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M Reim

Publications and source records attributed to M Reim.

At least 145 records · Page 8Linked to original sources
PubMed1990

Retinal circulation times in quantitative fluorescein angiography.

We tried to obtain an overview of the quantitative state of the retinal circulation. Optical density measurements by an image analyzer were performed on video fluorescein angiograms for the determination of dyedilution curves. To ensure that curves with a sharp peak were obtained, 1 ml sodium fluorescein 10% was flushed with 20 ml physiological saline. From dilution curves of a retinal circulation times, T(x) (x = 1, 25, 50, 75, and 100) and Tm, were calculated. T(1) corresponds to the difference in the time of initial dye appearance; T(50), to the so-called half-maxim time difference; T(100), to the difference in the time to peak intensity; and Tm, to the mean circulation time. T(50) showed the best reproducibility when it was examined at 49 retinal regions of 10 healthy volunteers with a double video-fluorescein angiogram that was obtained within 1 min. Normal values (mean +/- SD) at the temporal superior region of 37 healthy volunteers were as follows: T(1) = 0.87 +/- 0.66 s, T(25) = 1.52 +/- 0.48 s, T(50) = 1.83 +/- 0.50 s, T(75) = 2.12 +/- 0.56 s, T(100) = 2.73 +/- 0.76 s, and Tm = 2.69 +/- 1.25 s. We believe that these values give a general overview of the quantitative state of normal retinal circulation.

Adolescent↗
PubMed1990

[A new treatment concept for severe caustic and thermal burns of the eyes].

Combined surgical and drug therapy has proved efficacious in the treatment of severe eye burns. Initially, necrotic epibulbar tissue is excised. The sclera, denuded over a large area and in many cases ischemic, is covered with tenon flaps, prepared and advanced from the undamaged parabulbar connective tissue. For several months, artificial epithelium is used to protect the denuded and to a large extent acellular corneal stroma. Subsequently drug therapy, including corticosteroids, Healon, and prostaglandin synthesis inhibitors, is instituted to reduce the inflammatory reaction of the burned anterior segment. Regeneration of the conjunctival and later also the corneal epithelia may be improved by epidermal growth factor, autologous fibronectin, and proteinase inhibitors (Trasylol). This therapy avoids some complications which could not previously be influenced, and creates more favorable conditions for later corneal grafts.

Administration, Topical↗
PubMed1990

[The metabolism of organ cultures of cornea in TC 199 with added dextran 500 or hydroxyethyl starch 450].

Pig corneas were stored at room temperature for 20 days in TC 199 culture medium supplemented with 10% pig blood serum, antibiotics, and to reduce swelling with 10% Dextran 500 or 10% hydroxyethyl starch HAES 450. The high molecular weight of these additions, 500,000 and 450,000 Daltons respectively, prohibited swelling by their osmotic pressure. The water content of the cultured corneas was 80.6 +/- 0.5% with HAES 450 and 76.4 +/- 2.0% with Dextran 500. The epithelial cells of the cultured cornea rounded and desquamated after 12 to 16 days of culture. The endothelium showed vacuoles. The metabolism of the cultured corneas was measured by glucose and lactate levels in the epithelium, the stroma, and the medium as well as by the glycogen, ATP, and ADP content in the corneal epithelium. The cultured corneas consumed reasonable amounts of glucose and produced lactate. The glycogen content and the ATP levels decreased slightly, but the ATP/ADP ratio showed a good energy state. In the cultures containing HAES 450 the entire system was flooded with glucose released from hydroxyethyl starch. The Dextran 500 culture system could prove suitable for culturing human donor material without swelling.

Adenosine Diphosphate↗
PubMed1990

[Coincidence of hypertensive changes of the eye fundus and regulation disorders of peripheral microcirculation: I--Skin].

