Vitreous fluorophotometry in patients with no or minimal diabetic retinopathy.

Vitreous fluorophotometry was used to estimate fluorescein leakage into the posterior vitreous of 20 insulin-dependent diabetic patients with no or minimal diabetic retinopathy 60 min after intravenous administration of 14 mg X kg-1 fluorescein. The permeability coefficient (p), a measure of fluorescein penetration through the blood-retinal barrier (BRB) into the vitreous, and the diffusion coefficient (D), a measure of fluorescein dispersion within the vitreous, were obtained by fitting a mathematical model to the vitreous fluorescence scan and plasma free fluorescence curve. A permeability index (PI) was also derived by dividing the area under the fluorescence scan by the area under the plasma free fluorescence time curve. The fluorescence concentrations at discrete distances from the retina were also noted. The mean +/- SD for p, D, and PI were 1.95 +/- 1.03 cm X s-1 X 10(-7), 1.74 +/- 1.53 cm2 X s-1 X 10(-5), and 2.14 +/- 1.21 cm X s-1 X 10(-7), respectively, and were not significantly different from values determined in normal subjects. Diabetic patients and normal subjects also had similar fluorescence measurements at corresponding distances from the retina. Quantitative indices of fluorescein leakage did not correlate with either the microaneurysm counts on fluorescein angiograms or the duration of diabetes. Vitreous fluorophotometry did not detect any abnormality of the BRB in diabetic patients with no or minimal retinopathy on fluorescein angiography.

Oxidative effects of laser photocoagulation.

Diabetic proliferative retinopathy is a common and sight-threatening condition. Oxidative stress is an integral and possibly causative part of the pathogenesis. Although laser photocoagulation is usually a beneficial treatment it remains unclear how it works. The possibility that it induces a sudden, temporary increase in free radical activity either by direct thermal damage or by oxygen reperfusion is explored in this clinical study by measuring the oxidative status in the peripheral blood of 13 patients undergoing panretinal photocoagulation. There were significant increases at one hour in malondialdehyde-like material (MDA-LM), 8.1 (6.9-9.6) nmol/mL, to 9.1 (7.6-9.8) nmol/mL, (less than 0.005); plasma thiols (PSH), 423 (352-457) microns/L, to 444 (382-478) microns/L, (p less than 0.005) and red cell reduced glutathione (GSH), 1357 (1295-1655) microns/L, to 1480 (1305-1760) microns/L, (p less than 0.01). Diene conjugates rose over the first hour 0.55 (0.36-0.79) od/mL, to 0.58 (0.34-0.85) od/mL falling to 0.56 (0.36-0.79) od/mL at 2 h but these changes were not significant. At 2 h, MDA-LM 8.4 (6.7-9.6) nmol/mL and PSH 404 (379-462) microns/L had returned to baseline but GSH remained significantly elevated 1500 (1325-1675) microns/L, (p less than 0.005 compared to baseline). This is a new observation and in some circumstances such generation of free radicals could explain the mechanism behind the complications of photocoagulation by direct or indirect damage to vascular endothelium leading to increased vascular permeability manifest as macular oedema or choroidal effusions.

The effect of acute hyperglycemia on flow velocity in the macular capillaries.

The effect of acute hyperglycemia on retinal blood flow was measured in 12 diabetic patients (mean blood glucose, 276 mg%) on continuous subcutaneous insulin infusion and six nondiabetic controls (mean blood glucose, 198 mg%). Flow velocity measurements in macular capillaries were made using the blue field entoptic method. Retinal artery and vein diameters were measured using red-free fundus photographs. No significant change in flow velocity or retinal vessel diameter was noted in either group.

Measurement of blood-retinal barrier function in central retinal vein occlusion.

Vitreous fluorophotometry was used to measure blood-retinal barrier permeability to fluorescein in eight patients (mean age, 42.9 years; range, 30 to 55 years) with central retinal vein occlusion (CRVO). Permeability coefficient was derived by fitting a mathematical model to the posterior vitreous fluorescence scan and plasma-free fluorescein concentration curve at 60 minutes after intravenous fluorescein sodium (14 mg X kg-1). A permeability index (PI) was estimated by dividing the area under the vitreous fluorescence scan by the area under the plasma-free fluorescein curve. The permeability coefficient and PI were comparable and highly correlated. Initial mean permeability coefficient was 28.78 X 10(-7) cm X s-1 (range, 14.42 X 10(-7) to 41.10 X 10(-7) and 1.89 X 10(-7) cm X s-2 (range, 0.96 X 10(-7) to 2.76 X 10(-7) in eight affected and seven unaffected eyes, respectively. The permeability coefficient and PI in unaffected eyes did not differ significantly from 18 eyes of ten normal subjects. After three to 12 months, permeability coefficient and PI in affected eyes approached the values in the contralateral eyes of four patients with mild and one patient with moderate CRVO but remained elevated in the remaining patients. The permeability coefficient and PI correlated well with changes in severity of retinal appearances on color photographs and fluorescein angiograms. Vitreous fluorophotometry quantitated changes in blood-retinal barrier permeability in CRVO.

