Blood glucose control and microvascular complications--what do we do now?
Explore the source record for details and available documents.
Blood Glucose↗
Biomedical subjects
O Brinchmann-Hansen
Publications and source records attributed to O Brinchmann-Hansen.
Impaired contrast sensitivity in adolescents and young type 1 (insulin-dependent) diabetic patients with microalbuminuria.
We compared neurosensorial visual function by psychophysical tests (macular recovery time and contrast sensitivity) in two well matched groups of young Type 1 (insulin-dependent) diabetic patients with micro- and normoalbuminuria, respectively. The patients had normal visual acuity (> or = 1.0) and either no retinopathy or non-proliferative retinopathy. Thirty patients with microalbuminuria (albumin excretion > or = 15 micrograms/min in a least two out of three timed overnight urine samples) were matched (age, diabetes duration, mean one-year HbA1c, gender) with normoalbuminuric (n = 27) patients. Retinopathy (50 degree colour fundus photography) was assessed by counting microaneurysms and hemorrhages as 'red spots'. Contrast sensitivity was examined for the spatial frequencies of 1.5, 3, 6, 12 and 18 cycles per degree (cpd). Macular recovery time (nyctometry) refers to the time-related (2 min) ability of the retina to regain visual acuity following exposure to bright light (photostress). Contrast sensitivity score was reduced in patients with microalbuminuria compared to those without; 18 cpd (mean and 95% confidence intervals): [4.2 (3.8-4.7) vs 5.0 (4.6-5.4), p = 0.03]. Macular recovery performance was not significantly reduced: [21.0 arbitrary units (17.5-24.6) vs 26.0 (22.6-30.7), p = 0.12]. We conclude that impaired contrast sensitivity independent of background retinopathy is shown in a group of young Type 1 (insulin-dependent) diabetic patients with low-grade microalbuminuria compared to a group of patients with normoalbuminuria.
Adolescent↗
Accurate vessel width measurement from fundus photographs: a new concept.
Accurate determination of retinal vessel width measurement is important in the study of the haemodynamic changes that accompany various physiological and pathological states. Currently the width at the half height of the transmittance and densitometry profiles are used as a measure of retinal vessel width. A consistent phenomenon of two 'kick points' on the slopes of the transmittance and densitometry profiles near the base, has been observed. In this study, mathematical models have been formulated to describe the characteristic curves of the transmittance and the densitometry profiles. They demonstrate the kick points being coincident with the edges of the blood column. The horizontal distance across the kick points would therefore indicate the actual blood column width. To evaluate this hypothesis, blood was infused through two lengths of plastic tubing of known diameters, and photographed. In comparison with the known diameters, the half height underestimated the blood column width by 7.33% and 6.46%, while the kick point method slightly overestimated it by 1.40% and 0.34%. These techniques were applied to monochromatic fundus photographs. In comparison with the kick point method, the half height underestimated the blood column width in veins by 16.67% and in arteries by 15.86%. The characteristics of the kick points and their practicality have been discussed. The kick point method may provide the most accurate measurement of vessel width possible from these profiles.
Fluorescein Angiography↗
[Blood glucose level means everything].
Explore the source record for details and available documents.
Blood Glucose↗
Pilocarpine drops do not reduce intraocular pressure sufficiently in pseudoexfoliation glaucoma.
The reason for the poorer prognosis of pseudoexfoliation syndrome glaucomas (PXSG) compared with primary open angle glaucomas (POAG) is not fully understood. An open, comparative, cross-over study was performed in 15 patients (= eyes) with POAG and 15 patients (= eyes) with PXSG. Two different pharmacokinetic principles of drug administration were applied to uncover possible differences in short-term (hours) response to topical antiglaucomatous treatment. Intermittent pilocarpine drop medication (2%) and continuous low-dose pilocarpine delivery by a membrane-controlled Ocusert unit (P40) were used. The 'carry-over' pressure reduction of an ordinary four times a day drop medication was significantly less effective in controlling the morning intraocular pressure (9 a.m.) in PXSG than in POAG. The duration of action of pilocarpine drops was reduced in PXSG. Defining 'normotensive' pressure as < or = 20 mmHg, only 1 of the 15 PXSG eyes (6.7%) reached a normotensive level in the morning, compared with 8 of the 15 POAG eyes (53.3%). Using a continuous supply of pilocarpine (Ocusert), no differences between POAG and PXSG eyes were found. The study demonstrates the insufficient control of intraocular pressure in PXSG, compared with POAG, by identical antiglaucomatous drop medications. This may suggest an insufficient depot function of topical drugs in PXSG. In consequence, pseudoexfoliation material (PXM) must be sought in eyes with glaucoma, as PXM eyes will probably benefit from a more intense medical treatment compared with eyes without PXM.
