory disorders of the retina].

20 patients (age: 68 +/- 9 years) with an acute central artery obstruction of the retina were examined in a prospective study. All patients received a hyper- or isovolemic hemodilution depending on the haematocrit value for a period of 10 days. Clinical, hemodynamical and rheological data of these patients were recorded before therapy, after 10 days and after 6 weeks. Under this therapy, 10 patients presented an improved central vision by 2 or more stages. The degree of the distributed circulation can be determined by means of the arteriovenous passage time (AVP) and the dye bolus velocity (MDV). Compared to a control group, a significantly increased arterious-venous passage time and decreased dye bolus velocity can be observed initially. The values after 10 days of therapy and after 6 weeks were significantly improved (p less than 0.01) compared to the initial values.

Aged↗

PubMed1991

[Retinopathy as the first symptom of hairy cell leukemia].

Hairy cell leukemia is a seldom non-Hodgkin-lymphoma of the B-cells. The case of a 39 year old male with loss of vision as first sign of hairy cell leukemia is presented. The decrease of vision was caused by intraretinal bleeding into the macula. By means of ophthalmoscopy and angiography we found intraretinal bleedings, soft exudates, microaneurysms and capillary occlusions. The examination of blood cells showed leucocytosis (48.900/microliter), anemia (hemoglobin 8.7 g/l), thrombocytopenia (67.000/microliter) and hairy cells in peripheral blood and in bone marrow. Under treatment with alpha-Interferon visual acuity became normal and the fundus lesions decreased. This case points out that a retinopathy with bleedings and soft exudates can be caused by leukemia which should therefore be excluded by differential blood count.

Adult↗

PubMed1991

[Rheologic findings in patients with diabetic retinopathy].

The rheological parameters hematocrit, plasma viscosity, red blood cell aggregation and blood cell rigidity were measured in 256 adult-onset (type II) diabetics. The stage of diabetic retinopathy was graded by means of ophthalmoscopy and videofluorescein angiography. The mean values of hematocrit (men 45 +/- 5%, women 42 +/- 5%) and red blood cell rigidity (1.01 +/- 0.08) were equal to those in normal subjects. Plasma viscosity (1.40 +/- 0.10) mPas, normals: 1.24 +/- 0.05 mPas) and red blood cell aggregation (16.0 +/- 4.2, normals: 14.6 +/- 3.2) were increased over the values in normals. The groups with different stages of diabetic retinopathy showed no difference in all rheological parameters. Plasma viscosity and red blood cell aggregation were determined partly by the levels of the large plasma proteins. In the type II diabetics fibrinogen was the most markedly elevated large plasma protein (4.1 +/- 1.2 g/l, normals: 3.2 +/- 0.6 g/l). Significant correlations were found between plasma viscosity and fibrinogen (0.49); plasma viscosity and alpha-2-macroglobulin (0.33); red blood cell aggregation and alpha-2-macroglobulin (0.28); and red blood cell aggregation and immunoglobulin M (0.25). The elevation of red blood cell aggregation and plasma viscosity may be one of the reasons for disturbed microcirculation and fundus changes in diabetic retinopathy.

Adult↗

PubMed1991

[Conjunctival microcirculation and hemorheology in patients with venous occlusions of the retina].

Forty-two patients with branch vein or central retinal vein occlusion were enrolled in this randomized placebo-controlled study. We studied the influence of hemodilution therapy with hydroxyethyl-starch (HAES-steril) combined with pentoxifylline (Trental) for 6 months. In the bulbar conjunctiva, capillary red blood cell (RBC) velocities and vessel diameters and rheological parameters of hematocrit, erythrocyte aggregation and plasma viscosity were examined. In the hemodilution group we observed no changes in vessel diameter and a significant increase in RBC velocity after therapy. After 6 weeks the RBC velocity showed 30% higher values but there was no statistically significant difference. After hemodilution therapy hematocrit, erythrocyte aggregation and plasma viscosity were significantly different from those in the control group. After 6 weeks we observed significant differences only in erythrocyte aggregation. This examination verifies the positive influence of hemodilution therapy on microcirculation and hemorheology.

Adult↗

PubMed1991

[Thrombolytic treatment of retinal arterial occlusions with plasminogen activator].

Tissue-type plasminogen activator (rt-PA), a gene-technologically manufactured fibrinolytic compound, has been employed successfully for treatment of cardial and peripheral arterial vascular occlusions. The advantage of this compound is its lytic effect. It selectively displays its effect in therapeutic dosage on fresh thrombuses, showing only minimal influence on physiological clotting as such. Two patients with stop of the retinal arterial bloodflow in videofluorescence angiography were treated with short term lysis with 100 mg rt-PA, the onset of therapy was 7 and 6.5 hours after loss of vision. Already during the infusion of the compound reperfusion was achieved. Inspite of the relatively late onset of treatment, the visual fields of both patients improved. We assume lytic therapy with rt-PA to be an effective therapy for patients with retinal arterial occlusion, if applied within the first eight hours after acute loss of vision. The number of patients who could potentially benefit from this therapy is limited considering the high rate of spontaneous reperfusion before the first eye exam in 84% of the cases and considering the manifold contraindications for this therapy: 35% of the patients above 70 years of age, 56% of the patients with arterial hypertension (RR 160/100 and above) as well as 10% of the patients treated with Coumarine-derivatives should not undergo lysis. Only 43% of the patients with occlusion of central retinal artery and 21% of the patients with occlusion of retinal branch arteries received the first eye exam within the first 8 hours after the occlusion.

Adult↗

PubMed1991

[Measuring electrical impedance in normal and pathologic corneas].

With a new technique the impedance of 89 normal and 7 severely damaged corneas was determined in vivo to look into the correlation between impedance and corneal cell damage. We found highly significant differences in impedance between normal and pathologically altered corneas. At 500 Hz frequency the impedance of normal corneas was 53.6 kOhm while the impedance of burned corneas only averaged 8.0 kOhm. There seems to be a correlation between the degree of pathological alteration of the corneal tissue and impedance as measured with this technique. The electrode head used allows fast, reproducible measurement of corneal impedance without any strain on the patient. Further studies must elucidate whether the method can be used as an early indicator of corneal damage before the onset of macroscopic change.

Burns, Chemical↗

PubMed1991

[Differential intraocular tumor diagnosis in MRI using gadolinium DTPA: value in comparison with other ophthalmologic examination procedures].

To improve the tissue characterizing information obtained by MRI we examined 35 patients with 43 different intraocular lesions by applying Gadolinium-DTPA for the first time. Histology was available in seven cases. Twenty patients were diagnosed as having a malignant uveal melanoma, 2 had a melanoma of the ciliary body and the iris, 3 patients were found to have a naevus of the uvea and 3 patients suffered metastatic uveal infiltrates, 4 patients had a senile maculopathy and 10 patients had either a vitreal or a subretinal haemorrhage, 1 patient had an angioma and another a lymphoma of his vitreous. Ruthenium plaques were applied to 13 out of 20 melanoma patients. These patients were followed-up by MRI examinations at regular intervals after therapy. The pretherapeutic signals of melanotic melanomas were high before applying Gadolinium-DTPA and demonstrated a further increase after contrast enhancement. Following ruthenium therapy the drop of the precontrast signal was more pronounced than the postcontrast signal. In complicated clinical situations MRI offers additional information to enable the differentiation between intraocular tumors and haemorrhages.

Adult↗