Obsessive-compulsive characteristics: from symptoms to syndrome.

OBJECTIVE: To assess the distribution and severity of obsessions and compulsions in a nonclinical adolescent population. METHOD: During preinduction military screening, 861 sixteen-year-old Israelis completed a questionnaire regarding the lifetime presence of eight obsessive-compulsive (OC) symptoms and three severity measures. The presence or absence of obsessive-compulsive disorder (OCD) or subclinical OCD was ascertained by an independent interview. RESULTS: Although only 8.0% and 6.3% of respondents reported disturbing and intrusive thoughts, respectively, 27% to 72% of subjects endorsed the six remaining OCD symptoms. Twenty percent of subjects regarded the symptoms they endorsed as senseless and 3.5% found them disturbing; 8% reported spending more than an hour daily on symptoms. OCD and subclinical OCD cases differed significantly from non-OCD cases, but not from each other, in distress and mean number of symptoms. Although the distribution of nine of the items differed for noncases, compared with OCD and subclinical OCD cases, the distributions for all items overlapped markedly across the three groups. CONCLUSIONS: OC phenomena appear to be on a continuum with few symptoms and minimal severity at one end and many symptoms and severe impairment on the other. Defining optimal cutoff points for distinguishing between psychiatric disorder and OC phenomena that are common in the general population remains an open question.

Measurement of retinal blood flow in diabetes by the blue-light entoptic phenomenon.

Retinal blood flow velocity was measured in 24 normal volunteers and compared with the results obtained in 101 diabetics at different stages of retinopathy. The blue-light entoptic phenomenon was used to measure retinal flow velocity. Results showed that there was a significantly higher capillary flow velocity in those patients with background retinopathy (0.74 +/- 0.32 mms/s) over the group of normals (0.54 +/- 0.19 mm/s) and those diabetics with no retinopathy (0.51 +/- 0.24 mm/s). Retinal flow velocity was reduced at the preproliferative stage of retinopathy to 0.37 +/- 0.2 mm/s. Proliferative retinopathy showed a slightly greater flow velocity (0.56 +/- 0.27 mm/s), which was reduced following photocoagulation (0.42 +/- 0.14 mm/s).

Long-term follow-up of retinal blood flow in diabetes using the blue light entoptic phenomenon.

The blue light entopic phenomenon was used to measure retinal blood flow in 87 diabetics and 10 normal controls in a longitudinal study. The time interval between the initial and final studies was 21-39 months (mean 31.4). The retinal blood flow velocity did not change in the 10 subjects in the control group nor in those nine patients with no retinopathy, all but one of whom remained free of retinal lesions. In the 24 with background retinopathy the flow velocity fell significantly from 0.71 (SD 0.35) mm/s to 0.48 (0.13) mm/s (p less than 0.01). The velocity also decreased in the preproliferative group of 16 patients from 0.62 (0.39) mm/s to 0.41 (0.14) mm/s (p less than 0.05). The retinopathy status changed in 11 of this group. In those with proliferative retinopathy (now treated) and those treated previously there was no change in flow velocity.

Autoregulation of retinal blood flow in diabetic retinopathy measured by the blue-light entoptic technique.

Autoregulation of retinal blood flow was measured in 23 diabetic patients, 9 with nonproliferative retinopathy, 9 with proliferative retinopathy, and 5 with photocoagulated retinopathy. Three of the proliferative patients were studied on two occasions, at the proliferative stage and after photocoagulation. The stimuli to autoregulation used were isocapnic hyperoxia and hypoxia. Flow velocity of leukocytes in the perifoveal circulation was measured using the blue-field entoptic technique, and retinal artery and vein diameters were measured using a computerized digitizing system. Results under conditions of isocapnic hypoxia showed a mean increase in flow velocity of 41.0 +/- 33.0% (P less than 0.05) in nonproliferative retinopathy, 3.5 +/- 17.0% (not significant) in proliferative retinopathy, and 30.0 +/- 17.0% (P less than 0.05) after photocoagulation. In hyperoxia, flow velocity fell by a mean of 21.0 +/- 21.6% (P less than 0.05) in nonproliferative retinopathy, 33.0 +/- 19.9% (P less than 0.005) in proliferative retinopathy, and 21.0 +/- 26.0% (not significant) in photocoagulated retinopathy. The results are compared with a group of nondiabetic subjects reported previously.

Errors in EMG reporting.

In a review of 112 electromyographic reports from 112 different electromyographers, errors were classified as anatomic, terminologic, technical and interpretative. Ninety-seven of the reports had substantive errors. The EMG report should be complete, precise, accurate and logical and include a summary of the anatomic and neurophysiologic data with a translation into a probable clinical diagnosis.

Measurement of autoregulation of retinal blood flow using the blue field entoptic phenomenon.

