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Biomedical subjects

F Koerner

Publications and source records attributed to F Koerner.

66 records · Page 4Linked to original sources
PubMed1978

[Controlled suction in vitrectomy (author's transl)].

A peristaltic pump (type "Perpex", J. H. Guldener, Zürich, Switzerland) was modified for controlled aspiration in vitrectomy (fig. 1). The surgeon operates start, instantaneous stop and back flush with a single foot pedal. Suction and cutting device are controlled independently. Suction flow can continuously be varied between 0 and 16 ml/min (fig. 2). This less critical function is operated by the assistent. The upper limit of suction flow depends on infusion resistance and preselected differential pressure (fig. 3). The infusion resistance and its reciprocal, the inflow rate, vary considerably with different instruments. In four devices infusion resistance was measured and found to vary by a factor of up to 4.6. Low infusion resistance allows high suction flow and thus shorter operation time for certain conditions such as "ochre membranes" or intrasurgical bleedings. Further aids which we use in combination with a Zeiss OPMI-8 are an intense external xenon light source for variable slit illumination which makes the use of intravitreal fiber optics unnecessary, and a mirror combination to achieve an 11 degrees semi-coaxial stereoscopic view of the operation field for the assistent.

Eye Diseases↗
PubMed1977

Diabetic retinopathy study. Data acquisition and its reliability.

The documentation of ophthalmologic data of patients with diabetic retinopathy (DR) is described. Special attention has been paid to the standardized grading of opacities of the dioptric media as well as to the assessment of classified arteriolar abnormalities. The reproducibility of these judgments was determined by a double evaluation test. The reliability of the assessment of classified retinal lesions on panorama fundus photographs was reported elsewhere. A further section of the questionnaire that concerns the documentation of the patient's history, of general medical and laboratory findings, and of reasons why individual patients "drop out" from the study, is described in this contribution.

Animals↗
PubMed1976

Diabetic retinopathy study. Assessment and comparison of retinal lesions for computer analysis.

A method of documentation of a diabetic retinopathy (dR) is described. Panorama fundus photographs (PPhs) of each eye are taken every 3-6 months. The retinopathy is classified according to qualitative, quantitative, and topographic criteria. The retinal lesions are assessed according to a subjective grading scale. Data of direct readings and of comparisons between two PPhs of one eye are transferred to punch cards for storage and computer processing. In a double evaluation of 200 PPhs, the overall reliability of readings was found to be approximately 95%.

Diabetic Retinopathy↗
PubMed1976

Diabetic retinopathy study. Preliminary results from 215 patients treated uniocularly with photocoagulation.

Preliminary results of a controlled study on diabetic retinopathy are reported. Two hundred and fifteen patients with proliferative (PDR) and nonproliferative (NPDR) retinopathy were uniocularly treated by Xenon photocoagulation and followed for a minimum of 6 months--6 years. Intra- and epiretinal new vessel formations (RNF) decreased in treated but increased in untreated eyes at a high statistical significance. A transition of background retinopathy into the proliferative stage was significantly retarded after photocoagulation. An improvement of new vessel formations on the disc (DNF) was not evident after 3 years of follow-up. The progression of preretinal neovascularization (PRNF) was significantly reduced only for 1--2 years after treatment. The incidence of massive vitreous hemorrhages, however, which showed the highest quotient of contingency with PRNF was much lower in treated eyes also after 3 years. The difference was significant only in extensively photocoagulated eyes with more than 100 lesions on average. The effect of photocoagulation on diabetic maculopathy with preservation of a useful visual acuity was highly significant only in diabetics under 60 years of age, the effect increasing with time as the control eyes fared worse. By contrast, in patients over 60 years of age, the course of maculpathy was not influenced, and a linear decrease of visual acuity occurred in both treated and untreated eyes.

Age Factors↗
PubMed1975

Traumatic kidney rupture in hydronephrosis.

The hydrostatic pressure, intrapelvic volume, and specific elasticity and strength of strips of tissue from the parenchyma and the pelvis of eight hydronephrotic kidneys were investigated and compared with the tissue characteristics of the pelvis of four control kidneys. Hydronephorsis manifested itself by a sixfold reduction of tissue strength, and dynamically by a ninefold reduction of the energy absorptive capacity of the parenchyma as compared with the pelvis. Its further response to trauma appeared to be influenced by internal pressure, the law of mass variation, and the energy absorptive capacity of surrounding anatomical structures. The vulnerability of the hydronephrotic kidney in situ depends on its volume and topography, the parenchyma being the part that may be regarded as the site most predisposed to rupture.

Biomechanical Phenomena↗
PubMedDate not supplied

Ocular tilt reaction associated with a sudden idiopathic unilateral peripheral cochleovestibular loss.

We recently observed a female patient who was suffering from acute right peripheral cochleovestibular loss associated with a marked vertical diplopia. Otoneurological examination showed profound deafness, and absence of nystagmic response to caloric and pendular rotatory test in the right ear. Neuroophthalmological examination showed skew deviation with right hypotropia, excyclotorsion, and tilt of the static visual vertical directed to the right side. Immunological and serological examinations were normal. Neurological examination and extensive neuroradiological investigations failed to demonstrate any central nervous system involvement. In this patient, skew deviation and tilt of the static visual vertical were interpreted as signs of an acute unilateral otolithic dysfunction, due to a sudden idiopathic peripheral vestibular loss.

Diplopia↗
PubMedDate not supplied

A mydriatic eye-drop combination without systemic effects for premature infants: a prospective double-blind study.

Eye drops used for diagnostic mydriasis may produce systemic side effects in preterm infants. Studies on the pupil dilating and systemic effect of various mydriatic agents yielded conflicting results. We conducted a prospective randomized double-blind study on the systemic effect of two mydriatic eye-drop combinations. Thirty-nine preterm infants were randomly assigned to two groups. An eye-drop combination of 2.5% phenylephrine and 0.5% tropicamide (group D) was compared with the combination of 0.5% cyclopentolate and 0.5% tropicamide (group F). Either eye-drop combination was followed by 0.5% tropicamide given 20 minutes later. Heart rate (HR) and the systolic, mean, and diastolic blood pressure (BP) were recorded before and after eye-drop instillation and after ophthalmoscopy. A control session with NaCl eye drops was added for each infant. A significant increase of BP and HR peak values was observed within 7 to 10 minutes after the cyclopentolate/tropicamide combination only. On the other hand, the mydriatic effect of the phenylephrine/tropicamide combination was significantly superior to that of the cyclopentolate/tropicamide combination. We recommend the combination of 2.5% phenylephrine and 0.5% tropicamide to achieve a sufficient diagnostic mydriasis without systemic side effects in preterm infants.

Blood Pressure↗