Higher levels of bodily pain in people with long-term type 1 diabetes: associations with quality of life, depressive symptoms, fatigue and glycaemic control - the Dialong study.

AIMS: To compare reported level of bodily pain, overall and health-related quality of life (QoL), depression and fatigue in people with long-term type 1 diabetes vs. a comparison group without diabetes. Further, to examine the associations of total bodily pain with QoL, depression, fatigue and glycaemic control in the diabetes group. METHODS: Cross-sectional study of 104 (76% of eligible) people with type 1 diabetes of ≥ 45 years' duration attending the Norwegian Diabetes Centre and 75 persons without diabetes who completed questionnaires measuring bodily pain (RAND-36 bodily pain domain), shoulder pain (Shoulder Pain and Disability Index), hand pain (Australian/Canadian Osteoarthritis Hand Index), overall QoL (World Health Organization Quality of Life - BREF), health-related QoL (RAND-36), diabetes-specific QoL (Audit of Diabetes-Dependent Quality of Life; only diabetes group), depression (Patient Health Questionnaire) and fatigue (Fatigue questionnaire). For people with type 1 diabetes, possible associations between the bodily pain domain (lower scores indicate higher levels of bodily pain) and other questionnaire scores, were measured with regression coefficients (B) per 10-unit increase in bodily pain score from linear regression. RESULTS: The diabetes group reported higher levels of bodily (P = 0.003), shoulder and hand pain (P < 0.001) than the comparison group. In the diabetes group, bodily pain was associated with lower overall and diabetes-specific QoL [B (95% confidence intervals)]: 0.2 (0.1, 0.2) and 0.2 (0.1, 0.3); higher levels of depression -1.0 (-1.3, -0.7) and total fatigue -1.5 (-1.9, -1.2); and worse glycaemic control HbA1c (mmol/mol; %) -0.8 (-1.5, -0.1); -0.1 (-0.1, -0.01). CONCLUSIONS: People with long-term type 1 diabetes experience a high level of bodily pain compared with a comparison group. Total bodily pain was associated with worse QoL and glycaemic control.

Variation in the achievement of HbA1c , blood pressure and LDL cholesterol targets in type 2 diabetes in general practice and characteristics associated with risk factor control.

AIMS: To identify population, general practitioner, and practice characteristics associated with the achievement of HbA1c , blood pressure and LDL cholesterol targets, and to describe variation in the achievement of risk factor control. METHODS: We conducted a cross-sectional survey of 9342 people with type 2 diabetes, 281 general practitioners and 77 general practices in Norway. Missing values (7.4%) were imputed using multiple imputation by chained equations. We used three-level logistic regression with the achievement of HbA1c , blood pressure and LDL cholesterol targets as dependent variables, and factors related to population, general practitioners, and practices as independent variables. RESULTS: Treatment targets were achieved for HbA1c in 64%, blood pressure in 50%, and LDL cholesterol in 52% of people with type 2 diabetes, and 17% met all three targets. There was substantial heterogeneity in target achievement among general practitioners and among practices; the estimated proportion of a GPs diabetes population at target was 55-73% (10-90 percentiles) for HbA1c , 36-63% for blood pressure, and 47-57% for LDL cholesterol targets. The models explained 11%, 5% and 14%, respectively, of the total variation in the achievement of HbA1c , blood pressure and LDL cholesterol targets. Use among general practitioners of a structured diabetes form was associated with 23% higher odds of achieving the HbA1c target (odds ratio 1.23, 95% confidence interval (CI) 1.02-1.47) and 17% higher odds of achieving the LDL cholesterol target (odds ratio 1.17, 95% CI 1.01-1.35). CONCLUSIONS: Clinical diabetes management is difficult, and few people meet all three risk factor control targets. The proportion of people reaching target varied among general practitioners and practices. Several population, general practitioner and practice characteristics only explained a small part of the total variation. The use of a structured diabetes form is recommended.

Population, general practitioner and practice characteristics are associated with screening procedures for microvascular complications in Type 2 diabetes care in Norway.