Autoregulation of retinal blood flow was studied in seven normal volunteers. The stimuli to autoregulation used were hyperoxia and hypoxia under controlled conditions of isocapnia. Macular blood flow was measured using the blue field entoptic phenomenon and retinal artery and vein diameters were measured using a computerised digitising system. Results under conditions of isocapnic hypoxia showed a 38 per cent average increase in blood flow and an increase in diameter of 8.2 per cent and 7.4 per cent in retinal arteries and veins respectively. In hyperoxia blood flow fell by an average of 36 per cent and retinal artery and vein diameter decreased by 5.6 per cent and 10 per cent respectively.

Retinal vascular autoregulation in conditions of hyperoxia and hypoxia using the blue field entoptic phenomenon.

Autoregulation of retinal blood flow was studied in seven normal volunteers. The stimuli to autoregulation used were hyperoxia and hypoxia under controlled conditions of isocapnia. Macular blood flow was measured using the blue field entoptic phenomenon, and retinal artery and vein diameters were measured using a computerized digitising system. Results under conditions of isocapnic hypoxia showed a 38% average increase in blood flow and an increase in diameter of 8.2% and 7.4% in retinal arteries and veins, respectively. In hyperoxia, blood flow fell by an average of 36% and retinal artery and vein diameter decreased by 5.6% and 10%, respectively.

Quantitative changes in blood-retinal barrier function in central retinal vein occlusion.

Posterior vitreous fluorescence was measured with a fluorophotometer 60 minutes after intravenous sodium fluorescein (14 mg/kg) in 6 patients (age range 30 to 54 years) with central retinal vein occlusion (CRVO). Plasma free fluorescein was measured at frequent intervals for 60 minutes. A permeability index (PI) was estimated by dividing the area under the vitreous fluorescence scan by the area under the plasma free fluorescein curve. Initially mean PI was 24.3 (range 12.6-31.6) and 2.1 (range 1.3-31.) cm s-1 X 10(-7) in affected and unaffected eyes respectively. After 6 to 12 months, PI in affected eyes approached the values in the unaffected eyes of 5 patients with mild CRVO but remained elevated in one patient who presented with severe (ischaemic) CRVO. In each patient qualitative changes in retinal appearances paralleled quantitative changes in PI. The effect of venous outflow obstruction on the blood-retinal barrier can be quantitated by fluorophotometry.

Role of fluorescein glucuronide and its metabolism in vitreous fluorophotometry.

Rabbits were given fluorescein or fluorescein glucuronide intravenously. Fluorescein and fluorescein glucuronide concentrations in plasma and vitreous samples were measured by high-performance liquid chromatography. Vitreous fluorophotometry was performed using the Fluorotron Master to compare scans after administration of fluorescein and fluorescein glucuronide, and for comparison of in vivo fluorescence with in vitro high-performance liquid chromatography analysis. Fluorescein glucuronide was shown to enter the vitreous as early as 1 hr after injection. Fluorescein glucuronide was the dominant molecule in both vitreous and plasma of all rabbits at 6 hr. Because fluorescein glucuronide has a lower fluorescence than fluorescein, the fluorophotometer overestimates the vitreous concentration of fluorescein after its administration. Since fluorescein is metabolized rapidly to fluorescein glucuronide in man, entry of fluorescein glucuronide into the eye should be considered in measurements of blood-ocular barrier permeability by vitreous fluorophotometry.

Long-term follow-up of patients who underwent yttrium-90 pituitary implantation for treatment of proliferative diabetic retinopathy.

Between 1960 and 1976 117 patients underwent pituitary implantation with yttrium-90 (90Y) for treatment of proliferative retinopathy at the Hammersmith Hospital, London. Mean age at operation was 35 +/- 11 years (mean +/- SD), and mean duration of diabetes 18.6 +/- 10.0 years. Mean insulin dosage prior to implant was 67.2 +/- 24 units, falling to 30.4 +/- 14.9 units post-implant. Thirty-two per cent of patients are still living, 60% are deceased and 8% are lost to follow-up. The 5-year survival rate was 82%. Of the causes of death, 21% died of infection, adrenal insufficiency or hypoglycaemia, 12% of renal failure, and 47% of myocardial or cerebral vascular disease. Ophthalmological follow-up was carried out on the 100 patients operated on between 1965 and 1976. The mean age of this group at implant was 35 +/- 10.5 years, and mean duration of diabetes 17.2 +/- 8.7 years. Visual acuity in the better eye at operation was 6/12 or better in 84% of patients, and this percentage remained similar at the time of the 5 and 10 year follow-up. Blindness (6/60 or worse) in both eyes was present in 12% of patients at the time of 5 and 10 year assessments. By 5 years new vessels on the disc had improved from a mean grading of 2.7 +/- 1.6 to 0.8 +/- 1.2 (p less than 0.001), and by 10 years there was no disc neovascularisation in any eye. There was a similar improvement in the grading of hard exudates, microaneurysms and haemorrhages, but there was an increase in fibrous retinitis proliferans.(ABSTRACT TRUNCATED AT 250 WORDS)