Retinal haemodynamics inpatients withearly diabetes mellitus

AimsIBackground-The circulationwasinvestigated ina groupof19 patients withinsulin dependent diabetes mellitus withlessthan4yearsofdisease duration and no evidence ofdiabetic retinopathy. Results ofthese patients were comparedwiththoseof16age-matched normalcontrols. Methods-Venous diameter(D) was measuredfrommonochromatic fundus photographs. Maximum erythrocyte velocity (V.,) wasassessed bybidirectional laserDopplervelocimetry inthe majorretinal veinsofoneeyeofeach subject. Totalvolumetric bloodflowrate (QT) was calculated byadding theflow rates ofthemajorretinal veins. Results-Average QTwas12%larger than normalindiabetic patients (onetailed, non-paired Student's ttest, p<005).A statistically significant correlation was observed between QTanddisease duration (r=035,p<004).Patients withlonger disease duration tended tohavesomewhat larger QT.Theaverage retinal vascular regulatory responses tohyperoxia were notsignificantly different fromnormalin diabetic patients. Inthesepatients, however,higherbloodglucose levels were associated withdecreased regulatory responses tohyperoxia. Conclusions-Patients withdiabetes mellitusofrelatively shortduration have Deparent of mildly increasedQT,suggesting that Ophthamnology, increased bloodflowmay playan early Scheie EyeInstituteroleinthedevelopment ofdiabetic retinal School ofMedicine,microangiopathy.