AIMS: To assess population, general practitioner (GP) and practice characteristics associated with the performance of microvascular screening procedures and to propose strategies to improve Type 2 diabetes care. METHODS: A cross-sectional survey in Norway (281 GPs from 77 practices) identified 8246 people with a Type 2 diabetes duration of 1 year or more. We used multilevel regression models with either the recording of at least two of three recommended screening procedures (albuminuria, monofilament, eye examination) or each procedure separately as dependent variable (yes/no), and characteristics related to the person with diabetes, GP or practice as independent variables. RESULTS: The performance of recommended screening procedures was recorded in the following percentages: albuminuria 31.5%, monofilament 27.5% and eye examination 60.0%. There was substantial heterogeneity between practices, and between GPs within practices for all procedures. Compared with people aged 60-69 years, those aged < 50 years were less likely to have an albuminuria test performed [odds ratio (OR) 0.75, 95% CI 0.61 to 0.93] and eye examination (OR 0.79, 95% CI 0.66 to 0.95). People with macrovascular disease had fewer screening procedures recorded (OR 0.68, 95% CI 0.59 to 0.78). Use of an electronic diabetes form was associated with improved screening  (OR 2.65, 95% CI 1.86 to 3.78). GPs with high workload recorded fewer procedures (OR 0.59, 95% CI 0.39 to 0.90). CONCLUSIONS: Performance of screening procedures was suboptimal overall, and in people who should be prioritized. Performance varied substantially between GPs and practices. The use of a structured diabetes form should be mandatory.

The prevalence of radiological glenohumeral osteoarthritis in long-term type 1 diabetes: the Dialong shoulder study.

OBJECTIVES: This study compares the prevalence of radiological osteoarthritis (OA) in patients with type 1 diabetes mellitus (DM1) for > 45 years and controls, and explores the association with shoulder pain and glycaemic burden in patients with DM1. METHOD: The Dialong study is a cross-sectional, observational study with 30 years of historical data on long-term glycaemic control. We included 102 patients with DM1 and 73 diabetes-free controls. Demographic data, worst shoulder pain last week [numeric rating scale (NRS) 0-10], pain on abduction at examination (NRS 0-10), and current and historical glycosylated haemoglobin (HbA1c) levels were collected. Standardized shoulder X-rays were taken and interpreted for OA applying the Kellgren-Lawrence classification. RESULTS: In the diabetes group (49% women), the mean ± sd duration of DM1 was 50.6 ± 4.8 years, mean 30 year HbA1c 7.4%, and age 61.9 ± 7.1 years. The mean age of controls (57% women) was 62.6 ± 7.0 years. Radiological glenohumeral OA was found in 36 diabetes patients (35%) and 10 controls (14%) [odds ratio (OR) 3.4, 95% confidence interval (CI) 1.6 to 7.5; p = 0.002]. Few persons had moderate and severe OA [6.9% vs 1.3%, OR 5.3 (95% Cl 0.6 to 44.1); p = 0.1]. Fifteen diabetes patients had painful OA versus two controls (adjusted OR 5.4, 95% CI 0.6 to 47.9; p = 0.13). There was no association between OA and long-term glycaemic burden (mean 30 year HbA1c) in the diabetes group (p > 0.2). CONCLUSIONS: Radiological glenohumeral OA was more common in patients with DM1 than in controls for mild, but not moderate and severe OA. The radiological findings were not associated with shoulder pain or long-term glycaemic burden.

Visual information processing in high-functioning individuals with autism spectrum disorders and their parents.

The authors assessed visual information processing in high-functioning individuals with pervasive developmental disorders (PDD) and their parents. The authors used tasks for contrast sensitivity, motion, and form perception to test visual processing occurring relatively early and late in the magnocellular-dorsal and parvocellular-ventral pathways. No deficits were found in contrast sensitivity for low or high spatial frequencies or for motion or form perception between individuals with PDD in comparison with a matched control group. Individuals with PDD performed equally with or better than controls on motion detection tasks. In addition, the authors did not find differences on any of the tasks between parents of the PDD group and matched control parents. These results indicate that high-functioning individuals with PDD and their parents are able to process visual stimuli that rely on early or late processing in the magnocellular-dorsal and parvocellular-ventral pathways as well as controls.

Cost of diabetes in Norway 2011.