In cases of arterial hypertension, funduscopy is an established method of estimating systemic vascular lesions. In this study the relation between the extent of retinal vascular changes and dynamic processes in the microcirculation of the skin was investigated by nailfold capillaroscopy in 88 patients. With increasing vascular changes a progressive loss of vasodilator reserve and transcutaneous partial pressure was observed (no morphologic changes--fundus hypertonicus II--fundus hypertonicus III). It thus appears possible to evaluate the functional state of the macro- and microcirculation by funduscopy.

Adult↗
PubMed1990

[A method for recording the network topology of human retinal vessels].

Network analysis of the human retinal vessels must be based on a thorough knowledge of the topology of the network. This derives from the numerical composition of the network's individual components. Using histologic specimens, centrifugal and centripetal ordering methods were compared. It was found necessary to use an ordering system which takes both dichotomous as well as lateral branching into account, and Strahler's centripetal ordering system was found to be suitable. For various representative areas of human retinae it could be shown that the number of segments of each Strahler order forms an inverse geometric sequence which enables the Horton branching quotient RB to be calculated. It is thus possible to predict the number of vessel segments within the individual orders. Although the method ignores detailed vessel morphology, with knowledge of the vessel lengths and diameters determined in the same manner it enables the conductivity and resistance of human retinal vessels to be measured.

Blood Viscosity↗
PubMed1990

Particulate matter contamination in the corneal stroma of severe eye burns in humans.

Corneal buttons obtained from keratoplasty were examined by energy dispersive x-ray analysis (EDXA) combined with scanning electron microscopy (SEM). This method enables to assay the mineral composition of minute parts of tissue samples identified in SEM images. Samples were cut from paraffin embedded corneae, deparaffinized in xylol, dried in aceton, critical-point desiccated, covered by evaporating with a thin layer of carbon and examined by SEM. In healthy human donor eyes, only some iron particles had been found. In the 22 patients samples high amounts of different particles were identified, materials from rubber stoppers, chromesteel, titanium pigments, talcum, barium and glass. Furthermore a lot of different metal particles containing varying amounts of Na, Mg, Al, Si, P, S, Cl, K, Ca, Fe, Cu, Cr, Zn, La and Ce were detected. Some particles may be caused by the initial trauma, others by therapy. Such contaminations might have supported leucocyte and fibrocyte invasion increasing the inflammatory reaction in the burnt cornea.

Corneal Stroma↗
PubMed1990

Corneal silver deposits following Crede's prophylaxis an examination with electron dispersive x-ray analysis (EDX-analysis) and scanning electron microscope (SEM).

In a case of silver nitrate injury after Credé's prophylaxis, the cornea of a newborn presented yellow-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 obtained by 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. 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. 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 silver nitrate solution, that was taken from a disposable ampoule (Mova-Nitrat R) was reported, nor any corneal injury during sectio mentioned. Nevertheless the method of EDX-analysis and SEM proved the diagnosis of corneal silver deposits, so that the origin of the granullar opacification of the cornea could be determined.

Cornea↗
PubMed1990

Microvascular network topology of the human retinal vessels.

A quantitative analysis of blood flow in the human retinal vessels requires a detailed picture of the microvascular network topology. In order to lay the foundation for a quantitative microcirculatory network analysis of the human retina, a novel technique for tissue preparation and network characterization was developed. After injection of hydrogen peroxide into the human bulb, the microvasculature was filled with oxygen produced by endothelial catalase and visualized after embedding in a mixture of cedar oil and gum damar. The vessel topology was documented in the form of photomicrographs, which permitted complete reconstruction of the microvasculature on transparent overlays. By considering the complete capillary system it was possible to divide the retinal network into dichotomous, asymmetric arteriolar and venular trees. The Strahler ordering method, which considers both dichotomous and side branching configurations, was selected and applied to analyze the retinal vascular trees, using the capillaries as the zero order reference vessels. The number of vessel segments was found to be an approximate logarithmic function of the order number, in accordance with Horton's law. Vessel lengths within each order were found to be log-normal distributed, and median lengths for different orders could be approximated by a 2nd degree polynomial curve. Diameters within each order could be approximated by a Gaussian distribution, and the mean values for different orders could be expressed by an exponential curve. These data provide the basis for conductance, pressure and flow computations within the retinal microvessels.