Adult↗
Psychophysical visual function, retinopathy, and glycemic control in insulin-dependent diabetics with normal visual acuity.
We studied relations between psychophysical visual function and grade of retinopathy, glycemic control and clinical background data in 51 insulin-dependent diabetic patients, aged 17-47 years. Three separate qualities of visual function were examined, macular recovery time (nyctometry; 2 min adaptation), contrast sensitivity (Vistech 6000 chart; between 1.5 and 18 cycles per degree (cpd)) and colour vision (Fletcher DS8; protan/deutan and tritan). Only contrast sensitivity of 6 cpd was associated with the grade of retinopathy; reduced function was found in patients with retinopathy compared to those without. No correlations between macular recovery, contrast sensitivity and colour vision were found. None of the visual functions was significantly related to glycemic control, age, duration of diabetes, blood pressure, intraocular pressure, or urinary albumin excretion. Our data suggests that the neurosensory function of contrast sensitivity correlates more sensitively to the grade of diabetic retinopathy than macular recovery and colour vision. Cross-sectional assessments of different psychophysical visual functions seem to be of restricted clinical value as indicators of preceding glycemic control in diabetic patients with no or mild nonproliferative retinopathy.
Adolescent↗
Blood glucose concentrations and progression of diabetic retinopathy: the seven year results of the Oslo study.
OBJECTIVE: To study insulin dependent diabetic patients for change in non-proliferative retinopathy and its relation to glycaemic control and to various clinical background data. DESIGN: Prospective study with follow up for seven years. SETTING: Outpatient departments of university hospitals. MAIN OUTCOME MEASURES: Glycated haemoglobin concentration; degree of retinopathy. RESULTS: Retinopathy worsened by an overall increase in counts of microaneurysms and haemorrhages from 17 (SD 25) to 45 (58) (p = 0.005). Intensified insulin treatment and home blood glucose monitoring improved concentrations of glycated haemoglobin (HbA1) from 11.2% (2.2%) at the start of the study to a mean of 9.5% (1.5%) over the seven years of the study (p less than 0.0001). A mean value for HbA1 greater than 10% was associated with an increased risk of progression of retinopathy and a mean value less than 8.7% was associated with a diminished risk. Multiple regression analysis identified four independent variables as indicative of outcome of retinopathy after seven years: HbA1 value at baseline; the change in HbA1 from start to the mean level through the seven years; duration of diabetes; and retinopathy at start. Age, blood pressure, and urinary albumin excretion were not related to the presence or progression of retinopathy. CONCLUSION: Secondary intervention by long term lowering of glycated haemoglobin has a beneficial impact on non-proliferative retinopathy. A four factor regression model can determine patients at high risk of severe retinopathy.
Adolescent↗
A nationwide cross-sectional study of retinopathy and microalbuminuria in young Norwegian type 1 (insulin-dependent) diabetic patients.
