Association among low whole blood viscosity, haematocrit, haemoglobin and diabetic retinopathy in subjects with type 2 diabetes.

OBJECTIVES: Haemorheological variables influence endothelial function through the release of several factors. Clinical studies have described an association among blood viscosity, haematocrit, haemoglobin and macro-angiopathy. Few data are reported about the association between haemorheological variables and micro-angiopathy. The aim of the present study was to evaluate the association between these variables and retinopathy in subjects with type 2 diabetes. METHODS: 111 men, 79 postmenopausal women, and 95 healthy age- and sex-matched controls were recruited. Haematocrit and haemoglobin were measured by standard methods. Blood viscosity was calculated according to the formula (0.12× haematocrit)+(0.17× (plasma proteins-2.07)). Subjects were grouped according to the presence or absence of diabetic retinopathy, while the severity of retinopathy was classified according to the Early Treatment Diabetic Retinopathy Study scale. RESULTS: Haemoglobin, haematocrit and whole blood viscosity were significantly lower in subjects with retinopathy compared to subjects without retinopathy in both sexes. These variables significantly decreased with increasing severity of retinopathy. A multiple logistic regression analysis confirmed the independent inverse association among viscosity, haematocrit, haemoglobin and retinopathy (p<0.01). CONCLUSION: Results demonstrate the association among low viscosity, haemoglobin, haematocrit and diabetic retinopathy. The mechanisms responsible for this association can be hypothesised. Reduced haemoglobin might cause direct organ damage. Low blood viscosity, through the reduction of shear stress, might inhibit the anti-atherogenic functions of endothelial cells.

Subclinical visual field alterations are commonly present in patients with Graves' Orbitopathy and are mainly related to the clinical activity of the disease.

The present study was aimed to investigate optic nerve involvement by computerized perimetry in 40 (29 women, 11 men) consecutive GO patients not showing definite dysthyroid optic neuropathy (DON). All patients presenting visual acuity defects, pallor or swelling of the optic nerve, concomitant eye disease, evidence of apical crowding or optic nerve stretching at either MRI or CT imaging were excluded. Normal perimetry occurred in 7 patients (17.5%), 5 patients (12.5%) had "indeterminate" results and 28 patients (70%) presented abnormal perimetry. Particularly, 7 isolated paracentral, 5 pericentral and 16 combined peri and paracentral scotomas were found. On the contrary, 15/20 patients in the group without GO had normal perimetry, isolated scotomas were found in 5 cases (1 pericentral and 4 paracentral) and no case of combined scotoma occurred. The difference between the 2 groups was statistically significant (x2 = 9.17; p = 0.025). Overall, the sensitivity resulted 70%, the specificity 75% and the positive predictive value 84.8%. In patients with GO, the proportion of visual field alterations was significantly increased for Clinical Activity Score > or = 3 (p = 0.0005), while no relationship occurred with proptosis degree (p = 0.115). In conclusion, a great proportion of GO patients without clinically evident DON presents visual field defects, mainly related to GO activity.