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Biomedical subjects

F Koerner

Publications and source records attributed to F Koerner.

At least 55 records · Page 3Linked to original sources
PubMed1989

[Clinical diagnosis of proliferative vitreoretinopathy].

The clinical features of a proliferative vitreoretinopathy (PVR) are systematically described. The patient's history reveals moderate lost of vision and metamorphopsia. Ophthalmoscopy, biomicroscopy of the fundus with the contact lens, and black-and-white photography usually lead to the correct diagnosis. Early stages of PVR are characterized by increased reflectance and a cellophane appearance of the inner retinal surface and tortuosity of both small and larger vessels. Advanced epiretinal tissue formation causes development of surface wrinkling and single or multifocal star-folds. In cases of retinal detachment with PVR, the retina is immobile, the detachment being concave due to traction or bullous if there are secondary breaks. In the final stages of posterior and/or anterior PVR the detached retina forms a narrow or closed funnel.

Fluorescein Angiography↗
PubMed1988

[Proliferative vitreoretinopathy: relation to the extent of retinal detachment, size of retinal tears and coagulation surface].

Preretinal dispersion of stimulated RPE cells has been suggested as a possible cause of the development of proliferative vitreoretinopathy (PVR). Retinal detachment (RD) and retinal breaks are associated with an exposure of corresponding areas of retinal pigment epithelium (RPE) which has been mechanically stimulated by coagulation. In a prospective, controlled study of 141 patients between 20 and 75 years of age, PVR grades were determined before and RD surgery and within six months following it PVR grades were correlated with the extent of RD, size of breaks, and area of coagulation. The severity of the PVR correlated significantly with both the extent of RD as well as the total number of coagulation exposures. There was a tendency toward higher grades of PVR with larger retinal breaks. The results are compatible with the hypothesis that at least certain variations of PVR are caused by preretinal dispersion of stimulated RPE cells.

Adult↗
PubMed1986

Retinopathy of prematurity: the influence of gestational age and retinal maturity on the statistical behavior of risk factors.

The clinical and laboratory data on 140 premature infants, 74 cases with retinopathy of prematurity (ROP) and 66 control cases without ROP, were correlated with ROP grades of increasing severity. By using multiple linear regression (MLR), it is shown that for predicting ROP grades the importance of certain variables varies considerably depending on the gestational age. Below 32 weeks of gestation, acidosis, hyperoxemia, gestational age, pathologic paCO2 levels, and multiple birth are strong regressors. Above 31 weeks, the most important regressors are multiple birth and acidosis, while gestational age and duration of FiO2 greater than 0.4 are much less influential. Blood transfusions and artificial ventilation do not seem important in the MLR of either group. When ROP is regressed on the number of paO2 values above 100 torr and gestational age or on the number of paCO2 values above 50 torr and gestational age, the regression coefficients of these variables drop to near zero at a gestational age of about 32 weeks. This loss of weight of the two variables paO2 and paCO2 with increasing gestational age coincides with a comparable drop of the relative incidence of ROP and the relative incidence of immature retinal vessels. It is hypothesized that it is the proportion of infants with an immature retinal vasculature in populations of given gestational ages rather than the gestational age itself which is responsible for the widely varying importance of certain factors during the development of ROP.

Gestational Age↗
PubMed1986

Incidence of retinopathy of prematurity in low birth weight infants with peri-intraventricular hemorrhage.

Data from 80 high-risk low birth infants were analysed to determine whether there is a clinical association between Retinopathy of Prematurity (ROP) and Peri-Intraventricular Hemorrhages (PIVH) in preterm newborns. Diagnosis of retinopathy was made by retinal examination at approximately four weeks of age. All infants were routinely and repeatedly scanned by real-time ultrasound to diagnose the presence of Peri-Intraventricular Hemorrhages. PIVH was clearly present in 41 (51.2%) of them, whereas 39 (48.7%) infants had no evidence of intracerebral bleeding. We found no statistically significant association between cicatricial retinopathy and PIVH (P = 0.1). We suppose therefore, that the sensitivity of retinal vasculature and cerebral vasculature to the various factors considered to be important in the development of PIVH is different.