AIMS: To quantify the excess cost of diabetes in Norway in 2011. METHODS: A national cross-sectional cost-of-illness analysis of direct and indirect diabetes-related healthcare costs, based on pseudonymised data from six public national registers, international studies, and clinical expertise. Direct medical costs are estimated from primary and secondary health care registers and the national prescription database. Indirect costs include social and productivity costs. RESULTS: The total excess cost of diabetes in Norway in 2011 was €516 million. Direct costs amounted to €408 million and indirect costs amounted to €108 million. Scenario analysis proposes an upper boundary of total cost at €575 million, direct costs at €428 million and indirect costs at €161 million. Expenditure on blood glucose lowering agents was €71 million and expenditure on blood glucose monitoring strips was €55 million. Blood glucose lowering agents-, lipid lowering agents, and antihypertensives represented 28% of the direct costs. Loss of productivity (€0.9 million) scored highest among the indirect costs. CONCLUSIONS: The cost implications of diabetes in Norway in 2011 were high and comparable to previous studies in Scandinavia. Prevention of complications contributed to a higher cost than treating diabetes-related complications. The more than five-fold higher expenditure in other countries might be due to differences in budget priorities, efficacy of healthcare, indirect healthcare cost applications, or research methodology.

A novel technique of Roux-en-Y gastric bypass reversal for postprandial hyperinsulinemic hypoglycaemia: A case report.

BACKGROUND: We describe an evaluation of the effects of partial Roux-en-Y gastric bypass (RYGB) reversal on postprandial hyperinsulinaemic hypoglycaemia, insulin and GLP-1 levels. CASE SUMMARY: A 37 year old man was admitted with neuroglycopenia (plasma-glucose 1.6mmol/l) 18 months after RYGB, with normal 72h fasting test and abdominal CT. Despite dietary modifications and medical treatment, the hypoglycaemic episodes escalated in frequency. Feeding by a gastrostomy tube positioned in the gastric remnant did not prevent severe episodes of hypoglycaemia. A modified reversal of the RYGB was performed. Mixed meal tests were done perorally (PO), through the gastrostomy tube 1 (GT1), 4 weeks (GT2) after placement and 4 weeks after reversal (POr), with assessment of glucose, insulin and GLP-1 levels. RESULTS: Plasma-glucose increased to a maximum of 9.6, 5.4, 6.5 and 5.8mmol/l at the PO, GT1, GT2 and POr tests respectively. The corresponding insulin levels were 2939, 731, 725 and 463pmol/l. A decrease of plasma-glucose followed: 2.2, 3.0, 3.9 and 2.9mmol/l respectively and insulin levels were suppressed at 150min: 45, 22, 21 and 14pmol/l, respectively. GLP-1 levels increased in the PO test (60min: 122pmol/l, 21 fold of basal), but was attenuated in the two latter tests (12-23pmol/l at 60min). CONCLUSIONS: Reduction of plasma-glucose, insulin and GLP-1 excursions and symptoms were seen after gastric tube placement and partial RYGB reversal. This attenuation of GLP-1 response to feeding could reflect an adaptation to nutrients.

Measurement of stray light and glare: comparison of Nyktotest, Mesotest, stray light meter, and computer implemented stray light meter.

AIM: To evaluate the properties of devices for measuring stray light and glare: the Nyktotest, Mesotest, "conventional" stray light meter and a new, computer implemented version of the stray light meter. METHODS: 112 subjects, divided in three groups: (1) young subjects without any eye disease; (2) elderly subjects without any eye disease, and (3) subjects with (early) cataract in at least one eye. All subjects underwent a battery of glare and stray light tests, measurement of visual acuity, contrast sensitivity, refraction, and LOCS III cataract classification. Subjects answered a questionnaire on perceived disability during driving. RESULTS: Repeatability values were similar for all glare/stray light tests. Validity (correlation with LOCS III and questionnaire scores), discriminative ability (ability to discriminate between the three groups), and added value (to measurement of visual acuity and contrast sensitivity) were all superior for both stray light meters. Results of successive measurements are interrelated for the conventional but not the new stray light meter. This indicates a better resistance to fraud for the latter device. CONCLUSIONS: The new computer implemented stray light meter is the most promising device for future stray light measurements.

Increased serum levels of advanced glycation end products (AGEs) in children and adolescents with IDDM.