A nationwide cohort of Type 1 (insulin-dependent) diabetic patients was studied to determine the prevalence of retinopathy and microalbuminuria and to evaluate the association to various risk factors. Of 600 subjects with mean age of 19.8 years (range 8.0-30.3) and a mean duration of diabetes of 10.5 years (range 6.2-17.3), 371 (60%) volunteered for a clinical examination which included fundus photography, timed overnight urine samples for albumin excretion rate, measurement of arterial blood pressure and determination of HbA1c. Retinopathy was found in 122 of 371 patients (32.8%), in 3 of 41 (7.3%) patients aged less than 13 years. The youngest subject with retinopathy was 9.6 years old. Microalbuminuria was found in 44 of 351 patients (12.5%), in 1 of 41 (2.4%) patients aged less than 13 years. The youngest subject with microalbuminuria was 11.5 years old. Mean HbA1c was 8.6% (normal range 4.5-601%). Patients with retinopathy had significantly higher mean age (p = 0.0001), longer mean duration of diabetes (p = 0.0001), higher mean HbA1c (p = 0.009), and higher mean arterial blood pressure (p = 0.0001) compared to patients without retinopathy. In microalbuminuric patients HbA1c (p = 0.001) and mean arterial blood pressure (p = 0.01) were significantly higher compared to non-microalbuminuric patients, but there was no difference in age or diabetes duration. In a multiple logistic regression model, age, HbA1c, duration of diabetes and mean arterial blood pressure were found to be significantly associated with retinopathy, while HbA1c, mean arterial blood pressure and onset before 13.0 years of age were found to be associated with microalbuminuria.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Blood glucose control and diabetic microvascular complications: long-term effects of near-normoglycaemia.
Explore the source record for details and available documents.
Blood Glucose↗
Macular recovery time, diabetic retinopathy, and clinical variables after 7 years of improved glycemic control.
Effects of long-term improved glucose control on neurosensory retinal function are investigated. Changes in macular recovery of nyctometry (photostress) are assessed in 45 insulin-dependent diabetic patients between study start and after 7 years prospective follow-up (the Oslo Study). Intensified insulin treatment improved glycosylated hemoglobin (HbA1) from 11.7 +/- 2.2% at start to a 7-year cumulative mean of 9.5 +/- 1.5% (p less than 0.0001). Improved macular recovery performance was observed in patients with 7-year mean HbA1 below 10%, compared to a worsening in those above 10% (p less than 0.001-0.02), and non-proliferative retinopathy progressed less in those with HbA1 below 10%, than in those above (p less than 0.01). Macular recovery at study start did not predict progression or outcome of retinopathy 7 years later. Intraocular pressure fell during the 7 years (p less than 0.001) and was cross-sectionally negatively correlated to macular recovery at the 7-year end-point (p less than 0.001-0.002). Macular recovery was not related to age, duration of diabetes, systemic blood pressure, or urinary albumin excretion level. The study indicates that severity of retinopathy, glycemic control and intraocular pressure are interesting covariants to neurosensory dysfunction in diabetes. Furthermore, the study suggests a critical level of long-term blood glucose or retinopathy, or both, above which neurosensory function of macular recovery is significantly reduced.
Adult↗
Oscillatory potentials, retinopathy, and long-term glucose control in insulin-dependent diabetes.
The main objective of the study was to assess effects of long-term lowering of glucosylated hemoglobin (HbA1%) on neurosensory function in insulin-dependent diabetes. Individual (OP-1, OP-2, OP-3) and summed (OP-sum) amplitudes of oscillatory potentials (OPs) of electroretinography were recorded at study start and 7-years later in 45 patients (the Oslo study). As an overall 7-year change, amplitudes of OP-2, OP-3 and OP-sum were reduced (p < 0.0001-0.01), retinopathy worsened (p = 0.005), intraocular pressure decreased (p < 0.001), systolic blood pressure increased (p < 0.0002), and glycemic control improved from HbA1 of 11.2 +/- 2.2% at study start to a 7-year cumulative mean of 9.5 +/- 1.5% (p < 0.0001). Multiple regression analysis did not identify any independent relations between change in OP-1, OP-2, OP-3, OP-sum and change in glycemic control or background variables, including change in age and duration of diabetes. However, cross-sectional observations at 7 years showed negative correlations between all OPs and age (p < 0.0001-0.003), and between OP-3 and duration (p = 0.003) and counts of microaneurysms (p = 0.02). The data suggest that various clinical background variables may influence individual and summed amplitudes of OPs differently. Reduced neurosensory retinal function (OPs) seemed to appear after 7-years, independently of vascular defects of retinopathy and long-term improvement in glucose control.
Adolescent↗
Prolonged photostress macular recovery after reduced blood pressure.