Cerebral Hemorrhage↗
PubMed1985

Inflow and outflow relations after intraocular fluid-Healon exchange in a case of chronic ocular hypotension.

A 47-year-old patient was legally blind in her only eye for months due to long-lasting ocular hypotension following chronic uveitis and several operations for cataract and secondary glaucoma. With injections of 0.7 to 2.5 cc 1% Healon into the anterior chamber and vitreous cavity at intervals of 2 to 12 months, intraocular pressure levels between 5 and 12 mmHg could be maintained resulting in an improvement of the visual acuity up to 25/100. The treatment has been continued for over 5 years. A positive correlation was found between the volume of injected Healon and the integral of intraocular pressure over time, and between visual acuity and pressure level. Reduced aqueous flow, high trabecular outflow resistance, and a low rate of clearance of Healon from the vitreous cavity is obviously responsible for the long-lasting elevation of low intraocular pressure levels and for the restoration of useful vision.

Blindness↗
PubMed1985

Calcium dobesilate in diabetic retinopathy. A retrospective controlled study.

The effect of calcium dobesilate (Doxium) therapy on the evolution of diabetic retinopathy has been assessed in a retrospective study. 54 patients with diabetic retinopathy received calcium dobesilate (average 650 mg/day) for 6-30 months (average 18 months) and were compared to a correspondingly selected control group. The patients were divided into three subgroups (mild, moderate, and severe diabetic retinopathy). Microaneurysms, blot hemorrhages, striate hemorrhages, and hard exudates were assessed semiquantitatively from panorama fundus photographs, using a scoring system. The effect of calcium dobesilate was statistically significant for cases with moderate background diabetic retinopathy on summing up the scores of the various retinal lesions. There was no favorable effect on diabetic maculopathy or visual acuity. In the proliferative stages of diabetic retinopathy, photocoagulation is offering, in the majority of cases, the only chance to slow down the progression of this disease; however, drug therapy might be beneficial in nonproliferative diabetic retinopathy.

Adolescent↗
PubMed1984

Retinopathy of prematurity: a risk factor analysis with univariate and multivariate statistics.

Seventy-three out of 639 ophthalmoscopically examined newborns (11.4%) showed varying degrees of retinopathy of prematurity (ROP). Three infants were blind (0.5%). Sixty-six patients were matched with controls according to gestational age, birth weight, birth date and neonatal unit. Using univariate statistics, the variables representing the extent of O2-exposure, elevated paO2, elevated paCO2, paCO2-fluctuations, acidosis, blood transfusions, and artificial ventilation were found to be significantly associated with ROP. In contrast, the variables representing hypocapnia, Hb-levels, parenteral fluid administration and fluid retention showed no correlation with ROP. When a multivariate statistical method was used, the variables representing gestational age, elevated paO2, elevated paCO2 and paCO2-fluctuations as well as the ones defining blood transfusions lost their association with ROP. Episodes of acidosis, multiple birth, birth weight, total hours with Fio2 greater than 0.4, and total duration of artificial ventilation remained in the regression, and hypocapnia gained a significant negative correlation with ROP. This comparative survey based on univariate and multivariate statistics demonstrates that significance levels of identically defined biological and therapeutic variables obtained from the same population of patients are to be interpreted with caution. This fact may also explain contrasting opinions on risk factors in the literature. Multivariate statistical analyses are useful for a relative comparison of significance within a given set of variables. Conclusions on a possible causal relationship as well as on prophylactic measures are not possible.

Humans↗
PubMed1983

Plasma fibronectin concentration in animal models of sepsis and endotoxemia.

Plasma fibronectin is a nonspecific opsonin which mediates phagocytosis of particulate matter by macrophages. Fibronectin depletion results in depression of reticuloendothelial system phagocytic function. This may potentiate microvascular embolization and sludging in critical illness. It has been hypothesized that sepsis is a major cause of fibronectin depletion. To explore this hypothesis, plasma fibronectin concentrations were measured in rats with intraabdominal abscesses and in rabbits subjected to the generalized Shwartzman reaction (spaced doses of endotoxin). In both groups of animals there was a significant increase (P less than 0.05) rather than decrease in fibronectin concentrations at times when sepsis and disseminated intravascular coagulation were manifest. This study does not support the hypothesized relationship between sepsis and fibronectin depletion. Until the kinetics of fibronectin production and utilization are further delineated, caution must be exercised in the interpretation of immunoreactive plasma fibronectin levels.