OBJECTIVE: To investigate whether the serum levels of advanced glycation end products (AGEs) are increased in IDDM children and adolescents and to study the effect of puberty on serum levels of AGEs (S-AGEs). RESEARCH DESIGN AND METHODS: A total of 68 children and adolescent IDDM patients (age, 13.3 +/- 4.0 years; duration of diabetes, 5.0 +/- 3.6 years; HbA1c, 8.2 +/- 2.0%; Tanner stage [public hair], 1 vs. 2-5, 24/42) recruited from the pediatric outpatient clinic at Aker University Hospital were compared with 25 healthy nondiabetic control subjects. S-AGEs were measured by a fluoremetric immunoassay. RESULTS: S-AGEs were significantly elevated in the diabetic group when compared with the control group (14.4 +/- 3.5 vs. 11.7 +/- 3.0 U/ml, P < 0.002). A significant correlation (r = 0.26, P < 0.04) was found between S-AGEs and HbA1c in the diabetic group but not in the control group. No significant correlation was found between S-AGEs and the duration of diabetes in the diabetic group or S-AGEs and blood glucose concentration or age in either group. We found no difference between S-AGEs in boys and girls and in prepubertal and pubertal diabetic or control subjects. CONCLUSIONS: S-AGEs are increased in young patients with diabetes before puberty. Since AGEs are linked to the pathogenesis of vascular complications, this observation suggests that the pathological processes leading to diabetic late complications start even before puberty.

Serum levels of advanced glycation end products are increased in patients with type 2 diabetes and coronary heart disease.

OBJECTIVE: To investigate whether serum levels of advanced glycation end products (AGEs) and the glycoxidation product Nepsilon-(carboxymethyl)lysine (CML) are increased in patients with type 2 diabetes compared with nondiabetic control subjects and whether levels of AGEs and/or CML differ in patients with type 2 diabetes with or without coronary heart disease (CHD). RESEARCH DESIGN AND METHODS: Serum levels of AGEs and CML were measured with an immunoassay in 32 men and 21 women aged 59.3+/-6.2 years (means +/- SD) with type 2 diabetes for 7.3 + 3.1 years and in 17 men and 17 women aged 56.2+/-4.2 years without diabetes. Of the patients with diabetes, 18 had CHD. RESULTS: The serum levels of AGEs and CML were significantly increased in patients with type 2 diabetes compared with nondiabetic control subjects (median [5th-95th percentile]: AGEs 7.4 [4.4-10.9] vs. 4.2 [1.6-6.4] U/ml, P < 0.0001; CML 15.6 [5.6-29.9] vs. 8.6 [4.4-25.9] U/ml, P < 0.0001). The median level of AGEs but not CML was significantly increased in patients with type 2 diabetes and CHD compared with patients without CHD (8.1 [6.4-10.9] vs. 7.1 [3.5-9.8] U/ml, P = 0.03). There were significant positive correlations between serum levels of AGEs and CML in both patients and control subjects. CONCLUSIONS: Levels of AGEs and CML were significantly increased in patients with type 2 diabetes compared with nondiabetic control subjects, and levels of AGEs but not CML were significantly higher in patients with type 2 diabetes and CHD than in patients without diabetes. These results may indicate a role for non-CML AGEs in the development of macrovascular disease in patients with type 2 diabetes.

Severity of glomerulopathy predicts long-term urinary albumin excretion rate in patients with type 1 diabetes and microalbuminuria.

OBJECTIVE: To investigate whether the degree of glomerular structural lesions in young patients with type 1 diabetes and microalbuminuria was associated with urinary albumin excretion rate (AER) 6 years later and whether the AER level was influenced by blood glucose control, blood pressure, or glomerular filtration rate (GFR). RESEARCH DESIGN AND METHODS: There were 17 young adults with type 1 diabetes and microalbuminuria, 8 men and 9 women with mean age 20 years (95% CI: 18-22) and duration of diabetes of 11 years (10-13), who participated in a 6-year prospective study. Kidney biopsies (measurements of basement membrane thickness [BMT] and mesangial and matrix volume fractions) and GFR were performed at baseline. AER and HbA1c were measured at least three times a year and blood pressure once a year. RESULTS: In a multivariate analysis, baseline BMT and mean 6-year HbA1c contributed significantly to AER at the end of the study (R2 = 0.69, P < 0.01). When mesangial volume fraction replaced BMT as the independent variable, this parameter and AER at baseline predicted the AER at 6 years (R2 = 0.55, P < 0.55). Mesangial volume fraction and BMT (in separate analysis) contributed significantly to change in AER during the study. During the study, neither AER (30 micrograms/min [19-40] to 16 micrograms/min [7-90]) nor blood pressure (96 mmHg [92-102] to 95 mmHg [91-98]) changed significantly in the group. However, HbA1c was reduced from 10.3 (9.6-11.0) to 8.4% (7.8-9.1) (P < 0.01). CONCLUSIONS: In young patients with microalbuminuria, the long-term urinary AER was predicted by the degree of glomerular structural changes and associated with blood glucose control, but not with blood pressure or GFR.

