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Biomedical subjects

O Brinchmann-Hansen

Publications and source records attributed to O Brinchmann-Hansen.

At least 37 records · Page 2Linked to original sources
PubMed1989

Reliable measurements from fundus photographs in the presence of focusing errors.

When measuring the width of the blood column and the superimposed central light reflex of retinal vessels from fundus photographs, we find that the measurements are affected by focusing error, unless certain steps are taken to reduce its effect. Thus, we recommend using a scanning microdensitometer to extract the density profile of the blood column from the negative, and convert the density profile to an intensity profile by means of the characteristic curve of the film. In this paper we model the imaging process on a computer, and find that the half value width of the intensity profile is relatively insensitive to focus error. However, the maximum intensity of the central light reflex is still sensitive to focus error. Both these results are in agreement with experimental studies.

Fundus Oculi↗
PubMed1989

Blood pressure, intraocular pressure, and retinal vessels after high altitude mountain exposure.

Identical test protocols were used before and after 2 to 7 weeks of high altitude exposure in 23 climbers participating in 3 separate mountain expeditions in the Himalayas. The three groups reached altitudes of 4,000 m, 5,200, and 5,850 m, respectively. High altitude retinal hemorrhages (HARH) were found in three subjects (13%). Two weeks after the mountain exposure, reduced mean values of systolic (p less than 0.005) and diastolic (p less than 0.05) blood pressure and intraocular pressure (p less than 0.005) were found. Retinal veins were dilated 2.6% (p less than 0.001), and in both arteries (p less than 0.001) and veins (p less than 0.005) we observed a tendency for small vessels to dilate and large vessels to constrict. The intensity of reflection of light ("the central light reflex") from arteries was reduced (p = 0.003), indicating hemorrheology changes in the vessels. This study shows that significant changes in blood pressure, intraocular pressure and retinal vascularity follow hypoxic and physical strain of high altitude. The vascular conditioning of altitude acclimatization can be demonstrated in the retinal circulation 2 weeks after the exposure.

Adult↗
PubMed1988

Transient proliferative diabetic retinopathy during intensified insulin treatment.

Two women aged 22 and 19 years who had had diabetes for 11 and four years, respectively, developed proliferative retinopathy after five to seven months of significantly improved metabolic control. They were participants in two separate prospective studies including 97 insulin-dependent patients. At inclusion, one patient showed minimal background retinopathy and the other showed no retinopathy. Their level of glycosylated hemoglobin was initially high (14.3% and 17.5%) but within five to six months had fallen by 5.7% and 7.5%. The improved metabolic control was obtained by home blood glucose monitoring and insulin pump in the older patient and by home blood glucose monitoring only in the other. By maintaining near normoglycemia, regression of the proliferative retinopathy was achieved. Photocoagulation was not performed. After five and two years of follow-up, respectively, only mild background retinopathy has been noted in both patients. We concluded that a significant lowering of blood glucose may provoke proliferative retinopathy and that sustained good metabolic control may reverse this retinopathy without photocoagulation.

Adult↗
PubMed1988

The response of diabetic retinopathy to 41 months of multiple insulin injections, insulin pumps, and conventional insulin therapy.

Forty-five diabetic patients were randomized and treated with continuous subcutaneous insulin infusion (CSII), multiple insulin injections (MI), or conventional insulin treatment (CIT) for 41 months. Near-normoglycemia was obtained with CSII and MI but not with CIT. A transient increase in microaneurysms and hemorrhages was seen at three months in CSII-treated patients. After 41 months, a moderate progression in microaneurysms and hemorrhages was registered, as assessed from fundus photographs, in all treatment groups. Fluorescein angiograms indicated a tendency (not statistically significant) to retarded progression of retinopathy in MI- and CSII-treated patients compared with CIT-treated patients. Soft exudates developed after three to six months of rapid tightening of metabolic control in 50% of patients on CSII and MI regimens. Those patients who had soft exudates had a slower progression of retinopathy three years later than those who did not develop soft exudates. Transient progression of retinopathy may be related to fluctuations in blood glucose levels, although a favorable effect of long-term improved metabolic control was not documented.

Adult↗
PubMed1988

Oscillatory potentials, macular recovery time, and diabetic retinopathy through 3 years of intensified insulin treatment.