Abdomen↗
PubMed1982

Postoperative retinal fibrosis--a controlled clinical study of systemic steroid therapy.

In a prospective clinical trial, the effect of systemic steroids on the incidence and severity of retinal fibrosis following retinal detachment surgery was tested against placebo. Several grades of retinal fibrosis of various degrees of severity were defined prior to the study. The maximum postoperative incidence of eyes with any signs of retinal fibrosis was 65% (75.4% in the placebo group, 63.3% in the steroid group). A set of fibrosis criteria was identified that had a tendency to respond to systemic steroids with a statistical significance increasing with time. The majority of these steroid-responsive criteria was of a mild degree and located at the posterior pole. The mean visual acuity was significantly lower in eyes with retinal fibrosis. The effect of systemic steroids on retinal fibrosis tested under clinical conditions was considerably weaker than that known from experimental conditions with intravitreal injections of triamcinolone acetonide.

Adult↗
PubMed1982

[Retinopathy of prematurity (retrolental fibroplasia): old and new facts].

Retinopathy of prematurity (ROP) is found in 10% of patients in neonatological units. Most often, there is spontaneous restitution. Rarely, severe degrees develop (retrolental fibroplasia); occasionally, infants become blind even nowadays. The etiological role of oxygen is undisputed. Additional factors, however, are also found with significant frequency in the history of infants with ROP. These are elevated pCO2-values, an acidotic pH, and blood transfusions. These three parameters lead to increased availability of oxygen for the tissue. Data from animal experiments confirm this effect. The statistical significance of these factors is clear, whereas their clinical significance has not yet been proved. Probably, the most effective prophylactic measure for preventing severe degrees of ROP is the repeated examination of newborns presenting defined risks by especially trained ophthalmologists.

Animals↗
PubMed1980

[A safety suture for sclerotomy in vitrectomy (author's transl)].

A safety suture with twisted 6-0 silk material for immediate closure of a sclerotomy wound after pars plana vitrectomy is described. The needle is first carried about 5 mm intrasclerally toward the edge of the sclerotomy and, after an oblique pass across the scleral incision, another intrascleral passage of 5 mm follows on the opposite side (Fig. 1). Bimanual stretching of the safety suture (Fig. 2) by the assistant provides a watertight adaptation of the sclerotomy and facilitates the placing of about four 10-0 interrupted nylon sutures without loss of intraocular pressure. After closing the sclerotomy, the safety suture is cut close to the sclera, and the remaining end of the suture is gently pulled out of the sclera.

Humans↗
PubMed1978

[Retinal circulation time in diabetic retinopathy treated with photocoagulation (author's transl)].

A preliminary report is given on studies of the retinal circulation in diabetic retinopathy before and after photocoagulation treatment. The local retinal circulation time RCT of selected retinal areas was calculated by means of a fluorescein long-term infusion technique. In 7 eyes with diabetic retinopathy (DR) the mean RCT was significantly higher (2.0 +/- 0.58 sec. range 1.27-2.6) than in 15 control eyes (1.11 +/- 0.34 sec, range 0.50-1.82, Niesel 1976). Assuming an increase of blood flow in DR (L'Esperance 1971, Kohner 1975) the increase of RCT by a factor 2 would imply an increase of the vascular volume by a factor hardly less than 3 indicating the marked impairment of retinal hemodynamics in DR. After photocoagulation, the mean RCT was significantly shortened only in eyes with preoperative RCT values above 2 sec. The reduction of local RCT correlated with the extent of treated retinal areas. The cross-sectional area of the retinal veins measured near the optic disc was generally reduced independently of the extent of coagulation treatment. Taking also the obvious postoperative reduction of the total retinal vascular volume into account, photocoagulation resulted in a marked decrease of blood flow not only in extensively treated but also in areas with little coagulation effects. In DR the disturbed retinal circulation in general tends to normalize following extensive photocoagulation.

Blood Volume↗