Abstract
Purpose: :
To determine if alteration of retinal blood flow (RBF) in diabetic patients with no to mild diabetic retinopathy (DR) is correlated with long term retinopathy progression.
Methods: :
RBF was determined from 60 eyes of 32 diabetic patients with no to mild DR using scanning laser ophthalmoscopy fluorescein angiography and dye dilution methodolgy. Patients with diabetes mellitus (DM) were subsequently followed at the Beetham Eye Institute/Joslin Diabetes Center for an average of 11.2+1.5 years (range 8.4-14.3) with an average of 17 subsequent visits (3-50). Outcomes including best corrected visual acuity, dates of DR progression, time of therapeutic interventions, and onset of systemic co-morbidities were collected by retrospective chart review using standardized forms.
Results: :
32 patients (60 eyes) were evaluated with a mean DM duration of 21.1+ 9.9 years (median 18.7, range 8-55). Mean age was 47+11 years (range 27-75), with 52% female, 18% Type 2 DM, and HbA1c of 7.2+1.9% (6-10%). Initial mean RBF was 49.4 arbitrary units (AU) (median 33.8 AU, range 13-166). Within individual patients, the eye with slower RBF was the eye with faster DR progression in 67.9% of cases (N=19). In contrast, it was the slower progressing DR eye only 32.1% of the time (N=9, chi-squared, p=0.035). Development of proliferative DR occurred in 18.3% of eyes (N=11) and was associated with a significantly higher baseline RBF (61.6+26.7 AU) as compared with patients who did not progress or developed only non-proliferative DR (40.4 AU+28.6, N=49) during follow-up (p=0.032). Patients who eventually developed microvascular complications of either nephropathy or neuropathy tended to have faster RBF (66.5 AU+46.2) than patients who did not (39.2 AU+20.8), but this only approached statistical significance (p=0.09).
Conclusions: :
Baseline RBF measurements in patients with DM and no to mild DR may be correlated with progression of DR over the following decade. Diabetic patients without DR have known decreased RBF compared to age-matched non-diabetic subjects, but this data now provides evidence that a greater decrease in RBF during early DM may be a predictor of faster non-proliferative DR progression among fellow eyes of a given individual. In addition, a faster baseline RBF may predict the eventual onset of proliferative DR and other microvascular complications. If these associations are confirmed by larger studies, they could have significant impact on our evaluation and counseling of patients with early diabetes in relation to risks of long-term complications.
Keywords: diabetic retinopathy • clinical (human) or epidemiologic studies: outcomes/complications • clinical (human) or epidemiologic studies: risk factor assessment