Forty-five diabetic patients, 18 to 45 years of age, with mild or no retinopathy, were randomly assigned to continuous subcutaneous insulin infusion (CSII), multiple injections (Mls), and conventional insulin treatment (CIT). The effects of near-normoglycemia (CSII and MI) on oscillatory potentials (electroretinography [ERG]) and macular recovery time (nyctometry) were studied prospectively for 41 months. Before randomization, the amplitudes of oscillatory potentials were negatively correlated to age (P = 0.002) and positively correlated to the diameter of retinal veins (P less than 0.05). Men had shorter macular recovery time than women (P = 0.03). Nyctometry and oscillatory potentials were not related to mean blood glucose values, glycosylated hemoglobin (HbA1), retinopathy, blood pressure levels, or duration of diabetes. Changes in metabolic control (MI and CSII; P less than 0.01) and in microaneurysms and hemorrhages (CSII and CIT) during the study did not affect oscillatory potentials or nyctometry. Soft exudates (15 patients) and proliferative retinopathy (1 patient) transiently developed with MI and CSII regimens. No changes in oscillatory potentials or nyctometry were observed and no pretreatment characteristics of these parameters predicted the occurrence of these ischemic lesions. At the stage of proliferation, however, lowered amplitudes of oscillatory potentials and lengthened macular recovery time were observed.

Adult↗
PubMed1988

Effects of intensified insulin treatment on retinal vessels in diabetic patients.

Forty-five diabetic patients were randomly assigned to treatment with continuous subcutaneous insulin infusion (CSII), multiple injections (MI), and conventional insulin treatment (CIT). They were prospectively followed up for one year. A computerised scanning microdensitometer was applied on fundus photographs of retinal vessels, and we studied changes in calibres of the blood column (W0) and in width (Wr/W0) and intensity (Ir) of the central 'light reflex'. After six months of improved metabolic control the Ir was reduced in both MI and CSII cases compared with CIT cases (p less than 0.01), indicating haemorrheological changes in the retinas. Within these six months cotton-wool spots appeared in half the patients (n = 15) on CSII and MI, but not in CIT patients. Subjects who developed cotton-wool spots, compared with those who did not, had greater intensities of reflection and larger calibres of vessels at the start of the study (p less than 0.01). On intensifying the treatment they were characterised by a larger fall in hemoglobin A1 (p less than 0.01) and by a larger decrease in Ir on arteries (p less than 0.05) and veins (p less than 0.01). The behaviour of the retinal circulation is different in patients developing transient ischaemic lesions on intensified insulin treatment from its behaviour in those who do not.

Adolescent↗
PubMed1987

The light reflex in retinal vessels and its relation to age and systemic blood pressure.

The light streak characteristics on retinal vessels were studied by microdensitometry on fundus photographs. We compared the width and the intensity of the reflex in a young group (mean: 19.7-year-old; n = 40) and in an older group (mean: 45.3-years-old; n = 22) of normal subjects. By subgrouping according to age and blood pressure levels, we studied possible effects of these parameters on the light streak. We found higher intensity of reflection from both arteries and veins in the older group (P less than 0.01). This effect seemed mostly related to the age of the subjects. We also registered a relation between systolic blood pressure and intensity of reflection from veins in the young group (P less than 0.03). Optical changes in the vessel walls in the ageing process and intravascular pressure effects on the indices of refraction in the erythrocytes/plasma may account for these findings. The width of the reflex was not found to be related to either the age or the blood pressure level of the subjects.

Adolescent↗
PubMed1987

The central light reflex of retinal arteries and veins in insulin-dependent diabetic subjects.

The width (Wr/Wo) and the intensity (Ir) of the central light reflex were studied on retinal arteries and veins in insulin-dependent diabetic patients. A diabetic group (n = 45) was compared to normal subjects (n = 57), and the groups were matched according to age and blood pressure levels. A computerized scanning microdensitometer was applied across various sites on vessels in fundus photographs. The Ir of the reflected light was significantly reduced in diabetic arteries and veins compared to the vessels in the control group (P less than 0.001). This may implicate abnormalities in blood rheology of the retinal circulation in diabetes. The Wr/Wo was found narrower in veins in diabetic patients (P less than 0.001). This probably indicates differences in haemodynamics of venous flow in diabetic and normal subjects. The intensity was correlated to the duration of diabetes (P less than 0.05), while neither the width nor the intensity were found related to sex, metabolic control, intraocular pressure or retinopathy.

Adolescent↗
PubMed1986

Effect of near normoglycaemia for two years on progression of early diabetic retinopathy, nephropathy, and neuropathy: the Oslo study.

Forty five insulin dependent diabetics were randomised to treatment with continuous subcutaneous insulin infusion (CSII), multiple insulin injections (five or six daily), or conventional twice daily insulin injections. Near normoglycaemia was obtained with CSII and multiple injections but not with conventional treatment (p less than 0.01). Hypoglycaemic coma was observed less frequently with CSII than with multiple injections and conventional treatment (p less than 0.001), but blood glucose concentrations below 2.5 mmol/l (45 mg/100 ml) were more common. After two years fewer retinal microaneurysms and haemorrhages had developed in the patients given CSII and multiple injections compared with those given conventional treatment, in whom the number had increased significantly (p less than 0.01). Motor nerve conduction velocity deteriorated in the patients given conventional treatment; in those given CSII it was unchanged during the first year but had improved after two years (p less than 0.01). Glomerular hyperfiltration was reduced with CSII, but no change occurred in urine albumin excretion rates. Long term near normoglycaemia may prevent the progression of early stages of late diabetic complications.