Serum levels of advanced glycation end products are associated with left ventricular diastolic function in patients with type 1 diabetes.

OBJECTIVE: Impairment of left ventricular diastolic function, possibly caused by increased collagen cross-linking of the cardiac muscle, is common in patients with type 1 diabetes even without coronary artery disease. Advanced glycation end products (AGEs) cross-link tissue collagen and are found within myocardial fibers. The aim of this study was to examine for a possible association between circulating AGEs and left ventricular cardiac function. RESEARCH DESIGN AND METHODS: Left ventricular diastolic and systolic function were assessed by M-mode and Doppler echocardiography in 52 patients with type 1 diabetes, age 40 +/- 13 (mean +/- SD) years, diabetes duration 17 +/- 13 years, and HbA1c 8.3 +/- 1.1%. Serum levels of AGEs and N epsilon-(carboxymethyl)lysine (CML) were measured by newly developed competitive immunoassays. RESULTS: A positive correlation was found between serum levels of AGEs and isovolumetric relaxation time (IVRT), r = 0.46 (P < 0.0008), and left ventricular diameter during diastole, r = 0.37 (P < 0.008). The systolic parameters did not correlate with serum levels of AGEs. Stepwise regression analysis showed that 21% of the IVRT variation could be explained by serum levels of AGEs (F = 11.4, P < 0.002), whereas serum levels of CML, HbA1c, albumin excretion rate, diabetes duration, and mean arterial blood pressure were of no importance. AGE levels were significantly increased in men compared with women (P < 0.03) and present or former smokers (P < 0.04). CONCLUSIONS: Increased serum levels of AGEs, unlike serum levels of CML, are associated with heart stiffness in patients with type 1 diabetes, possibly mediated by the cross-linking properties of AGEs.

The advanced glycation end product Nepsilon-(carboxymethyl)lysine is increased in serum from children and adolescents with type 1 diabetes.

OBJECTIVE: To investigate whether children and adolescents with type 1 diabetes have increased serum levels of the glycoxidation product Nepsilon-(carboxymethyl)lysine (CML) at an early stage of the disease. RESEARCH DESIGN AND METHODS: The serum levels of CML in 38 patients with type 1 diabetes aged 14+/-3.2 (mean+/-SD) years were compared with those in 26 control subjects aged 16+/-1.7 years. The mean duration of diabetes was 5+/-4.7 years, ranging from 0.5 to 15 years. The mean levels of HbA1c were 10.3+/-2.5% in the patient group. The serum levels of CML were measured using a monoclonal anti-CML antibody in a fluoremetric immunoassay. Serum protein levels of advanced glycation end products (AGEs) were assayed using a polyclonal antibody from rabbit immunized with AGE-RNase (pAGE). RESULTS: The serum levels of CML and pAGE were significantly increased in the patient group versus the control group: 1.08 (0.45-2.97) U/ml CML (median 10-90 percentiles) vs. 0.70 (0.36-1.79) U/ml CML, P < 0.03, and 6.6 (5.1-9.9) U/ml pAGE vs. 5.5 (3.7-8.2) U/ml AGEs, P < 0.01. A significant relationship between CML and pAGE was found in the IDDM group, r = 0.76, P < 0.001. The CML levels were not associated with the HbAlc levels (n = 23, r = -0.02, NS), cholesterol levels (n = 21, r = 0.07, NS), age, sex, or diabetes duration. CONCLUSIONS: Serum levels of CML are increased in patients with type 1 diabetes. This increase precedes the development of micro- and macrovascular complications.

Hydroperoxides in plasma are reduced by intensified insulin treatment. A randomized controlled study of IDDM patients with microalbuminuria.