In order to investigate an association between systemic blood pressure and restitution of normal visual function in dim illumination after photostress, macular recovery time and blood pressure were measured in two groups: 1) 90 young and healthy military pilots and applicants for military pilot training; and 2) 10 hypertensive patients before and after 12 weeks of antihypertensive treatment. Young normotensive subjects (20/20 vision) with low diastolic blood pressure performed less well (longer macular recovery time) than those with higher pressure (r = -0.42, p less than or equal to 0.05). Among the hypertensive patients three were given doxazosin, three, prazosin, and four, placebo. The treatment period produced significant fall in blood pressures, a small reduction in intraocular pressure (p less than or equal to 0.03) and a lengthening of initial monocular recovery period (p = 0.04) in addition to reduced monocular (p = 0.015) and binocular (p = 0.022) macular recovery in the remaining part of the 2-min test period. This observation may be important for antihypertensive treated patients whose occupation requires fast visual adjustment to changing stimuli in dim light.
Adaptation, Physiological↗
The response of the light reflex of retinal vessels to reduced blood pressure in hypertensive patients.
The response of retinal arteries and veins to 3 months of antihypertensive medication was studied in 10 patients (39-56 years old) with essential hypertension. We used computerized microdensitometry on fundus photographs, a technique allowing for objective and simultaneous measures of the caliber of blood columns and the width and intensity of their central 'light reflex'. A moderate lowering of diastolic and systolic blood pressures (P less than 0.001) resulted in a significant reduction in the intensity of reflection from retinal arteries (38.6%; P less than 0.005). An increase in the width of the blood column (2.8%; n.s.) and the reflex (8.6%; n.s.) was indicated. Traditionally, changes in light reflectivity has been associated with arteriosclerosis of the vessel wall. The study shows, however, that the vascular reflex is most sensitive to changes in the systemic blood pressure. This signals a need for critical reviewal of interpretation and usefulness of classical grading systems of ophthalmoscopic signs of hypertensive retinopathy.
Adult↗
Vascular response of retinal arteries and veins to acute hypoxia of 8,000, 10,000, 12,500, and 15,000 feet of simulated altitude.
Computerized scanning microdensitometry of fundus photographs was used to study the effect of acute hypoxia on vessel diameters of 238 retinal arteries and 227 veins in 40 men aged 18-23 years. Fundus photography was performed at sea level and at simulated altitudes in a low-pressure chamber, randomly selecting 10 men to each of four altitudes--8,000, 10,000, 12,500, and 15,000 ft (2,400, 3,000, 3,800, and 4,500 m). After 15 min of hypoxic exposure, the caliber of small arteries (less than 75 microns) increased 4% (p less than 0.01) and that of large arteries (greater than or equal to 75 microns) 7% (p less than 0.05), already at 8,000 ft (2,400 m). The caliber of large veins did not change until an increase of 6% (p less than 0.01) was observed at 15,000 ft (4,500 m). Although large arteries increased 7% (p less than 0.05) and 8% (p less than 0.01) in diameter at 10,000 ft (3,000 m) and 15,000 ft and small veins 9% (p less than 0.05) and 12% (p less than 0.01) at the same altitudes, respectively, no change was observed at 12,500 ft (3,800 m). Thus, the dilating effect of hypobaric hypoxia was nonlinear from sea level to 15,000 ft of simulated altitude. As an overall response to the four simulated altitudes the vasodilation was negatively correlated to the vessel diameter at sea level (r = -0.20) in both arteries and veins (p less than 0.01). The variability of hypoxic vascular response was as great within different parts of individual retinas as between different retinas.
Adolescent↗
Retinal vessel responses to exercise and hypoxia before and after high altitude acclimatisation.
Computerised microdensitometry was used to study diameter changes in 93 arterial and 91 venous vessel sites in the retinas of four mountain climbers before and after spending seven weeks in the Himalaya mountains. The vascular response to short-term strenuous exercise was measured at sea level, to acute hypoxia of simulated altitude of 15,000 ft (4,572 m) at rest, and to strenuous exercise while acutely exposed to the same hypoxic condition. Before the mountain exposure, retinal vessels constricted during exercise -1.9% (arteries); -3.3% (veins) and dilated in acute hypoxia 9.4% (arteries); 8.1% (veins). Superimposed exercise on hypoxic dilated arteries reduced the vasodilation (9.4% to 6%). After acclimatisation, the same physical work load at sea level constricted the arteries more (-5.4% vs -1.9%) but did not constrict the veins (0.2% vs -3.3%). Superimposed exercise on hypoxic dilated vessels, excessively dilated both arteries (8.4% vs 6.0%) and veins (13.7% vs 8.4%), compared to changes seen before the mountain sojourn. This study shows that physical conditioning and long adaptation to hypoxia, significantly change the vascular response of the retina to physical activity both in normal atmospheric conditions and during hypoxic stress. High altitude retinal hemorrhages (HARH) were present in one climber, and the study may indicate why HARH is seen often in young and physical well-trained subjects.