Blood Glucose↗
PubMed1986

The width of the light reflex on retinal arteries and veins.

A computerized microdensitometric technique was applied to fundus photographs of 40 young male subjects. The width of the blood column and the width of the central light reflex were measured on 240 arteries and 240 veins of various sizes. No light streaks were registered on vessels of caliber less than 50 micron. The ratio of the widths: light streak/blood column showed wider reflexes on small (less than 100 micron) compared to larger (greater than or equal to 100 micron) vessels in both arteries and veins (P less than 0.01). Small retinal veins had wider light streaks than small arteries (P less than 0.01). The results of these objective measurements are partly in conflict with previous ophthalmoscopic observations, and we challenge accepted views on clinical interpretation on reflectivity differences in normal retinal vessels. Our results are discussed on a background of hemodynamics of microcirculatory flow.

Adult↗
PubMed1986

The intensity of the light reflex on retinal arteries and veins.

The intensity profiles of the central light streak on various sized retinal vessels were measured by a computerized high quality scanning microphotometer. From the fundus photographs in 40 young men 240 arteries and 240 veins were analysed, and light streaks were found on 171 arterial and 170 venous sites. Differences in reflected intensities between arteries and veins and between small and large vessels were studied. In the whole range of vessels measured (50-200 microns) significantly higher intensities were found on arteries compared to veins (P less than 0.01). Large vessels (100-200 microns) reflected the light more intensely than small vessels (50-99 microns) (P less than 0.001). Variations in haemodynamics of flow and in physical properties of the streaming erythrocytes might account for the reflectivity differences between arteries and veins.

Adult↗
PubMed1985

Effects of intensified insulin treatment on various lesions of diabetic retinopathy.

Mild background retinopathy was studied prospectively during long-term strict blood glucose control in insulin-dependent diabetes mellitus. Forty-five subjects (21 women and 24 men with a mean age of 26.3 years and a mean duration of diabetes of 12.8 years) were randomly assigned to continuous subcutaneous insulin infusion, multiple injections, and conventional two-injection treatment. Eyes were examined two months before treatment, at the beginning of treatment, and after three, six, and 12 months. A progressive deterioration was found in the two-injection group during the study, but no significant changes were found in patients receiving multiple injections. A transient deterioration occurred after three months of continuous subcutaneous insulin infusion. Soft exudates appeared in 50% of the patients on the two intensified regimens, but no exudates were found in patients given conventional treatment. The morphologic changes seemed to be related to a large and rapid decrease in mean blood glucose or to an increased frequency of hypoglycemia, or both.

Adolescent↗
PubMed1985

Rapid tightening of blood glucose control leads to transient deterioration of retinopathy in insulin dependent diabetes mellitus: the Oslo study.

In a study of retinopathy during one year of tight blood glucose control 45 type I (insulin dependent) diabetics without proliferative retinopathy were randomised to receive either continuous subcutaneous insulin infusion, multiple insulin injections, or conventional insulin treatment (controls). Near normoglycaemia was achieved with continuous infusion and multiple injections but not with conventional treatment. Blind evaluation of fluorescein angiograms performed three monthly showed progression of retinopathy in the control group, transient deterioration in the continuous infusion group, and no change in the multiple injection group. Half the patients receiving continuous infusion and multiple injections developed retinal cotton wool spots after three to six months. These changes regressed in all but four patients after 12 months. Control patients did not develop cotton wool spots. Patients who developed cotton wool spots are characterised by a larger decrement in glycosylated haemoglobin and blood glucose values, more frequent episodes of hypoglycaemia, a longer duration of diabetes, and more severe retinopathy at onset. A large and rapid fall in blood glucose concentration may promote transient deterioration of diabetic retinopathy.

Adolescent↗
PubMed1985

The influence of strict control on diabetic complications.

We studied 45 IDDM without c-peptide response, duration 7-22 years, without proliferative retinopathy. After 2 months run-in period, they were randomly assigned to: (P) 15 received CSII: (C) 15 received multiple s.c. injections via butterfly 5-6x daily;: (M) 15 received twice daily mixed rapid and long acting insulin. All groups improved blood glucose control in the run-in period (p less than 0.0001). After change of treatment (P) and (M) improved further (p less than 0.01) but (C) was unchanged. GFR was supranormal and decreased in (P) and (M). No regression of retinopathy was shown in any group. One in (P) had transient florid pre-proliferative retinopathy which regressed spontaneously without laser treatment. We conclude that retinal response to strict control is complex. A transient deterioration may been seen.

Adolescent↗