OBJECTIVE: An association between reactive oxygen species and diabetic micro- and macrovascular complications has been proposed. In the present study, we have examined the effect of an improved blood glucose control on plasma levels of hydroperoxides in patients with IDDM. RESEARCH DESIGN AND METHODS: Subjects included 30 young IDDM patients with microalbuminuria who were randomized to receive either continuous subcutaneous insulin infusion (CSII) by a portable insulin pump (n = 15) or conventional insulin treatment (CIT) (n = 15) for 24 months. Plasma levels of hydroperoxides were measured by the ferrous oxidation with Xylenol Orange, version 2 (FOX2) assay. This method measures total lipid hydroperoxides and, unlike other methods, does not suffer from extraction losses. RESULTS: The mean HbA1c level was lower in the CSII group at the end of the study than in the CIT group: (mean [95% CI]) 8.6 (8.1-9.1) vs. 9.6 (9.0-10.3)%, respectively (P < 0.002). The level of plasma hydroperoxides was very similar at the start of the study but was significantly lower in the CSII group compared with the CIT group at the end of the study: 2.9 (2.1-3.7) vs. 4.3 (3.2-5.4) mumol/l, respectively (P < 0.02). In the CSII group, hydroperoxides were reduced by 31% from baseline (P < 0.001), whereas there was no change in levels of hydroperoxides in the CIT group. Mean hydroperoxide levels correlated with mean HbA1c during the study (r = 0.39, P < 0.04). Hydroperoxide levels were associated with the levels of microalbuminuria (r = 0.45, P < 0.02). CONCLUSIONS: This study provides support for the hypothesis that hyperglycemia is an important factor in the generation of hydroperoxides, and, thus, reactive oxygen species, in the circulation of IDDM patients.

Bronchopulmonary dysplasia and lung rupture in hyaline membrane disease: influence of continuous distending pressure.

Review of 158 patients with hyaline membrane disease was undertaken. The introduction of artificial ventilation with a positive end-expiratory pressure (IPPB and PEEP) has doubled the prevalence of pneumothorax, pneumomediastinum and interstitial emphysema from 20.7% to 39.7%). Continuous negative distending pressure during spontaneous ventilation (CNP) was associated with a prevalence of lung rupture similar to that occurring spontaneously (4.8%). No patient treated with CNP alone developed bronchopulmonary dysplasia. Patients treated with IPPB with PEEP had a marked decreased prevalence of bronchopulmonary dysplasia (17.2%) when compared to patients treated with IPPB alone (36.2%), probably related to the enhanced overdistension of relatively normal areas of the lung may be related to the increased prevalence of lung rupture seen during IPPB with PEEP.

Quantal and visual efficiency of fluorescence in the lens of the human eye.

PURPOSE: To document quantitatively the fluorescence in the human lens relevant to its interference with visual function. To explain quantitatively the experimental findings relative to loss of visual function. To study the relation between the fluorescence and the light transmission of the lens. METHODS: Three normal lenses, from 22-, 28-, and 69-year-old donors, were used. Fluorescent light was induced by a 4-mm diameter pencil beam of 380, 400, or 420 nm. It was measured as a function of the deflection angle from -10 to 150 degrees for different wavelengths. RESULTS: The shapes of the emission spectra were comparable to those reported in the literature. Total quantal efficiency of fluorescence was between 5% for 69 years and 380 nm excitation and 0.4% for 22 years and 420 nm excitation. The forward intensity was less than the backward intensity because of secondary absorption. CONCLUSIONS: Fluorescence of the lens causes light with wavelengths of 420 nm and lower to be much more visually effective. A marked homogeneous veil is added to the point spread function. The total increase in luminous efficiency was a factor 3 to 6 at 400 nm, and a factor 70 to 150 at 380 nm. For other visual effects (glare) the increase can be larger.

Light scattering by donor lenses as a function of depth and wavelength.

PURPOSE: To determine quantitatively dependence on the wavelength and angle, as a function of depth, of light scattering in the human lens. To compare the result for forward directions with psychophysical data. To derive candidate particle distributions that might be responsible for nuclear light scattering as significant in the psychophysical situation. METHODS: The amount of light scattered by donor lenses (n = 15, ages 48 to 82 years) from a 1-mm x 0.1-mm white slit beam was measured as a function of depth in the lens for seven angles from 10 degrees to 165 degrees, and for four wavelengths from 400 to 700 nm. Absolute values for light scattering (Rayleigh ratios) were derived. RESULTS: The light-scattering data are confounded by the short wavelength-absorbing pigments in the lens. After correction, backward light scattering in the nucleus followed wavelength to a power of -4. In the superior layers and for forward directions in the nucleus, light scattering was less dependent on wavelength. The nuclear data could be explained on the basis of a bimodal protein particle distribution: particles much smaller than wavelength, in quantitative accordance with the literature, and particles larger than wavelength, which control forward light scattering. CONCLUSIONS: The particles of significance for forward light scattering have, on average, a mean radius of 692 nm and constitute only 0.000003 of the volume. The wavelength dependence of retinal stray light is lessened by: the large sizes, the contribution of superficial lenticular layers, the lenticular pigments, and the contribution of other components of the eye.