Arteriovenous Anastomosis↗
PubMed1990

[Quantifying retinal capillary circulation using the scanning laser ophthalmoscope].

The quantitative picture analysis of video fluorescein angiograms allows one to evaluate retinal hemodynamics. However, this method does not permit us to quantify the retinal capillary perfusion. Now, for the first time, we are able to quantify capillary bloodflow directly and objectively by means of scanning laser ophthalmoscopy. Even the measurement of the bloodflow velocity in all capillaries is now possible. Using digital frame-to-frame picture analysis of digital recordings, bloodflow velocities can be measured on the basis of the movement of dye boluses.

Blood Flow Velocity↗
PubMed1989

Retinal and retinocortical times to pattern stimulation in amblyopic children.

In order to determine whether in amblyopes retinal conduction delays contribute to the cortical measureable delays in the visual evoked cortical potential (VECP), peak latencies of the pattern electroretinogram (ERG) are measured in amblyopic children. The results are compared with those of the normal fellow eyes and those of a healthy control group. Simultaneously the latencies in the VECP are recorded and the determination of the retinocortical times is performed. Statistically retinal b-wave (Q) and a-wave (P) of the pattern ERG of amblyopic eyes do not show significant delays of peak latency. In retincortical times, however, there are significant prolongations. During occlusion therapy retinocortical values of normal fellow eyes are also delayed in comparison with the control group. A pathological conduction delay of visual information on the retinal level up to the generators of the pattern ERG can thus be excluded in amblyopia. The total latency delay in the VECP of amblyopes consists solely in a prolongation of retinocortical times.

Adolescent↗
PubMed1989

Video fluorescein angiography: method and clinical application.

Video fluorescein angiography, combined with a picture analyzing system, is a clinically applicable, objective method of evaluating the retinal blood-flow parameters. Optical density measurements were performed on videorecordings of fluorescence angiograms by means of a picture-analyzing system in order to determine the circulation parameters of the retina. These included: the arm-retina time (ART), the arteriovenous passage time (AVP), and the mean arterial dye-bolus velocity (MDV). Normal values for these parameters were derived from measurements in 75 healthy volunteers. The mean arm-retina time (ART) was 11.2 +/- 3.3 s, the mean arteriovenous passage time (AVP) 1.45 +/- 0.4 s and the mean arterial dye-bolus velocity (MDV) 6.39 +/- 1.7 mm/s. No significant correlation could be shown between pulse or blood pressure and one of the retinal circulation parameters. A group of ten healthy volunteers was examined twice in order to obtain the intraindividual variation for the measuring parameters. The coefficient of variation for the ART was 18%, 10% for the AVP, and 26% for the MDV.

Adolescent↗
PubMed1989

[Tenonplasty as a new surgical principle in the early treatment of the most severe chemical eye burns].

A special danger in cases of severe chemical and thermal eye burns is the development of corneoscleral ulceration. To treat these most severe burns tenonplasty was developed as a new surgical treatment. The principle of tenonplasty is based on a plastic operation in which vital connective tissue of the orbit is used. First, all necrotic tissue is removed from the conjunctiva and sclera. The Tenon tissue is then bluntly separated from the equatorial region of the globe and from extraocular muscles. It is important to keep its blood vessels intact and to prepare the Tenon sheet with a smooth surface, because regenerating conjunctival epithelium has to slide on this layer. After preparation, the elastic Tenon flap can be moved to the limbus and sutured tightly to the sclera, thus providing a revascularization of the denuded sclera and the limbus region. In all patients the scleral ulceration healed and the eyes were saved from anterior segment necrosis. Although rapid regeneration of conjunctival epithelium on the Tenon layer always occurred rapidly, the cornea was completely covered by new epithelium in only a few cases: an artificial epithelium was therefore applied early in most patients. After tenonplasty and application of an artificial epithelium high local doses of corticosteroids can be given to suppress reactive inflammation and prevent neovascularization of the cornea.

