|Year : 1983 | Volume
| Issue : 5 | Page : 543-544
Plasma viscosity in diabetic retinopathy
OP Kulshrestha, Madhu Mathur
Department of Ophthalmology, S.M.S. Medical College, Jaipur, India
O P Kulshrestha
Department of Ophthalmology, S.M.S. Medical College, Jaipur
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Kulshrestha O P, Mathur M. Plasma viscosity in diabetic retinopathy. Indian J Ophthalmol 1983;31:543-4
The viscosity of blood is considered an important factor in genesis of diabetic retinopathy since it determines the peripheral resistance to blood flow through the micro circulation. A rise of plasma viscosity is considered to increase the resistance to blood flow in the capillaries contributing to fluid transfer and could explain onset of exudates and haemorrhages in the retina in diabetics.
| Material and Methods|| |
In this study, estimation of plasma viscosity was done in patients of diabetic retinopathy and compared with normal individuals. Selected group was 45 patients with diabetes, 10 of which were diabetic without retinopathy while 35 with retinopathy. In addition estimation in 30 healthy non-diabetic individuals was done for comparison. The diagnosis of such retinopathy was by history, increased level of blood sugar (fasting and postprandial), urine sugar examination and funduscopy.
Plasma viscosity was estimated by Ostwald's capillary Viscometer and employing his technique. This instrument requires only 2.5 ml. of plasma and is relatively easy to work.
Using minimal stasis about 7 ml. of blood was collected in a glass vial containing EDTA (1 mg/ml) and mixed well and then centrifuged at 5000 rpm for 10 minutes. Plasma was separated by pipette and put at 37'C. in a clean glass vial. The calculations were done according to Oswald method.
| Observations|| |
The plasma viscosity in normal healthy individuals varied from a minimum of 1.42 cpo to 1.76 cpo with an average for the group 1.58 cpo. In diabetics without retinopathy it varied from a minimum of 1.64 cpo to a maximum of 2.20 cpo. In diabetics with retinopathy the readings varied from a minimum of 1.80 cpo to a maximum of 3.10 cpo with an average for the group 2.175 cpo.
| Discussion|| |
Different mechanisms may explain the ability of baemorrhagic changes in diabetics to initiate the vascular changes. A rise in plasma viscosity is expected to increase the resistance to blood flow particularly on capillary micro circulation and if blood flow remains constant a 160% increase in plasma viscosity would generate nearly a 10% increase in pressure gradiet required for usual flow. This would in turn increase fluid transfer out of the microcirculation unless vessels wall dilatation occurs.
In our study in the 30 normal cases, plasma viscosity ranged from 1.42 to 1.76 cpo, the mean being 1.58 cpo. This gradually increased in patients with diabetes without and with retinopathy. The mean plasma viscosity in patients without retinopathy was 1.86 cpo while it was 2.175 cpo in patients with retinopathy.[Table - 1]
Mc Millan  studied serum viscosity in 30 healthy individuals, 45 non diabetic hospital patients and 45 diabetic patients with and without retinopathy. He found a significant elevation in plasma viscosity in diabetic patients as compared to both healthy and non diabetic hospital patients. The plasma viscosity in healthy persons was found to be 1.250 ± 0.066 cpo, while it was 1.251 ± 0.07 cpo in diabetic without retinopathy and 1.258 -T 0.057 cpo in diabetic patients with retinopathy. The mean plasma viscosity in non diabetic hospital patients was 1.175 ± 0.047 cpo.
Skovoborg et al  studied plasma viscosity in 16 diabetic and 16 healthy controls. Their results showed that plasma viscosity was at an average 20% higher in diabetic group.
Cogan et al  determined blood viscosity and found that average blood viscosity was elevated in all diabetic patients. Blood viscosity in normal was 1.62 cpo and in diabetics without retinopathy 1.73 cpo and in diabetics with retinopathy 1.75 cpo.
Mc Millan and Barbara  found a striking increase in plasma viscosity in diabetics markedly so in diabetics with micro angiopathy. The increase was as pronounced in diabetics in its first five years as in the more long standing disorder. They postulated that the increase in plasma viscosity could be just an effect of disturbed cellular activities which themselves cause the microcirculatory damage rather than a factor directly operative in its production.
In the present study the mean plasma viscosity increased by 17.7% when normal individuals were compared with the diabetic patients without retinopathy. In diabetics with retinopathy it had increased on an average by 37.6% as compared to normal individuals. The maximum plasma viscosity in normal individuals was 1.76 cpo while it was 3.10 cpo and diabetics with retinopathy. This is a very significant finding. Further plasma viscosity is much higher in our patients with retinopathy as compared to reports from the western countries.
| Summary|| |
Estimation of plasma viscosity was done by Ostwald's method in normal healthy individuals and diabetics without retinopathy and with retinopathy. A definite increase of viscosity values were observed in diabetics and in diabetics with retinopathy.
| References|| |
McMillan D.E., J. Clin. Invest., 53, 1071-79, 1974.
Skovoborg, F. Nielson, A.V. Schlient krull, J., Ditzel, J., Lancet, 129, 1966.
Cogan, D.G., Merola, L. Laibson, P.R., Diabetes,
10, 393, 1961.
McMillan, D.E. and Barbara, S., Proc. of conference on Diabetic micro angiography,
25, Suppl. 2, p. 858, 1976.
[Table - 1]