Depth-dependent forward light scattering by donor lenses.

PURPOSE: To determine quantitatively forward light scattering in the human lens as a function of depth. To use this to explain the psychophysical result, verified earlier in vitro, showing total light scattering in the human lens to decrease with scattering angle according to an approximate power law (power -2). METHODS: The amount of light scattered by donor lenses (n = 15; age range, 43 to 82 years) from a 1 mm x 0.1 mm white slit beam was measured as a function of depth in the lens for seven angles from 10 degrees to 165 degrees and for four wavelengths from 400 to 700 nm. Absolute values for light scattering (Rayleigh ratios) were derived. RESULTS: Light scattering of the total lens corresponded quantitatively to psychophysically determined in vivo stray light data. Powers were approximately -2.2. An important source of forward scattered light is located superficially at the anterior and the posterior poles. Nuclear forward light scattering varied over 2 log units, more or less in line with clinical assessment of nuclear opacity (LOCS III NO score). Nuclear powers were approximately -1.4. CONCLUSIONS: In vitro forward light scattering of donor lenses as a whole corresponded with in vivo data, but different depths in the lens contributed differently. Studies on functionally relevant light scattering by the human lens proteins should be conducted to explain true (in vivo) lenticular light scattering.

Relationship between spectral transmittance and slit lamp color of human lenses.

PURPOSE: To study the relationship between subjective lens color as observed with slit lamp biomicroscopy and spectral transmittance of the lens. To propose a model for this relationship to derive quantitative information on lens pigmentation from slit lamp observation. METHODS: Twenty-nine normal lenses, from donors aged 14 to 86 years, were used. The fraction of light transmitted from a narrow beam was measured as function of wavelength. The spectra were fitted with the one-parameter TL model of Pokorny et al. The relationship between this parameter and the color grading from Chylack et al. (lens opacity classification system III nuclear color score) was established. RESULTS: After slight adaptation of the TL model, the shapes of the transmittance spectra corresponded closely to the TL model (average residual error 0.05 log units). Log transmittance and lens opacity classification system nuclear color score were closely related (r = 0.90, 0.77, and 0.55 for 400, 500, and 602 nm, respectively). CONCLUSIONS: A mathematical relationship between TL parameter and lens opacity classification system nuclear color score could be established to predict lens transmittance from lens opacity classification system nuclear color score. This relationship was successful in predicting the correction for lens absorption needed in blue-on-yellow perimetry.

Conversion of lens slit lamp photographs into physical light-scattering units.

PURPOSE: To derive from lens slit lamp photographs by means of densitometry the physically defined quantity for light scattering (the Rayleigh ratio) and to expand the use of the Lens Opacity Classification System (LOCS III) to include clear lenses and also to calibrate the LOCS III Nuclear Opacity (NO) score in physical terms. METHODS: Series of slit lamp photographs were taken from 38 eyes from 29 subjects (age range 18 to 84 years old) including cataracts, for 0.1- and 0.2-mm slit width, using 200 ASA and 1600 ASA film speed (Kodak professional; Eastman Kodak, Rochester, NY) and different flash settings with a Topcon SL-6E (12 slit/speed/flash combinations; Paramus, NJ). Additionally 19 eyes were photographed with a Zeiss 40 SL/P (8 slit/speed/flash combinations; Carl Zeiss, Thornwood, NY). A calibrated suspension of latex spheres also was photographed at the same 20 conditions. Densitometry was performed on the nuclear area of all photographs including the LOCS III standards, using a photometrically corrected photocell. Slit width and flash intensity settings were photometrically calibrated. All eyes and the suspension were digitally "photographed" with the EAS-1000 (Nidek, Gamagori, Japan) Scheimpflug system. RESULTS: For each eye and the suspension, the series of 20 or 12 densities, corresponding to a range of about 1 log unit in the amount of light used, proved to follow closely a course common to all eyes (the two film characteristics), apart from a shift in the amount of light (because of the differences in light back scattering). CONCLUSIONS: From normal slit lamp photographs, the physical quantity for light (back) scattering can be derived using transformation graphs derived in this study. The LOCS III NO score also can be used for clear lenses and translated into physical units. In this way, slit lamp photography can be used better for more precise studies, provided some minimal calibration of the photograph slit lamp.