Burns, Chemical↗
PubMed1989

[Automated measurement of distance vision based on the DIN strategy].

A method for automated measurement of far vision is described which meets the test requirements laid down in the new DIN standards. The subject sits 5 m from a high-resolution monitor on which either Landolt rings or Snellen's types are generated by a computer. By moving a joystick the subject indicates to the computer whether he can see the critical detail (e.g., the direction of opening of the Landolt ring). Depending on the subject's input and the course of the test so far, the computer generates the next test symbol until the threshold criterion is reached. The sequence of presentation of the symbols and the threshold criterion are also in accordance with the DIN standard. Initial measurements of far vision using this automated system produced similar results to those obtained by conventional methods.

Distance Perception↗
PubMed1989

[Video fluorescein angiography follow-up of patients with retinal artery occlusion].

Forty patients (age 67 +/- 9 years) with acute central artery obstruction (CAO; n = 20) or branch artery occlusion (BAO; n = 20) of the retina were examined in a prospective study. All patients received a hypervolemic or isovolemic hemodilution, depending on their hematocrit values, for a period of ten days. Clinical, hemodynamic, and rheological data of these patients were recorded before therapy, after ten days, and after six weeks. Under this therapy the central vision of 24 patients (CAO: n = 10; BAO: n = 14) improved by two or more stages. The extent of the circulatory disturbance was determined by arteriovenous passage time and dye bolus velocity. Compared with a control group, a significantly increased arteriovenous passage time and decreased dye bolus velocity were observed initially. The values after ten days of therapy and after six weeks were significantly improved (P less than 0.01) as compared to the initial values. Patients with longer latency showed almost normal retinal hemodynamics, even without therapy, after some weeks. However, in most cases the spontaneous improvement occurred too late. Therefore, it appears important to achieve early reperfusion by therapy.

Adult↗
PubMed1989

[Diverse ocular manifestations in Boeck disease].

The clinical picture of sarcoidosis varies widely; in many cases there are few symptoms. In cases where the initial symptoms of sarcoidosis are ocular the diagnosis can only be established if systemic disease is considered in differential diagnosis. Five cases with ocular manifestation and unusual findings or development are described.

Aged↗
PubMed1989

[Cell density of the corneal endothelium following cataract surgery].

Endothelial cell loss following extracapsular cataract extraction and implantation of a posterior chamber lens was studied and the influence of various factors analyzed. In 56 eyes, the mean reduction in cell density in the superior zone of the cornea was 19%. In the eyes with epithelial edema endothelial damage was more severe than average. Lower cell density was also found in particular in patients over 75 years old and those with pre-existing cornea guttata. In contrast, preexisting glaucoma, a history of corneal trauma, and, astonishingly, the surgeon's experience had no detectable influence on endothelial cell damage.

Aged↗
PubMed1989

[Effect of beta blockers on retinal hemodynamics. A double-blind study in healthy probands].

In a randomized double-blind study the effect of topically applied Timolol (Chibro-Timoptol 0.5%) on the retinal circulation was investigated. In order to quantify the retinal hemodynamics 20 healthy volunteers were examined twice using video fluorescein angiography. The arteriovenous passage time (AVP) and the dye bolus velocity (MDV) were quantified using an image-analyzing system. Following administration of Timolol, IOP decreased from 14.5 +/- 1.9 mm Hg to 9.4 +/- 1.7 mm Hg (P less than 0.010). The study also showed that there was a significant reduction in AVP from 1.75 +/- 0.5 s to 1.56 +/- 0.3 s (P less than 0.05) and an increase in MDV following local application of Timolol. No effect on systemic blood pressure or pulse rate was observed. The results indicate that in addition to its pressure-lowering effect, timolol also leads to increased retinal perfusion.

Adult↗