Acclimatization↗
Psychophysical and electrophysiological testing of retinal function. Macular recovery time and oscillatory potentials in normal subjects.
We evaluated different aspects of 1) psychophysical and 2) electrophysiological testing procedures of retinal function, represented by macular recovery time (nyctometry) and oscillatory potentials (electroretinography), respectively. Ninety healthy males, aged 18-28 years, were used in the study. We registered two different phases of macular recovery time, IRT: initial recovery time (less than 40 sec) and AUC: area under the curve (less than 120 sec) and both individual and summed nodes of oscillatory potentials (OPs). A significant effect of training was observed in monocular registration of IRT and AUC (P less than 0.01), and the superiority of binocular recovery was numerically compared to monocular recovery (P less than 0.01). The inter-variability (coefficient of variation) of IRT was high (40%) in both monocular and binocular registrations, while AUC had a smaller variability binocularily than monocularily (33% vs 21%). The inter-variability of OPs was low (16%). Intra-variability, between first and second eye tested, showed highly correlated values in IRT, AUC and OPs (r = 0.51-0.82; P less than 0.004), while IRT/AUC was not correlated to amplitudes of OPs. The results emphasize that selecting one eye, mean of two eyes or both eyes are critical for accuracy and validity in psychophysical testing of visual performance.
Adolescent↗
The effect of hypoxia on the central light reflex of retinal arteries and veins.
Computerized scanning microdensitometry was used on fundus photographs of 40 men (aged 18-23 years) and effects of hypoxia on intensity profiles of the 'light reflex' in 140 arteries and 138 veins were analysed. Changes from sea level to four levels of acute hypoxia of simulated altitude were studied: 8000 feet (ft) (2438 meters) (m), 10,000 ft (3048 m), 12,500 ft (3810 m), and 15,000 ft (4572 m) using a low-pressure chamber. The intensity of the reflex increased at 12,500 ft and 15,000 ft by 24% (P less than 0.05) and 39% (P less than 0.01) in arteries and 50% and 33% in veins (P less than 0.05), respectively. As an overall response from sea level to all four altitudes, the width of the reflex was reduced. The reduction in width was negatively correlated to the diameter of the arteries (P less than 0.0001) and veins (P less than 0.001) at sea level, and the variability of changes was larger in veins (P less than 0.01). Funduscopic light reflected from intravascular blood columns of retinal vessels is thus influenced by hypoxic stress, and 12,500 ft of simulated altitude represents a threshold value of circulatory interest.
Adolescent↗
The effect of hypoxia upon macular recovery time in normal humans.
Bright light illumination (photostress) of the macula produces a negative after-image in the form of a central scotoma. The time needed for restoring normal visual acuity function, "macular recovery time," may be measured using a nyctometer. We have measured the recovery in 30 normal men, aged 18 to 23 years, at sea level and at 8,000 ft (n = 10), 15,000 ft (n = 10), and 18,000 ft (n = 10) of simulated altitudes in a low pressure chamber. The degree of initial recovery (the first 30-40 s) was unaffected by hypoxia equivalent to 8,000, 15,000, and 18,000 ft. The recovery at 2 min was impaired by hypoxia at an altitude of 18,000 ft (p = 0.009) but not at 8,000 ft or 15,000 ft. The initial phase of recovery may represent the neural phase of macular function and appears to be more resistant to hypoxia than the recovery at 2 min, the latter probably being dominated by photochemical recovery. The study establishes a critical level of hypoxia where complete recovery of macular sensitivity is not achieved.
Adolescent↗